CA2918904A1

CA2918904A1 - Switchable polysaccharides, methods and uses thereof

Info

Publication number: CA2918904A1
Application number: CA2918904A
Authority: CA
Inventors: Philip G. Jessop; Kyle J. BONIFACE; Pascale Champagne; Michael F. Cunningham; Haidong Wang; Omar Garcia Valdez; Alex Cormier; Shijian Ge; Joaquin Arredondo Luna
Original assignee: Queens University at Kingston
Current assignee: Queens University at Kingston
Priority date: 2015-03-20
Filing date: 2016-01-26
Publication date: 2016-09-20
Also published as: WO2016149815A1

Abstract

The present application provides a reversibly switchable composite material comprising a polysaccharide and a polysaccharide-supported switchable moiety that is switchable between a neutral, hydrophobic first form and an ionized, hydrophilic second form. The composite material converts to, or is maintained in, its second form when the switchable moiety is exposed to an ionizing trigger, such as CO2, at amounts sufficient to maintain the ionized form. The composite material converts to, or is maintained in, the first form when CO2 is removed or reduced to an amount insufficient to maintain the ionized form. Also provided are uses of these composite materials including, but is not limited to, manipulating and/or controlling dispersibility (e.g., CNC dispersibility); surface cleaning; separation applications (e.g., membranes); absorption/flocculation applications; and water treatment.

Description

SWITCHABLE POLYSACCHARIDES, METHODS AND USES THEREOF
FIELD OF THE INVENTION
[0001] The present application pertains to the field of materials. More particularly, the present application relates to polysaccharide-based materials that are switchable between two distinct forms, and their methods of manufacture and uses thereof.
INTRODUCTION

[0002] Certain types of polysaccharide-based materials have been investigated due to their physical and chemical properties and/or characteristics, which have made them desirable for particular applications. For example, cellulose nanocrystals (CNCs) have been investigated for their biodegradability, low density, high specific surface area, as well as interesting optical and mechanical properties [Habibi, Y.; etal., 0. J. Chem. Rev. 2010, 110, 3479-3500; Eichhorn, S. J. Soft Matter2011, 7,303-315; Habibi, Y. Chem. Soc. Rev.
2014, 43, 1519-1542; Klemm, D.; et al.. Angew. Chem., mt. Ed. 2011, 50, 5438-5466]. Due to their properties, CNCs have been considered for use as nanofillers, and absorbents/flocculants, etc. CNCs can be produced by acid hydrolysis (e.g., via use of concentrated sulfuric acid or hydrochloric acid) from a variety of cellulose sources; after which, amorphous cellulose is removed and cellulose nanocrystal (CNC) residue remains, generally as nanorod-shaped CNCs measuring 100 - 200 nm in length, and 10 nm in width [Habibi, Y.; etal.
Chem. Rev.
2010, 110, 3479-3500; Klemm, D etal. Angew. Chem., Int. Ed. 2011, 50,5438-5466]. CNCs prepared by sulfuric acid hydrolysis have negatively charged sulfate groups residing on the surface that provide electrostatic repulsion among CNC crystals, thereby yielding stable aqueous dispersions [Dong, X. M.; Revol, J. F.; Gray, D. G. Cellulose 1998, 5, 19-32]. In addition to the sulfate groups, the CNC surface may also possess a large concentration of hydroxyl groups, which can be chemically modified to manipulate CNC surface properties.
Various chemical approaches have been applied to CNC surface modification, such as sulfonation [Dong, X. M.; etal. Cellulose 1998, 5, 19-32], TEMPO-mediated oxidation [Way, A. E.; etal. J. ACS Macro Lett. 2012, 1, 1001-1006; Habibi, Y.; etal.
Cellulose 2006, 13, 679-687], amidation [Way, A. E.; etal. ACS Macro Lett. 2012, 1, 1001-1006;
Hemraz, U. D.;
etal. Can. J. Chem. 2013, 91, 974-981], etherification [Hasani, M.; etal. Soft Matter 2008, 4, 2238-2244; Zaman, M.; etal. Carbohydr. Polym. 2012, 89, 163-170], and polymer grafting [Morandi, G.; etal. Langmuir 2009, 25,8280-8286; Azzam, F.; etal.
Biomacromolecules 2010, 11, 3652-3659; Harrisson, S.; etal. Biomacromolecules 2011, 12, 1214-1223; Araki, J.; et al. Langmuir 2001, 17, 21-27; Majoinen, J.; et aL Biomacromolecules 2011, 12, 2997-3006; Kan, K. H. M.; etal. Biomacromolecules 2013, 14,3130-3139; Zoppe, J. O.;
etal.
Biomacromolecules 2010, 11,2683-2691; Kloser, E.; Gray, D. G. Langmuir 2010, 26, 13450-13456; Yi, J.; etal. Polymer 2008, 49, 4406-4412], to improve dispersibility of CNCs through electrostatic [Dong, X. M.; etal. Cellulose 1998, 5,19-32; Way, A. E.; et al.
ACS Macro Lett.
2012, 1, 1001-1006; Habibi, Y.; etal. Cellulose 2006, 13, 679-687; Hemraz, U.
D.; et aL
Can. J. Chem. 2013, 91,974-981; Hasani, M.; etal. Soft Matter 2008, 4,2238-2244; Kan, K.
H. M.; etal. Biomacromolecules 2013, 14, 3130-3139] or steric stabilization [Azzam, F.; et al. Biomacromolecules 2010, 11, 3652-3659; Harrisson, S.; etal.
Biomacromolecules 2011, 12, 1214-1223; Araki, J.; etal. Langmuir 2001, 17, 21-27; Majoinen, J.; etal.
Biomacromolecules 2011, 12, 2997-3006; Zoppe, J. 0.; et aL Biomacromolecules 2010, 11, 2683-2691; Kloser, E.; Gray, D. G. Langmuir 2010, 26, 13450-13456]. Some of these modified CNCs were based on either small molecule modification with carboxyl [Way, A. E.;
etal. ACS Macro Lett. 2012, 1, 1001-1006; Habibi, Y.; etal. Cellulose 2006, 13, 679-687], amine [Way, A. E.; etal. ACS Macro Lett. 2012, 1, 1001-1006; Hemraz, U. D.;
etal.. Can. J.
Chem. 2013, 91, 974-981], or quaternary ammonium cation [Hasani, M.; et aL
Soft Matter 2008, 4, 2238-2244] functionalities or polymer grafting with carboxyl [Majoinen, J.; etal.
Biomacromolecules 2011, 12, 2997-3006] pyridine [Kan, K. H. M.; etal.
Biomacromolecules 2013, 14, 3130-3139], or tertiary amine [Tang J.T. etal. (2014) Biomacromolecules 15(8):3052-3060] side groups. Carboxyl/amine-terminated [Way, A. E.; etal. ACS
Macro Lett. 2012, 1, 1001-1006], poly(4-vinylpyridine)-grafted [Kan, K. H. M.; et aL

Biomacromolecules 2013, 14, 3130-3139], and poly[2-(dimethylamino)ethyl methacrylate]
(PDMAEMA)-grafted [Tang J.T. et al. (2014) Biomacromolecules 15(8):3052-3060]
CNCs have exhibited pH-responsiveness [Way, A. E.; etal. ACS Macro Lett. 2012, 1, 1001-1006]
and [Kan, K. H. M.; etal. Biomacromolecules 2013, 14, 3130-3139] reported pH-responsive gels/nanocomposites and flocculants, respectively [Tang J.T.; etal. (2014) Biomacromolecules 15(8):3052-3060] reported pH/thermal dual responsive heptane-in-water and toluene-in-water emulsions stabilized by PDMAEMA-grafted CNC. However, adjusting pH by liquid acid/base addition for controlling dispersibility might not be an ideal approach:
removal of acid, base or salt (added for pH adjustment) from final colloidal particles can be time-consuming and incomplete; and, repeated pH adjustments can result in salt accumulation and a commensurate increase in ionic strength, which negatively affects colloidal stability.

[0003] Other examples of polysaccharide materials that have been investigated due to their physical and chemical properties and/or characteristics include: cellulose, which has been sought after as a material for fabric for clothes, membranes (e.g., osmosis, dialysis, filtration, ultrafiltration, etc.), paper, chromatography, insulation, and for conversion to cellulose derivatives such as viscose, celluloid, cellophane, cellulose acetate (e.g., polymer films, cigarette filters, etc.), and nitrocellulose (e.g., gun cotton, gunpowder, films, etc);
chitin/chitosan, which has been used in edible films, food additives, binders (e.g., in dyes, fabrics, adhesives, etc.), threads, membranes, chromatography (e.g., ion exchange chromatography, etc.), filtration, wine making, and seed treatment in agriculture; starch, which has been used in food, pharmaceutical tablets, paper, corrugated cardboard, clothing, laundry, wallboards, glues, textiles, drilling fluids, ceiling tiles, and for chemical modification to make other chemicals such as cationic starches (e.g., flocculants), maltose (malt sugar for food), glutamic acid (food additive known as MSG), cyclodextrins (e.g., Febreze, etc.), dextrins (e.g., adhesives, binders, froth flotation, etc.), and starch acetate (e.g., clear films for packaging, etc.); dextran, which has been used for medical, biological, and chromatographic applications; and, hemicellulose, which has been used in animal feed, and has been industrially converted to xylose (chemical precursor to xylitol and furfural) and then to xylitol (sweetener in chewing gum).

[0004] Carbon dioxide (CO2) is a relatively benign, inexpensive, and abundant reagent that has found use in various industrial processes. In view of that, Jessop et al.
have developed switchable technologies that can be switched "on" and "off" in the presence and absence of CO2; such as, switchable solvents [Jessop, P. G.; et aL Nature 2005, 436, 1102-1102] and surfactants [Liu, Y. X.; etal. Science 2006, 313, 958-960]. In addition, CO2 switchable concepts have been applied to a synthesis of worm-like micelles [Su, X.; et al. Chem.
Commun. 2013, 49, 2655-2657], as well as polymer latexes prepared by emulsion polymerization using a switchable surfactant and initiator [Mihara, M.; etal.
Macromolecules 2011, 44, 3688-3693; Fowler, C. I.; etal. Macromolecules 2011, 44, 2501-2509;
Fowler, C.
I.; etal. Macromolecules 2012, 45, 2955-2962], switchable co-monomer and initiator [Pinaud, J.; et aL ACS Macro Lett. 2012, 1, 1103-1107] or only switchable initiator [Su, X.; et aL Macromolecules 2012, 45, 666-670]. These polymer latexes could be dispersed and aggregated upon exposure to and removal of CO2, respectively [Fowler, C. I.;
etal.
Macromolecules 2011, 44,2501-2509; Fowler, C. I.; etal. Macromolecules 2012, 45,2955-2962; Pinaud, J.; etal. ACS Macro Lett. 2012, 1, 1103-1107; Su, X.; etal.
Macromolecules 2012, 45, 666-670].

[0005] Zhu etal. [Zhang Q.; et al. (2011) Macromolecules 44(16):6539-6545;
Zhang Q.; et al. (2012b) Macromol Rapid Commun 33(10):916-921; Zhang Q.; et al. (2012c) Langmuir 28(14):5940-5946; Zhang Q.; etal. (2013) Macromolecules 46(4):1261-1267] and Zhao et al. [Zhao Y.; et al. (2012) Soft Matter 8(46):11687-11696] have studied CO2-switchable polymer latexes. Zhu et al. also developed the CO2-switchable lignin nanoparticles for Pickering emulsion application [Qian Y.; etal. (2014) Green Chem 16(12):4963-4968]. CO2-switchable technology has been applied to polymers [Han D.H.; etal. (2012b) ACS Macro Lett 1(1):57-61], polymer gels [George M, Weiss RG (2001) J Am Chem Soc 123(42):10393-10394; Han D.H.; et al. (2012a) Macromolecules 45(18):7440-7445], polymer vesicle [Yan B.; etal. (2013) Soft Matter 9(6):2011-2016], and switchable surfaces [Kumar S.; etal.
(2013) Chem Commun 49(1):90-92]. In addition, CO2-switchable polymers and surfactants have been used for nanoparticle modification (e.g., carbon nanotubes (Ding et al. 2010; Guo et al. 2012) and gold nanoparticles (Zhang et al. 2012a) to render their surfaces CO2-switchable.

[0006] For manipulating colloidal dispersibility, for example, (e.g., polymer latexes or nanoparticle dispersions), using CO2 as a trigger, rather than acid or base addition, allows for facile removal of the trigger from aqueous media by sparging with inert gases and/or applying heat [Liu, Y. X.; et al. Science 2006, 313, 958-960]; resulting in minimal to no additional residual ionic strength after removal of CO2. In contrast, stimuli-responsive CNCs, for example, have used pH [Way, A. E.; etal. ACS Macro Lett. 2012, 1, 1001-1006; Kan, K.
H. M.; etal. Biomacromolecules 2013, 14, 3130-3139], temperature [Zoppe, J.
0.; etal.
Biomacromolecules 2010, 11, 2683-2691], or solvent [Capadona, J. R.; et aL
Science 2008, 319, 1370-1374] for switching.

[0007] The above information is provided for the purpose of making known information believed by the applicant to be of possible relevance to the present invention. No admission is necessarily intended, nor should be construed, that any of the preceding information constitutes prior art against the present invention.
SUMMARY OF THE INVENTION

[0008] An object of the present invention is to provide switchable polysaccharides, and methods and uses thereof. In accordance with an aspect of the present application, there is provided a composite material that is reversibly switchable between a first form and a second form, said composite material comprising a polysaccharide and polysaccharide-supported switchable moiety attached to said polysaccharide via a linker, the switchable moiety comprising a functional group that is switchable between a neutral form associated with said first form of said composite material, and an ionized form associated with said second form of the composite material, wherein the switchable moiety comprises an amine, amidine, or guanidine.

[0009] In accordance with one embodiment, there is provided a composite material wherein the switchable moiety is an amine and the neutral form of the switchable moiety is bound to the polysaccharide via a linker XY; and wherein the first form of the composite material has the structure of formula .1.I- -_( 1 R -....õ. ...,.. R2) N n X
I - m 1--Y P
I;and (1) the second form of the composite material comprising the ionized form of the switchable moiety bound to the polysaccharide via a linker XY has the structure of formula 2 ( N HCE3 )n X

1 - m 1 Y P
1 (2);
wherein:
n is an integer 1, 2 or 3;
p is an integer between 1 and 4, wherein when Y is absent, p is 1;
m is an integer between 1 and 10 000, wherein m x p is 10 000 of less; or, m is an integer between 1 and 10 000 when Y is absent;

E is 0, S, or a combination thereof;
Y is absent, or a divalent moiety bonded to the polysaccharide and X, and is a linear or branched C1-C15 alkylene, a C15-C30 alkylene, a Cl-C15 alkenylene, a alkenylene, a C1-C15 alkynylene, a C15-C30 alkynylene, an arylene, a heteroarylene, a thiol, a silane, or a siloxane, each of which may be substituted; or, Y is a divalent cycle, or heterocycle, each of which may be substituted;
each X is a divalent moiety bonded Y, or to the polysaccharide when Y is absent, and the switchable moiety; each X is independently a linear or branched C1-015 alkylene, a C15-C30 alkylene, a C1-C15 alkenylene, a C15-C30 alkenylene, a Cl-alkynylene, a C15-C30 alkynylene, an arylene, a heteroarylene, a thiol, a silane, or a siloxane, each of which may be substituted; or, each X is independently is a divalent cycle, or heterocycle, each of which may be substituted; or, each X, and one or two of R1 and R2, together with the atoms to which they are attached, are connected to form a heterocycle, which may be substituted;
wherein each X optionally comprises one or more amine, amide, amidine, guanidine, carbamate ester, carbonate diester, ether, ester, thioether, thioester, silane, silyl alkyl ether, or siloxane moieties, or a combination thereof, within its linear or branched carbon chain, or at one of said chain's termini; and NR1R2 and NR1R2+ are each a switchable functional group, wherein R1 and R2 are each independently H, a Ci to Clo aliphatic group that is linear, branched, or cyclic, a CnSin, group where n and m are independently a number from 0 to 10 and n + m is a number from 1 to 10, a C5 to 010 aryl group, or a heteroaryl group having 4 to

10 ring atoms, each of which may be substituted; or R1 and R2, together with the atoms to which they are attached, are connected to form a cycle, or heterocycle, each of which may be substituted; or R2 is repeat unit -(X-NR1),,-Z, wherein m, X and R1 are as defined above, and Z is a monovalent moiety bonded to the switchable functional group, and is a linear or branched C1-C15 alkyl, a 015-030 alkyl, a Ci-C15 alkenyl, a C15-C3o alkenyl, a alkynyl, a 015-030 alkynyl, an aryl, a heteroaryl, a thiol, a silane, or a siloxane, each of which may be substituted; or, Z is a monovalent cycle, or heterocycle, each of which may be substituted;

wherein, [X(NR1R2)n]rn and [X(NR1R2+)n]m constitute a chain of repeat units that is linear or branched, each repeat unit in said chain being the same, or different, relative to other repeat units; and wherein, (a) if both of Wand R2 are H, than X is a sterically hindered group or, (b) if one of R1 andR2 is H, then either (i) the other one of R1 and1:12 is a sterically hindered group, or (ii) X is a sterically hindered group.
[0010] In accordance with another embodiment, there is provided a composite material wherein the first form of the composite material has the structure of formula la when Y is absent, p is 1, and 1:12 is repeat unit -(X-NR1)m-Z, Z
I
I
\ X
/rn (la); and the second form of the composite material has the structure of formula 2a, Z

HN¨R1 HCEP\
I
\ X
im (2a).

[0011] In accordance with another embodiment, there is provided a composite material wherein the first form of the composite material has the structure of formula lc when Y is absent, p is 1, and m is 1, / \

\
I In X

(lc); and the second form of the composite material has the structure of formula 2c, 1 0 \
R-IHR2 e \ N HCE3 i I / n X
I
(2c).

[0012] In accordance with another embodiment, there is provided a composite material comprising a polysaccharide and polysaccharide-supported switchable moiety, wherein the switchable moiety is an amine and the neutral form of the switchable moiety is bound to a polysaccharide via a linker X, wherein the first form of the composite material has the structure of formula 1, with a proviso that, when the polysaccharide is a CNC, Y is absent, p is 1, and X is -CH2-C(CH3)2-0O2-(CH2)2-, only one of R1 and R2 is CH3.

[0013] In accordance with another embodiment, there is provided a composite material wherein the switchable moiety is an amidine and the neutral form of the switchable moiety is bound to the polysaccharide via a linker XY; and wherein the first form of the composite material has the structure of formula 3a, 3b, or 3c, N I II
.....,N.......c/....-Ns....... R5,,, 7C.
R4 I R3 N R4 R3 N \
/ n X
I
I -I
P i_ I -I
P 1_ -m}
P
Y Y Y
I I I
(3a) (3b) (3c); and the second form of the composite material comprising the ionized form of the switchable moiety bound to the polysaccharide via a linker XY has the structure of formula 4a, 4b, 4c, { R4 0,-IRNI
HCE93\
\
--IP
- 4/ Nr= HIc(I 3C ,.
E' NH
\3\/
-I
P
5'XN1I
1(R3cH/i\R Rt(7 R3 I-Y Y Y

(4a) (4b) (4c);
wherein:
n is an integer 1, 2 or 3;
p is an integer between 1 and 4, wherein when Y is absent, p is 1;
m is an integer between 1 and 10 000, wherein m x p is 10 000 of less; or, m is an integer between 1 and 10 000 when Y is absent;
E is 0, S, or a combination thereof;
Y is absent, or a divalent moiety bonded to the polysaccharide and X, and is a linear or branched C1-C15 alkylene, a C15-C30 alkylene, a C1-C15 alkenylene, a alkenylene, a Cl-C15 alkynylene, a C15-C30 alkynylene, an arylene, a heteroarylene, a thiol, a silane, or a siloxane, each of which may be substituted; or, Y is a divalent cycle, or heterocycle, each of which may be substituted;
each X is a divalent moiety bonded Y, or to the polysaccharide when Y is absent, and the switchable functional group; each X is independently a linear or branched C1-C15 alkylene, a C15-C30 alkylene, a Ci-C15 alkenylene, a C15-C30 alkenylene, a Ci-C15 alkynylene, a C15-C30 alkynylene, an arylene, a heteroarylene, a thiol, a silane, or a siloxane, each of which may be substituted; or, each X is independently is a divalent cycle, or heterocycle, each of which may be substituted; or, each X, and one or more of R3, R4, and R5, together with the atoms to which they are attached, are connected to form a heterocycle, which may be substituted; and wherein each X optionally comprises one or more amine, amide, amidine, guanidine, carbamate ester, carbonate diester, ether, ester, thioether, thioester, silane, silyl alkyl ether, or siloxane moieties, or a combination thereof, within its linear or branched carbon chain, or at one of said chain's termini; and N=CR3NR4R5 , R3N=CNR4R5, R3N=CR4NR5, and (N=CR3NR4R5)+, (R3N=CNR4R5)+, (R3N=CR4NR5)+ are each switchable functional groups, wherein R3, R4, and R5 are independently H, a C, to Clo aliphatic group that is linear, branched, or cyclic;
a C,-,Sim group where n and m are independently a number from 0 to 10 and n +
m is a number from 1 to 10, a C5 to C10 aryl group, or a heteroaryl group having from 4 to 10 carbon atoms in the aromatic ring, each of which may be substituted; or, any combination of R3, R4, and R5, together with the atoms to which they are attached, are connected to form a heterocycle, which may be substituted; or, any one of R3, R4, and R5 is repeat unit -(X-N=CR3NR4)m-Z, -(X-N=CNR4R5)m-Z;
or -(X-C=NR3NR4)m-Z, -(X-C=NNR4R5)m-Z; or -(X-NCR4=NR3)m-Z, -(X-NR5CR4=N)m-Z, -(X-NR5C=NR3)m-Z, wherein X and R3, R4, and R5 are as defined above, and Z is a monovalent moiety bonded to the switchable functional group, and is a linear or branched C1-C15 alkyl, a C15-C30 alkyl, a Cl-C15 alkenyl, a C15-C30 alkenyl, a Ci-C15 alkynyl, a C15-C30 alkynyl, an aryl, a heteroaryl, a thiol, a silane, or a siloxane, each of which may be substituted; or, Z is a monovalent cycle, or heterocycle, each of which may be substituted;
wherein, [X(N=CR3NR4R5)nim, [X(R3N=CNR4R5),,]m, [X(R3N=CR4NR5)dm, and [X(N=CR3NR4R5-)nim, [X(R3N=CNR4R5),4-n, [X(R3N=CR4NR5+)dm constitute a chain of repeats units that is linear or branched, each repeat unit in said chain being the same, or different, relative to other repeat units.

[0014] In accordance with another embodiment, there is provided a composite material wherein the first form of the composite material has the structure of formula 3d, 3d', 3e, 3e', 3f, 3f', or 3f" when Y is absent, p is 1, and R3, R4, or R5 is repeat unit -(X-N=CR3NR4)m-Z, -(X-N=CNR4R5),Z; or -(X-C=NR3NR4)m-Z, -(X-C=NNR4R5)m-Z; or -(X-NCR4=NR3)m-Z, -(X-NR5CR4=N)m-Z, -(X-NF5C=NR3)m-Z, Z

N N
N \
I I
(R4/ N,,, c rz \ R3 N N
\ I /
I m = I m = m (3d) (3d') (3e) Z

I
i N N z N7R3\

II
=-..,... ,...- R5 r Vc\ R4 N/c\ R4 N
mZ
I \
\ 1 X
= X
I
(3e') (3f) (3f') II
N-Ix Z
I m (3f"); and the second form of the composite material has the structure of formula 4d, 4d', 4e, 4e', 4f, 4f', or 4f", Z
7 R4 z 7R/R5 \4 N
e i: iie HcE3 HcE3 .0 c c= R
C
-,'NH 1 0 R3 = NH HCE3 \ 1/ Z 1 X \ X im I m = I m = 1 .
(4d) (4d') (4e);

R5 HN." \ 7 5 HN.---\\---7 It' = 8 0 \ Z e lj -L, R , R4 .C. N17 R4 N R

HcE3 e e \ x E3 /
im \ x I /ni = 1 x I
=
1 im ,or (4e') (4f) (4f') 7 HN..,R3 t:
R5 = u N
e HcE3 z \ x I m (4f").

[0015] In accordance with another embodiment, there is provided a composite material wherein the first form of the composite material has the structure of formula 3g, 3h, or 3i when Y is absent, p is 1, and m is 1, / R4 R5 \
1\1 / R5 \ / N7 R3 \
I I II
C 1 , \ R3 -N in \ R4- -C' -R3/n R51\1 CR,4 1 xi I 1 /n X X

(3g) (3h) (3i); and the second form of the composite material has the structure of formula 4g, 4h, or 4i, HNV
/ R4 R5 \ 7 R5 HCE3e \
7 R e \
N I H 0 li HcE3 IR4 d e N = ,,,N R5 -C e HcE3 7'R3 N-7 \ R-A
\ R3 -NH / \
/ \ 1 /
IX X

(4g); (4h); (4i).

[0016] In accordance with another embodiment, there is provided a composite material wherein the switchable moiety is a guanidine, and the neutral form of the switchable moiety is bound to the polysaccharide via a linker XY; and wherein the first form of the composite material has the structure of formula 5a, 5b, 5c, c _ _ _ _ _ 7 ___RNI,R6 7 HNR1 \ 7 e .
HNwo \
HCEP il 0 HCEP li \HCE3 he R9 -c. 6 R9 R6 R9 -c-: R6 \ i = r / ---N - = N
\ IR8 1 / ---N - = N
I /

X

m ¨ m I ¨ m Y Y Y
I I I
(5a); (5b); (5c);

the second form of the composite material comprising the ionized form of the switchable moiety bound to the polysaccharide via a linker XY has the structure of formula 6a, 6b, 6c, _ ..1 _ _ m}
/ eR.N7 R6 \
_ HcR9E3 eil NH \
I
R8 1 ln X
I ¨ m HN
e l!so C

'N' = N
\ I
tHC R8 Rio I1 ;
n ¨
P t 1_ HN
HCE3 .

C wo / R)¨ /
----NI' = N
\ 1 X
I I
R7 n ¨ m P
Y Y Y

(6a); (6b); (6c); or wherein:
n is an integer 1, 2 or 3;
p is an integer between 1 and 4, wherein when Y is absent, p is 1;
m is an integer between 1 and 10 000, wherein m x p is 10 000 of less; or, m is an integer between 1 and 10 000 when Y is absent;
E is 0, S, or a combination thereof;
Y is absent, or a divalent moiety bonded to the polysaccharide and X, and is a linear or branched Cl-C15 alkylene, a C15-C30 alkylene, a Ci-C15 alkenylene, a alkenylene, a C1-C15 alkynylene, a C15-C30 alkynylene, an arylene, a heteroarylene, a thiol, a silane, or a siloxane, each of which may be substituted; or, Y is a divalent cycle, or heterocycle, each of which may be substituted;
each X is a divalent moiety bonded Y, or to the polysaccharide when Y is absent, and the switchable functional group; each X is independently a linear or branched C1-C15 alkylene, a C15-C30 alkylene, a Cl-C15 alkenylene, a C15-C30 alkenylene, a Ci-C15 alkynylene, a C15-C30 alkynylene, an arylene, a heteroarylene, a thiol, a silane, or a siloxane, each of which may be substituted; or, each X is independently is a divalent , cycle, or heterocycle, each of which may be substituted; or, each X, and one or more of R6, R7, R8, R9 and R10, together with the atoms to which they are attached, are connected to form a heterocycle, which may be substituted; and wherein each X optionally comprises one or more amine, amide, amidine, guanidine, carbamate ester, carbonate diester, ether, ester, thioether, thioester, silane, silyl alkyl ether, or siloxane moieties, or a combination thereof, within its linear or branched carbon chain, or at one of said chain's termini; and N=CNR6R7NR8R9, R10N.CNR6NR81:19, iN
io rs -k.
=CNR6R7NR9, and (N=CNR6R7NR8R9)+,ri CNR6NR8Fo i-lo (r-lok iN .= y, km N=CNR6R7NR9)+ are each switchable functional groups, wherein R6, R7, R8, R9 and R1 are independently H, a Ci to Cio aliphatic group that is linear, branched, or cyclic; a CnSim group where n and m are independently a number from 0 to 10 and n + m is a number from 1 to 10, a C5 to C10 aryl group, or a heteroaryl group having from 4 to 10 carbon atoms in the aromatic ring, each of which may be substituted; or, any combination of R6, R7, R8, R9 and R10, together with the atoms to which they are attached, are connected to form a heterocycle, which may be substituted; or, any one of R6, R7, R8, R9 and R1 is repeat unit -(X-N=CNR6R7NR8)m-Z, -(X-N=CNR7NR8R9)m-Z, or -(X-NR6C=NNR8R9)m-Z, -(X-NR6C=NR10NR8)õ-Z, -(X-NC=NR10NR8R9)m-Z, wherein X and R6, R7, R8, R9 and 1:11 are as defined above, and Z is a monovalent moiety bonded to the switchable functional group, and is a linear or branched C1-C15 alkyl, a C15-C30 alkyl, a Cl-C15 alkenyl, a C15-C30 alkenyl, a C1-C15 alkynyl, a C15-C30 alkynyl, an aryl, a heteroaryl, a thiol, a silane, or a siloxane, each of which may be substituted; or, Z is a monovalent cycle, or heterocycle, each of which may be substituted;
wherein at least one of R6, R7, R8, R9 and R1 is an electron withdrawing group;
and wherein, [X(N=CNR6R7NR8R9)n]m, [X(R10N=CNR6NR8R9)n]rn, [X(R10N=CNR6R7NR9),],, [X(N=CNR6R7NR8R9)+n]m, [X(R10N=CNR6NR8R9)+n]m, [X(1310N.CNR6R7NR9)+n], constitute a chain of repeats units that is linear or branched, each repeat unit in said chain being the same, or different, relative to other repeat units.

[0017] In accordance with another embodiment, there is provided a composite material wherein the first form of the composite material has the structure of formula 5d, 5d', 5d", 5e, or 5e' when Y is absent, p is 1, and R6, R7, R8, R9 or R1 is repeat unit -(X-N=CNR6R7NR8)m-Z, -(X-N=CNR7NR8R9)m-Z, or -(X-NR6C=NNR8R9)m-Z, -(X-NR6C=NR19NR8)m-Z, -(X-NC=NR16NR8R9)m-Z, ( \ (----N,./
'/\ N/

R8NCNVR6J R6 R8 .....__N/CNIl \ RN1, -Z
\ IR8 I I

I m 1 m I m (5d); (5d'); (5d");
7 I=17 N R6\ ( Fi7N\c'Z
Z I I
R9., N /CN
N N
1 m I m (5e) (5e'); and the second form of the composite material has the structure of formula 6d, 6d', 6d", 6e, or 6e' z R10 R10., 7 HN Hf< 7 Hi<
HCEP li 0 Z HCEPco R6 li e I:
HcE3 .0 z R6 c ¨ c N
R9 .-- ==:,.. ,. ..- =.:.. R94-'N c " N
I I I I \ IR8 I
\ R8 X R8 X i I m 1 m I m (6d); (6d'); (6d");

CA 02918904 2016-01:26 R7 R6\ 7 RcZ N
N
z HCE-1n il 0 HCEP
' N = NH '117 = Ni11-1 I

I m 1 m (6e) (6e').

[0018] In accordance with another embodiment, there is provided a composite material wherein the first form of the composite material has the structure of formula 5f, 5g, or 5h when Y is absent, p is 1, and m is 1, 7 Rc R6 \

R10 \
7 /R10 \
N
I II II
R9 /Cli R9 R9C\ N/ R6 \ 1 /
n \ 18 I in \ I 1 R /

R7 n (5f) (5g) (5h); and the second form of the composite material has the structure of formula 6f, 6g, or 6h, ( FI7 R6 \

WO
e .N 7 rL HN 7 r_._ HN
HCE3 i HCE-' Ii r. HCE-f lir, C R) C"-rJ

Rg -- --'NH R9 / R9 /
\ i I in ----N = = N
\ 1 I n r µ11 R8 X R8 X X R7 n (6f); (6g); (6h).

[0019] In accordance with another embodiment, there is provided a composite material whereinthe switchable moiety is a pyridine, and the neutral form of the switchable moiety is bound to the polysaccharide via a linker XY; and wherein the first form of the composite material has the structure of formula 7, _{
7 (R15)0--_-N ¨
_\ S __________________________________ )) X ni P
Y
(7); and the second form of the composite material comprising the ionized form of the switchable moiety bound to the polysaccharide via a linker XY has the structure of formula 8, 7 (R15)0/=¨_ -__NH
_ ¨
{
HCE S ____________________________________ ) \ 3 X /
_ml P
y (8), wherein:
n is an integer 1, 2 or 3;
o is an integer 1, 2 or 3;
p is an integer between 1 and 4, wherein when Y is absent, p is 1;
m is an integer between 1 and 10 000, wherein m x p is 10 000 of less; or, m is an integer between 1 and 10 000 when Y is absent;

E is 0, S, or a combination thereof;
Y is absent, or a divalent moiety bonded to the polysaccharide and X, and is a linear or branched C1-C15 alkylene, a C15-C30 alkylene, a C1-C15 alkenylene, a alkenylene, a C1-C15 alkynylene, a C15-C30 alkynylene, an arylene, a heteroarylene, a thiol, a silane, or a siloxane, each of which may be substituted; or, Y is a divalent cycle, or heterocycle, each of which may be substituted;
each X is a divalent moiety bonded Y, or to the polysaccharide when Y is absent, and the switchable moiety; each X is independently a linear or branched C1-C15 alkylene, a C15-C30 alkylene, a Cl-C15 alkenylene, a C15-C3o alkenylene, a Ci-alkynylene, a C15-C3o alkynylene, an arylene, a heteroarylene, a thiol, a silane, or a siloxane, each of which may be substituted; or, each X is independently is a divalent cycle, or heterocycle, each of which may be substituted; or, each X, and one or two of R1 and R2, together with the atoms to which they are attached, are connected to form a heterocycle, which may be substituted;
wherein each X optionally comprises one or more amine, amide, amidine, guanidine, carbamate ester, carbonate diester, ether, ester, thioether, thioester, silane, silyl alkyl ether, or siloxane moieties, or a combination thereof, within its linear or branched carbon chain, or at one of said chain's termini; and (R15)0./--- ---N (R15)0 /-=----NH
/an ) is a switchable functional group, wherein R15 is H, a C1 to Clo aliphatic group that is linear, branched, or cyclic, a CnSim group where n and m are independently a number from 0 to 10 and n + m is a number from 1 to 10, a C5 to C10 aryl group, or a heteroaryl group having 4 to 10 ring atoms, each of which may be substituted; or any two of R15, together with the atoms to which they are attached, are connected to form a cycle, or heterocycle, each of which may be substituted; or /=N\ \
(x v any one of R15 is repeat unit ;.75-;ci in , wherein X and R15 are as defined above, q is integer 1 or 2, and Z is a monovalent moiety bonded to the switchable functional group, and is a linear or branched C1-C15 alkyl, a C15-C30 alkyl, a C1-C15 alkenyl, a C15-C30 alkenyl, a Cl-C15 alkynyl, a C15-C3o alkynyl, an aryl, a heteroaryl, a thiol, a silane, or a siloxane, each of which may be substituted; or, Z is a monovalent cycle, or heterocycle, each of which may be substituted;
7 (R15)0 -/-=---N \ _ _ (R15)0 x wherein, ¨ ¨In and ¨ ¨rn constitute a chain of repeat units that is linear or branched, each repeat unit in said chain being the same, or different, relative to other repeat units.

[0020] In accordance with another embodiment, there is provided a composite material wherein the first form of the composite material has the structure of formula 7a when Y is ( .r- -_ -_ .. .. N 1 _____________________________________________ Z
15 , absent, p is 1, and 1:115 is repeat unit x V ) (R15)0¨_-2.\_1z S _____________________________________ 1 X
im (7a); and the second form of the composite material has the structure of formula 8a, AR15)0 /-z-_--. -NH z \) HCEP _________________________________ , \ X
m (8a).

[0021] In accordance with another embodiment, there is provided a composite material wherein the first form of the composite material has the structure of formula 7b when Y is absent, p is 1, and m is 1, ((R15)0/_--=N
S _____________________________________ )/
\ / n X
(7b); and the second form of the composite material has the structure of formula 8b, 7 (R15)0 /--NH \
HCEC S ________________________________ /j X
(8b).

[0022] In accordance with another embodiment, there is provided a composite material wherein the neutral form of the switchable moiety is bound to the polysaccharide via a linker XY; and wherein the first form of the composite material has the structure of formula 9a, 9b, 9c, or 9d, 1Ri2i N C
\ R13 ..õ,(11\
; N

X
I al 1( _ -- i2 RiiIIin _ P
FlN
N

X
I C ¨
Ria }/n _ p Y Y
I I
(9a); (9b);

13 ¨
p /
/
R141 NC Rizi {
}
Y Y P
I
(9c); (9d); and the second form of the composite material comprising the ionized form of the switchable moiety bound to the polysaccharide via a linker XY has the structure of formula 10a, lob, 10c, or 10d, ( R12 ¨__ r\i=-, 0 j\i(EHiCRE11? i m \ R13 C---X
I ¨
P i__ KR12):(:)NcliEli-ICEPi }
x1-7 R14n 1 _ P
Y Y

(10a); (10b);

/ Ria sic::::='N Ri2 Nzz., /
Rii ,õ\\:\:.) HCE?
1 \ Li C)j } ¨ 7 n \ in }
X X
I _ P ¨ I ¨
Y Y P

(10c); (10d); and wherein:
n is an integer 1, 2 or 3;
p is an integer between 1 and 4, wherein when Y is absent, p is 1;
m is an integer between 1 and 10 000, wherein m x p is 10 000 of less; or, m is an integer between 1 and 10 000 when Y is absent;
E is 0, S, or a combination thereof;
Y is absent, or a divalent moiety bonded to the polysaccharide and X, and is a linear or branched Ci-C15 alkylene, a C15-C30 alkylene, a Ci-C15 alkenylene, a alkenylene, a Cl-C15 alkynylene, a C15-C30 alkynylene, an arylene, a heteroarylene, a

- 23 -thiol, a silane, or a siloxane, each of which may be substituted; or, Y is a divalent cycle, or heterocycle, each of which may be substituted;
each X is a divalent moiety bonded Y, or to the polysaccharide when Y is absent, and the switchable moiety; each X is independently a linear or branched C1-C15 alkylene, a C15-C30 alkylene, a Ci-C15 alkenylene, a C15-C30 alkenylene, a Cl-alkynylene, a C15-C30 alkynylene, an arylene, a heteroarylene, a thiol, a silane, or a siloxane, each of which may be substituted; or, each X is independently is a divalent cycle, or heterocycle, each of which may be substituted; or, each X, and one or two of R1 and R2, together with the atoms to which they are attached, are connected to form a heterocycle, which may be substituted;
wherein each X optionally comprises one or more amine, amide, amidine, guanidine, carbamate ester, carbonate diester, ether, ester, thioether, thioester, silane, silyl alkyl ether, or siloxane moieties, or a combination thereof, within its linear or branched carbon chain, or at one of said chain's termini; and R11, R12, R13, and rs 1-.14 are each independently H, a C1 to Clo aliphatic group that is linear, branched, or cyclic; a CnSin, group where n and m are independently a number from 0 to 10 and n + m is a number from 1 to 10, a C5 to C10 aryl group, or a heteroaryl group having from 4 to 10 carbon atoms in the aromatic ring, each of which may be substituted; or, any combination of R11, R12, ri r",13, and R14, together with the atoms to which they are attached, are connected to form a cycle or heterocycle, each of which may be substituted; or any one of R11, R12, R13, and R14 is repeat unit -(X-Im)m-Z, wherein X is as defined above, Im is an optionally substituted imidazole ring, and Z is a monovalent moiety bonded to the switchable functional group, and is a linear or branched alkyl, a C15-C30 alkyl, a Cl-C15 alkenyl, a C15-C30 alkenyl, a Ci-C15 alkynyl, a C15-C30 alkynyl, an aryl, a heteroaryl, a thiol, a silane, or a siloxane, each of which may be substituted; or, Z is a monovalent cycle, or heterocycle, each of which may be substituted;
wherein, the repeat unit [X(1m)dm and [X(Im)+,-]m constitute a chain of repeat units that is linear or branched, each repeat unit in said chain being the same, or different, relative to other repeat units.

- 24 -[0023] In accordance with another embodiment, there is provided a composite material wherein the first form of the composite material has the structure of formula 9e, 9f, 9g, or 9h when Y is absent, p is 1, and m is 1, 7\

(R11\ R127 t\c N R12 c \ R13 C

/n 1 in x x (9e); (9f);

\
/ R14 \
Ri,,_o i \
R _____c 1 1 .\\ \
\ N
R13 in X X
I I
(9g); (9h); and the second form of the composite material has the structure of formula 10e, 10f, 10g, or 10h, ) _____________________ (HCE? / (zir 7 R HCE?

1\1,_10 ,I\IH \ R12 \.-/C
\ -\ e R14 n 1 in x x (10e); (10f);

- 25 -,, H
HCE3e C- R C q /
y_ Rii 0A HcE3 \ FI'll in \ n X X
I
(10g); (10h).
[0024] In accordance with another embodiment, there is provided a composite material comprising a polysaccharide and polysaccharide-supported switchable moiety, wherein the switchable moiety is an amidine and the neutral form of the switchable moiety is bound to the polysaccharide via a linker X, and wherein the first form of the composite material has the structure of formula 9f, with the proviso that, when the polysaccharide is a CNC, n is 1, and X is -0O2-NH-(CH2)3-, only two of R11, R12, or R14 is H.
[0025] In accordance with another embodiment, there is provided a composite material wherein the first form of the composite material has the structure efiN
N---j 0 _______________________________ (NH

I .
, and the second form of the composite material has the structure

- 26 -e1NH3 e N ____________________________ HCE3 0 ____________________________ (NH

I .
[0026] In accordance with another embodiment, there is provided a composite material wherein the polysaccharide is cellulose nanocrystal (CNC), cellulose, dextran, cotton, starch, chitin, chitosan, or any combination thereof.

[0027] In accordance with another embodiment, there is provided a composite material wherein said first form of the composite material is neutral and hydrophobic, and the second form of the composite material is ionized and hydrophilic.

[0028] In accordance with another embodiment, there is provided a composite material wherein the composite material converts to, or is maintained in, said second, ionized form when the switchable moiety is exposed to an ionizing trigger at an amount sufficient to maintain said switchable moiety in its ionized form; and, wherein the composite material converts to, or is maintained in, said first form when said ionizing trigger is removed or reduced to an amount insufficient to maintain said switchable moiety in its ionized form. In one embodiment, the ionizing trigger is an acid gas. In another embodiment, the acid gas is CO2, COS, CS2, or a combination thereof.

[0029] In accordance with another embodiment, the ionizing trigger is removed or reduced by exposing the composite material to: (i) an at least partial vacuum; (ii) heat; (iii) a flushing inert gas (iv) a liquid substantially devoid of an ionizing trigger; or, (v) any combination thereof; in the presence or absence of agitation. In one embodiment, the inert gas is N2, Ar or air. In another embodiment, exposing to heat is heating to 5 60 C, 5 80 C, or 5 150 C.

[0030] In accordance with another embodiment, the ionizing trigger is a Bronsted acid sufficiently acidic to ionize said switchable moiety from its neutral form;
or, any Bronsted base sufficiently basic to de-ionize said switchable moiety from its ionized form.

[0031] In accordance with another embodiment, there is provided a second form of the composite material wherein % ionization of the material's switchable moieties is 5100%; or alternatively, 575 /0; or alternatively 550%.

[0032] In accordance with another embodiment, there is provided a composite material wherein each repeating unit of formulas 1 and 2, or la and 2a; 3a, 3b, 3c and 4a, 4b, 4c, or 3d, 3d', 3e, 3e', 3f, 3f', 3f" and 4d, 4d', 4e, 4e', 4f, 4f', 4f"; 5a, 5b, 5c and 6a, 6b, 6c, or 5d, 5d', 5d", 5e, 5e' and 6d, 6d', 6d", 6e, 6e'; 7 and 8, or 7a and 8a; or 9a, 9b, 9c, 9d, and 10a, 10b, 10c, 10d is either the same, or different, relative to other repeat units, thus forming a homopolymer or a copolymer. In one embodiment, said copolymer is a graft copolymer or block copolymer. In another embodiment, the copolymer is a random copolymer.

[0033] In accordance with another aspect of the application, there is provided a method for switching a composite material, as described herein, between its first form and second form, comprising:
exposing the neutral and hydrophobic composite material to (i) an aqueous liquid, or (ii) a non-aqueous liquid and water, to form a mixture, and exposing said mixture to an ionizing trigger, thereby protonating the switchable moiety and rendering the composite material ionized and hydrophilic; and/or exposing the neutral and hydrophobic composite material to an aqueous carbonated liquid to form a mixture, wherein the carbonated liquid protonates the switchable moiety to render the composite material ionized and hydrophilic;
and optionally, separating the ionized hydrophilic composite material from the mixture.

[0034] In accordance with another aspect of the application, there is provided a method for switching a composite material, as described herein, between its second form and first form, comprising:
exposing an ionized hydrophilic composite material to: (i) an at least partial vacuum; (ii) heat; (iii) a flushing inert gas; (iv) a liquid substantially devoid of an ionizing trigger; or, (v) any combination thereof; in the presence or absence of agitation, thereby expelling the ionizing trigger from the switchable moiety and rendering the composite material neutral and hydrophobic; and optionally, separating the neutral and hydrophobic composite material from the mixture.

[0035] In accordance with one embodiment, there is provided a method wherein the ionizing trigger is an acid gas. In another embodiment, the acid gas is CO2, COS, CS2, or a combination thereof.

[0036] In accordance with another embodiment, there is provided a method wherein the inert gas is N2, Ar or air.

[0037] In accordance with another embodiment, there is provided a method wherein exposing to heat is heating to 5. 60 C, 5 80 C, or 5 150 C.

[0038] In accordance with another aspect of the application, there is provided a use for the composite materials, as herein described, for manipulating and/or controlling dispersibility, for example, CNC dispersibility.

[0039] In accordance with another aspect of the application, there is provided a use for the composite materials, as herein described, as a separation membrane.

[0040] In accordance with another aspect of the application, there is provided a use for the composite materials, as herein described, for formation of a membrane comprising a chiral nematic liquid crystalline structure.

[0041] In accordance with another aspect of the application, there is provided a use for the composite materials, as herein described, as an absorbent.

[0042] In accordance with another aspect of the application, there is provided a use for the composite materials, as herein described, as a drying agent.

[0043] In accordance with another aspect of the application, there is provided a use for the composite materials, as herein described, as a flocculent.

[0044] In accordance with another aspect of the application, there is provided a use for the composite materials, as herein described, for water or wastewater treatment.
In accordance with one embodiment, the water or wastewater treatment comprises removal of organic contaminants or metal contaminants.

[0045] In accordance with another aspect of the application, there is provided a use for the composite materials, as herein described, for cleaning a surface.

[0046] In accordance with another aspect of the application, there is provided a use for the composite materials, as herein described, for formation of a switchable fabric.

[0047] In accordance with another aspect of the application, there is provided a use for the composite materials, as herein described, for formation of a switchable filter paper.

[0048] In accordance with another aspect of the application, there is provided a use for the composite materials, as herein described, for stabilizing an emulsion.

[0049] In accordance with another aspect of the application, there is provided a use for the composite materials, as herein described, as a switchable viscosity modifier.

[0050] In accordance with another aspect of the application, there is provided a use for the composite materials, as herein described, for use in chromatography.
BRIEF DESCRIPTION OF TABLES AND FIGURES

[0051] For a better understanding of the application as described herein, as well as other aspects and further features thereof, reference is made to the following description which is to be used in conjunction with the accompanying tables and drawings, where:

[0052] Table 1 delineates zeta potential and z-average size of native CNC (ca.
0.5 mg/ml dispersion) in response to continuous repeated CO2/N2 sparging;

[0053] Table 2 delineates elemental analysis data for 1-(3-aminopropyl)innidazole functionalized CNC (CNC-APIm)and native CNC;

[0054] Table 3 delineates Z-average sizes of CNC-APIm (ca. 0.5 mg/mL
dispersion) in response to continuous repeated CO2/N2 sparging;

[0055] Table 4 delineates zeta potential and z-average size of CNC-APIm in discarded supernatant (ca. 0.5 mg/ml dispersion) in response to continuous repeated CO2/N2 sparging;

[0056] Table 5 delineates time-dependent Z-average size and zeta potential changes of CNC-APIm (ca. 0.5 mg/mL dispersion) in response to CO2/N2 sparging;

[0057] Table 6 delineates degree of protonation of HPIm calculated by different protons in different conditions measured by 1H NMR (see Figure 3 for assignment of different protons in HPIm);

[0058] Table 7 delineates mass of water absorbed by Cotton-APInn versus non-functionalized Cotton;

[0059] Table 8 delineates contact angle analysis via the sessile drop method for unfunctionalized cotton linen and functionalized Cotton-APIm;

[0060] Table 9 delineates contact angle analysis via the sessile drop method for native and functionalized (i.e. waxy) filter paper;

[0061] Table 10 delineates contact angle analysis via sessile drop method for unfunctionalized cotton linen and functionalized Linen-pDEAEMA via "grafting-from" method;

[0062] Table 11 delineates investigation of switchable celluloses, prepared via synthetic method 1, as drying agents;

[0063] Table 12 delineates investigation of switchable celluloses, prepared via synthetic method 2, as drying agents;

[0064] Table 13 delineates elemental analysis (C%, H%, N%) of switchable polymers grafted on crystalline nanocellulose via nitroxide-mediated polymerization;

[0065] Table 14 delineates percent composition of switchable polymers grafted on crystalline nanocellulose via nitroxide-mediated polymerization;

[0066] Table 15 delineates potential and pH measurements for CNC-g-PDMAEMA in the presence of glycolic acid (GlAc) 0.5 M and NaOH 0.5 M;

[0067] Table 16 delineates -potential and pH measurements for CNC-g-PDEAEMA in the presence of glycolic acid (GlAc) 0.5 M and NaOH 0.5 M;

[0068] Table 17 delineates -potential and pH measurements for CNC-g-PDMAPMAm in the presence of glycolic acid (GlAc) 0.5 M and NaOH 0.5 M;

[0069] Table 18 delineates 4-potential and pH measurements for CNC-g-PDMAEMA
in the presence of CO2/N2;

[0070] Table 19 delineates 4-potential and pH measurements for CNC-g-PDEAEMA
in the presence of CO2/N2; and

[0071] Table 20 delineates 4-potential and pH measurements for CNC-g-PDMAPMAm in the presence of of CO2/N2.

[0072] Figure 1 depicts synthesis of 1-(3-aminopropyl)imidazole functionalized CNC (CNC-APIm) through CDI-mediated coupling with APIm;

[0073] Figure 2 depicts reversible aggregation and redispersion of CNC-APIm in absence and presence of CO2;

[0074] Figure 3 depicts a DRIFT-IR spectra of native CNC and CNC-APIm, wherein band A
is carbonyl C=0 stretching, band B is amide II N-H bending, and band C is C-0 stretching;

[0075] Figure 4 depicts (a) zeta potential changes of CNC-APIm (ca. 0.5 mg/mL
dispersion) in response to continuous repeated CO2/N2 sparging; (b) turbidities of CNC-APIm and native CNC dispersions (ca. 2.5 mg/mL) measured at 500 nm wavelength in response to continuous repeated CO2/N2 sparging cycles (some standard deviations were smaller than data point symbol);

[0076] Figure 5A/5B depicts (a-c), (e) and (f): CO2-switchability of CNC-APIm at different concentrations (CO2 and N2 sparging for 5 and 30 min, respectively); in (a), sample vials (under N2) were held against light so that CNC-APIm aggregates could be clearly observed;
(d) sedimentation of CNC-APIm after sparging N2 for 30 min (arrow indicates upper level of aggregates); (g) native CNC dispersions in presence of CO2 and N2 (CO2 and N2 sparging for 5 and 30 min, respectively);

[0077] Figure 6A depicts 1H nuclear magnetic resonance (NMR) spectra of HPIm in 90%
H20+10% D20 without and with water presaturation;

[0078] Figure 6B depicts 1H nuclear magnetic resonance (NMR) spectra of HPIm in 90%
H20+10% D20 in different conditions;

[0079] Figure 7 depicts transmission electron microscope (TEM) images of native CNC (a) and CNC-APIm (b);

CA 02918904 2016-01-.26

[0080] Figure 8 depicts synthesis of1-(3-Aminopropyl)imidazole functionalized cellulose dialysis bag (Cellulose-APIm);

[0081] Figure 9 depicts a comparison of non-functionalized and functionalized cellulose dialysis bag via % transmittance Infrared Spectroscopy (IR) spectra to demonstrate, at least qualitatively, that at least part of the cellulose dialysis bag was functionalized;

[0082] Figure 10 depicts contact angle analysis of Cellulose-APIm;

[0083] Figure 11 depicts a demonstrative, non-limiting example of a proposed, alternative synthesis to switchable polysaccharides involving a coupling reaction between a switchable group-functionalized carboxylic acid and CDI;

[0084] Figure 12 depicts a demonstrative, non-limiting example of a proposed, alternative synthesis to switchable polysaccharides involving a coupling reaction between a switchable group-functionalized amine and methyl chloroformate;

[0085] Figure 13 depicts a demonstrative, non-limiting example of a investigation into functionalizing filter paper via a CDI-medited coupling reaction;

[0086] Figure 14 depicts functionalization of chitosan (CTS) with glycidyl methacrylate (GMA);

[0087] Figure 15 depicts a synthesis of poly((diethylamino)ethyl methacrylate) (PDEAEMA) via nitroxide mediated polymerization (NMP);

[0088] Figure 16 depicts grafting PDEAEMA to CTS-g-GMA via NMP;

[0089] Figure 17 depicts a 1H NMR spectra of chitosan-g- glycidyl methacrylate CTS-g-GMA with the integrated signals;

[0090] Figure 18 depicts a gel permeation chromatography trace of synthesized PDEAEMA;

[0091] Figure 19 depicts 1H NMR spectra of CTS-g-GMA-PDEAEMA;

[0092] Figure 20 depicts thermogravimetric analysis (TGA) of CTS -g-GMA-PDEAEMA;

[0093] Figure 21 (A)-(C) depicts a) CTS-g-GMA-PDEAEMA before bubbling CO2; b) CTS-g-GMA-PDEAEMA right after bubbling CO2; and c) CTS-g-GMA-PDEAEMA right after bubbling N2;

,

[0094] Figure 22 depicts results of Ni(II) sorption equilibrium studies with CTS -g-PDEAEMA and native CTS;

[0095] Figure 23 depicts results of CO2 regeneration studies with CTS-g-PDEAEMA and native CTS;

[0096] Figure 24 depicts functionalization of CNC with glycidyl methacrylate (GMA);

[0097] Figure 25 depicts grafting PDEAEMA to CNC-g-GMA via nitroxide-mediated polymerization;

[0098] Figure 26 depicts modification of CNC-g-GMA with PDEAEMA via free radical polymerization;

[0099] Figure 27 depicts a CP/MAS 13C NMR spectra of CNC and CNC-g-GMA;

[00100] Figure 28 depicts CP/MAS 13C NMR spectra of CNC-g-GMA-PDEAEMA
obtained via nitroxide-mediated polymerization;

[00101] Figure 29 depicts TGA of a) CNC, b) PDEAEMA and c) CNC-g-PDEAEMA
(obtained via nitroxide-mediated polymerization);

[00102] Figure 30 depicts CP/MAS 13C NMR spectra of CNC-g-GMA-PDEAEMA
obtained via free radical polymerization;

[00103] Figure 31 depicts TGA of a) CNC, b) PDEAEMA and c) CNC-g-PDEAEMA
(obtained via free radical polymerization);

[00104] Figure 32 depicts a demonstrative, non-limiting example of a switchable starch synthesis involving a coupling reaction between a switchable group-functionalized amine and CDI;

[00105] Figure 33 depicts functionalization of cotton linen with PDEAEMA;

[00106] Figure 34 depicts an Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) of non-functionalized linen (bottom) compared to Linen-pDEAEMA
(top).

[00107] Figure 35 depicts preparation of cellulose functionalized with switchable group 3-(dimethylamino)-1-propylamine via synthetic method 1;

[00108] Figure 36 depicts preparation of cellulose functionalized with switchable group 3-(dimethylamino)-1-propylamine via synthetic method 2;

[00109] Figure 37 depicts a preparation of a functionalized filter paper via a CDI-medited coupling reaction (Method 2);

[00110] Figure 38 depicts a preparation of a functionalized filter paper via a CDI-medited coupling reaction (Method 3);

[00111] Figure 39 depicts a preparation of a functionalized filter paper via a CDI-medited coupling reaction (Method 4);

[00112] Figure 40 depicts grafting switchable polymers from crystalline nanocellulose via nitroxide-mediated polymerization

[00113] Figure 41 depicts a graphical representation of 4-potential and pH
measurements for CNC-g-PDMAEMA in the presence of glycolic acid (GlAc) 0.5 M
and NaOH 0.5 M;

[00114] Figure 42 depicts a graphical representation of 4-potential and pH
measurements for CNC-g-PDEAEMA in the presence of glycolic acid (GlAc) 0.5 M
and NaOH 0.5 M;

[00115] Figure 43 depicts a graphical representation of 4-potential and pH
measurements for CNC-g-PDMAPMAm in the presence of glycolic acid (GlAc) 0.5 M
and NaOH 0.5 M;

[00116] Figure 44 depicts a graphical representation of 4-potential and pH
measurements for CNC-g-PDMAEMA in the presence of CO2/N2;

[00117] Figure 45 depicts a graphical representation of 4-potential and pH
measurements for CNC-g-PDEAEMA in the presence of CO2/N2;

[00118] Figure 46 depicts a graphical representation of 4-potential and pH
measurements for CNC-g-PDMAPMAm in the presence of of CO2/N2;

[00119] Figure 47 depicts a graphical representation of pKaH values required for a base to have a specified % protonation when mixed with water at 25 C. Dashed lines show =
required pKaH to obtain specified % protonation in absence of CO2. Solid lines show pKaH
required to obtain specified % protonation values in presence of 0.1 MPa of CO2; and

[00120] Figure 48 depicts a graphical representation of pKaH values required for a base to have a specified % protonation when mixed with water at 60 C. Dashed lines show required pKaH to obtain specified % protonation in absence of 002. Solid lines show pKaH
required to obtain specified % protonation values in presence of 0.1 MPa of CO2.
DETAILED DESCRIPTION

[00121] Definitions

[00122] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[00123] As used in the specification and claims, the singular forms "a", "an" and "the"
include plural references unless the context clearly dictates otherwise.

[00124] The term "comprising" as used herein will be understood to mean that the list following is non-exhaustive and may or may not include any other additional suitable items, for example one or more further feature(s), component(s) and/or ingredient(s) as appropriate.

[00125] As used herein, "switchable moiety" refers to a N-containing functional group that exists in a first form, such as a hydrophobic form, at a first partial pressure of 002, and, in the presence of water or other aqueous solutions, exists in a second form, such as a hydrophilic form, at a second partial pressure of CO2 that is higher than the first partial pressure of 002. This term also applies to cases wherein COS, CS2, or a mixture of any or all of 002, COS, or CS2, is employed in place of CO2 recited above. The switchable moiety may be an amine, amidine, or guanidine that comprises a nitrogen atom sufficiently basic to be protonated by an ionizing trigger such as 002, COS, CS2, or a combination thereof.

[00126] As used herein, the term "unsubstituted" refers to any open valence of an atom being occupied by hydrogen. Also, if an occupant of an open valence position on an atom is not specified then it is hydrogen.

=

[00127] As used herein, "substituted" means having one or more substituent moieties present that either facilitates or improves desired reactions and/or functions of the invention, or does not impede desired reactions and/or functions of the invention.
Examples of substituents include alkyl, alkenyl, alkynyl, aryl, aryl-halide, heteroaryl, cyclyl (non-aromatic ring), Si(alkyl)3, Si(alkoxy)3, halo, alkoxyl, amino, amide, amidine, hydroxyl, thioether, alkylcarbonyl, alkylcarbonyloxy, arylcarbonyloxy, alkoxycarbonyloxy, aryloxycarbonyloxy, carbonate, alkoxycarbonyl, aminocarbonyl, alkylthiocarbonyl, phosphate, phosphate ester, phosphonato, phosphinato, cyano, acylamino, imino, sulfhydryl, alkylthio, arylthio, thiocarboxylate, dithiocarboxylate, sulfate, sulfato, sulfamoyl, sulfonamide, nitro, nitrile, azido, heterocyclyl, ether, ester, silicon-containing moieties, thioester, or a combination thereof. Preferable substituents are alkyl, aryl, heteroaryl, and ether. Alkyl halides are known to be quite reactive, and are acceptable so long as they do not interfere with the desired reaction.

[00128] As used herein, "aliphatic" refers to hydrocarbon moieties that are linear, branched or cyclic, may be alkyl, alkenyl or alkynyl, and may be substituted or unsubstituted. "Aryl" means a moiety including a substituted or unsubstituted aromatic ring, including heteroaryl moieties and moieties with more than one conjugated aromatic ring;
optionally it may also include one or more non-aromatic ring. "C5 to Cio Aryl"
means a moiety including a substituted or unsubstituted aromatic ring having from 5 to 10 carbon atoms in one or more conjugated aromatic rings. Examples of aryl moieties include phenyl, biphenyl, naphthyl and xylyl.

[00129] As used herein, "alkyl" or "alkylene" refers to a linear, branched or cyclic, saturated or unsaturated hydrocarbon, which consists solely of single-bonded carbon and hydrogen atoms, which can be unsubstituted or is optionally substituted with one or more substituents; for example, a methyl or ethyl group. Examples of saturated straight or branched chain alkyl groups include, but are not limited to, methyl, ethyl, 1-propyl, 2-propyl, 1-butyl, 2-butyl, 2-methyl-1-propyl, 2-methyl-2-propyl, 1-pentyl, 2-pentyl, 3-pentyl, 2-methyl-1-butyl, 3-methyl-1-butyl, 2-methyl-3-butyl, 2,2-dimethy1-1-propyl, 1-hexyl, 2-hexyl, 3-hexyl, 2-methyl-1-pentyl, 3-methyl-1-pentyl, 4-methyl-1-pentyl, 2-methyl-2-pentyl, 3-methyl-2-pentyl, 4-methyl-2-pentyl, 2,2-dimethy1-1-butyl, 3,3-dimethy1-1-butyl and 2-ethyl-1-butyl, 1-heptyl and 1-octyl. As used herein the term "alkyl" encompasses cyclic alkyls, or cycloalkyl groups.

CA 02918904 2016-01-.26

[00130] As used herein, "alkenyl" or "alkenylene" refers to a hydrocarbon moiety that is linear, branched or cyclic and comprises at least one carbon to carbon double bond which can be unsubstituted or optionally substituted with one or more substituents.
"Alkynyl" or "alkynylene" refers to a hydrocarbon moiety that is linear, branched or cyclic and comprises at least one carbon to carbon triple bond which can be unsubstituted or optionally substituted with one or more substituents.

[00131] As used herein, "aryl" or "arylene" refers to hydrocarbons derived from benzene or a benzene derivative that are unsaturated aromatic carbocyclic groups from 5 to 100 carbon atoms, or from which may or may not be a fused ring system, in some embodiments 5 to 50, in other embodiments 5 to 25, and in still other embodiments 5 to 15.
The aryls may have a single or multiple rings. The term "aryl" or "arylene" as used herein also include substituted aryls. Examples include, but are not limited to, phenyl, naphthyl, xylene, phenylethane, substituted phenyl, substituted naphthyl, substituted xylene, substituted 4-ethylphenyl, etc.

[00132] As used herein, "cycloalkyl" refers to a non-aromatic, saturated monocyclic, bicyclic or tricyclic hydrocarbon ring system containing at least 3 carbon atoms. Examples of C3-C cycloalkyl groups include, but are not limited to, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, norbornyl, adamantyl, bicyclo[2.2.2]oct-2-enyl, and bicyclo[2.2.2]octyl.

[00133] As used herein, "cycle" refers to an aromatic or nonaromatic monocyclic or bicyclic ring of carbon atoms, and which can be substituted or unsubstituted.
Included within the term "cycle" are cycloalkyls and aryls, as defined above.

[00134] As used herein, "heteroaryl" refers to a moiety including a substituted or unsubstituted aryl ring or ring system having from 3 to 20, or 4 to 10 carbon atoms and at least one heteroatom in one or more conjugated aromatic rings. As used herein, "heteroatom" refers to non-carbon and non-hydrogen atoms, such as, for example, 0, S, and N. Examples of heteroaryl moieties include pyridyl, bipyridyl, indolyl, thienyl, and quinolinyl.

[00135] As used herein, a "heterocycle" is an aromatic or nonaromatic monocyclic or bicyclic ring of carbon atoms and from 1 to 10, or 1 to 4, heteroatoms selected from oxygen, nitrogen and sulfur, and which can be substituted or unsubstituted. Included within the term "heterocycle" are heteroaryls, as defined above.

[00136] As used herein, "polysaccharide" refers to polymeric carbohydrate molecules composed of chains of monosaccharide monomer units, which range in structure from linear to highly branched. Repeating units in the polysaccharide may include one or more rings.
The polysaccharide may comprise chains, or chains of rings, wherein the monomer units are non-repeating. The polysaccharide may contain some sections or branches of repeating monomer units and some sections or branches that comprise non-repeating monomers. The polysaccharide may be branched or linear. As used herein, "polysaccharides"
also refer to oligosaccharides, which may encompass, but is not limited to di- and tri-saccharides.

[00137] The term "switch/switched" means that physical properties have been modified. "Switchable" means able to be converted from a first form with a first set of physical properties, e.g., a hydrophobic form, to a second form with a second set of physical properties, e.g., a hydrophilic form, or vice-versa from the second state to the first state. A
"trigger" is a change of conditions (e.g., introduction or removal of a gas, change in temperature) that causes a change in physical properties. The term "reversible" means that a reaction can proceed in either direction (backward or forward) depending on reaction conditions.

[00138] It should be understood, for the purposes of this application, that any switch that can be induced by CO2 can also be induced by COS, CS2, a combination thereof, or a mixture of CO2 with any one of, or both of, COS and CS2.

[00139] As used herein, "carbonated water" means a solution of water in which carbon dioxide has been dissolved, at any partial pressure.

[00140] As used herein, an "inert gas" means that the gas has insufficient carbon dioxide, CS2 or COS content to interfere with removal of carbon dioxide, CS2 or COS from a switchable moiety and/or a gas that has insufficient acidity to maintain a switchable moiety in its second, hydrophilic form. For some applications, air may be a gas that has substantially no carbon dioxide, CS2 or COS and is insufficiently acidic. Untreated air may also be successfully employed, i.e., air in which the carbon dioxide, CS2 or COS
content is unaltered; this would provide a cost saving. For instance, air may be an insufficiently acidic gas that has substantially no carbon dioxide because in some circumstances, the approximately 0.04% by volume of carbon dioxide present in air is insufficient to maintain a switchable moiety in its second form, such that air can be a trigger used to remove carbon dioxide from a switchable moiety and cause switching.

[00141] As used herein, the term "hydrogen carbonate" refers to a switchable moiety's second form's counter ion, with a formula [HCO3]. However, wherein CS2, COS, or a combination thereof has been used, the counter ion will have a formula [HCE3]-, where E is 0, S, or a combination thereof.

[00142] As used herein, "annidine" refers to a switchable functional group with a structure such as X-N=CR3NR4R5, R3N=C(-X)NR4R5, R3NH=CR4N(-X)R5where R3 through R5 are hydrogen or alkyl, alkenyl, alkynyl, aryl, or heteroaryl, each of which may be substituted, and X indicates a point of attachment. The second, ionic form of an amidine after exposure to carbon dioxide, CS2 or COS is termed an "amidinium hydrogen carbonate".
As would be readily appreciated by a worker skilled in the art, the structures drawn herein to depict amidines encompass all rotational isomers thereof.

[00143] As used herein, "amine" refers to a switchable functional group with a structure -NR1 R2, where R1 and R2 are hydrogen or alkyl, alkenyl, alkynyl, aryl, or heteroaryl, each of which may be substituted. The second, ionic form of an amine after exposure to carbon dioxide, CS2 or COS, or a combination thereof, is termed an "ammonium hydrogen carbonate".

[00144] As used herein, "guanidine" refers to a switchable functional group with a structure such as X-N=CNR4R5NR6R7, R3N=CN(X)R5NR6R7, R3N=CNR4R5N(X)R7where R3 through R7 are hydrogen or alkyl, alkenyl, alkynyl, aryl, or heteroaryl, each of which may be substituted, and X indicates a point of attachment. The second, ionic form of an guanidine after exposure to carbon dioxide, CS2 or COS is termed an "guanidinium hydrogen carbonate". As would be readily appreciated by a worker skilled in the art, the structures drawn herein to depict guanidines encompass all rotational isomers thereof.

[00145] As used herein, "sterically hindered group" refers to any functional group or substituent that causes steric crowding. Inclusion of a sterically hindered group around a switchable moiety, as defined herein, can inhibit formation of a carbamate salt upon exposure of the switchable moiety to an ionizing trigger.

[00146] As used herein, "ionic" means containing or involving or occurring in the form of positively or negatively charged ions, i.e., charged moieties. "Neutral" as used herein means that there is no net charge. "Ionic salt" and "salt" as used herein are used interchangeably to refer to compounds formed from positively and negatively charged ions.
These terms do not imply a physical state (i.e., liquid, gas or solid). It is important to note, however, that the terms "neutral form" and "ionic form" when used to refer to switchable polysaccharides do not refer to the overall ionized state of the polysaccharide. As would be readily appreciated by a worker skilled in the art, the switchable polysaccharide can comprise other functional groups that do not change their ionic state in response to the addition or removal of an ionizing trigger. Furthermore, in switching a switchable polysaccharide, the polysaccharide may not become fully ionized or neutralized at each switchable moiety by addition or reduction/removal of CO2, respectively.
However, the most fully ionized form, under the conditions used, is referred to herein as the ionic form and the most fully neutralized form is referred to herein as the neutral form.

[00147] As used herein, "hydrophobic" is a property of a switchable moiety or composite material that results in it repelling water. Hydrophobic moieties or materials are usually nonpolar, and have little or no hydrogen bonding ability. Such molecules are thus compatible with other neutral and nonpolar molecules.

[00148] As used herein, "hydrophilic" is a property of a switchable moiety or composite material that results in it attracting water. Hydrophilic moieties or materials are usually polar/ionized, and have a hydrogen bonding ability. Such molecules are thus compatible with other ionized/polar molecules.

[00149] As used herein, the term "contaminant" refers to one or more compounds that is intended to be removed from a mixture and/or surface and is not intended to imply that the contaminant has no value. For example, oil, which has significant value, may conveniently be called a contaminant when describing oil sands.

[00150] Embodiments .

[00151] A composite material has now been developed that comprises a polysaccharide and polysaccharide-supported switchable moiety. The switchable moiety includes a functional group that is switchable between a first form and a second form. Such composite materials are termed switchable natural materials. The composite material's first form is neutral and hydrophobic, and its second form is ionized and hydrophilic. The composite material converts from one form to another when in the substantial presence of or substantial absence of an ionizing trigger. Descriptions of such triggers, and uses for these materials will follow a description of the composite material.

CA 02918904 2016-01-.26

[00152] Jessop et al. have described previously switchable materials having switchable stimuli-responsive properties (see International Patent Application No.
PCT/CA2014/050897 entitled Switchable Materials, Methods and Uses Thereof).
That is, materials that can reversibly switch between a hydrophobic form and a hydrophilic form upon application of external stimuli. Such switchable materials are used, for example, as switchable drying agents and/or surfaces. As described, these switchable materials comprised non-ionized forms of general formulas (A) and (Bi, Bii and Biii):
( R1 R2 ) \ N
In X
I
(A);
/ R4 R5 \ R3 r\l / R5 \ / N
I I II
\ RN / \ R4- 'C' 'IR3/n \R5 R4 jn I n I I
X X X

(Bi); (Bii); (Biii);
wherein X is bound to a solid.

[00153] The switchable materials of PCT/CA2014/050897 comprised ionized forms of general formulas (C) and (Da-c):
7 0 \

1 R1 FiCIR2 I
X

(C);
( R4 R5 \ 7 03 HN V R \
I H 0 li Hco?
li HCO 3 N, 0 N
, C \ R4 C -- R3 R5 C
R3 - NH /n in n X X X
I I
(Da); (Db); (Dc);
wherein X is bound to a solid.

[00154] These switchable materials relied on a known, readily reversible, reaction of water with an acid gas, such as CO2, COS, CS2, or a mixture thereof, that allowed it to bind to amines, amidines and related compounds; for example, see Equation 1:
NR3 + H20 + CO2-4 [NR3H+][HCO3-] (Eq. 1).

[00155] These switchable materials can be used as switchable drying agents, such as switchable particle beads; switchable chromatography supports for separation applications;
and switchable surfaces to provide hydrophobic / hydrophilic, super-hydrophobic / super-hydrophilic, or super-oleophilic / super-oleophobic surfaces, for example, for cleaning applications. The solid to which the switchable group of the switchable materials was bound, as described in PCT application PCT/CA2014/050897, comprised polymeric materials, such as polymeric beads thin films, or monoliths; silica-based materials, such as glass, mesoporous silica or silica gel; semi-metallic or metallic composite materials such as steel, silicon wafers, silicon oxides, or gold-films.

[00156] None of the materials described in PCT application comprised a switchable moiety bound to the surface of polysaccharide-based material such as CNCs or other similar polysaccharides (e.g., cellulose, cotton, starch, hemicellulose, dextran, and chitin/chitosan).

[00157] Stimuli-responsive Polysaccharide-based Materials CA 02918904 2016-01-.26

[00158] As discussed above, stimuli-responsive polysaccharides have been previously investigated and described. For example, pH-responsive CNCs have been prepared by covalently introducing, for example, carboxyl or amine functionalities onto CNC
surface through small molecule modification or polymer grafting.
Thermoresponsive CNCs has also been prepared via surface grafting of thermoresponsive polymers such as poly(N-isopropylacrylamide) (PNIPAM) or polyethylene glycol (PEG) [Zoppe, J. 0.;
Habibi, Y.;
Rojas, 0. J.; Venditti, R. A.; Johansson, L. S.; Efimenko, K.; Osterberg, M.;
Laine, J.
Biomacromolecules 2010, 11, 2683-2691]. However, manipulation of colloidal dispersibility by either pH or temperature may present challenges, particularly if applying such systems to industrial processes; for example, with pH-responsive CNC dispersions, pH
adjustment generally occurs by adding acid or base, though removal of resultant electrolytes from final CNC products may be time-consuming and potentially incomplete. Further, repeated pH
adjustment may result in salt accumulation, and a commensurate increase in ionic strength that may negatively affect colloidal stability.

[00159] For thermoresponsive CNC dispersions, manipulation of dispersion temperature can be energy-consuming and/or time-consuming, which could become problematic when a large volume of CNC dispersion is used.

[00160] Other approaches for collecting/redispersing CNC have utilized centrifugation or membrane process, with techniques such as sonication has been used for redispersion.
Centrifugation of CNC dispersions generally requires high centrifugal force using potentially costly instruments. Membrane processes are generally considered to be cost-effective processes that can be scaled up for industrial production, however, these processes are often inefficient with respect to fouling when separating nanoparticles, such as CNC.
Sonication for redispersing CNC cakes, which may be physically hard and thus difficult to redisperse, after centrifugation or membrane process is also energy-intensive, and not easily scaled up [Habibi, Y.; Lucia, L. A.; Rojas, 0. J. Chem. Rev. 2010, 110,3479-3500; Klemm, D.; Kramer, F.; Moritz, S.; Lindstrom, T.; Ankerfors, M.; Gray, D.; Dorris, A.
Angew. Chem., Int. Ed. 2011, 50, 5438-5466].

[00161] It has generally been observed that such stimuli-responsive materials (e.g., non-acid gas pH- and/or thermo-responsive materials) do not exhibit a reproducible switch from one form to another, such as is reproducibly observed with the previously discussed switchable technologies (e.g., switchable materials, switchable surfactants, etc.); further, it has been observed that many pH-responsive materials lack a sufficient CO2-responsiveness CA 02918904 2016-01-.26 to function as a herein described switchable material or technology (e.g. lack a pH
responsive moiety sufficiently basic to be protonated by an acid gas, such as CO2).

[00162] Switchable Polysaccharides, Synthesis and Applications Thereof

[00163] Switchable Polysaccharides

[00164] It has now been found that composite materials having switchable properties can be successfully prepared by incorporation of one or more switchable moieties on a polysaccharide via a cross-linker. Accordingly, the present application provides composite material that is reversibly switchable between a first form and a second form, said composite material comprising a polysaccharide and polysaccharide-supported switchable moiety attached to said polysaccharide via a linker, the switchable moiety comprising a functional group that is switchable between a neutral form associated with said first form of said composite material, and an ionized form associated with said second form of the composite material, wherein the switchable moiety comprises an amine, amidine, or guanidine.

[00165] In accordance with one embodiment, there is provided a composite material wherein the switchable moiety is an amine and the neutral form of the switchable moiety is bound to the polysaccharide via a linker XY; and wherein the first form of the composite material has the structure of formula - -.{(R 1 \ N/P2) n I
X
...
I -m 1-Y P
I;and (1) the second form of the composite material comprising the ionized form of the switchable moiety bound to the polysaccharide via a linker XY has the structure of formula 2 CA 02918904 2.016-01726 - _ i-( H
R1 ..........R2 xN HCE3 ) I n - m 1-Y P
I (2);
wherein:
n is an integer 1, 2 or 3;
p is an integer between 1 and 4, wherein when Y is absent, p is 1;
m is an integer between 1 and 10 000, wherein m x p is 10 000 of less; or, m is an integer between 1 and 10 000 when Y is absent;
E is 0, S, or a combination thereof;
Y is absent, or a divalent moiety bonded to the polysaccharide and X, and is a linear or branched C1-C15 alkylene, a C15-C30 alkylene, a Cl-C15 alkenylene, a alkenylene, a Ci-C15 alkynylene, a C15-C30 alkynylene, an arylene, a heteroarylene, a thiol, a silane, or a siloxane, each of which may be substituted; or, Y is a divalent cycle, or heterocycle, each of which may be substituted;
each X is a divalent moiety bonded Y, or to the polysaccharide when Y is absent, and the switchable moiety; each X is independently a linear or branched C1-C15 alkylene, a C15-C30 alkylene, a C1-C15 alkenylene, a C15-C30 alkenylene, a Ci-alkynylene, a C15-C30 alkynylene, an arylene, a heteroarylene, a thiol, a silane, or a siloxane, each of which may be substituted; or, each X is independently is a divalent cycle, or heterocycle, each of which may be substituted; or, each X, and one or two of R1 and IR', together with the atoms to which they are attached, are connected to form a heterocycle, which may be substituted;
wherein each X optionally comprises one or more amine, amide, amidine, guanidine, carbamate ester, carbonate diester, ether, ester, thioether, thioester, silane, silyl alkyl ether, or siloxane moieties, or a combination thereof, within its linear or branched carbon chain, or at one of said chain's termini; and NR1R2 and NR1R2+ are each a switchable functional group, wherein IR1 and R2 are each independently H, a Ci to Clo aliphatic group that is linear, branched, or cyclic, a CnSim group where n and m are independently a number from 0 to 10 and n + m is a number from 1 to 10, a C5 to C10 aryl group, or a heteroaryl group having 4 to 10 ring atoms, each of which may be substituted; or R1 and R2, together with the atoms to which they are attached, are connected to form a cycle, or heterocycle, each of which may be substituted; or R2 is repeat unit -(X-NR1)m-Z, wherein m, X and R1 are as defined above, and Z
is a monovalent moiety bonded to the switchable functional group, and is a linear or branched C1-C15 alkyl, a C15-C30 alkyl, a Cl-C15 alkenyl, a C15-C30 alkenyl, a Ci-C15 alkynyl, a C15-C30 alkynyl, an aryl, a heteroaryl, a thiol, a silane, or a siloxane, each of which may be substituted; or, Z is a monovalent cycle, or heterocycle, each of which may be substituted;
wherein, [X(NR1R2)r]m and [X(NR1R2)dm constitute a chain of repeat units that is linear or branched, each repeat unit in said chain being the same, or different, relative to other repeat units; and wherein, (a) if both of R1 and R2 are H, than X is a sterically hindered group or, (b) if one of R1 and R2 is H, then either (i) the other one of R1 and R2 is a sterically hindered group, or (ii) X is a sterically hindered group.

[00166] In accordance with another embodiment, there is provided a composite material wherein the first form of the composite material has the structure of formula la when Y is absent, p is 1, and R2 is repeat unit -(X-NR1)m-Z, Z
/ I
I
\ X
in1 (la); and the second form of the composite material has the structure of formula 2a, Z

(H¨R1 I
X
1 HCEP \
/rn (2a).

[00167] In accordance with another embodiment, there is provided a composite material wherein the first form of the composite material has the structure of formula lc when Y is absent, p is 1, and m is 1, / \

\
I / n x (lc); and the second form of the composite material has the structure of formula 2c, / 0 \
1:11 H./ R2 0 \ N HCE3 i I / n x I
(2c).

[00168] In accordance with another embodiment, there is provided a composite material comprising a polysaccharide and polysaccharide-supported switchable moiety, wherein the switchable moiety is an amine and the neutral form of the switchable moiety is bound to a polysaccharide via a linker X, wherein the first form of the composite material has the structure of formula 1, with a proviso that, when the polysaccharide is a CNC, Y is absent, p is 1, and X is -CH2-C(CH3)2-0O2-(CH2)2-, only one of R1 and R2 is CH3.

[00169] In accordance with another embodiment, there is provided a composite material wherein the switchable moiety is an amidine and the neutral form of the switchable moiety is bound to the polysaccharide via a linker XY; and wherein the first form of the composite material has the structure of formula 3a, 3b, or 3c, I
1 1 ..i ( R'RcN:RN5 \
I
l P N5 -7 I' R4.--- ......,c1,-,...- =-=.,R3 -I
I /
-I
1 -m P -ll _(R5 XN11 'c'1:14 \ -/
-m}
P
Y Y Y

(3a) (3b) (3c); and the second form of the composite material comprising the ionized form of the switchable moiety bound to the polysaccharide via a linker XY has the structure of formula 4a, 4b, 4c, -lie t -( R5 HCEP \ - - 7 R4 R5 \ HN,R3 e \
NI I H 0 I: HCE3 .- s().,N FicE 3 N R4 R NH R 5 =C
I I \
c,, c = R3 N 3 '--X
I -I
P I -I -P 1_ I -m}
P
Y Y Y

(4a) (4b) (4c);
wherein:
n is an integer 1, 2 or 3;
p is an integer between 1 and 4, wherein when Y is absent, p is 1;
m is an integer between 1 and 10 000, wherein m x p is 10 000 of less; or, m is an integer between 1 and 10 000 when Y is absent;

E is 0, S, or a combination thereof;
Y is absent, or a divalent moiety bonded to the polysaccharide and X, and is a linear or branched Cl-C15 alkylene, a C15-C30 alkylene, a Ci-C15 alkenylene, a alkenylene, a Cl-C15 alkynylene, a C15-C30 alkynylene, an arylene, a heteroarylene, a thiol, a silane, or a siloxane, each of which may be substituted; or, Y is a divalent cycle, or heterocycle, each of which may be substituted;
each X is a divalent moiety bonded Y, or to the polysaccharide when Y is absent, and the switchable functional group; each X is independently a linear or branched Ci-C15 alkylene, a C15-C30 alkylene, a Ci-C15 alkenylene, a C15-C30 alkenylene, a alkynylene, a C15-C30 alkynylene, an arylene, a heteroarylene, a thiol, a silane, or a siloxane, each of which may be substituted; or, each X is independently is a divalent cycle, or heterocycle, each of which may be substituted; or, each X, and one or more of R3, R4, and R5, together with the atoms to which they are attached, are connected to form a heterocycle, which may be substituted; and wherein each X optionally comprises one or more amine, amide, amidine, guanidine, carbamate ester, carbonate diester, ether, ester, thioether, thioester, silane, silyl alkyl ether, or siloxane moieties, or a combination thereof, within its linear or branched carbon chain, or at one of said chain's termini; and N=CR3NR4R5 , R3N=CNR4R5, R3N=CR4NR5, and (N=CR3NR4R5)+, (R3N=CNR4R5)+, (R3N=CR4NR5)+ are each switchable functional groups, wherein R3, R4, and R5 are independently H, a C1 to Cio aliphatic group that is linear, branched, or cyclic;
a CnSim group where n and m are independently a number from 0 to 10 and n + m is a number from 1 to 10, a C5 to C10 aryl group, or a heteroaryl group having from 4 to 10 carbon atoms in the aromatic ring, each of which may be substituted; or, any combination of R3, R4, and R5, together with the atoms to which they are attached, are connected to form a heterocycle, which may be substituted; or, any one of R3, R4, and R5 is repeat unit -(X-N=CR3NR4)m-Z, -(X-N=CNR4R5)m-Z;
or -(X-C=NR3NR4)m-Z, -(X-C=NNR4R5)m-Z; or -(X-NCR4=NR3)m-Z, -(X-NR5CR4.1\)m-Z, -(X-NR5C=NR3),-Z, wherein X and R3, R4, and R5 are as defined above, and Z is a monovalent moiety bonded to the switchable functional group, and is a linear or branched C1-C15 alkyl, a C15-C30 alkyl, a Ci-C15 alkenyl, a C15-C30 alkenyl, a Ci-C15 alkynyl, a C15-C30 alkynyl, an aryl, a heteroaryl, a thiol, a silane, or a siloxane, each of CA 02918904 2,016-01726 which may be substituted; or, Z is a monovalent cycle, or heterocycle, each of which may be substituted;
wherein, [X(N=CR3NR4R5)dm, [X(R3N=CNR4R5)n]m, [X(R3N=CR4NR5)n]m, and [X(N=CR3NR4R5),]m, [X(R3N=CNR4R5)n]m, [X(R3N=CR4NR5+)dm constitute a chain of repeats units that is linear or branched, each repeat unit in said chain being the same, or different, relative to other repeat units.

[00170] In accordance with another embodiment, there is provided a composite material wherein the first form of the composite material has the structure of formula 3d, 3d', 3e, 3e', 3f, 3f', or 3f" when Y is absent, p is 1, and R3, R4, or R5 is repeat unit -(X-N=CR3NR4)m-Z, -(X-N=CNR4R5)m-Z; or -(X-C=NR3NR4)m-Z, -(X-C=NNR4R5)m-Z; or -(X-NCR4=NR3)m-Z, -(X-NR5CR4=N)m-Z, -(X-NR5C=NR3)m-Z, Z

4 --\Z R5 4N ( ,N \
N
I I N
R3 Tim C

N
\ Z I X /
= I m ; m (3d) (3d') (3e) z i N7c IN, A

R4 C R4 NVc\ R4 \ \ \

1 im I R3) 7 m I im ; ; ;
(3e') (3f) (3f) il NV
\ I Z
I m (3f"); and the second form of the composite material has the structure of formula 4d, 4d', 4e, 4e', 4f, 4f', or 4f", Z

N
e I: lir+) HCE3 .0 Cs"'" R4 N
HCE3 vEc)...N R3 C
..- ' -=- NH / e R3 = 11H / HCE3 /
Z I /
X / X im I m = 1 m = I =
(4d) (4d') (4e);

7 il--Z

7 IN.@ \ z,,(, HN, el N_7=CR4 R5 R47 C.= - c N R4 \ X

m = 1 FICE 3 irn x I ; \ 1 HcE3 in \ x I ;or , (4e') (4f) (4f') t:
R5 = u ,,,, .7 N
e I FICE3 z I m (4f").

[00171] In accordance with another embodiment, there is provided a composite material wherein the first form of the composite material has the structure of formula 3g, 3h, or 3i when Y is absent, p is 1, and m is 1, / R4 1=i5 \
1\1- / R5 \ / R3\N
I I II
,C , \ R3 N in \
xI
xI I
X

(3g) (3h) (3i); and the second form of the composite material has the structure of formula 4g, 4h, or 4i, u,õ R3 7 R nu 4 R5 \ 7 R5 c3 7 HN/
0 \
N I H ci li HcE3 li(.4 HC e N= 0 N R5N,7-CR4 E3 ..-,...
\ R3 -NH / \
/ \ 1 /
I
X X X

(4g); (4h); (4i).

[00172] In accordance with another embodiment, there is provided a composite material wherein the switchable moiety is a guanidine, and the neutral form of the switchable moiety is bound to the polysaccharide via a linker XY; and wherein the first form of the composite material has the structure of formula 5a, 5b, 5c, CA 02918904 2016-01-.26 NH /
HCE3 :I X 0 \-R9: -7 ==,, i I

e Hr\r,Rio R

c¨
R9 --)--------N- = N _ 1HcE
\ I I 11_1 {/ \

CE
H -1 lic, ----"N - = N
I I /

¨ m j P
Y Y Y
I I I
(5a); (5b); (5c);
the second form of the composite material comprising the ionized form of the switchable moiety bound to the polysaccharide via a linker XY has the structure of formula 6a, 6b, 6c, _ 7 c)R.N R6 \
_ HCR9E3 NH
_{
I

X
i 7... e HN
HCE3 k) C
R9 4'= -., /
----N- = N
I
R8 Rio \

I /n 1 { \ x X
1 -m P HCE3 lb C Rio ----N= -N

I I in - m 1 P
Y Y Y

(6a); (6b) ' , (6c); or wherein:
n is an integer 1, 2 or 3;
p is an integer between 1 and 4, wherein when Y is absent, p is 1;
m is an integer between 1 and 10 000, wherein m x p is 10 000 of less; or, m is an integer between 1 and 10 000 when Y is absent;
E is 0, S, or a combination thereof;
Y is absent, or a divalent moiety bonded to the polysaccharide and X, and is a linear or branched Ci-C15 alkylene, a C15-C30 alkylene, a Cl-C15 alkenylene, a alkenylene, a Ci-C15 alkynylene, a C15-C30 alkynylene, an arylene, a heteroarylene, a thiol, a silane, or a siloxane, each of which may be substituted; or, Y is a divalent cycle, or heterocycle, each of which may be substituted;
each X is a divalent moiety bonded Y, or to the polysaccharide when Y is absent, and the switchable functional group; each X is independently a linear or branched C1-C15 alkylene, a C15-C30 alkylene, a Ci-C15 alkenylene, a C15-C30 alkenylene, a alkynylene, a C15-C30 alkynylene, an arylene, a heteroarylene, a thiol, a silane, or a siloxane, each of which may be substituted; or, each X is independently is a divalent cycle, or heterocycle, each of which may be substituted; or, each X, and one or more of R6, R7, ri 1-03, R9 and R19, together with the atoms to which they are attached, are connected to form a heterocycle, which may be substituted; and wherein each X optionally comprises one or more amine, amide, amidine, guanidine, carbamate ester, carbonate diester, ether, ester, thioether, thioester, silane, silyl alkyl ether, or siloxane moieties, or a combination thereof, within its linear or branched carbon chain, or at one of said chain's termini; and N=CNR6R7NR8R9, rs r-oo N=CNR6NR8R9, R10N=CNR6R7NR9, and (N=CNR6R7NR8R9) /Rio +, k N=CNR6NR8R9)+,io.INc r N NR6R7NR9)+ are each switchable ., functional groups, wherein R6, R7, R8, R9 and R19 are independently H, a C1 to Clo aliphatic group that is linear, branched, or cyclic; a CnSim group where n and m are independently a number from 0 to 10 and n + m is a number from 1 to 10, a C5 to C10 aryl group, or a heteroaryl group having from 4 to 10 carbon atoms in the aromatic ring, each of which may be substituted; or, any combination of R6, R7, R8, R9 and R19, together with the atoms to which they are attached, are connected to form a heterocycle, which may be substituted; or, any one of R6, R7, 1:18, R9 and R16 is repeat unit -(X-N=CNR6R7NR8)m-Z, -(X-N=CNR7NR8R9)m-Z, or -(X-NR6C=NNR8R9)m-Z, -(X-NR6C=NR19NR8),õ-Z, -(X-NC L=NRioNR8R9)m_¨, wherein X and R6, R7, R8, R9 and R19 are as defined above, and Z is a monovalent moiety bonded to the switchable functional group, and is a linear or branched C1-C15 alkyl, a C15-C30 alkyl, a Ci-C15 alkenyl, a C15-C30 alkenyl, a Cl-C15 alkynyl, a C15-C30 alkynyl, an aryl, a heteroaryl, a thiol, a silane, or a siloxane, each of which may be substituted; or, Z is a monovalent cycle, or heterocycle, each of which may be substituted;

wherein at least one of R6, R7, R8, R9 and R19 is an electron withdrawing group;
and wherein, [X(N=CN R6R7N R8R9)11m, [X(R10N=CN R6N R8R9)n]m, [X( R1 N=CN R6R7N R9)n]m, [X(N=CN R6 R7N R8R9)dm, [X(R10N=CN R6N
R8R9)+11]m, [X(R10N=CN R6R7N R9)+dm constitute a chain of repeats units that is linear or branched, each repeat unit in said chain being the same, or different, relative to other repeat units.

[00173] In accordance with another embodiment, there is provided a composite material wherein the first form of the composite material has the structure of formula 5d, 5d', 5d", 5e, or 5e' when Y is absent, p is 1, and R6, R7, R8, R9 or R19 is repeat unit -(X-N=CNR6R7NR8)m-Z, -(X-N=CNR7NR8R9)m-Z, or -(X-NR8C=NNR8R9)m-Z, -(X-NR6C=NR19NR8)m-Z, -(X-NC=NR19NR8R9)m-Z, iRl N \ Rl N/
NilI--------Z Z II II Z
1=i8N/C\ N/ R6 /C\ N R6 R8....._N/C\N
N ...
1 \ I
X I I I R8 i R8 I
I m I im (5d); (5d'); (5d");
R7, 1:18\ 7 R7, .. Z
N N
zi I I
/CN R9 /c N ---- N N
I

1 m I m (5e) (5e'); and the second form of the composite material has the structure of formula 6d, 6d', 6d", 6e, or 6e' Rl R10) 7 HN------\--Z HN 7 HN
/
c HCEP h z HcEP I:: m. -.' HCEP
--- lio Z
C
R9 N Nc- R6 - = = N = = N ----NI - = N
\ 1 I I I I
R8 X i R8 \ R8 1 m 1 rn I I m (6d); (6d'); (6d");

Z
R7 ( Rc -...... \
n N
z HCE-1 il 0 HCE-1 N - NH ----N = NH
I
I /M I I

1 1 m (6e) (6e').

[00174] In accordance with another embodiment, there is provided a composite material wherein the first form of the composite material has the structure of formula 5f, 5g, or 5h when Y is absent, p is 1, and m is 1, 7 Rc 1=187 Rio 7 N Rio N N
I II II
\ R9õN/cNR9õN/c\ N/R) R9õN/c\ N/ R8 I I )n \ I I n \ I I /
R8 X R8 X X R7 n (5f) (5g) (5h); and the second form of the composite material has the structure of formula 6f, 6g, or 6h, , N...., ..,,, 6R

7 ,-, HN/ iR o (:-.) iN / ,-, HN
Lr.) ' .-') ii HCE-' il 6). HCE3 I: _a) HCE II
' 3 1a) C C R6 Cli R6 R9----- -7.. / R9 /
'N = - N R9 .- /
'N = = N
I I / \ 1 I / \ 1 x (6f); (6g); (6h).

[00175] In accordance with another embodiment, there is provided a composite material whereinthe switchable moiety is a pyridine, and the neutral form of the switchable moiety is bound to the polysaccharide via a linker XY; and wherein the first form of the composite material has the structure of formula 7, _1 _(\ (R15)0¨._ X _______________________________________ i _ ml P
Y
1 (7); and the second form of the composite material comprising the ionized form of the switchable moiety bound to the polysaccharide via a linker XY has the structure of formula 8, 7 ..1 (R15)0 ,¨_¨ 2,\-x /
_ nnl P
Y

(8), wherein:
n is an integer 1, 2 or 3;
o is an integer 1, 2 or 3;
p is an integer between 1 and 4, wherein when Y is absent, p is 1;
m is an integer between 1 and 10 000, wherein m x p is 10 000 of less; or, m is an integer between 1 and 10 000 when Y is absent;
E is 0, S, or a combination thereof;
Y is absent, or a divalent moiety bonded to the polysaccharide and X, and is a linear or branched C1-C15 alkylene, a C15-C30 alkylene, a C1-C15 alkenylene, a alkenylene, a C1-C15 alkynylene, a C15-C30 alkynylene, an arylene, a heteroarylene, a thiol, a silane, or a siloxane, each of which may be substituted; or, Y is a divalent cycle, or heterocycle, each of which may be substituted;
each X is a divalent moiety bonded Y, or to the polysaccharide when Y is absent, and the switchable moiety; each X is independently a linear or branched C1-C15 alkylene, a C15-C30 alkylene, a Cl-Cis alkenylene, a C15-C30 alkenylene, a Ci-alkynylene, a C15-C30 alkynylene, an arylene, a heteroarylene, a thiol, a silane, or a siloxane, each of which may be substituted; or, each X is independently is a divalent cycle, or heterocycle, each of which may be substituted; or, each X, and one or two of R1 and R2, together with the atoms to which they are attached, are connected to form a heterocycle, which may be substituted;
wherein each X optionally comprises one or more amine, amide, amidine, guanidine, carbamate ester, carbonate diester, ether, ester, thioether, thioester, silane, silyl alkyl ether, or siloxane moieties, or a combination thereof, within its linear or branched carbon chain, or at one of said chain's termini; and (R15)0/=-.-N (R15)0 .NH
)and ) is a switchable functional group, wherein Rth is H, a Ci to Cio aliphatic group that is linear, branched, or cyclic, a CnSirn group where n and m are independently a number from 0 to 10 and n + m is a number from 1 to 10, a C5 to Cio aryl group, or a heteroaryl group having 4 to 10 ring atoms, each of which may be substituted; or any two of R15, together with the atoms to which they are attached, are connected to form a cycle, or heterocycle, each of which may be substituted; or r.¨_¨ N\ z any one of R15 is repeat unit ( x (h15)q in , wherein X and R15 are as defined above, q is integer 1 or 2, and Z is a monovalent moiety bonded to the switchable functional group, and is a linear or branched C1-C15 alkyl, a C15-C30 alkyl, a C1-C15 alkenyl, a C15-C30 alkenyl, a C1-C15 alkynyl, a C15-C30 alkynyl, an aryl, a heteroaryl, a thiol, a silane, or a siloxane, each of which may be substituted; or, Z is a monovalent cycle, or heterocycle, each of which may be substituted;
(R15)0 -/=-N
( )/
in 7 (R15)0 a \ i----- \
S ________________________________________________________ /
n x wherein, ¨ ¨ m and ¨ _m constitute a chain of repeat units that is linear or branched, each repeat unit in said chain being the same, or different, relative to other repeat units.

[00176] In accordance with another embodiment, there is provided a composite material wherein the first form of the composite material has the structure of formula 7a ( x /----N\ z \11/

when Y is absent, p is 1, and R15 is repeat unit (,15)q n, (M15)0 /------- z S _______________________________________ i \ X

(7a); and the second form of the composite material has the structure of formula 8a, -...N1-z )(:' \) FICEP __ , X
im (8a).

[00177] In accordance with another embodiment, there is provided a composite material wherein the first form of the composite material has the structure of formula 7b when Y is absent, p is 1, and m is 1, ((R15)o ,/=---- --N \
X
(7b); and the second form of the composite material has the structure of formula 8b, CA 02918904 2016-01-,26 7 (R15)0 ..,-...21\
in X
(8b).

[00178] In accordance with another embodiment, there is provided a composite material wherein the neutral form of the switchable moiety is bound to the polysaccharide via a linker XY; and wherein the first form of the composite material has the structure of formula 9a, 9b, 9c, or 9d, ¨ RI, C..,_. _ ) /
/R12 Rii\ _N \ II
1\1, __ Nr R
{ \12/ N ---R14/n 1 1 x r - x I
P
v v (9a); (9b);
{/R13 rl ¨/ --c Nc4 1 r \_.
N-- /
Rii )NR13 /¨n }
/ n x x I _ P ¨ I
Y Y P
I I
(9c); (9d); and CA 02918904 2016-01-,26 the second form of the composite material comprising the ionized form of the switchable moiety bound to the polysaccharide via a linker XY has the structure of formula 10a, 10b, 10c, or 10d, ) _____________________ (HCE?
0,,, Ti HCiE43 :
m m ,N,10,,N1H IR11 1 \R12 x x I _ P I _ P
Y Y
I I
(10a); (10b);

_ 414 i \ HiRci4E? i \ N
:I e m ¨/Ril__S/N-0---(N
HcER 12/
n x x n-}-I _ P ¨ I ¨
Y Y P
I I
(10c); (10d); and wherein:
n is an integer 1, 2 or 3;
p is an integer between 1 and 4, wherein when Y is absent, p is 1;
m is an integer between 1 and 10 000, wherein m x p is 10 000 of less; or, m is an integer between 1 and 10 000 when Y is absent;

CA 02918904 2016-01-.26 E is 0, S, or a combination thereof;
Y is absent, or a divalent moiety bonded to the polysaccharide and X, and is a linear or branched C1-C15 alkylene, a C15-C30 alkylene, a C1-C15 alkenylene, a alkenylene, a C1-C15 alkynylene, a C15-C30 alkynylene, an arylene, a heteroarylene, a thiol, a silane, or a siloxane, each of which may be substituted; or, Y is a divalent cycle, or heterocycle, each of which may be substituted;
each X is a divalent moiety bonded Y, or to the polysaccharide when Y is absent, and the switchable moiety; each X is independently a linear or branched C1-C15 alkylene, a C15-C30 alkylene, a Ci-C15 alkenylene, a C15-C30 alkenylene, a Cl-alkynylene, a C15-C30 alkynylene, an arylene, a heteroarylene, a thiol, a silane, or a siloxane, each of which may be substituted; or, each X is independently is a divalent cycle, or heterocycle, each of which may be substituted; or, each X, and one or two of R1 and 1=12, together with the atoms to which they are attached, are connected to form a heterocycle, which may be substituted;
wherein each X optionally comprises one or more amine, amide, amidine, guanidine, carbamate ester, carbonate diester, ether, ester, thioether, thioester, silane, silyl alkyl ether, or siloxane moieties, or a combination thereof, within its linear or branched carbon chain, or at one of said chain's termini; and R11, R12, R13, and rs f-.14 are each independently H, a Ci to Cio aliphatic group that is linear, branched, or cyclic; a CnSim group where n and m are independently a number from 0 to 10 and n + m is a number from 1 to 10, a C5 to C10 aryl group, or a heteroaryl group having from 4 to 10 carbon atoms in the aromatic ring, each of which may be substituted; or, any combination of R11, R12, ri rN13, and R14, together with the atoms to which they are attached, are connected to form a cycle or heterocycle, each of which may be substituted; or any one of R11, R12, R13, and R14 is repeat unit -(X-Im)m-Z, wherein X is as defined above, Im is an optionally substituted imidazole ring, and Z is a monovalent moiety bonded to the switchable functional group, and is a linear or branched alkyl, a C15-C30 alkyl, a C1-C15 alkenyl, a C15-C3o alkenyl, a Cl-C15 alkynyl, a C15-C30 alkynyl, an aryl, a heteroaryl, a thiol, a silane, or a siloxane, each of which may be substituted; or, Z is a monovalent cycle, or heterocycle, each of which may be substituted;

CA 02918904 2016-01-.26 wherein, the repeat unit [X(Im)n]rn and [X(Im)l-n]m constitute a chain of repeat units that is linear or branched, each repeat unit in said chain being the same, or different, relative to other repeat units.

[00179] In accordance with another embodiment, there is provided a composite material wherein the first form of the composite material has the structure of formula 9e, 9f, 9g, or 9h when Y is absent, p is 1, and m is 1, 7R R11 \ R11 i2 ) ____ ( ill N N
R13 C Ri2 c \
õ.õ-- -.......
\ N Ria i 1 in x x (9e); (90;

/ \
7 R14 \
7 R14 _N

/ \ \ Rii___.) I\1 in \

X X
(9g); (9h); and the second form of the composite material has the structure of formula 10e, 10f, 10g, or 10h, CA 02918904 2016-01-.26 r.) ) _____________________ (HCE HCE3`jP NH
NC),I\JH
Ri3 c N
Ri2 _______________________________________________ \--vC
\ \
=7R14 -=
n in x x (10e); (10f);
7 R14 i13 H /R14 \
HcE3 6Nc-.-..-- Ri2 e \ / ile/
Ril \clA FicE3 NF113 1-I'N /
X X
(10g); (10h).

[00180] In accordance with another embodiment, there is provided a composite material comprising a polysaccharide and polysaccharide-supported switchable moiety, wherein the switchable moiety is an amidine and the neutral form of the switchable moiety is bound to the polysaccharide via a linker X, and wherein the first form of the composite material has the structure of formula 9f, with the proviso that, when the polysaccharide is a CNC, n is 1, and X is -0O2-NH-(CH2)3-, only two of R11, R12, or R14 is H.

[00181] In accordance with another embodiment, there is provided a composite material wherein the first form of the composite material has the structure CA 02918904 2016-01:26 el 0 _______________________________ (NH

I .
, and the second form of the composite material has the structure e"NH
...9, _____________________________ e N _________________________________ HCE3 0 _________________________________ (NH

1 .

[00182] In accordance with another embodiment, there is provided a composite material wherein the polysaccharide is cellulose nanocrystal (CNC), cellulose, dextran, cotton, starch, chitin, chitosan, or any combination thereof.

[00183] In accordance with another embodiment, there is provided a composite material wherein said first form of the composite material is neutral and hydrophobic, and the second form of the composite material is ionized and hydrophilic.

[00184] In accordance with another embodiment, there is provided a second form of the composite material wherein % ionization of the material's switchable moieties is 5100`)/0;
or alternatively, 575%; or alternatively 550`)/0.

[00185] In accordance with another embodiment, there is provided a composite material wherein each repeating unit of formulas 1 and 2, or la and 2a; 3a, 3h, 3c and 4a, 4b, 4c, or 3d, 3d', 3e, 3e', 3f, 3f', 3f" and 4d, 4d', 4e, 4e', 4f, 4f', 4f";
5a, 5b, 5c and 6a, 6b, 6c, or 5d, 5d', 5d", 5e, 5e' and 6d, 6d', 6d", 6e, 6e'; 7 and 8, or 7a and 8a;
or 9a, 9b, 9c, 9d, and 10a, 10b, 10c, 10d is either the same, or different, relative to other repeat units, thus forming a homopolymer or a copolymer. In one embodiment, said copolymer is a graft copolymer or block copolymer. In another embodiment, the copolymer is a random copolymer.

[00186] Synthesis

[00187] As herein described, there is a one-step modification process for preparation of switchable polysaccharides, wherein the polysaccharides' surface is functionalized with a switchable group, as defined above. Once modified, the polysaccharides can be switched from a neutral/hydrophobic form to an ionized/hydrophilic form in the presence of aqueous media and ionizing triggers, such as CO2, COS, CS2, or a combination thereof, via protonation/ionization of the polysaccharides' switchable group; while exposure to heat, reduced pressure (e.g. vacuum), sparging with a flushing gas (e.g. air, N2), or any combination thereof, either with agitation or no agitation, can switch the polysaccharides from an ionized/hydrophilic form to a neutral/hydrophobic form via deprotonate/de-ionize the polysaccharides' switchable group.

[00188] Examples of polysaccharides that can be functionalized to form a switchable material as described herein include, but are not limited to, CNC, cellulose, hemicellulose, cotton, starch, dextran, and chitin/chitosan, etc.

[00189] In one embodiment, there is described a one-step modification process for preparation of switchable CNCs, wherein the CNCs' surface is functionalized with a switchable group, as defined above. Once modified, the CNCs could be dispersed into aqueous media in the presence of ionizing triggers, such as CO2, COS, CS2, or a combination thereof via protonation/ionization of the CNCs' switchable group;
while exposure to heat, reduced pressure (e.g., vacuum), sparging with a flushing gas (e.g., air, N2), or any combination thereof, can deprotonate/de-ionize the CNCs' switchable group and separate the CNCs from the aqueous phase. Further, surfaces of switchable CNCs may be switched between hydrophilic and hydrophobic states; a switch between hydrophilic and hydrophobic states may provide a difference in adsorption properties, which may be beneficial for adsorption for different adsorbates.

[00190] In another embodiment, there is a switchable polysaccharide comprising an imidazole switchable functional group. It has been found that the imidazole group, as a switchable group, can be protonated when in the presence of an aqueous solution and CO2, COS, CS2, or a combination thereof, within a time frame at least comparable to previously described switchable systems however, it has been found that the imidazole group can be more completely, quickly and/or facilely de-protonated when exposed to flushing gases (e.g.
air, N2), heat, or a vacuum, as compared to previously described switchable systems; for example, it has been experimentally observed that imidazole-based switchable groups switch off within seconds, versus minutes for previous systems [Liu, Y. X.;
Jessop, P. G.;
Cunningham, M.; Eckert, C. A.; Liotta, C. L. Science 2006, 313, 958-960; Chai et al. J.
Surfact. Deterg. 2014, 17, 383-390.]

[00191] Although the present application may generally refer to use of CO2 gas as the external stimulus, or ionizing trigger, to switch a material from its non-protonated/non-ionized form to its protonated/ionized form, it should be understood that the CO2 can be replaced with another acid gas, such as COS, CS2, or a mixture of acid gases. In the case where the acid gas is COS or CS2, the product of the reaction would be a protonated CNC
as a salt with a sulfur substituted bicarbonate analogue. Removal of the CO2 trigger (or other acid gas or mixture thereof) to an amount insufficient to maintain or convert a switchable polysaccharide to its protonated/ionized form, will trigger a switch of the polysaccharide back to its neutral/non-protonated/non-ionized form. This trigger can be, as described above, reduced pressure, a flushing gas, heat, or a combination thereof, either with agitation or no agitation. The flushing gas can be air or an inert gas. Agitation may also be a viable means for removing the CO2 trigger, so long as it is energetically favourable to do so.

[00192] In one embodiment of the application as described herein, it has been considered that said switchable polysaccharides could be synthesized via a coupling reaction between CDI and a carboxylic acid, which is terminally-functionalized to comprise either: (a) a switchable moiety, such as, but not limited to, an amine, amidine, or guanidine;
or, (b) a functional group that can be synthetically transformed into, or coupled to, a switchable moiety. For a demonstrative, non-limiting example of one such synthesis, see Figure 11.

[00193] In another embodiment, it has been considered that said switchable polysaccharides could be synthesized via a coupling reaction between methyl chloroformate and an amine terminally functionalized with a switchable moiety, such as, but not limited to, an amine, amidine, or guanidine. For a demonstrative, non-limiting example of one such synthesis, see Figure 12.

[00194] In yet another embodiment, it has been considered that the switchable polysaccharides could be synthesized via a coupling reaction using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide with, for example, an primary amine functionalized with a switchable moiety.

[00195] Applications

[00196] It has been found that composite materials having switchable properties can be prepared by incorporation of one or more switchable moieties on a polysaccharide via a cross-linker, the present application also provides uses for the composite materials, as described herein.

[00197] Thus, in accordance with another aspect of the application, there is provided a use for the composite materials, as herein described, for: (i) manipulating and/or controlling dispersibility, for example, CNC dispersibility; (ii) for formation of a membrane comprising a chiral nematic liquid crystalline structure; (iii) for water or wastewater treatment, wherein, in one embodiment, the water or wastewater treatment comprises removal of organic contaminants or metal contaminants; (iv) for cleaning a surface; (v) for formation of a switchable fabric; (vi) for formation of a switchable filter paper; (vii) for stabilizing an emulsion; (viii) for use in chromatography; or (ix) any combination thereof.

[00198] In accordance with another aspect of the application, there is provided a use for the composite materials, as herein described, as: (i) a separation membrane; (ii) an absorbent; (iii) a drying agent; (iv) a flocculent; (v) a switchable viscosity modifier; or (vi) any combination thereof.

[00199] Further, as described herein, there are switchable polysaccharides having a surface with switchable hydrophilic/hydrophobic properties: in their neutral/
non-ionized form ('switched off'), the switchable polysaccharides are hydrophobic; in their ionized/protonated form ('switched on'), the switchable polysaccharides are hydrophilic. It has been considered that such switchable hydrophilic / hydrophobic systems may be used in separation applications, or used as adsorbents/flocculants in water/wastewater treatment.

[00200] Further, such a switch in hydrophilic/hydrophobic properties may be useful in adsorption processes to remove hydrophobic organic contaminants from water (e.g.
hydrophobic dyes, aromatics, etc.). For example, switchable polysaccharides, such as switchable CNCs, could be dispersed with aid of an ionizing trigger such as CO2 into wastewater containing hydrophobic contaminants; after complete dispersion of the switchable polysaccharides, a flushing gas (for example), such as N2, could be sparged through the dispersion, thereby precipitating the polysaccharides. During this process, the hydrophobic polysaccharides may adsorb hydrophobic contaminants from the wastewater prior to precipitation; after which the at least partially purified water could be separated from the precipitate, the precipitate could be diluted with water and redispersed in the presence of the ionizing trigger. Other switchable adsorption applications may include removal of ionic species from wastewater (e.g. heavy metals).

[00201] In another embodiment, as described herein, switchable polysaccharides, such as switchable chitosans, can be used to remove metal ions from aqueous solutions.
Once such contaminants are captured, the metal-laden chitosan can be separated from the aqueous solution and collected for a) combustion or digestion to liberate the captured metal, b) disposal or c) regeneration.

[00202] In another embodiment, as described herein, there is proposed use of switchable polysaccharides for controlling colloidal dispersibility. For example: typically, native or modified CNC can be dispersed in aqueous or organic medium, typically via electrostatic or steric stabilization [Dong, X. M.; Revol, J. F.; Gray, D. G.
Cellulose 1998, 5, 19-32]. Once well dispersed, native or modified CNCs can offer a platform for chemical/physical adsorption applications that could utilize CNC's high specific surface area.
However, collecting CNCs from the dispersion may eventually be required; for example, when adsorbate-saturated CNCs have to be removed from a dispersion medium, washed and reused (if possible).

[00203] It is generally understood that colloidal particle dispersibility can be dependent on surface charge and steric effect. Thus, controlling of CNC
dispersibility, by adjusting electrostatic or steric stabilization (if possible), may facilitate CNC
collection/redispersion. This could be further facilitated if the control could be exerted via application of benign stimuli; such as application of an ionizing trigger to a switchable CNC, to form an ionized/hydrophilic CNC.

[00204] Use of an ionizing trigger such as CO2, COS, CS2, or a combination thereof, when manipulating colloidal dispersibilities, allows for removal of the triggers from aqueous media by sparging with inert flushing gases (e.g. air, N2), applying heat or vacuum such that minimal residual ionic strength remains after removal of the CO2 - unlike pH-responsive colloidal dispersions, as described above.

[00205] Contrasted with other stimuli used to manipulate colloidal dispersions, use of ionizing triggers such as CO2, COS, CS2, or a combination thereof, can be more cost-effective (e.g. time cost and energy cost). Moreover, the ionizing trigger-switchable technique can be scaled up for industrial application, as it does not require additional chemicals, special equipment or significant amounts of energy.

[00206] Without wishing to be bound by theory, it has been further considered that switchable polysaccharides could be applied to many applications for which polysaccharides are used.

[00207] For example, when the herein described switchable polysaccharides are manufactured as porous membranes (e.g. microfiltration cellulose membrane), they can be applied to separations of hydrophilic/Iyophilic species; for example, when separating an oil/water mixture using a switchable polysaccharide membrane, it is expected that the water would pass through the membrane when the membrane's switchable functionality is in its protonated, hydrophilic state (i.e. 'switched on'), whereas the oil would not pass through, such that the oil/water mixture is separated. Herein described switchable polysaccharides, such as switchable cellulose, can also be manufactured as a super adsorbent material, such as for use in reusable diapers. For example, once in contact with urine, a relatively weak acid, the diaper's switchable polysaccharide(s) is 'switched on' to a hydrophilic state by protonation of its switchable groups, thereby adsorbing the urine; the diaper can be regenerated after laundering with a relatively weakly basic laundry detergent, which would 'switch off' the switchable polysaccharide(s) by deprotonating its switchable groups, thereby re-establishing the diaper's hydrophobicity.

[00208] In yet another application, switchable polysaccharides can be used in desorption processes wherein a precipitated and/or hydrophobic ('switched off') CNC or polysaccharide containing hydrophobic species can selectively release the species when exposed to ionizing triggers such as CO2. Further, it has been found that herein described switchable CNCs will gel above a certain concentration. It has been considered that this capacity for the CNCs to gel can provide a protective layer around any species that interacts with the 'switched off' CNC through a hydrophobic interaction (e.g., protein);
after which, the contents cam be released upon application of an ionizing trigger.

[00209] With respect to another application of the present switchable polysaccharides, it is known that aqueous dispersions, or alternatively some organic dispersions, of, for example, native CNC, undergo isotropic to anisotropic chiral nematic liquid crystalline phase change when the dispersion passes a critical concentration [Dong, X. M.;
Revol, J. F.; Gray, D. G. Cellulose 1998, 5, 19-32]. Following solvent evaporation, these native CNC
dispersions transform into semi-translucent CNC membranes that retain the chiral nematic liquid crystalline structure formed in dispersion. These membranes can be iridescent, and they reflect left-handed circularly polarized light determined by the chiral nematic pitch of the liquid crystal structure. These membranes show visible iridescence colors when the pitch of their helix is comparable with wavelengths of visible light. Thus, it has been considered that at least some switchable polysaccharides, such as switchable CNCs, can retain a chiral nematic structure, and that their helical pitch can be manipulated by controlling the CNCs switchable groups' degree of protonation, by way of ionizing triggers such as CO2, thereby adjusting the switchable CNCs' surface charge and subsquently influencing distances between CNC particles [Dong, X. M.; Revol, J. F.; Gray, D. G. Cellulose 1998, 5, 19-32]. As such, after drying the switchable CNC aqueous dispersion at room temperature to form membranes, the membrane thus prepared may have different iridescent properties that result from different dispersibilities under different protonation conditions.

[00210] Further to the aforementioned absorption/desorption applications, the herein described switchable polysaccharides may be useful for cleaning delicate surfaces and removing hydrophobic contaminants (e.g. removing dust, dirt, oils, etc). For example, a surface to be cleaned can be dipped into a dispersion of protonated, hydrophilic switchable polysaccharides ('switched on'), such as switchable CNCs, following which the dispersion can be sparged with an inert flushing gas (e.g. air, N2), thereby de-protonating the switchable CNCs, rendering them hydrophobic. The hydrophobic CNC can then 'adsorb' or 'encompass' the surface's hydrophobic impurities and remove them via precipitation or settling. The resultant wet, clean surface can then be dried; for example, by further sparging with an inert flushing gas.

[00211] Further, the herein described switchable polysaccharides may be switchable linens, wherein a linen is functionalized with a switchable moiety, such as an imidazole moiety, to allow the linen to be switched between one form and a second form.
Once functionalized, the linen can be maintained in a hydrophobic state until exposed to an ionizing trigger, such as CO2, COS, CS2, or a combination thereof, in an aqueous solution; at that point, the switchable moieties of the functionalized linen would be ionized, and would thus maintain the linen in a hydrophilic state. Consequently, once the linen was switched into its hydrophilic state, any hydrophobic materials contained within the linen would be expelled out of the linen. This can allow clothes to be washed in water/carbonated water rinse cycles, in the absence of detergents.

[00212] The herein described switchable polysaccharides may also be switchable starches (for example, see Example 4). The switchable starches, once ionized in the presence of an ionizing trigger, such as CO2, COS, CS2, or a combination thereof, and an aqueous solution, can be dissolved and/or dispersed throughout the aqueous solution, and used to capture water-born/aqueous solution-born pollutants such as metal ions. Once the contaminants were captured, the starch could then be switched from its ionized/hydrophilic state to a non-ionized/hydrophobic state, thus rendering the starch insoluble in the aqueous solution, and allowing the metal-laden starch to be separated from the aqueous solution and collected for a) combustion or digestion to liberate the captured metal, b) disposal or c) regeneration.

[00213] Further, said switchable starches can be used as drying agents, to capture and remove water from reaction media, organic solvents, etc. For a demonstrative, non-limiting example: a switchable starch can be added to a wet organic solvent (for example, 5 wt% water content), and the mixture can be exposed to CO2. In the presence of the organic solvent's water content and CO2, the switchable starch switches to its ionized/hydrophilic form, capturing some of the water content in the bicarbonate anion that forms as part of the switchable moiety's ionized form. It is expected that, most, if not all, of any remaining water interacts with the hydrophilic surface of the switchable starch (via a hydration sphere), and that consequently, the now 'wet' starch can be separated from the organic solvent via filtration. The 'wet' switchable starch can then be switched to its neutral/hydrophobic form in the presence of heat and/or a flushing gas, etc.; thus, releasing the captured water, and be ready for re-use.

[00214] The herein described switchable polysaccharides may be used to generate switchable filter paper (for proof of principal example, see Example 5). The filter paper can be functionalized with a switchable moiety capable of switching from one form to a second form, in the presence of an ionizing trigger such as CO2, COS, CS2, or a combination CA 02918904 2016-01:26 thereof, and an aqueous solution. Thus functionalized, such switchable filter paper can be used to selectively filter polar and non-polar species from a mixture; for example, if switched to its ionized/hydrophilic state, the filter paper would allow any hydrophilic species in a mixture to pass through, while preventing hydrophobic species from doing the same.
Similarly, switchable filter paper could function as a solid phase extraction substitute, using a carbonated aqueous mobile phase to selectively separate particular analytes in a mixture.

[00215] Without wishing to be bound by theory, it has been envisioned that switchable polysaccharides may find applicability as nanocomposites (improved strength, barrier properties and rheology), biodegradeable polymers, and iridescent films (e.g.
inks, varnishes, cosmetic and architectural industries, security paper). Further, switchable polysaccharides may be applicable for: oil absorption or oil recovery applications (for example, removal of oil from aqueous environments or from non-aqueous phase liquids, such as oil spills); as metal adsorbents; to metal separation applications;
or, to provide paper-based membrane filters for desalinization.

[00216] To gain a better understanding of the invention described herein, the following examples are set forth. It should be understood that these examples are for illustrative purposes only. Therefore, they should not limit the scope of this invention in any way.
WORKING EXAMPLES

[00217] General Experimental

[00218] Materials: Cellulose nanocrystals (CNC), provided by FPInnovations, were prepared by sulfuric acid hydrolysis of a commercial bleached softwood kraft pulp. 1,1'-Carbonyldiimidazole (CDI, reagent grade), 1-(3-aminopropyl)imidazole (API m, 97%), and NaOH (98%) were used as received from Sigma-Aldrich. 1-(3-HydroxypropyI)-1H-imidazole (HP1m, >98%) was purchased from Oakwood Products Inc. and used as received.
Dimethyl sulfoxide (DMSO, 99.8%, water content 50 ppm), and dichloromethane (DCM, 99.8%, water content 50 ppm) were used as received from EMD chemicals. HCI and absolute ethanol were used as received from Fisher Scientific Canada and Commercial Alcohols, respectively. CO2 (99.995%) and N2 (99.9999%) gases were used as received from MEGS.
Deionized water (DIW) from a Direct-Q 3 UV System (Millipore Corporation) had a resistivity of 18.2 Macm.

[00219] Instrumentation: Particle size and zeta potential of CNC samples (after CO2 and N2 sparging for 5 and 30 min respectively at room temperature) were measured at 25 C
on a Malvern Zetasizer Nano ZS instrument (size range: 0.3 nm-10.0 pm) using disposable folded capillary cells. No sonication, vortex, stirring or filtration was applied to samples throughout the overall CO2 and N2 sparging processes, or prior to any size and zeta potential measurements. Particle concentration was kept at ca. 0.5 mg/mL for all measurements.

[00220] Each measurement was performed in triplicate with any data presented (particle size, PDI, and zeta potential) being an averaged value. 1H nuclear magnetic resonance (NMR) spectra were recorded on a Bruker Avance 400 NMR spectrometer (400.13 MHz) at 25 C using 90% H2O + 10% D20 as solvent. Chemical shifts of protons on the HPIm imidazole ring were recorded at 1.0 M HCI and 1.0 M NaOH for 100% and 0%
degree of protonation, respectively. HPIm concentration was fixed at 15 mg/mL
for all measurements. No additional internal reference was used to avoid any interference.

[00221] All measurements were conducted at least in triplicate.
Turbidities of CNC
samples (with CO2 or N2 sparging for 5 and 30 min respectively at 25 C prior to measurements) were recorded on a UV-Vis spectrometer (PerkinElmer Lambda Bio/XLS) at 500 nm wavelength and room temperature with 2.5 mg/mL sample concentration.
Each measurement was performed in triplicate with any data presented being averaged. DRIFT-IR
spectra of CNC samples were recorded on a Varian 660 IR instrument equipped with a PIKE
Diffusl R accessory; 2 mg of sample was ground with 100 mg of dried KBr to form a homogeneous mixture which was then measured. For each measurement, a total of scans were averaged with a resolution of 4 cm-1.

[00222] Elemental analysis was performed by Micro Analysis Inc.
(Wilmington DE, USA). Samples were freeze-dried for 48 h, and then further oven-dried at 50 C under vacuum for at least 12 h before measurement. Two CNC-APIm samples = prepared in two independent batches (with identical recipes and experimental procedures), together with native CNC, were analyzed for C, H, N, and S concentrations. TEM
images were taken on a Hitachi H-7000 instrument operating at 75 kV. Native CNC or CNC-APIm (under CO2) aqueous dispersions were prepared using a vortex mixer with a concentration of ca. 1.0 mg/mL; the sample was then deposited on a carbon coated copper grid and left for 1 min before excess dispersant was removed. The sample was then stained by 2%
uranyl acetate aqueous solution for 5 min before taking TEM images.

[00223] EXAMPLE 1A: Selection of Functional Groups for CO2-Switchable Compounds

[00224] To determine whether a compound is suitable to act as a switchable functional group at a particular pH, one needs to understand the relationship between pH, basicity of the switchable group (as measured by the pKaH), and concentration of switchable species in water (moles of switchable groups per litre of solution). If it is assumed, for a simplest case, that the switchable compounds are fully dissolved in water in both neutral and protonated forms, then % protonation can be obtained using equation (1):
[F1301 % protonation =
[H30-1 + KaH (1) Switching of CO2-switchable compounds using equation 1 requires that pH of the aqueous solution in the absence of CO2 is above a system midpoint, and pH in the presence of CO2 is below said system midpoint. The system midpoint is defined as pH at which number of moles of unprotonated base in the system is equal to number of moles of protonated base in the system. Contrast this to a definition of an aqueous phase midpoint, which is defined as pH at which number of moles of unprotonated base in the aqueous phase is equal to number of moles of protonated base in the aqueous phase. In the simplest case, where the switchable species is fully dissolved in an aqueous phase in both its neutral form and cationic form, then the system midpoint and aqueous phase midpoint are equal, and occur when pH is equal to pKaH. In order for a compound to be "switched" adequately by CO2 addition, so that its properties are significantly changed, it must be converted from a largely unprotonated state (low % protonation) to a largely protonated state (high %
protonation).
Therefore, the best switchable functional group to choose is one that will ensure that pH
without CO2 and pH with CO2 are on opposite sides of the system midpoint.

[00225] Because CO2 is acidic, and therefore lowers pH, pH without CO2 should be above the system midpoint (meaning at a pH higher than the system midpoint);
and, pH with CO2 should be below the system midpoint (meaning at a pH lower than the system midpoint). Equation (2) predicts [H30+] concentration at any particular concentration of switchable species in water, for this simplest case where a switchable species is fully dissolved in both its neutral and cationic forms. From the [H30+] obtained using equation (2), CA 02918904 2016-01-.26 one can use equation (1) to calculate % protonation of switchable groups when CO2 is absent.

[00226] With regard to Equation (2), when a base is added to pure water at a concentration [B]o, under air, the resulting pH is in the basic region. The base is partly protonated due to production of hydroxide salt [BH+][0H-]. From [H30-], %
protonation can be calculated (equation (1)). For an ideal switchable compound, % protonation would be very low (for example, below 20%, ideally below 5%). Equation (3) can be used to calculate [H30+] (and then via equation (1), % protonation of the switchable groups) when CO2 is present at a pressure Pc02. Ideally, % protonation of switchable groups would be high (for example: above 60%, ideally above 95%) 0 = [H30-13 + (KaH+[B]o)[H30-]2 ¨ Kw[H30] -KwKaH (2) 0 = [H30]3 + (KaH+[B]o)[H30]2 ¨ (K*ai KHPco2+Kw)[H30+] -(K*al KH PCO2+Kw)KaH (3)

[00227] If one chooses a correct switchable compound for a desired set of conditions (temperature and concentration), then simply adding that compound to water at that concentration will give a pH at which % protonation is low, and then adding an atmosphere of CO2 will give a pH at which % protonation is high. Figures 47 and 48, which were derived from equations (1) and (2), show limitations on the basicity of the switchable group (as measured by its pKaH). Using equations (1), (2), and (3), similar graphs could be prepared for other temperatures (using appropriate values of the equilibrium constants) and/or other pressures of CO2. This information removes guesswork associated with designing and/or selecting switchable compounds.
If switchable compounds are bonded to insoluble materials such as linen, then trends will be similar but the numbers may not be exactly the same. The exact numbers may not be the same because, in cases where the switchable compounds are not completely dissolved in an aqueous phase, the system midpoint and the aqueous midpoint may differ. As before, the best switchable functional group to choose is one that will ensure that pH
without CO2 and pH with CO2 are on opposite sides of the system midpoint; but, in cases of partial or complete insolubility, the system midpoint may differ from the aqueous phase midpoint.

[00228] EXAMPLE 1B: Preparation of 1-(3-Aminopropyl)imidazole Functionalized CNC (CNC-APIm)

[00229] 600.0 mg of CNC (11.1 mmol of total hydroxyls) was mixed with 12 mL of anhydrous DMSO. The mixture was then vortexed at 3000 rpm until CNCs were completely dispersed. To the dispersion, 24 mL of DCM was added and the mixture was vortexed again.
The mixture was subjected to centrifugation (15000 g force, 20 C, 15 min). A
resulting centrifugation cake of CNC was redispersed into 40 mL of DCM.

[00230] Afterwards 899.9 mg (5.6 mmol) of CDI, dissolved in 18 mL DCM, was added to the CNC dispersion. The dispersion was then stirred, warmed to 25 C by a water bath.
After 2 h stirring, 1387.5 mg (11.1 mmol) of APIm was slowly added to the CNC
dispersion over 1 min with vigorous stirring. The reaction mixture was then stirred at 25 C for another 6 h and then centrifuged (15000 g force, 20 C, 15 min).

[00231] The resultant cake was redispersed into 60 mL of absolute ethanol and vigorously stirred overnight at room temperature. This dispersion was then centrifuged (15000 g force, 20 C, 6 min), and the resultant cake was vortexed with 60 mL
of absolute ethanol for 6 min (3 times at 3000 rpm for 2 min each, with 30 s intervals) before being centrifuged (15000 g force, 20 C, 6 min).

[00232] This dispersion-into-ethanol-with-vortex-and-centrifugation process was repeated until the centrifugation supernatant became turbid. The resultant cake (CNC-APIm) was redispersed into ca. 20 mL of deionized water (DIW) and dialyzed (cellulose dialysis tubing cut-off size: 14000 Da) against 950-1000 ml of DIW at 40 C, with the DIW changed 2-3 times daily for around 10 days until pH and conductivity of the DIW
reservoir stabilized.

[00233] The dialysis-purified CNC-APIm dispersion was then centrifuged (15000 g force, 20 C, 30 min), and then the resultant cake was vortexed with 30 mL of DIW for 15 min (5 times at 3000 rpm for 3 min each, with 30 s intervals) before another centrifugation (15000 g force, 20 C, 30 min). This centrifugation-vortex-centrifugation process was repeated until supernatant tubidity became such that further centrifugation could have caused substantial loss of samples.

[00234] Finally, the thoroughly purified CNC-APIm was redispersed into 40 mL of DIW
with 15 min vortex (3 min by 5 times at 3000 rpm with 30 s intervals) and stored at 4 C in a fridge as stock dispersion. Before each characterization, part of CNC-APIm stock dispersion was vortexed (2 min by 3 times at 3000 rpm with 30 s intervals), sparged with CO2 for at least 15 min, and centrifuged briefly (15000 g force, 20 C, 1 min) to remove a small amount of floating particles. Then the supernatant, used as prepared or diluted with carbonated DIW, was characterized or used for experiments.

[00235] EXAMPLE 1C: Calculation of Surface lmidazole and Sulfate Densities

[00236] Elemental analysis data (Table 2) demonstrated that two CNC-APIm samples were consistent, suggesting high reproducibility of the CNC-APIm preparation and purification procedures as described above; and, S concentrations for native CNC and CNC-APIm were similar, indicating that sulfate groups were not likely significantly hydrolyzed after CNC-APIm preparation and purification processes. According to TEM images (Figure 5), native CNC and CNC-APIm showed similar lengths, ranging from around 100 nm to 300 nm, and diameters of ca. 10 nm. Treating CNC as a nanorod with a square cross-section, assumptions were made before conducting an approximate calculation of APIm and sulfate densities on a CNC surface:
1. Both CNC and CNC-APIm were nanorods with a square cross-section of 7.1 nm x 7.1 nm (diagonal: 10 nm), having non-reactive ends;
2. Any cross-section of CNC and CNC-APIm, along an axial direction, was packed with cellulose 113 unit cells in an identical pattern, where these cellulose unit cells, as determined by X-ray diffraction [Sugiyama, J.; Vuong, R.; Chanzy, H.
Macromolecules 1991, 24, 4168-4175], had cross-sectional dimensions of 0.61 nm x 0.54 nm in directions parallel to two sides of CNC square cross-section [Habibi, Y.; Chanzy, H.; Vignon, M. R. Cellulose 2006, 13, 679-687];
3. Anhydrous glucose units (AGUs) were evenly distributed on four sides of each cellulose unit cell with two ends having no AGU;
4. Sulfate remained intact after the APIm coupling reaction;
5. CNC-APIm had same density as native CNC, which was around 1.6x10-21 ginm3 [Habibi, Y.; Lucia, L. A.; Rojas, 0. J. Chem. Rev. 2010, 110, 3479-3500;
Majoinen, J.; Walther, A.; McKee, J. R.; Kontturi, E.; Aseyev, V.; Malho, J. M.;
Ruokolainen, J.; lkkala, 0. Biomacromolecules 2011, 12, 2997-3006].

[00237] It was assumed that, if a 1 nm length (one unit volume) of CNC-APIm was taken (side of cross-section = 7.1 nm, as determined in above assumption), its volume and surface area would be 50.4 nm3 and 28.4 nm2, respectively. In the elemental analysis results (Table 2), an average of two CNC-APIm measurements was used for this calculation. So, imidazole and sulfate molarities in one unit volume were calculated to be (50.4x1.6x10-21)x3.75 /0/42.7.20x10-23 mol, and (50.4x1.6x10-21)x0.72 /0/32.1.81x10-23 mol, respectively. Assuming that all of these groups were at the surface, it was found that:
Surface imidazole density: 1.53 units/nm2 Surface sulfate density: 0.38 units/nm2.

[00238] In the same unit volume of CNC-APIm, there was calculated to be (50.4x1.6x10-21)/162.4.98x10-22 mol of AGUs.

[00239] The CNC-APIm surface cellulose units accounted for approximately 2x[(7.1/0.61+7.1/0.54)-2]/[7.1x7.1/(0.61x0.54)]=0.3 (30%) of the total mass. Consequently:
Surface AGU to imidazole molar ratio: 4.98x10-22x0.3/(7.20x10-23)=2.08;
Surface AGU to sulfate molar ratio: 4.98x10-22x0.3/(1.81x1023)=8.25.

[00240] Overall Results and Discussion

[00241] A one-step 1,1'-carbonyldiimidazole (CDI)-mediated coupling with 1-(3-aminopropyl)imidazole (APIm) was used to chemically immobilize imidazole functionalities onto a CNC surface (CNC-APIm's; Figure 1) [Liebert, T. F.; Heinze, T.
Biomacromolecules 2005, 6, 333-340]. Imidazole functionality has been used for preparations of CO2-switchable polymers and surfactants [Quek, J. Y.; Roth, P. J.; Evans, R. A.; Davis, T.
P.; Lowe, A. B. J.
Polym. Sc!., Part A: Polym. Chem. 2013, 51, 394-404; Chai, M. F.; Zheng, Z.
B.; Bao, L.;
Qiao, W. H. J. Surfactants Deterg. 2014, 17, 383-390].

[00242] The modified CNC-APIm's structure was confirmed by DRIFT-IR
(Figure 3): a strong carbonyl absorption band (C=0 stretching) was observed at ca. 1710 cm-1; a typical amide ll absorption (N-H bending) was observed at ca. 1550 cm-1; and, a C-0 stretching band was observed at ca. 1268 cm-1. These IR bands were not observed for native CNC, suggesting that APIm was chemically immobilized onto the CNC surface hydroxyl groups, forming carbamate linkages.

[00243] A CO2-switchable aggregation/redispersion mechanism of CNC-APIm is depicted in Figure 2: imidazole functionalities on the CNC surface, with a pKaH 6.0-6.5 [Kim, T.; Rothmund, T.; Kissel, T.; Kim, S. W. J. Control. Release 2011, 152, 110-119; Lin, W.;
Kim, D. Langmuir 2011, 27, 12090-12097], formed charged, bicarbonate salts with CO2 in an aqueous environment; sparging with N2 through the dispersion reversed the bicarbonate formation, thereby removing the charge from the imidazole group.

[00244] CNC surface sulfate groups were not removed since it was an additional step, which would have added to process costs and lowered product yields. The CNC
surface imidazole density was higher than the sulfate density (see Table 2, as well as calculation of surface imidazole and sulfate densities in Example 1B). Therefore, upon exposure to CO2, the imidazole rings' positive charge exceeded the sulfate's negative charges, and yielded a positively charged CNC-APIm. When CO2 was removed, neutral hydrophobic propyl-imidazole gave rise to aggregation of CNC-APIm, due to a combined effect of surface hydrophobicity and a decrease in surface charge.

[00245] CNC-APIm dispersions exhibited reversible CO2-switchable behaviours (Figure 4). Under a CO2 atmosphere of, CNC-APIm's zeta potential was 55-60 mV
due to formation of imidazolium bicarbonate salts; N2 sparging reduced that zeta potential to 20-35 mV.

[00246] For colloidal dispersions, a zeta potential of less than 30 mV
(absolute value) can give rise to the destabilization of the system [Freitas, C.; Muller, R. H.
mt. J. Pharm.
1998, 168, 221-229]. Under a N2 atmosphere, CNC-APIm's zeta potential was approximately 30 mV or lower (Figure 4), which led to flocculation into macroscopically visible aggregates (Table 3; Figures 5A and 5B). Turbidity measurements also demonstrated the reversible CO2-switchability of CNC-APIm (Figure 4b). In the presence of CO2 and N2, %
transmittance of CNC-APIm dispersions continuously switched between around 80% and 20%, suggesting reversible transitions between a transparent dispersion and a turbid dispersion containing macroscopically visible aggregates. Transmittance of CNC-APIm dispersions returned to a consistent level (78-83%) after sparging CO2, suggesting reversible switching of the CNC-APIm from an aggregated to a dispersed state.

[00247] Dynamic light scattering (DLS) was used to provide a relative measure of CNC particle sizes. The DLS software functioned by calculating a spherical equivalent diameter; while this was not considered an accurate measure of an anisotropic material like CNC, it was useful for monitoring size changes attributed to processes such as aggregation and redispersion.

[00248] CNC-APIm experienced a relatively large, but reversible change in particle size when CO2 was added or removed (Table 3): dispersed CNC-APIm (under CO2) had a Z-average size of 201 nm; after N2 sparging, it increased to several tens of microns (macroscopically visible aggregates). After 6 cycles of CO2/N2 sparging, the CNC-APIm still retained dispersibility (no macroscopically visible aggregates under CO2). No sonication, vortex or stirring was used during these tests for either native CNC or CNC-APIm; reversible size and zeta potential changes for CNC-APIm were observed by alternatively sparging with CO2/N2.

[00249] Native CNC particles differed from CNC-APIm in responsiveness to (Table 1). Sulfate groups on native CNC surface did not respond to CO2 stimuli due to its weak basicity, as shown by a lack of response when CO2 and then N2 were sparged through dispersions of native CNC. Native CNC remained well dispersed throughout three sparging cycles, with Z-average sizes staying between 130-160 nm. Particle size varied slightly with each sparging cycle, but there was no apparent evidence of CO2-switchability. It was noted that CNC-APIm's original size was a larger than the native CNC (Zeta-average size: 201 vs. 159 nm).

[00250] Following the dialysis process (see Example 1A), repeated centrifugations were performed to further purify CNC-APIm. The centrifugation supernatants discarded in the repeated centrifugations contained ca. 15-20% of the total CNC-APIm;
without wishing to be bound by theory, it was considered that centrifuging the samples may have separated heavier (read: larger) particles from lighter (read: smaller) particles.
Consequently, discarded supernatant was analyzed and found to have a smaller particle size than the CNC-APIm that settled during centrifugation (Zeta-average size: 167 nm); it was observed that these smaller particles also exhibited reversible CO2-switchability (Table 4).

[00251] CNC-APIm dispersion/aggregation behavior with varying sparging times was also investigated (Table 5). Only 30 seconds of CO2 sparging was needed to convert macroscopically visible aggregates of CNC-APIm to a dispersion without visible aggregates.
For the reverse process, as N2 was sparged through fully dispersed CNC-APIm, the zeta potential decreased, and continued to decrease even after 20 minutes. It was observed that the Z-average particle size showed little change as the zeta potential decreased from 57 mV
to 47 mV. However, when the zeta potential approached ca. 35 mV, particle size rose to over 10 pm and the CNC-APIm dispersion showed macroscopically visible aggregates. After a total of 20 min of N2 sparging, the zeta potential was reduced to 31.7 mV.
Lowest zeta potential achieved was ca. 20 mV (after 30 min N2 sparging at 50 C), suggesting that there were still some charged surface imidazoles after N2 sparging. This was found to be consistent with previous observations using amidine-based switchable surfactants to stabilize polymer colloids [Fowler, C. I.; Jessop, P. G.; Cunningham, M. F.
Macromolecules 2012, 45, 2955-2962].

[00252] CO2-switchability and sedimentation of aggregates were studied over a wide range of concentrations (0.02-10 mg/ml; Figures 5A and 5B). All CNC-APIm dispersions, regardless of concentration, showed CO2-switchability upon being alternatively exposed to CO2 and N2, while native CNCs had no visible responsiveness to CO2. Even a CNC-APIm dispersion with a concentration as low as 0.025 mg/ml formed aggregates that settled out of solution within -60 min after sparging N2 (Figure 5A (a)).

[00253] At a concentration approximately 5.5 mg/ml or above, CNC-APIm showed reversible dispersion/gelation properties upon alternating exposure to CO2 and N2 (Figures 5A (e) and (f)). Without wishing to be bound by theory, it was considered that this dispersion/gelation property followed a hydrogen-bonding-driven mechanism:
well-dispersed charged CNC-APIm surfaces (under CO2) would not promote formation of hydrogen-bonding among surface hydroxyls; however, upon aggregation (under N2), surface hydroxyls would be brought into close proximity with hydroxyls on adjacent nanocrystals, which could lead to network formation and gelation. Such a gelation process was expected to be concentration-dependent, given that a minimum particle density would likely be required for gel formation.
It was found that the "gelation concentration" of CNC-APIm dispersions was approximately 5.5-10 mg/ml.

[00254] The hydrogen-bonding-driven gelation process was similar to Weder et al.'s findings [Capadona, J. R.; Shanmuganathan, K.; Tyler, D. J.; Rowan, S. J.;
Weder, C.

Science 2008, 319, 1370-1374]; wherein, switching hydrogen-bonding "on" or "off" among CNCs by removal or addition of water enabled formation of, or breaking of, CNC
percolating networks. This led to stiffness changes in the CNC nanocomposites. Figure 5A
(d) depicts images where CNC-APIm (0.25 mg/ml dispersion) aggregated and sedimented relatively quickly (under N2): within 16 min, the CNC-APIm settled, leaving a clear transparent upper layer. For CNC-APIm dispersions with higher concentrations, settling was observed to occur in a similar manner within a similar time frame; for the 0.025 mg/ml dispersion, it took longer (approximately one hour) for complete sedimentation.

[00255] 1-(3-HydroxypropyI)-1H-imidazole (HPIm) was used as a model for APIm to estimate, by 1H NMR spectroscopy, a fraction of protonated imidazole groups under CO2 and N2, respectively, so that an estimate of CNC-APIm surface charge density could be obtained (Figure 6). Presaturation was used for water signal suppression, and it was found that all chemical shifts obtained with and without presaturation were identical (Figure 6A).
Fortunately, the water peak did not overlap or interfere with HPIm peaks.
Therefore, all calculations were based on the original 1H NMR spectra without applying presaturation.

[00256] Chemical shifts of three protons on the HPIm imidazole ring were used to calculate the degree of protonation of imidazole under CO2 and N2, using a method described previously [Fowler, C. I.; Jessop, P. G.; Cunningham, M. F.
Macromolecules 2012, 45, 2955-2962; Scott, L. M.; Robert, T.; Harjani, J. R.; Jessop, P. G. RSC
Adv. 2012, 2, 4925-4931]. Under the aformentioned experimental conditions (15 mg/ml HPIm in 90% H20 + 10% D20 as solvent), data showed that up to 94% of imidazole rings could be protonated upon exposure to CO2, while sparging with N2 decreased degree of protonation down to 26%
(Table 6). All three protons examined on the imidazole ring showed decent reversibilities, i.e.
sparging N2 restored the chemical shifts to near their original values (Figure 6 and Table 6).
This observation was consistent with the reversible zeta potential and particle size changes discussed above. NMR measurements and calculations were based on HPIm's solution properties; while it was recognized that this was unlikely to be exactly the same as on a CNC
surface, it was considered a reasonable qualitative representation of APIm behaviour on a CNC surface.

[00257] Transmission electron microscope (TEM) images of native CNC and CNC-APIm are presented in Figure 7. CNC-APIm showed similar dimensions and morphologies to those of native CNCs, which suggested that the CNC crystalline structure was preserved after the CDI-mediated coupling reaction with APIm. Particle size information from TEM

images, together with elemental analysis data (Table 2), was used to obtain an approximate estimate of CNC-APIm surface imidazole and sulfate densities (see Example 1B).
The calculated surface imidazole and sulfate densities were 1.53 units/nm2(surface anhydrous glucose units to imidazole molar ratio: 2.1) and 0.38 units/nm2 (surface anhydrous glucose units to sulfate molar ratio: 8.3), respectively.

[00258] Taking into consideration the degree of protonation data as measured by NMR spectroscopy the model compound (Table 6), the surface imidazole charge density after sparging CO2 (94% charged imidazole) was 1.44 e/nm2, and thus net surface charge was 1.06 e/nm2. After sparging N2, only 26% of the surface imidazole groups were charged (Table 6), with surface imidazole charge and net charge densities decreasing to 0.4 e/nm2 and 0.02 e/nm2, respectively. This suggested a surface charge difference between CO2 and N2 sparged CNC-APIm dispersions, which was consistent with the above findings on zeta-potentials and sizes of CNC-APIm (Figure 4 and Table 3).

[00259] Conclusions

[00260] Described herein is a one-step approach for preparation of switchable CNCs that reversibly respond to CO2/N2 stimuli. The prepared CNC-APIm showed fast and reversible CO2 switchable dispersion behaviours (no sonication, vortex, or stirring was used for re-dispersion of CNCs), while CNC-APIm dispersions with higher concentrations (5.5-10 mg/ml) were switched between gels and dispersions. It was considered that the herein described CO2-switchable CNCs could have potential in applications such as CO2-switchable adsorbents or flocculants, taking advantage of their high specific surface area.

[00261] EXAMPLE 2A: Preparation and Analysis of 1-(3-Aminopropyl)imidazole Functionalized Cotton Linen (Cotton-APIm)

[00262] N,N-dimethylformamide (DMF; dry, 50 mL, >99%) was added to a 100 mL
round bottom flask. Cotton (0.419 g; unbleached, undyed cotton muslin) was then added to the flask, and stirred in DMF for 10 min; following which, 1,1'-Carbonyldiimidazole (0.908 g, 5.601 mmol) was added, and stirred for an additional 2 hours. 1-(3-aminopropyl)imidazole (1.312 g, 10.48 mmol) was then added to the flask drop-wise over 1 min, and was stirred for 24 hours. The cotton was then removed, washed 3 times with DMF (20 mL), and left to dry for 24 h in air, in a fume hood.

[00263] Once prepared, a quantitative analysis of the Cotton-APIm's surface tension was undertaken to measure the cotton's surface hydrophilicity or hydrophobicity when it was 'switched on' (protonated) and 'switched off' (non-protonated) using contact angle analysis.
A contact angle is the angle at which a liquid interface meets a solid surface, which can be measured via contact angle goniometry using a Goniometer. To measure the Cotton-APIm's contact angle, the material was held rigidly in place on an observation deck of the Goniometer. The Goniometer was then used to deposit a droplet of MilliporeTM, carbonated water (0.75 uL), and hexadecane (0.75 uL) onto the non-functionalized cotton linen's surface and Cotton-APIm's surface, and capture a high-resolution image of the droplet.
Using the Goniometer's software, a contact angle could then be calculated (see Table 8).
This procedure is commonly referred to as a sessile droplet method.

[00264] Further to contact angle analysis, water absorption analysis was undertaken.
Millipore water (100mL) was placed into a 150 mL beaker. The Cotton-APIm was weighed, and the dry mass recorded. The Cotton-APIm was placed into the water for 30 seconds, and then carefully removed so as to not disturb bound water on the Cotton-APIm's surface, and held above the water for an additional 30 seconds to 'drip dry'. Resultant "wet" weight was then recorded.

[00265] Results and Discussion

[00266] It was qualitatively observed that, once functionalized, the cotton was more physically ridged than non-functionalized cotton.

[00267] Once functionalized, Cotton-APIm was analyzed, by way of contact angle tests, to investigate its hydrophobic / hydrophilic properties. The contact angle of water, carbonated water, and oil were measured from the Cotton-APIm's surface, and contrasted with non-functionalized cotton. It was observed, as is delineated in Table 8, that the non-functionalized cotton linen was hydrophilic in the presence of water and carbonated water;
and, oleophilic in the presence of hexadecane. It was observed that the Cotton-APIm was hydrophilic in the presence of water and carbonated water; and, oleophilic in the presence of hexadecane; however, qualitatively, it was observed that the carbonated water absorbed into the linen faster than the water.

[00268] In addition to analyzing the Cotton-APim by way of contact angle, water absorption tests were also undertaken, wherein Cotton-APIm was submerged in water to further test its affinity for water. The functionalized cotton was weighed before and after being submerged, and the amount of water absorbed (by mass) was determined;
this was then contrasted with non-functionalized cotton that received equal treatment (Table 7). It was found that the Cotton-APIm absorbed 0.55 0.06 g, while the non-functionalized cotton absorbed 0.33 0.02 g. Without wishing to be bound by theory, this was considered at least qualitatively indicative of Cotton-APIm's increased hydrophilicity as compared to the non-functionalized cotton.

[00269] EXAMPLE 2B: Preparation and Analysis of Poly(diethylamino)ethyl methacrylate (p-DEAEMA) Functionalized Cotton Linen (Cotton-API m)via Surface-initiated Atom-Transfer Radical-Polymerizaion (SI-ATRP)

[00270] Linen Preparation:

[00271] Cotton linen (0.2 g) was first subjected to a surface oil extraction by ref luxing in tetrahydrofuran (THF) 100 mL for 1 hour. After, the linen was air-dried and placed in a 250 mL schlenk two-neck round bottom flask and heated at 120 C overnight under vacuum to remove excess water.

[00272] Grafting polymer from cotton linen surface via Surface Initiated Atom Transfer Radical Transfer (SI-ATRP):

[00273] Please note: assumed 20 mmol/g of functionalizable surface hydroxyls on linen surface.

[00274] Cotton linen (0.2 g) was placed into a two-neck schlenk round bottom flask was first flame-dried under vacuum to remove excess water. The prepared linen, still stored in the two-neck round bottom flask, was purged 3 times with Ar2 gas. Anhydrous dichloromethane (DCM; 100 mL) was then cannula transferred into the linen-containing round bottom flask. Next, diisopropylethylamine (0.70 mL) was added to the same round bottom flask and stirred for 1 hr. The resultant linen mixture was then cooled down to 0 C
using an ice bath, and 0.50 mL of oc-bromoisobutyryl bromide (BIBB) was added dropwise.
This mixture was then heated to 40 C and left to stir for 24 hr.

[00275] Next, the linen was removed from the flask and washed with 3 x 50 mL of dichloromethane (DCM), and then with water and subsequently air-dried. While the linen was left to dry, 2-(diethylamino)ethyl methacrylate (DEAMEA, 41 mL) was run through a basic alumina column to extract any inhibitor. The dried linen was then placed into a 250 mL
schlenk round bottom flask, and flame dried under vacuum and purged 3 times with Ar gas.

Dry methanol (40 mL) was then cannula transferred into the linen-containing round bottom flask followed by DEAMEA (41 mL). Cu(II)Br (0.60 g) was weighed into an oven dried vial using an Ar-filled glove bag. Next, dry methanol (25 mL) was cannula transferred into the dried vial along with ligand N,N,N',N',N"-pentamethyldiethylenetriamine (PMDTA; 0.84 g).
Contents of the dried vial and linen-containing flask were stirred and degassed for 1 hr.

[00276] Cu(II)Br-ligand mixture was then cannula transferred to the linen-containing flask and left to stir under reflux at 70 C for 48 hours. The final solution turned deep blue and the linen was rinsed first in methanol, then in a ethylenediaminetetraacetic acid (EDTA) water mixture to remove excess copper. See Figure 33.

[00277] Contact Angle Analysis:

[00278] Once prepared, a quantitative analysis of the pDEAEMA-functionalized linen surface tension was undertaken to measure the linen's surface hydrophilicity or hydrophobicity when it was 'switched on' (protonated) and 'switched off' (non-protonated) using contact angle analysis. See Table 10.

[00279] Switching the linen surface "on" was achieved by using glycolic acid in water.
Contact angles were measured via a sessile drop method using MilliporeTM
water.
Approximately 0.75 L droplets of water were exposed to the surface and images were taken using a Veho VMS-004 USB Microscope and processed using ImageJ and DropSnake software [A.F. Stalder, G. Kulik, D. Sage, L. Barbieri, P. Hoffmann, Colloids And Surfaces A:
Physicochemical And Engineering Aspects, vol. 286, no. 1-3, pp. 92-103, September 2006].

[00280] Discussion:

[00281] Grafting switchable polymer DEAEMA onto a cotton linen surface was achieved through SI-ATRP/ "grafting-from" approach. The cotton linen's surface, after extracting from it natural oil, was hydrophilic. Following surface functionalization with PDEAEMA, the linen's surface became hydrophobic, as demonstrated by contact angles before and after functionalization (Table 10). Presence of PDEAEMA on the linen's surface was also corroborated by ATR-FTIR (see Figure 34): a peak was observed at -1727 cm-1 in the IR spectrum, which was considered to correspond with the PDEAEMA ketone functional group. The functionalized linen was then subjected to glycolic acid to "switch-on", or ionize, the switchable polymer, thereby charging the surface to allow for water to be absorbed.

,

[00282] Preliminary results indicated that cotton linen can be functionalized with a switchable functional group, such that the surface properties of the linen can be switched from hydrophobic to hydrophilic in the presence of a trigger (e.g., glycolic acid). It has been considered that such switchable polysaccharides are applicable to cotton linen diapers; for example: a diaper functionalized with a switchable polymer, such as PDEAEMA, is switched on by an infant's naturally acidic urine; the acidic urine changes the linen diaper's surface properties by ionizing the switchable polymer; and the ionized surface results in water-uptake by the polymer, thereby absorbing the infant's urine. It has also been considered that such switchable polysaccharides are applicable to membrane applications: the "switched-on", ionic, hydrophilic form of the switchable linen allows water to filter through, while simultaneously capturing and filtering out hydrophobic compounds, such as oil.
Commonly, membranes, such as cellulose membranes, foul over time; but a switchable polysaccharide allows for self-cleaning. For example, a switchable-functionalized linen's properties are switched on and off, in the presence of a trigger, thereby releasing any hydrophobic compounds fouling its surface.

[00283] EXAMPLE 3: Preparation and Analysis of a 1-(3-Aminopropyl)imidazole Functionalized Cellulose Dialysis Bag (Cellulose-API m)

[00284] Preparation of Cellulose-APIm membrane: Cellulose membrane (ca.
0.5 g;
cut-off size 14,000) was placed in a 100 ml three-neck flask together with a magnetic stir bar; following which, approximately 25 mL of N'N-dimethylformamide (DMF) was added, the flask was sealed with three rubber stoppers, and then the mixture was magnetically stirred at room temperature for 1 h. The DMF was then decanted.

[00285] In a 100 mL beaker, 50 mL of fresh DMF was added, following which 1,1'-carbonyldiimidazole (CDI; 1 g) was added, together with a magnetic stir bar.
The 100 mL
beaker was then magnetically stirred at room temperature for 3 min to dissolve CDI into DMF. The CDI in DMF solution was then transferred into the 100 mL three-neck flask containing the cellulose membrane. The three-neck flask was sealed again with rubber stoppers, and magenitcally stirred while partially submersed into a 50 C oil bath. Two 16G
needles were inserted into the two side rubber stoppers of the three-neck flask, and then the mixture continued to be stirred for 4 h in the 50 C oil bath. Folowing that, 1-(3-Aminopropyl) imidazole (APIm; 2.0 mL) was added into the mixture, and the reaction proceeded for another 12 h in the 50 C oil bath; after which, the membrane was removed, added to a separate flask, and magnetically stirred in 50 mL absolute ethanol, three separate times (15 min each time; absolute ethanol was refreshed each time). The membrane was then rinsed extensively with deionized water (DIW) until pH and conductivity of the DIW, after rising, was close to that of pure DIW. The purified, modified membrane (Cellulose-APIm) was sandwiched between two filter papers, and dried in an oven at 80 C for 2 h.
After 2 h, the dried Cellulose-APIm was ready for characterization. As a control group, native cellulose membrane was stirred with 100 mL of DIW in a 50 C water bath for 2 h, during which the DIW was refreshed once after 1 h of stirring. The native cellulose membrane was then sandwiched between two filter papers, and dried in an oven at 80 C for 2 h.

[00286] FT-IR characterization: FT-IR spectra of dried membranes were collected on a Varian 660 IR instrument. Transmission measurements were conducted with 16 scans at a resolution of 4 cm-1. Each sample was measured three times at a different location of the membrane to check reproducibility of measurements (see Figure 8).

[00287] Membrane surface hydrophilic-lipophilic property characterizations: Dried Cellulose-APIm or native cellulose membrane was placed on Parafilm Me on a bench top. A
micropipette was used to quickly and gently place 30 [.11_ DIW or Dodecane on the Cellulose-APIm or native cellulose membrane. A photo of DIW or dodecane droplet on each membrane's surface was then taken from different angles. DIW and dodecane droplets were places at different locations of the membrane to check reproducibility of measurements.

[00288] Discussion:

[00289] A 1-(3-aminopropyl)imidazole surface-functionalized cellulose dialysis bag was prepared via the CDI chemistry used to immobilize 1-(3-aminopropyl)imidazole (APIm) onto CNC and cotton, and analyzed by Infrared spectroscopy (IR). The IR
analysis was compared and contrasted with that of non-functionalized cellulose (Figure 8).

[00290] It was found that the functionalized and non-functionalized cellulose membranes were too thin for Attenuated Total Reflectance IR spectroscopy (ATR-IR), in that no signal was observed. Despite the thickness of the membranes being a hindrance for %
transmittance IR spectroscopy, as many peaks' full height could not be observed, %
transmittance IR was still used for analysis; a carbonyl band, indicative of Cellulose-APIm, could still be observed and identified in the IR spectrum (Figure 9).

[00291] Once functionalized, the Cellulose-APIm was investigated by way of contact angle analysis. At least four different positions on the membrane were analyzed for contact angle measurements. Each time, two drops of water (30 1.11._ each: deionized (DIW) and carbonated water) were added to the membrane, one right after the other (Figure 10).

[00292] It was observed that, generally, carbonated water contacted the Cellulose-APIm at a relatively smaller contact angle than noncarbonated water. Without wishing to be bound by theory, it was considered that this was a result of the protonated APIm on the cellulose membrane, and its hydrophilicity. It was observed that the contact angles did not change significantly with time (at least within a couple of minutes). The difference in contact angles observed using the DIW suggests that the functionalized membrane is more hydrophobic under these conditions than when in the presence of CO2 from the carbonated water.

[00293] As a means of comparing and contrasting the effect surface functionalization had on the cellulose bag, a non-functionalized cellulose dialysis bag was similarly treated:
two drops of water (30 pl_ each: DIW and carbonated water) were added to the non-functionalized membrane, one right after the other. It was observed that the water droplets collapsed/absorbed upon contact with the membrane surface. Without wishing to be bound by theory, it was considered that this was a result of the membrane's hydrophilicity even in the absence of CO2.

[00294] EXAMPLE 4A: Synthesis of Switchable Starches

[00295] Synthesis #1:

[00296] Starch (CAS 9005-84-9, J.T. Baker; 2 g, 36.6 mmol, 1 eq.) was added to a round bottom flask containing N,N-dimethylformamide (50 mL) and heated until it dissolved.
In a separate round bottom flask, carbonyldiimidazole (5.8 g, 36.6 mmol, 1 eq.), imidazole hydrochloride (9.6 g, 91.5 mmol, 2.5 eq.), and 3-diethylaminopropylamine (6.4 mL, 40 mmol, 1.1 eq,) were added to N,N-dimethyformamide (100 mL). The solution was heated to 60 C
and magnetically stirred rapidly for 2 h. After 2 h, the hot dissolved starch was added to the round bottom flask containing the carbonyldiimidazole, imidazole hydrochloride, and 3-diethylaminopropylamine. At this point, more imidazole hydrochloride (5.7 g, 55 mmol, 1.5 eq.) was added. The solution was heated to 80 C for approximately 72 h. The reaction was allowed to cool, and the starch was recovered via vacuum filtration. The starch was rinsed thoroughly with N,N-dimethylformamide (3 times), followed by rinsing with methanol (3 times). Functionalized starch (1.6919 g) was recovered and used as is for further experimentation (for example, see Figure 32).

[00297] Synthesis #2:

[00298] Starch (0.4 g, 7.3 mmol, 1 eq.) was added to a round bottom flask containing dimethylsulfoxide (40 mL) and heated to 110 C. In a separate round bottom flask, carbonyldiimidazole (1.4 g, 8.6 mmol, 1.2 eq.), imidazole hydrochloride (1.35 g, 13 mmol, 1.5 eq.), and 3-diethylaminopropylamine (1.3 mL, 8.6 mmol, 1.2 eq,) were added to N,N-dimethyformamide (50 mL). The solution was heated to 100 C and stirred rapidly for 1 h.
After 1 h, the hot dissolved starch was added to the round bottom flask containing the carbonyldiimidazole, imidazole hydrochloride, and 3-diethylaminopropylamine.
The solution was heated at a constant at 110 C for approximately 16 h. The reaction was allowed to cool, and the starch was recovered via vacuum filtration. The starch was rinsed thoroughly with dimethylformamide (3 times), followed by rinsing with methanol (3 times).
Functionalized starch (0.12 g) was recovered and used as is for further experimentation (for example, see Figure 32).

[00299] A slight variation on the above experimental #2 entailed heating the reaction solution at a constant 50 C as opposed to 100 C; however, the starch was still preheated at 110 C until fully dissolved. Without wishing to be bound by theory, it was considered that this modification would help slow amine oxidation, which would result in a loss of the amino functionality on the starch. It was found that, as another alternative, adding excess amine (3-diethylaminoproylamine) also helped.

[00300] Discussion:

[00301] It was observed that starch was not soluble in water at room temperature, but that it could be solubilized by boiling in water for a short period of time.
Once solubilized into hot water, the resultant starch solution could be cooled and stored for a moderate period of time, though it was observed that the starch would eventually aggregate and precipitate out of water.

[00302] Synthesis of a switchable starch, involving surface functionalization to comprise switchable moieties as defined above, was initially investigated to provide means for solubilizing starch without use of excessive heat: without being bound by theory, it was postulated that once the switchable starch was switched to its ionized form, in the presence of an aqueous solution and an ionizing trigger such as CO2, that it would be more soluble in water at room temperature than non-functionalized starch.

[00303] EXAMPLE 4B: Synthesis of Switchable Cellulose, and Investigations into Their Use as Drying Agents

[00304] Synthetic method 1:

[00305] Preparation of ethylformate-functionalized cellulose:

[00306] Cellulose fibers (Sigma-Aldrich, Sigmacell cellulose type 101, high purified, fibers) were dried overnight at 110 C in an oven. Dried cellulose was then used as is, with no other pre-treatments. Dried cellulose fiber (6.5 g) was added to a 250 mL
round bottom flask and flame dried under vacuum. Using Schlenk techniques for inert conditions, diisopropylethylamine (1.6 eq., 0.19 mol) and anhydrous dichloromethane (150 mL, alkene stabilized) were added to the round bottom flask. The round bottom flask was cooled in an ice bath for approximately 30 minutes, after which ethylchloroformate (1.5 eq., 0.18 mol) was added drop-wise via addition funnel to the cooled mixture. The solution was warmed to room temperature and allowed to react for 12 h. The cellulose fibers were recovered by vacuum filtration and washed thoroughly with ethanol, followed by multiple washings with distilled water. The washed particles were dried at 110 C overnight, then stored under Ar(g) until further use.

[00307] Representative preparation switchable-functionalized cellulose:

[00308] Ethylformate-functionalized cellulose (compound 2 of Figure 35; 1 g) was added to a 150 mL round bottom flask. Following a literature procedure [Kim, B., et al., Synthesis. 2012, 44, 42-5], tetrahydrofuran (THF; 80 mL) with 0.2 % H20 was added to the round bottom flask and stirred for 30 min. Potassium tert-butoxide (2.2 eq.) was added, turning the clear solution to a cloudy light yellow. A select amine (1.1 eq.) was added to the reaction mixture, which was then left stirring overnight at room temperature (26 C) exposed to air.

[00309] Representative procedure for testing switchable celluloses as drying agents:

[00310] Solvent chosen to compare utility of switchable cellulose materials as drying agents was isobutanol, which was doped with 5 wt% H20. The switchable cellulose and 'wet' isobutanol solution was added to a vial, and CO2 was bubbled through the solution for 1 h.

The vial was then sealed and stirred for 15 h. The swItchable cellulose was separated from the wet isobutanol solution via vacuum filtration; water content remaining in the isobutanol solution after filtration was analyzed via gas chromatography thermal conductivity detector (GC-TCD). Results are reported in Table 11.

[00311] There were a total of 5 amines prepared and tested via the procedures delineated above, each being assigned a title Al - A5. Al: 3-(dimethylamino)-1-propylamine.
A2: 3-(dibutylamino)-1-propylamine. A3: 3-(diethylamin o)-1-propylamine. A4: 1-(3-aminopropyl)imidazole. A5: N-(3-aminopropyl)piperidine. In the case of Al, compound 3 of Figure 35 was formed.

[00312] Synthetic method 2:

[00313] Preparation of ethylformate-functionalized cellulose:

[00314] Cellulose fibers (Sigma-Aldrich, Sigmacell cellulose type 101, high purified, fibers) were dried overnight at 110 C in an oven. Dried cellulose was then used as is, with no other pre-treatments. Dried cellulose fiber (6.5 g) was added to a 250 mL
round bottom flask and flame dried under vacuum. Using Schlenk techniques for inert conditions, diisopropylethylamine (1.6 eq., 0.19 mol) and anhydrous dichloromethane (150 mL, alkene stabilized) were added to the round bottom flask. The round bottom flask was cooled in an ice bath for approximately 30 minutes, after which ethylchloroformate (1.5 eq., 0.18 mol) was added drop-wise via addition funnel to the cooled mixture. The solution was warmed to room temperature and allowed to react for 12 h. The cellulose fibers were recovered by vacuum filtration and washed thoroughly with ethanol, followed by multiple washings with distilled water. The washed particles were dried at 110 C overnight, then stored under Ar(g) until further use.

[00315] Preparation of switchable cellulose:

[00316] 3-(dimethylamino)-1-propylamine (DMAPA, 1 eq. 75.2 mmol) was added drop-wise under inert conditions to a cooled (ice bath, ca. 1 C) suspension of sodium hydride (1 eq., 75.2 mmol) in tetrahydrofuran (40 mL). The ice bath was removed and the mixture was stirred rapidly while being allowed to warm to room temperature (ca. 26 C) over the course of ca. 3 h. In a separate round bottom flask, the ethylformate-functionalized cellulose (2) was dried at 110 C for 3 h and then stored temporarily under dynamic argon.
The mixture of 3-(dimethylamino)propy1-1-amine and sodium hydride (comprising sodium (3-aminopropyl) dimethylamine; compound 1 of Figure 36) was then transferred via cannula into the round bottom containing the ethylformate-functionalized cellulose (compound 2 of Figure 36). The resultant mixture was stirred rapidly at room temperature overnight to yield (compound 3 of Figure 36). The reaction was neutralized using an ca. 1.3 eq.
solution of ammonium chloride (in excess) in water. Functionalized cellulose (Al) was recovered using vacuum filtration. In order to deprotonate any of the cellulose protonated by the excess ammonium chloride, it was mixed overnight in a solution of tetramethylguanidine /
tetrahydrofuran (1:4 v/v). The functionalized cellulose )Al) was then rinsed with copious amounts of ethanol, followed by sonication for 20 minutes in 50 mL of ethanol (repeated three times). The functionalized cellulose (Al) was then dried in an oven at 110 C for 4 h, after which it was characterized by FTIR: non-functionalized cellulose: 3242 cm-1(s, b), 2899 cm-1(m, b), 1651 cm-1(w, b), 1433-1261 cm-1(m, b), 1162-1059 cm-1(s, b), 896 cm-1(w, sh);
functionalized cellulose: 3241 cm-1(s, b), 2921 cm-1(m, b),1616 cm-1(m, b), 1433-1261 cm-1 (m, b), 1162-1059 cm-1(s, b), 896 cm-1(w, sh), 750-85C (w, sh); m=medium, w=weak, s=strong, n=narrow, b=broad, sh=sharp.

[00317] Representative procedure for testing switchable celluloses as drying agents:

[00318] Solvent chosen to compare utility of switchable cellulose materials as drying agents was isobutanol, which was doped with 5 wt% H20. The switchable cellulose and 'wet' isobutanol solution was added to a vial, and CO2 was bubbled through the solution for 1 h.
The vial was then sealed and stirred for 15 h. The sw tchable cellulose was separated from the wet isobutanol solution via vacuum filtration; water content remaining in the isobutanol solution after filtration was analyzed via gas chromatography thermal conductivity detector (GC-TCD). Results are reported in Table 12.

[00319] Discussion:

[00320] FT-IR analysis of Al, Method 2 suggests functionalization of cellulose with 3-(dimethylamino)-1-propylamine was successful: the IR spectrum of Al was different from the IP spectrum of non-functionalized cellulose, in that the peak at -1600 cm-1 was broader for Al than non-functionalized cellulose, and is indicative of functionalization.

[00321] EXAMPLE 5: Functionalization of Filter Paper

[00322] Method 1 (Figure 13):

[00323] As described above, it has been postulated that the herein described switchable polysaccharides can find use as switchable filter papers. Though work is on going to investigate this application of switchable polysaccharides, a proof of principal experiment was undertaken to functionalize Whatman Type I filter paper with a long-chain (i.e. waxy) carboxylic acid via a COI-mediated coupling, a demonstrative, non-limiting example of which is depicted in Figure 13.

[00324] The resultant functionalized filter paper was then analyzed by way of contact angle analysis via the sessile drop method (see Table 9); it was found that, following functionalization, the filter paper was hydrophobic, suggesting that the functionalization had been successful.

[00325] The present Example indicates that a switchable filter paper can be synthesized by functionalizing standard filter paper Jsing an appropriate carboxylic acid functionalized with a switchable moiety, as described herein.

[00326] Method 2 (Figure 37):

[00327] A cellulosic substrate (whatman type 1 filter paper, 42.5 mm) was dried at 110 C overnight and placed into a 250 mL round bottom flask and stored under Ar gas. In a separate round bottom flask, a solution of carbonyldiimidazole (5.14 mmol, 1eq.) and 3-(dimethylamino)propionic acid hydrochloride (5.14 mmol, 1 eq.) in tetrahydrofuran (ca. 50 mL) was mixed rapidly for 4 h. A solution-containing compound 1 of Figure 37 was transferred into the round bottom flask containing the cellulosic substrate;
the resultant mixture was left stirring under a dynamic flow of CO2 overnight at room temperature (ca.
26 C) [Vaidyanathan, R. et al., J. Org. Chem. 2004, 69, 2565-2568]. The substrate was rinsed with copious amounts of ethanol, followed by sonication for 20 minutes in 50 mL of ethanol (repeated three times). In order to activate the functionalized cellulose substrate by removing the hydrochloride salt of 1 of Figure 37, the substrate was mixed overnight in a solution of tetramethylguanidine / tetrahydrofuran (1:4 v/v). The cellulosic substrate was then rinsed with copious amounts of ethanol, followed by sonication for 20 minutes in 50 mL
of ethanol (repeated three times). The functionalized substrate was then dried in an oven at 110 C for 4 h.

[00328] Method 3 (Figure 38):

[00329] A cellulosic substrate (whatman type 1 filter paper, 42.5 mm) was dried at 110 C overnight and placed into a 250 mL round bottom flask and stored under argon. In a separate round bottom flask, a solution of carbonyldiimidazole (5.14 mmol, 1 eq.) and 3-(dimethylamino)propionic acid hydrochloride (5.14 mmol, 1 eq.) in tetrahydrofuran (ca. 50 mL) was mixed rapidly for 4 h. The solution containing compound 1 of Figure 38, as well as imidazole hydrochloride (mild acid catalyst; 25.7 mmol, 5 eq.), were added to the round bottom flask containing the cellulosic substrate. The resultant mixture was left mixing overnight at room temperature (ca. 26 C). The substrate (compound 2 of Figure 38) was rinsed with copious amounts of ethanol, followed by sonication for 20 minutes in 50 mL of ethanol (repeated three times). In order to deprotonate the functionalized cellulose substrate by removing the hydrochloride salt of 1 of Figure 38, the substrate was mixed overnight in a solution of tetramethylguanidine / tetrahydrofuran (1:4 v/v). The cellulosic substrate (compound 3 of Figure 38) was then rinsed with copious amounts of ethanol, followed by sonication for 20 minutes in 50 mL of ethanol (repeated three times). The functionalized substrate was then dried in an oven at 110 C for 4 h.

[00330] Method 4 (Figure 39):

[00331] A cellulosic substrate (whatman type 1 filter paper, 42.5 mm) is dried at 110 C overnight and placed into a 250 mL round bottom flask and stored under argon. In a separate round bottom flask, a solution of carbonyldiimidazole (5.14 mmol, 1 eq.) and 3-(dimethylamino)propionic acid hydrochloride (5.14 mmol, 1eq.) in tetrahydrofuran (ca. 50 mL) was mixed rapidly overnight. Compound 1 of Figure 39 is isolated and treated with methyliodide (4eq.) in acetonitrile at room temperature (ca. 26 C) and is stirred for 24 h.
The solvent is removed under vacuum to yield compound 2 of Figure 39. Compound 2 (1 eq.) is added to a round bottom flask containing the dried filter paper and triethylamine (1 eq.), and the solution is stirred at room temperature (ca. 26 C) for 24 h.
The substrate is rinsed with copious amounts of ethanol, followed by sonication for 20 minutes in 50 mL of ethanol (repeated three times). To deprotonate the functionalized cellulose substrate by removing the hydrochloride salt of compound 3 of Figure 39, the substrate is mixed overnight in a solution of tetramethylguanidine / tetrahydrofuran (1:4 v/v).
The cellulosic substrate is then rinsed with copious amounts of ethanol, followed by sonication for 20 minutes in 50 mL of ethanol (repeated three times). The functionalized substrate (compound 4 of Figure 39) is then dried in an oven at 110 C for 4 h.

[00332] EXAMPLE 6: Synthesis and characterization of CO2 responsive Chitosan-g-Poly(Diethylaminoethyl methacrylate).

[00333] Materials: Chitosan (CTS, Aldrich, degree of deacetylation of 85%), glycidyl methacrylate (GMA, Aldrich, 97%), hydroquinone (Fisher), acetic acid (Fisher, 99.7%), tetrahydrofuran (THF, ACP, 99+%), deuterium oxide (Cambridge Isotope Laboratories, D
99.9%). Styrene (St, Aldrich, 99+%) and 2-(Diethylamino)ethyl methacrylate (DEAEMA, Aldrich, 99%) were passed over a column containing basic aluminum oxide (Aldrich,-150 mesh, 58 A) to remove the inhibitor and stored below 5 C prior to polymerization. N,N"-dicyclohexylurea was purchased from Aldrich and used as received. SG1 (N-tert-butyl-N-(1-diethylphosphono-2,2-dimethylpropyl) nitroxide) (85%, kindly supplied by Arkema). N-Hydroxysuccinimide-BlocBuilder (NHS-BB) was synthesized from BlocBuilder (BB, N-(2-methylpropy1)-N-(1-diethylphosphono-2,2-imethylpropy1)-0-(2-carboxylprop-2-y1) hydroxylamine (BB, 99%, provided by Arkema) according to the reported procedure [J.
Vinas, N. Chagneux, D. Gigmes, T. Trimaille, A. Favier and D. Bertin, Polymer, 2008, 49, 3639-3647.], as follows: BB (5 g, 13.1 mmol) and N-hydroxysuccinimide (1.81 g, 15.7 mmol) were dissolved in THF (20 mL) and deoxygenated by nitrogen bubbling for 15 min. Then, a degassed solution of N,N"dicyclohexylcarbodiimide (3 g, 14.4 mmol) in THE (5 mL) was added. After stirring at 0 C for 1.5 h, the precipitated N,N"-dicyclohexylurea was removed by filtration and the filtrate volume was reduced under vacuum to one third and placed at -20 C
for 2 h in order to precipitate the residual N,N"-dicyclohexylurea. After filtration, the solution was concentrated under reduced pressure and precipitation was performed in pentane. The obtained solid was further washed with water to remove N-hydroxysuccinimide.
After drying under vacuum, alkoxyannine 1 was obtained as a white powder. Nickel sulphate (NiSO4=6H20, Aldrich, 99%), concentrated nitric acid (Aldrich, 68.0-70%) and carbon dioxide gas (MEGS, bone dry 99.8%) were obtained for the equilibrium absorption studies.

[00334] Instrumentation: 1H NMR spectroscopy was performed on an FT-NMR
Bruker Avance 400 MHz spectrometer with a total of 256 scans, at room temperature using D20/CH3000H 0.4 M as solvent at 5 mg/mL. Fourier Transform Infrared (FT-IR) spectroscopy was carried out on a Thermo Scientific. Thermogravimetric analysis (TGA) was performed using a TA Instruments 0500 TGA analyser by heating the sample using the following ramp: 10 C min-1 from 30 to 75 C, held for 30 min at a plateau of 75 C, and 10 C
min-1 to 600 C. Gel Permeation Chromatography (GPC) analysis was performed with a Waters 2690 Separation Module and Waters 410 Differential Refractometer with THF as the eluent. The column bank consisted of Waters Styragel HR (4.6x300 mm) 4, 3, 1, and 0.5 separation columns at 40 C. pH measurements were completed with a Thermo Fisher Scientific Inc. Orion Star A211 Benchtop Meter. Agitation for equilibrium absorption studies was completed with a 120V, VWR International LLC. Standard Orbital shaker model 5000 (shaker table).

[00335] Synthesis of Chitosan-g-glycidyl methacrylate (CTS-g-GMA):

[00336] CTS-g-GMA was synthesized (see Figure 14) using a methodology published by Garcia-Valdez et al., which offered slight modifications over a previous report [0. Garcia-Valdez, R. Champagne-Hartley, E. Saldivar-Guerra, P. Champagne and M. F.
Cunningham, Polymer Chemistry, 2015; 0. Garcia-Valdez, R. Champagne-Hartley, E.
SALDIVAR-GUERRA, P. Champagne and M. F. Cunningham, POLYMER-15-185, 2015; E.
A. ElizaIde-Pelia, N. Flores-Ramirez, G. Luna-Barcenas, S. R. Vasquez-Garcia, G.
Arambula-Villa, B. Garcfa-Gaitan, J. G. Rutiaga-Quiriones and J. Gonzalez-Hernandez, European Polymer Journal, 2007, 43, 3963-3969]. Chitosan (1.0 g) was dissolved in 100 mL
of 0.4 M acetic acid solution (2.4 g, 2.28 mL in 100 mL of de-ionized water) in a 250 mL
three neck round bottom flask under magnetic agitation using an egg-shaped stir bar (size:
1.90 x 0.95 cm). After that, 5 mL of 0.05 M KOH (0.014g of KOH dissolved in 5mL of water) and 10 mL of 9.08 mM hydroquinone solution (0.01 g, 9.08*10-5 mol in 10 mL of water) was added to the mixture. A mercury thermometer and a condenser were connected to the three neck round bottom flask while water at 5 C was circulated. Then the mixture was degassed under nitrogen for 30 minutes prior to be heated to 65 C in an oil bath. When the chitosan solution reached 65 C, GMA (24.0 mmol, 3.53 g, 3.30 mL) was injected to the flask dropwise and the mixture was magnetically stirred for 2 hours under these conditions.
The solvent was removed under vacuum and the product was washed twice with THF (-80 mL) and once with de-ionized water (-80 mL) and filtered under vacuum. CTS-g-GMA was analyzed by 1H
NMR.

[00337] CTS-g-GMA was synthesized by reaction of an epoxide group of GMA
with a primary alcohol from CTS under acidic conditions (pH=3.8). Protection of the CTS amino groups was achieved by performing the reaction under acidic conditions, where the amino groups were protonated and thus, were not able to react with the epoxy group of the GMA.
1H NMR for CTS-g-GMA (Figure 17) showed peaks at 3.09, 3.67, 3.83, and 4.52 ppm attributed to H2, H5-6, H3-6, and H1 respectively. Peaks at 4.24 ppm were attributed to protons H7, 8 of GMA, which were closest to CTS' ether linkage. Peaks at 5.71 and 6.11 ppm were attributed to vinyl protons H10, 11 protons of the GMA unit. Degree of functionalization of CTS with GMA was estimated to be 11 mol%, based on integral ratio between GMA's vinyl proton peak at 6.1 ppm and CTS' proton peak at 3.1 ppm.

[00338] Synthesis of Poly((Diethylamino)ethyl methacrylate) (PDEAEMA) via Nitroxide mediated polymerization:

[00339] Polymerization of DEAEMA was completed using similar NMP
methodology from previous publications [J. Nicolas, S. Brusseau and B. Charleux, Journal of Polymer Science Part A: Polymer Chemistry, 2010, 48, 34-47; J. Nicolas, C. Dire, L.
Mueller, J.
Belleney, B. Charleux, S. R. A. Marque, D. Bertin, S. Magnet and L. Couvreuer, Macrmolecules, 2006, 39, 8274-8282] (Figure 15). In a 250 mL three neck round bottom flask, the un-inhibited DEAEMA (0.26 mol, 50 g, 47.57 mL), styrene (0.03 mol, 3.12 g, 3.47 mL), NHS-BlocBuildere (0.0029 mol, 1.4038 g) and SG1 (0.0003 mol, 0.1016 g, 0.1022 mL) were mixed magnetically using an egg-shaped stir bar (size: 1.90 x 0.95 cm). A
mercury thermometer and a condenser were connected to the three neck round bottom flask while water at 5 C was circulated. The mixture was degassed under nitrogen for 30 minutes. The mixture was maintained at 80 C using an oil bath and stirred for 1 hour.
After, PDEAEMA
was precipitated in hexanes (250 mL) cooled with liquid nitrogen (300 mL), decanted, washed in THF (300 mL), re-precipitated in 250 mL of hexanes (cooled with liquid nitrogen) and decanted. Analysis was completed via GPC and TGA.

[00340] PDEAEMA was synthesized via nitroxide-mediated polymerization.
Conversion of monomer into polymer (determined by gravimetry) was 53%.
Molecular weight distribution of PDEAMEA obtained by GPC (Figure 18) was narrow, suggesting a well-controlled reaction. Average weight molecular weight (M,) was 13316 g/mol, and number average molecular weight (Me) was 9714 g/mol, which gave a dispersity index (D=Mw/Mn) of 1.37.

[00341] Synthesis of CTS-g-GMA-PDEAEMA:

[00342] Grafting to synthesis was conducted using the following procedure (see Figure 16). In a 250 mL three neck round bottom flask, CTS-g-GMA (1.2182 g) was dissolved in 100 mL of 0.1 M acetic acid (0.6 g, 0.57 mL in 100 mL of de-ionized water) solution. The pH of the solution was then adjusted to 5.0 using 50 mL of 1.0 M
KOH (0.2805 g in 50 mL of de-ionized water) solution. A mercury thermometer and a condenser were connected to the three neck round bottom flask while water at 5 C was circulated. The mixture was degassed for 30 minutes under a nitrogen atmosphere and heated to 90 C.

PDEAMEA (2.40 g) was dissolved in 60 mL of 0.1 M acetic acid (0.36 g, 0.342 mL
in 100 mL
of de-ionized water) solution and degassed for 30 minutes. When the CTS-g-GMA
solution reached 90 C, the polymer solution was added in a semi-batch manner: 20 mL
every hour.
The total reaction was 3 hours. After the reaction system was cooled in an ice bath, the solvent was removed under vacuum. The product was washed twice with THF (-80 mL), once with 0.1 M KOH (0.560 g in 100 mL of water) solution, once with de-ionized water (-80 mL) and vacuum dried. The product was analyzed via TGA and 1H NMR.

[00343] Proposed mechanism of grafting PDEAEMA chains to CTS-g-GMA was based on thermal dissociation of SG1 from the polymer chain resulting in two radicals: a stable SG1-nitroxide radical and a free radical at the end of the polymer chain; this chain-end radical reacted with the double bond of CTS-g-GMA before being deactivated by the SG1, covalently linking the polymer chain to CTS. Degree of functionalization of chitosan with PDEAEMA was determined by 1H NMR, by the ratio of methyl group protons of the PDEAEMA to the CTS backbone chain, divided by a number-average degree of polymerization of PDEMA in the polymer chain. It was determined that for every units, 2.7 chains of PDEAEMA were attached, which corresponds to 135 DEAEMA
units for every 100 chitosan units.

[00344] 1H-NMR spectra CTS-g-GMA-PDEAEMA (Figure 19) showed peaks of CTS
previously discussed. Signals characteristically belonging to PDEAEMA (PDEAEMA
methyl groups at 1.4 ppm, 3.21 and 3.45 ppm; signals attributed to six protons in a-position to the PDEAEMA amino group) suggested the success of the 'grafting to' synthesis.

[00345] CTS-g-GMA-PDEAEMA was also analyzed by thermogravimetric analysis (TGA) (Figure 20). The TGA indicated that CTS backbone chains decompose between 250 and 350 C, and the PDEAEMA around 350 and 450 C, which confirmed presence of PDEAEMA covalently attached to CTS.

[00346] Ni(II) Sorption Equilibrium Studies:

[00347] Equilibrium sorption studies were conducted using a combination of previously reported procedures [P. Champagne-Hartley, A Combined Passive System for the Treatment of Acid Mine Drainage, Ottawa, 2001; S. R. Popuri, Y. Vijaya, V.
M. Boddu and K. Abburi, Bioresources Technology, 2009, 100, 194-199]. Stock solutions were diluted to the desired Ni(II) concentrations of 50, 200, 500 and 1000 mg/L from nickel sulphate at ambient laboratory conditions. To a 250 mL beaker, 50 mg of a specific absorbent (e.g.

switchable chitosan) and 100 mL of a desired stock solution were added. After recording an initial pH, the beakers were covered and agitated at 150 rpm on a shaker table. After a 24 hour contact period, a final pH of the samples was recorded. 10 mL samples were filtered using 0.2 urn PTFE syringe filters and acidified with two drops of concentrated nitric acid.

[00348] Trials that required pH adjustment via carbon dioxide were prepared by adding 50 mg of an absorbent and 100 mL of de-ionized water to a 250 mL
beaker. After an initial pH reading, 1 hour of carbon dioxide gassing was completed and a final pH recorded.
Nickel sulphate was added in an appropriate proportion to meet a desired initial concentration (50, 200, 500 or 1000 mg/L), and the solution stirred with a magnetic star bar (size: 2.5 cm x 0.8 cm) at 350 rpm for 15 minutes to complete dissolution. For metal analysis, an initial 5 mL sample was taken and acidified with two drops of nitric acid, and the beaker was agitated at 150 rpm for 24 hours. Final metal content was analyzed via a 10 mL
sample acidified with two drops of nitric acid.

[00349] Metal concentrations were determined via ICP-OES analysis completed by Queen's University Analytical Services Unit.

[00350] For each absorbent, the unit equilibrium uptake capacity (qe, mg/g) was calculated according to mass balance (Equation 1).
C C

q. = e) V
(1)

[00351]

[00352] WhereCo andCe were the initial and equilibrium metal concentrations (mg/L), m was the mass of absorbent (g) and V was the volume of solution (L).

[00353] Figure 22 depicts absorption capacities of CTS versus CTS-g-PDEAEMA
without initial carbon dioxide gassing. Initial pH range for initial absorption trials was from 5.80 to 5.87. After the grafted material was removed, washed with de-ionized water, and placed in de-ionized water, initial pH readings were 8.57 to 8.94. After gassing with carbon dioxide for 1 hour, pH dropped to 5.47 to 5.63.

[00354] These results suggested that the synthesized CTS-g-GMA was not as a strong absorbent as pure CTS without carbon dioxide gassing. With 1 hour of carbon dioxide gassing, 25-82% of the absorbed metal was recovered off the grafted material.
After regeneration, the grafted material's absorbance capacity was increased by 196-241%, with it surpassing pure CTS at equilibrium nickel concentrations of approximately 300 mg/L.
Without wishing to be bound by theory, this increase in capacity was hypothesized to be attributed to residual charge on the grafted material that allowed for better dispersion and thus, improved interactions of dissolved nickel ions with the chelation sites on the material. It was considered that variation of the result trends may be attributed to natural variation of the natural biomaterial.

[00355] CO2 Regeneration Studies:

[00356] After completing the equilibrium sorption studies and preparing the 10 mL
sample for analysis, the remaining solution containing a grafted absorbent was filtered using Whatman 1 filter paper and washed de-ionized water (-20 mL). The grafted absorbent was collected and placed in an Erlenmeyer flask containing 20.0 mL of de-ionized water. Initial pH was recorded, the vials were covered and carbon dioxide gas was bubbled into the solution. After 1 hour of gassing, the final pH was recorded, a 10 mL sample was collected, filtered using 0.2 iim PTFE syringe filters and acidified with two drops of concentrated nitric acid. Again, metal concentrations were determined via ICP-OES analysis completed by Queen's University Analytical Services Unit. The remaining solution was filtered through using Whatman 1 filter paper and the grafted absorbent collected to air-dry overnight.

[00357] Figure 23 depicts absorption capacities of CTS versus CTS-g-PDEAEMA
with initial carbon dioxide gassing of the absorbent solution before addition of nickel.
After gassing, initial pH dropped to 4.09-4.17 for pure CTS and 4.56-4.83 for the grafted material. Recovery of absorbed nickel from the grafted material after 1 hour of carbon dioxide gassing was 30-67%.

[00358] These results suggested that, with the exception of the trials that equilibrated at 50 mg Ni(II)/L, pure CTS behaved as a better absorbent. However, the trend observed in the grafted material was not characteristic of an absorption isotherm, suggesting that the results were not conclusive. It has been hypothesized that again, natural variation of the material played a role in these inconsistencies, and that because the mass of absorbent used (50 mg) was relatively small, these effects were exacerbated.

[00359] CO2 Switchability:

[00360] In order to demonstrate switchable capability of CTS-g-GMA-PDEAEMA, 0.5 g of CTS-g-GMA-PDEAEMA was put in 10 mL of de-ionized water in a 20 mL vial with an egg-shaped stir bar (size: 1.27 x 0.31 cm) and the vial was sealed with a rubber cap. Then carbon dioxide was bubbled through the vial via a 5 cm needle for 2 hours under magnetic stirring. Then nitrogen was bubbled to the vial through for 2 hours under magnetic stirring.
Pictures (Figure 21) were taken before and after bubbling carbon dioxide.
Before carbon dioxide gassing, the copolymer appeared suspendended in the water (Figure 21(A)). After gassing with carbon dioxide for 2 hours, the material appeared visually swelled and more translucent (Figure 21(B)). Regeneration of the material to its initial form was evident after gassing with nitrogen (Figure 21(C)).

[00361] EXAMPLE 7: Modification of crystalline nanocellulose (CNC) with poly (diethylaminoethylmethacrylate) (PDEAEMA) combining nitroxide-mediated polymerization with grafting to approach, and free radical polymerization with grafting from approach.

[00362] Materials: Crystalline nanocellulose (CNC, from FP Innovations), glycidyl methacrylate (GMA, Aldrich, 97%), hydroquinone (Fisher), acetic acid (Fisher, 99.7%), tetrahydrofuran (THF, ACP, 99+%), deuterium oxide (Cambridge Isotope Laboratories, D
99.9%). Styrene (St, Aldrich, 99+%) and 2-(Diethylamino)ethyl methacrylate (DEAEMA, Aldrich, 99%) were passed over a column containing basic aluminum oxide (Aldrich,- 150 mesh, 58 A) to remove the inhibitor and stored below 5 C prior to polymerization. N,N"-dicyclohexylurea and 2,2'-Azobis(2-methylpropionitrile) (AIBN, 98%) were purchased from Aldrich and used as received. SG1 (N-tert-butyl-N-(1-diethylphosphono-2,2-dimethylpropyl) nitroxide) (85%, kindly supplied by Arkema). N-Hydroxysuccinimide-BlocBuilder (NHS-BB) was synthesized from BlocBuilder (BB, N-(2-methylpropy1)-N-(1-diethylphosphono-2,2-imethylpropy1)-0-(2-carboxylprop-2-y1) hydroxylamine (BB, 99%, provided by Arkema) according to the reported procedure [J. Vinas, N. Chagneux, D. Gigmes, T.
Trimaille, A.
Favier and D. Bertin, Polymer, 2008, 49, 3639-3647] just as follows: BB (5 g, 13.1 mmol) and N-hydroxysuccinimide (1.81 g, 15.7 mmol) were dissolved in THF (20 mL) and deoxygenated by nitrogen bubbling for 15 min. Then, a degassed solution of N,N"dicyclohexylcarbodiimide (3 g, 14.4 mmol) in THF (5 mL) was added. After stirring at 0 C for 1.5 h, the precipitated N,N"-dicyclohexylurea was removed by filtration and the filtrate volume was reduced under vacuum to one third and placed at -20 C for 2 h in order to precipitate the residual N,N"-dicyclohexylurea. After filtration, the solution was concentrated under reduced pressure and precipitation was performed in pentane. The obtained solid was further washed with water to remove N-hydroxysuccinimide. After drying under vacuum, alkoxyamine was obtained as a white powder.

[00363] Instrumentation: CP/MAS 13C NMR spectra were recorded on a Bruker Avance 600 spectrometer operating at 150.91 MHz using a Bruker 5 mm CP/MAS
probe. In a typical measurement, spinning rate was 12 kHz with a cross-polarization contact time of 3 ms and a repetition delay of 2 s. For all samples, number of scan was in excess of 1000 to guarantee sufficient signal-to-noise ratios. Thermogravimetric analysis (TGA) was performed using a TA Instruments 0500 TGA analyser by heating the sample using the following ramp:
C min-1 from 30 to 75 C, held for 30 min at a plateau of 75 C, and 10 C min-1 to 600 C.
Gel Permeation Chromatography (GPC) analysis was performed with a Waters 2690 Separation Module and Waters 410 Differential Refractometer with THF as the eluent.
Column bank consisted of Waters Styragel HR (4.6x300 mm) 4, 3, 1, and 0.5 separation columns at 40 C.

[00364] Functionalization of CNC with glycidyl methacrylate (CNC-g-GMA):

[00365] Functionalization of CNC with glycidyl methacrylate (CNC-g-GMA) is depicted in Figure 24, and was carried out following similar procedures previously reported [0.
Garcia-Valdez, R. Champagne-Hartley, E. Saldivar-Guerra, P. Champagne and M.
Cunningham, Polymer Chemistry, 2015]. CNC (1.0 g) was dispersed in 100 mL of 0.4 M
acetic acid solution (2.4 g, 2.28 mL in 100 mL of de-ionized water) solution in a 250 mL three neck round bottom flask under magnetic agitation using a Stir bar Egg-Shaped (size1.90 x 0.95 cm). After that, 5 mL of 0.05 M KOH (0.014g of KOH dissolved in 5mL of water) and 10 mL of 9.08 mM hydroquinone solution (0.01 g, 9.08'1 0-5 mol in 10 mL of water) was added to the mixture. A mercury thermometer and a condenser were adapted to a three neck round bottom flask by which water at 5 C was circulated. Then the mixture was degassed under nitrogen for 30 minutes prior to be heated to 65 C in an oil bath. When the CNC dispersion reached 65 C GMA (24.0 mmol, 3.53 g, 3.30 mL) was injected to the flask drop wise and the mixture was magnetically stirred for 2 hours under these conditions. The solvent was removed under vacuum and the product was washed twice with THF and once with de-ionized water and filtered. CNC-g-GMA was analyzed by TGA and 13C NMR CP-MAS.

[00366] After functionalization of CNC with GMA, CNC-g-GMA, due to its insolubility in common organic solvents, was analyzed only by CP/MAS 13C NMR; the respective spectra is shown in Figure 27. The spectra showed carbons C4 at 86-92 ppm, which indicated a crystalline region, while a 80-86 ppm signal indicated an amorphous region. For C6, 62.5-67.5 ppm and 58-65 ppm ranges indicated a crystalline region. Cl signal appeared at 105 ppm, while C2, C3, and C5 reside at 67-79 ppm. Around 170 ppm, a signal attributed to carbonyl (C=0) group from the GMA unit was observed, and at 15 ppm, a displacement attributed to a methyl group from GMA was observed.

[00367] Synthesis of Poly((Diethylamino)ethyl methacrylate) (PDEAEMA) via Nitroxide mediated polymerization:

[00368] Polymerization of DEAEMA was completed using NMP methodology from previous publications [J. Nicolas, S. Brusseau and B. Charleux, Journal of Polymer Science Part A: Polymer Chemistry, 2010, 48, 34-47; J. Nicolas, C. Dire, L. Mueller, J. Belleney, B.
Charleux, S. R. A. Marque, D. Bertin, S. Magnet and L. Couvreuer, Macrmolecules, 2006, 39, 8274-8282] (see Figure 15). In a 250 mL three neck round bottom flask, the un-inhibited DEAEMA (0.26 mol, 50 g, 47.57 mL), styrene (0.03 mol, 3.12 g, 3.47 mL), NHS-BlocBuildera (0.0029 mol, 1.4038 g) and SG1 (0.0003 mol, 0.1016 g, 0.1022 mL) were mixed magnetically using a Stir bar Egg-Shaped (size1.90 x 0.95 cm). A mercury thermometer and a condenser were adapted to a three neck round bottom flask by which water at 5 C was circulated. The mixture was degassed under nitrogen for 30 minutes. The mixture was stirred at 80 C for 1 hour. After reaction time, PDEAEMA was precipitated in hexanes (250 mL) cooled with liquid nitrogen (300 mL), decanted, washed in THF
(300 mL), re-precipitated in 250 mL of hexanes (cooled with liquid nitrogen) and decanted. Analysis was completed via GPO and TGA.

[00369] PDEAEMA was synthesized via nitroxide-mediated polymerization.
Conversion of monomer into polymer (determined by gravimetry) was 53%.
Molecular weight distribution of PDEAMEA obtained by GPO (Figure 18) was narrow, suggesting a well controlled reaction. Average weight molecular weight (M,) was 13316 g/mol, and number average molecular weight (Me) was 9714 g/mol, which gave a dispersity index (D=Mw/Mn) of 1.37.

[00370] Modification of CNC with PDEAEMA combining nitroxide-mediated polymerization with grafting to approach:

[00371] Figure 25 depicts grafting PDEAEMA to CNC-g-GMA via NMP. In a 250 mL
three neck round bottom flask, CNC-g-GMA (1.0 g) was dispersed in 100 mL of DMSO. A
mercury thermometer and a condenser were adapted to a three neck round bottom flask by which water at 5 C was circulated. The mixture was degassed for 30 minutes under a nitrogen atmosphere and heated to 90 C. PDEAMEA (1 g) was dissolved in 60 mL
of 1,4-dioxane and degassed for 30 minutes. The flask with the CNC-g-GMA dispersion was submerged in an oil bath at 95 C. When the CNC-g-GMA reached 90 C, the polymer solution was added in semi-batch manner to the system, 20 mL every hour. The total reaction was 3 hours. After the reaction system was cooled in an ice bath. The CNC-g-GMA-PDEAEMA dispersion was submitted to three centrifugation processes to separate it from the solvents and the remaining unreacted PDEAEMA. The product was washed twice with THF, and dried under vacuum. The product was analyzed using TGA and 13C NMR CP-MAS.

[00372] Mechanism of grafting PDEAEMA chains to CNC-g-GMA was previously proposed [0. Garcia-Valdez, R. Champagne-Hartley, E. SALDIVAR-GUERRA, P.
Champagne and M. F. Cunningham, POLYMER-15-185, 2015]. CNC-g-GMA-PDEAEMA
was analyzed by TGA and CP/MAS 13C NMR to confirm presence of PDEAEMA
covalently attached to CNC. The CP/MAS 13C NMR of CNC-g-GMA-PDEAEMA is depicted in Figure 28. The spectrum showed, besides characteristic signals of CNC-g-GMA
previously discussed, new signals attributed to grafted PDEAEMA. At 20-22 ppm there was observed signals attributed to methyl groups from PDEAEMA and GMA; at 35-45 ppm signals attributed to methylene groups (-CH2-); and at 175 ppm, signal of the C=0 group from the methacrylate unit.

[00373] CNC-g-GMA-PDEAEMA was also analyzed by TGA. Figure 29 depicts a TGA
corresponding thermogram for CNC, PDEAEMA and CNC-g-PDEAEMA. The thermogram of CNC (Figure 29 (A)) indicated its decomposition between 280 and 300 C. The thermogram of PDEAEMA (Figure 29 (B)) indicated the decomposition of the polymer between 320 and 450 C, and TGA for CNC-g-GMA-PDEAEMA (Figure 29 (C)) indicated decomposition of this new material between 300 and 450 C.

[00374] Modification of crystalline nanocellulose (CNC) with Poly(Diethylaminoethyl methacrylate) (PDEAEMA) combining and free radical polymerization (FRP) with grafting from approach:

[00375] Figure 26 depicts modified grafting of PDEAEMA to CNC-g-GMA via FRP. In a 250 mL three neck round bottom flask, CNC-g-GMA (0.45 g) was dispersed in 45 mL of DMSO. DEAEMA (4.5 g, 4.9 mL, and 0.0025 mol) and AIBN (0.17 g, 0.00125 mol) were added to three neck round bottom flask. A mercury thermometer and a condenser were adapted to a three neck round bottom flask by which water at 5 C was circulated. The mixture was degassed for 30 minutes under a nitrogen atmosphere prior to be heated to 80 C for 3 hours. After the reaction system was cooled in an ice bath. The CNC-g-GMA-PDEAEMA dispersion was submitted to three centrifugation process in order to separate it from the solvents and the remaining unreacted PDEAEMA. The product was washed twice with THF, and dried under vacuum. The products were analyzed using TGA and 13C
NMR
CP-MAS.

[00376] In this case, CNC-GMA was copolymerized with DEAEMA via FRP, using AIBN as initiator. Also were used TGA and CP/MAS 13C NMR to confirm presence of PDEAEMA covalently attached to CNC. The CP/MAS 13C NMR of CNC-g-GMA-PDEAEMA
is depicted in Figure 30, which indicated new signals attributed to grafted PDEAEMA. For example, at 20-22 ppm there was observed signals attributed to methyl groups from PDEAEMA and GMA; at 35-45 ppm there was observed signals attributed to methylene groups (-CH2-); and at 175 ppm, the signal of the C=0 group from the methacrylate unit.

[00377] CNC-g-GMA-PDEAEMA obtained via free radical polymerization was also analyzed by TGA. Figure 31 depicts TGA corresponding thermogram for CNC, PDEAEMA
and CNC-g-PDEAEMA. The thermogram of CNC (Figure 31(A)) indicated its decomposition between 280 and 300 C. The thermogram of PDEAEMA (Figure 31 (B)) indicated decomposition of this polymer between 320 and 450 C, and TGA for CNC-g-GMA-PDEAEMA obtained via free radical polymerization (Figure 31(C)) indicated decomposition of this new material between 300 and 450 C, which confirms that PDEAEMA is covalently attached to CNC backbone chain.

[00378] EXAMPLE 8: Grafting switchable polymers from crystalline nanocellulose via nitroxide-mediated polymerization

[00379] Materials: Crystalline nanocellulose (CNC), provided by FPInnovations, was prepared at FPInnovations pilot plant (Pointe-Claire, QC) by sulfuric acid hydrolysis of a commercial bleached softwood Kraft pulp. BlocBuilder (N-(2-methylpropyI)-N-(1-diethylphosphono-2,2-imethylpropy1)-0-(2- carboxylprop-2-y1) hydroxylamine (BB, 99%) was used as received from Arkema. 2-(Dimethylamino)ethyl methacrylate (DMAEMA, Aldrich, 99+%), 2-(Diethylamino)ethyl methacrylate (DEAEMA, Aldrich, 99+%) and 3-(Dimethylamino)propyl methacrylamide (DMAPMAm, Aldrich, 99+%) were passed over a column containing basic aluminum oxide (Aldrich, ¨150 mesh, 58 A) to remove the inhibitor and stored below 5 C prior to polymerization. Chloromethyl styrene (CMS, Aldrich 90%), and dimethyl sulfoxide (DMSO, Fisher, 99.9%) were used as received. All deionized (DI) water (18.2 MQ=cm resistivity) used in the experimental work was collected from a Direct-Q 3 Millipore ultrapure water system. SG1 is (N-tert-butyl-N-(1-diethylphosphono-2,2-dimethylpropyl) nitroxide).

[00380] Synthesis of crystalline nanocellulose (CNC) - chloromethyl styrene (CMS), (CNC-CMS):

[00381] Chloromethyl styrene (CMS, 2.6 mL, 18.5 mmol) was added dropwise to a 3 wt% solution of CNC (2 g) in DMSO (60 g) in the presence of solid sodium hydroxide at room temperature. The reaction was allowed to proceeded overnight before being precipitated with a minimal amount of ethanol. Styrene-functionalized CNC (CNC-CMS) was collected by centrifugation and thoroughly re-dispersed in DI water.
Centrifugation and re-dispersion were repeated again in water and twice with t-butanol. After the final sedimentation, the CNC-CMS was re-dispersed in a known quantity of t-butanol (-1 wt%
CNC in t-butanol) before being used in the subsequent step.

[00382] Synthesis of Crystalline nanocellulose (CNC) - BlocBuilder (BB), (CNC-BB):

[00383] A solution of BB (4.68 g, 12.3 mmol) in 10 mL t-butanol was added to the CNC-CMS dispersion (100 mL) in a 2-neck round bottom flask with a condenser and was bubbled with N2 for 30 minutes. The solution was introduced to an oil bath at 95 C under nitrogen and the reaction was allowed to ref lux for 90 minutes before being removed from the oil bath. CNC-BB was collected by centrifugation and re-dispersed in ethanol, and this procedure was repeated 3 times. After the final sedimentation, a small portion of the CNC-BB was freeze-dried for characterization and the remaining CNC-BB particles were subjected to a solvent exchange with dimethylsulphoxide (DMSO) to yield a 5 wt%
dispersion of CNC-BB in DMSO to be used for polymerization. Care was taken to ensure that the CNC modified particles were thoroughly cleaned and well dispersed, for both functionalization and characterization, via the sedimentation and solvent exchange method used.

[00384] Grafting poly((Dimethylamino)ethyl methacrylate) (PDMAEMA), poly((Diethylamino)ethyl methacrylate) (PDEAEMA), poly((Dimethylamino)propyl methacrylarnide) (PDMAPMAm), from CNC surface via Nitroxide-mediated polymerization:

[00385] In a typical experiment, 19 g of monomer, either DMAEMA, DEAEMA or DMAPMAm, was added drop-wise to 5 g of a 5 wt% CNC-BB dispersion in DMSO while stirring under nitrogen in a 3-neck round bottom flask affixed with a condenser. The flask was then submersed in an oil bath (time zero) at 90 C. Reaction times were 0.5 and 1 h. For polymerizations, 10 mork of the total monomer concentration was styrene to enhance control over the polymerization. Products were cleaned using the same solvent exchange procedure described above, with tetrahydrofuran (THF) as the wash solvent. All materials and precursors were analyzed by elemental analysis (CHN mode) in PerkinElmer Series II CHN Elemental Analyzer for the determination of carbon, hydrogen, and nitrogen content. 4-potential was meseured in a dynamic light scattering instrument "Zetasizer Nano ZS" using a Universal 'dip' cell. See Figure 40.

[00386] Elemental analysis of starting materials and products is provided in Table 1.
With respect to the CNC-BB entry of Table 13, nitrogen content was attributed to presence of SG1 moieties, which attached to CNC and allowed for graft polymerization.
For the remaining entries of Table 13, nitrogen content was attributed to the presence of the SG1 groups, and the tertiary amines of the corresponding grafted polymer chains.
From the nitrogen content in every sample, an amount of grafted polymer was calculated (see Table 14), representing the mass % of switchable polymer and CNC in the material.

[00387] Measurement of 4-potential and pH under glycolic acid/NaOH
enviroments of CNC-g-PDMAEMA, CNC-g-PDEAEMA and CNC-g-PDMAPMAnn:

[00388] General procedure:

[00389] Sample of either CNC-g-PDMAEMA, CNC-g-PDEAEMA or CNC-g-PDMAPMAm (0.1 g), was poured into dionized water (10 mL) in a 50 mL beaker in the presence of magnetic bar and a pH-meter probe. Afterwards, controlled amounts of glycolic acid (GlAc; 0.5 M, 5 mL) were added until pH decreased and measurement was stable; the 4-potential was then measured. After, controlled amounts of NaOH (0.5 M, 5 mL) were added to the resultant dispersion until pH decreased and measurement was stable; then the 4-potential was measured. This procedure was repeated 3 times.

[00390] 4-potential and pH measurements for CNC-g-PDMAEMA are reported in Table 15 and Figure 41; measurements for CNC-g-PDEAEMA are reported in Table 16 and Figure 42; and, measurements for CNC-g-PDMAPMAm are reported in Table 17 and Figure 43. The measurements of 4-potential at various pH suggested that when pH was low, the switchable amine polymers were protonated (glycolic acid protonated such groups). This was evidenced by the increased, positive 4-potential, which, when positive, indicates that a surface is protonated. When pH was high, the low, negative 4-potential indicated that the switchable amine polymers were de-protonated; and that, thus, the CNC surface was not protonated. Without wishing to be bound by theory, it was considered that these results suggested the CNC-g-polymer were pH responsive.

[00391] Measurement of pH vs 4-potential under CO2/N2 enviorements of CNC-g-PDEAEMA, CNC-g- PDMAEMA and CNC-g-PDMAPMAm:

[00392] General procedure:

[00393] Sample of either CNC-g-PDMAEMA, CNC-g-PDEAEMA or CNC-g-PDMAPMAm (0.1 g), was poured into dionized water (10 mL) in a 50 mL 3-neck round bottom flask in the presence of magnetic bar and a pH-meter probe. Afterwards, CO2 was bubbled to the flask until pH decreased and measurement was stable; then the 4-potential was measured. Afterwards, N2 was bubbled to the resultant dispersion until pH
decreased and measurement was stable; then the 4-potential was measured. This procedure was repeated 3 times.

[00394] 4-potential and pH measurements for CNC-g-PDMAEMA are reported in Table 18 and Figure 44; measurements for CNC-g-PDEAEMA are reported in Table 19 and Figure 43; and, measurements for CNC-g-PDMAPMAm are reported in Table 20 and Figure 44. The measurements of 4-potential at various pH suggested that when pH was low, the switchable amine polymers were protonated (CO2 in water protonated such groups). This was evidenced by the increased, positive 4-potential, which, when positive, indicates that a surface is protonated. When pH was high, the low, negative 4-potential indicated that the switchable amine polymers were de-protonated; and that, thus, the CNC surface was not protonated. Without wishing to be bound by theory, it was considered that these results suggested the CNC-g-polymer were CO2 responsive.

[00395] Table 1. Zeta potential and Z-average size of native CNC (ca. 0.5 mg/mL
dispersion) in response to continuous repeated CO2/N2 sparging cycles.
Number After CO2 Sparging After N2 Sparging of Cycles Zeta potential (mV) Zeta Potential (mV) Cycle 1 -46.8 2.4 -56.6 1.5 Cycle 2 -47.3 0.9 -59.5 2.1 Cycle 3 -47.9 1.3 55.7 2.0 Number After CO2 Sparging After N2 Sparging of Cycles Z-average Size (nm) PDI (-) Z-average Size (nm) PDI (-) Cycle 1 159 1 0.460 151 1 0.416 Cycle 2 133 1 0.412 149 2 0.418 Cycle 3 128 3 0.385 143 3 0.334

[00396] Table 2. Elemental analysis data for CNC-APIm and native CNC.
Sample %C %H %N %S
CNC-APIm #la 44.05 6.52 3.78 0.78 CNC-APIm #2a 43.75 6.87 3.71 0.66 CNC-APIm 43.90 6.70 3.75 0.72 (Average) Native CNCb 42.28 6.86 0.01 0.78 aTwo CNC-APIm were prepared in two independent batches using identical recipes and experimental procedures. b It was anticipated that native CNC and CNC-APIm would have comparable %C and %H values due to a smaller percentage of surface atoms available for functionalization (approx. 20-30%) versus atoms in the bulk.

[00397] Table 3. Z-average sizes of CNC-APIm (ca. 0.5 mg/mL dispersion) in response to continuous repeated CO2/N2 sparging cycles.
Number After CO2 Sparging After N2 Sparging of Cycles Z-average Size (nm) PDI (-) Z-average Size (nm)a Cycle 1 201 1 0.390 >10 microns Cycle 2 211 3 0.370 >10 microns Cycle 3 233 4 0.427 >10 microns Cycle 4 252 14 0.456 >10 microns Cycle 5 259 9 0.443 >10 microns Cycle 6 358 14 0.664 >10 microns aRecorded on a Malvern Zetasizer Nano ZS instrument where measured size data were in range of tens of microns (CNC-APIm macroscopically visible aggregates formed upon N2 sparging).

[00398] Table 4. Zeta potential and Z-average size of CNC-APIm in discarded supernatant (ca. 0.5 mg/mL dispersion) in response to continuous repeated CO2/N2 sparging cycles.
Number After CO2 Sparging After N2 Sparging of Cycles Zeta potential (mV) Zeta potential (mV) Cycle 1 45.3 2.1 20.9 4.0 Cycle 2 43.8 0.8 15.7 6.4 Cycle 3 43.2 0.9 24.2 4.1 Number After CO2 Sparging After N2 Sparging of Cycles Z-average Size (nm) PDI (-) Z-average Size (nm)a Cycle 1 167 1 0.311 >10 microns Cycle 2 176 2 0.392 >10 microns Cycle 3 190 6 0.406 >10 microns aRecorded on a Malvern Zetasizer Nano ZS instrument where the measured size data were in the range of tens of microns (CNC-APIm macroscopically visible aggregates formed upon N2 sparging).

[00399] Table 5. Time-dependent Z-average size and zeta potential changes of CNC-APIm (ca. 0.5 mg/mL dispersion) in response to CO2/N2 sparging cycles.
Z-average size and zeta potential changes in response to CO2 Time Z-average Size (nm) PDI (-) Zeta potential (mV) 0 s >10 micronsa / 20.9 0.8 30 s 217 1 0.384 58.8 0.8 60 s 215 1 0.376 57.9 0.6 min 210 4 0.366 57.0 1.4 Z-average size and zeta potential changes in response to N2 following CO2 stimulus Time Z-average Size (nm) PDI (-) Zeta potential (mV) Os 210 4 0.366 57.0 1.4 30s 213 1 0.372 58.2 1.4 2 min 217 1 0.436 54.5 0.4 3 min 220 3 0.367 49.5 1.2 4 min 215 2 0.384 48.3 1.4 min 208 7 0.377 46.9 0.3 6 min 30 s 349 53 0.620 43.4 1.0 9 min >10 microns' / 35.9 1.7 20 min >10 microns' / 31.7 4.1 aRecorded on a Malvern Zetasizer Nano ZS instrument where measured size data of CNC-APIm macroscopically visible aggregates were in range of tens of microns.

[00400] Table 6.
Degree of protonation of HPIm calculated by different protons in different conditions measured by 1H NMR (see Figure 3 for the assignment of different protons in HPIm).
Degree of protonation in different conditions' Protons Ornal CO2 Sparging (5 min) CO2+ N2 Sparging (5+30 min) 1 7.0 77 16 2 24.8 108 35 Average 17 94 26 aData were recorded on a Bruker Avance 400 NMR spectrometer at 25 C using 90%
H20 + 10% D20 as solvent. The degree of protonation was calculated as: 6 - 60 x100% , where 8, 6,,,,,, , and go gm - go denote a specific chemical shift and chemical shifts at 100% (1.0 M HCI) and 0% (1.0 M NaOH) degree of protonation, respectively. To check reproducibility, all NMR
measurements were conducted at least in triplicate and differences for all repeated measurements were less than 5%. Only one set of data were used for the calculation in this table. The degree of protonation value is not exact.

[00401] Table 7.
Mass of water absorbed by Cotton-APIm versus non-functionalized Cotton.
Initial (g) Mass Fina(g)l Mass A in Mass Average Cotton type Standard Deviation (g) (g) Functionalized 0.14983 0.76271 0.61288 0.54548 0.05844 0.15219 0.66692 0.51473 0.14527 0.6541 0.50883 Non-0.16277 0.52053 0.35776 0.33090 0.02425 functionalized 0.15891 0.48325 0.32434 0.1549 0.46551 0.31061

[00402] Table 8. Contact angle analysis via the sessile drop method for unfunctionalized cotton linen and functionalized Cotton-APIm Carbonated Water Hexadecane droplet Material Water droplet (CAavg) droplet (CAavg) (CAavg) Non-126 146 Completely absorbed functionalized Linen (Hydrophobic) ' (Hydrophobic) (Superoleophilic) Functionalized Completely absorbed Completely absorbed Completely absorbed Linen Superhydrophilic Superhydrophilic Superoleophilic

[00403] Table 9. Contact angle analysis via the sessile drop method for native and functionalized (i.e. waxy) filter paper.
Water droplet Carbonated Water droplet Hexadecane droplet Material (CAavg) (CAavg) (CAavg) Native Filter Completely absorbed Not tested Completely absorbed Paper (Superhydrophilic) (Superoleophilic) Waxy Filter 117 Completely absorbed Not tested Paper (Hydrophobic) (Superoleophilic)

[00404] Table 10. Contact angle analysis via sessile drop method for unfunctionalized cotton linen and functionalized Linen-pDEAEMA via "grafting-from" method Water droplet with Hexadecane droplet Material Water droplet (CAavg) glycolic acid (CAavg) (CAavg) Non- 126 functionalized N/A Completely absorbed Linen (hydrophobic) (Superoleophilic) Functionalized 142 Completely absorbed Completely absorbed Linen (hydrophobic) (Superhydrophilic) (Superoleophilic)

[00405] Table 11.
Investigation of switchable celluloses, prepared via synthetic method 1, as drying agents.
Water " W d"
Water removedater remove removed" (mg Materialg-1) (mg g-1) (mg g-1) Cycle 1 Cycle 2 Cycle 3 Control 1C 440 300 430 Control 2d 460 300 130 EF- Functionalized 430 Al Functionalized 230 340 480 A2 Functionalized 330 A3 Functionalized 320 A4 Functionalized 380 A5 Functionalized 460 a Reaction conditions: 10 g isobutanol with water at a concentration of 5 wt%, 0.5 g drying agent added, 1 h mixing with CO2 bubbling through solution then continued mixing in a sealed vial for 15 h, water content analyzed by GC-TCD.
b Drying agent regeneration was performed at 50 C for 4 h. b Water removed with respect to drying agent used.
Cellulose (as received) with CO2 bubbling.
d Cellulose (as received) w/o CO2 bubbling.

[00406] Table 12.
Investigation of switchable celluloses, prepared via synthetic method 2, as drying agents.
Water removed" Water removed" Water removed"
Material (mg g-1) (mg g-1) (mg g-1) Cycle 1 Cycle 2 Cycle 3 Control 1C 440 300 430 Control 2d 460 300 130 Al - Method 2 450 a Reaction conditions: 10 g isobutanol with water at a concentration of 5 wt%, 0.5 g drying agent added, 1 h mixing with CO2 bubbling through solution then continued mixing in a sealed vial for 15 h, water content analyzed by GC-TCD.
b Drying agent regeneration was performed at 50 C for 4 h. b Water removed with respect to drying agent used.
c Cellulose (as received) with CO2 bubbling.
d Cellulose (as received) w/o CO2 bubbling.

[00407] Table 13. Elemental analysis (C%, H%, N%) of switchable polymers grafted on crystalline nanocellulose via nitroxide-mediated polymerization Sample C% H% N%
CNC 39.48 6.39 CNC-BB 47.92 8.08 3.87 CNC-g-PDMAEMA (0.5 h) 59.97 9.52 7.23 CNC-g-PDMAEMA (1 h) 62.25 9.83 7.51 CNC-g-PDEAEMA (0.5 h) 62.09 9.81 5.58 CNC-g-PDEAEMA (1 h) 62.25 9.73 5.69 CNC-g-PDMAPMAm (0.5 h) 53.39 9.44 8.98 CNC-g-PDMAPMAm (1 h) 54.31 10.28 10.51

[00408] Table 14. Percent composition of switchable polymers grafted on crystalline nanocellulose via nitroxide-mediated polymerization Sample C N C `)/0 Polymer %
CNC-g-PDMAEMA (0.5 h) 47 53 CNC-g-PDMAEMA (1 h) 45 55 CNC-g-PDEAEMA (0.5 h) 61 39 CNC-g-PDEAEMA (1 h) 60 40 CNC-g-PDMAPMAm (0.5 h) 60 40 CNC-g-PDMAPMAm (1 h) 53 47

[00409] Table 15. -potential and pH measurements for CNC-g-PDMAEMA in the presence of glycolic acid (GlAc) 0.5 M and NaOH 0.5 M.
Z-potential pH
GlAc 26.90 3.18 NaOH -8.88 12 GlAc 27.00 3.21 NaOH -9.92 12 GlAc 27.10 3.15 NaOH -9.10 12 GlAc 26.80 3.25 NaOH -9.30 12.1

[00410] Table 16. -potential and pH measurements for CNC-g-PDEAEMA in the presence of glycolic acid (GlAc) 0.5 M and NaOH 0.5 M.
Z-potential pH
GlAc 25.90 2.196 NaOH -13.80 13.235 GlAc 26.30 2.438 NaOH -14.60 12.808 GlAc 25.20 2.213 NaOH -15.30 13.125 GlAc 25.60 2.277 NaOH -14.40 13.05

[00411] Table 17. 4-potential and pH measurements for CNC-g-PDMAPMAm in the presence of glycolic acid (GlAc) 0.5 M and NaOH 0.5 M.
Z-potential pH
NaOH -1.81 13.244 GlAc 21.40 2.283 NaOH -2.44 13.112 GlAc 22.80 2.52 NaOH -2.30 13.211 GlAc 22.70 2.45 NaOH -1.70 13.198 GlAc 20.90 2.55

[00412] Table 18. 4-potential and pH measurements for CNC-g-PDMAEMA in the presence of CO2/N2.
Z-potential pH time CO2 30.90 3.9 70 min N2 1.60 9.46 70 min CO2 30.40 3.89 70 min N2 1.53 9.3 70 min CO2 29.60 3.95 70 min N2 1.70 9.1 70 min CO2 31.00 4.05 70 min N2 1.65 9.23 70 min

[00413] Table 19. 4-potential and pH measurements for CNC-g-PDEAEMA in the presence of CO2/N2.
Z- time potential PH
CO2 30.00 4.84 70 min N2 13.70 9.31 70 min CO2 30.50 4.7 70 min N2 13.00 9.41 70 min CO2 31.50 4.75 70 min N2 15.20 9.52 70 min CO2 30.50 4.6 70 min N2 14.70 9.43 70 min

[00414] Table 20. 4-potential and pH measurements for CNC-g-PDMAPMAm in the presence of CO2/N2.
Z-potential pH time CO2 40.00 3.95 65 min N2 22.20 9.248 65 min CO2 38.80 4.04 65 min N2 24.10 9.57 65 min CO2 38.10 3.9 65 min N2 23.60 9.45 65 min CO2 38.90 3.98 65 min N2 22.00 9.37 65 min

[00415] All publications, patents and patent applications mentioned in this Specification are indicative of the level of skill of those skilled in the art to which this invention pertains and are herein incorporated by reference to the same extent as if each individual publication, patent, or patent applications was specifically and individually indicated to be incorporated by reference.

[00416] The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.

Claims

WE CLAIM:

1. A composite material that is reversibly switchable between a first form and a second form, said composite material comprising a polysaccharide and polysaccharide-supported switchable moiety attached to said polysaccharide via a linker, the switchable moiety comprising a functional group that is switchable between a neutral form associated with said first form of said composite material, and an ionized form associated with said second form of the composite material, wherein the switchable moiety comprises an amine, amidine, or guanidine.

2. The composite material of claim 1, wherein the switchable moiety is an amine and the neutral form of the switchable moiety is bound to the polysaccharide via a linker XY; and wherein the first form of the composite material has the structure of formula and the second form of the composite material comprising the ionized form of the switchable moiety bound to the polysaccharide via a linker XY has the structure of formula 2 wherein:
n is an integer 1, 2 or 3;

p is an integer between 1 and 4, wherein when Y is absent, p is 1;
m is an integer between 1 and 1 0 000, wherein m x p is 10 000 of less; or, m is an integer between 1 and 10 000 when Y is absent;
E is O, S, or a combination thereof;
Y is absent, or a divalent moiety bonded to the polysaccharide and X, and is a linear or branched C1-C15 alkylene, a C15-C30 alkylene, a C1-C15 alkenylene, a alkenylene, a C1-C15 alkynylene, a C15-C30 alkynylene, an arylene, a heteroarylene, a thiol, a silane, or a siloxane, each of which may be substituted; or, Y is a divalent cycle, or heterocycle, each of which may be substituted;
each X is a divalent moiety bonded Y, or to the polysaccharide when Y is absent, and the switchable moiety; each X is independently a linear or branched C1-C15 alkylene, a C15-C30 alkylene, a C1-C15 alkenylene, a C15-C30 alkenylene, a C1-alkynylene, a C15-C30 alkynylene, an arylene, a heteroarylene, a thiol, a silane, or a siloxane, each of which may be substituted; or, each X is independently is a divalent cycle, or heterocycle, each of which may be substituted; or, each X, and one or two of R1 and R2, together with the atoms to which they are attached, are connected to form a heterocycle, which may be substituted;
wherein each X optionally comprises one or more amine, amide, amidine, guanidine, carbamate ester, carbonate diester, ether, ester, thioether, thioester, silane, silyl alkyl ether, or siloxane moieties, or a combination thereof, within its linear or branched carbon chain, or at one of said chain's termini; and NR1R2 and NR1R2+ are each a switchable functional group, wherein R1 and R2 are each independently H, a C1 to C10 aliphatic group that is linear, branched, or cyclic, a C n Si m group where n and m are independently a number from 0 to 10 and n + m is a number from 1 to 1 0, a Cs tO C10 aryl group, or a heteroaryl group having 4 to 10 ring atoms, each of which may be substituted; or R1 and R2, together with the atoms to which they are attached, are connected to form a cycle, or heterocycle, each of which may be substituted; or R2 is repeat unit -(X-NR1)m-Z, wherein m, X and R1 are as defined above, and Z
is a monovalent moiety bonded to the switchable functional group, and is a linear or branched C1-C15 alkyl, a C15-C30 alkyl, a C1-C15 alkenyl, a C15-C30 alkenyl, a alkynyl, a C15-C30 alkynyl, an aryl, a heteroaryl, a thiol, a silane, or a siloxane, each of which may be substituted; or, Z is a monovalent cycle, or heterocycle, each of which may be substituted;
wherein, [X(NR1R2)dm and [X(NR1R214, constitute a chain of repeat units that is linear or branched, each repeat unit in said chain being the same, or different, relative to other repeat units; and wherein, (a) if both of R1 and R2 are H, than X is a sterically hindered group or, (b) if one of R1 and R2 is H, then either (i) the other one of R1 and R2 is a sterically hindered group, or (ii) X is a sterically hindered group.

3. The composite material of claim 2, wherein the first form of the composite material has the structure of formula la when Y is absent, p is 1, and R2 is repeat unit -(X-NR1)m-Z, the second form of the composite material has the structure of formula 2a,

4. The composite material of claim 2, wherein the first form of the composite material has the structure of formula lc when Y is absent, p is 1, and m is 1, the second form of the composite material has the structure of formula 2c,

5. The composite material of claim 1, wherein the switchable moiety is an amidine and the neutral form of the switchable moiety is bound to the polysaccharide via a linker XY; and wherein the first form of the composite material has the structure of formula 3a, 3b, or 3c, the second form of the composite material comprising the ionized form of the switchable moiety bound to the polysaccharide via a linker XY has the structure of formula 4a, 4b, 4c, wherein:
n is an integer 1, 2 or 3;
p is an integer between 1 and 4, wherein when Y is absent, p is 1;
m is an integer between 1 and 1 0 000, wherein m x p is 1 0 000 of less; or, m is an integer between 1 and 10 000 when Y is absent;
E is O, S, or a combination thereof;
Y is absent, or a divalent moiety bonded to the polysaccharide and X, and is a linear or branched C1-C15 alkylene, a C15-C30 alkylene, a C1-C15 alkenylene, a alkenylene, a C1-C15 alkynylene, a C15-C30 alkynylene, an arylene, a heteroarylene, a thiol, a silane, or a siloxane, each of which may be substituted; or, Y is a divalent cycle, or heterocycle, each of which may be substituted;
each X is a divalent moiety bonded Y, or to the polysaccharide when Y is absent, and the switchable functional group; each X is independently a linear or branched C1-C15 alkylene, a C15-C30 alkylene, a C1-C15 alkenylene, a C15-C30 alkenylene, a alkynylene, a C15-C30 alkynylene, an arylene, a heteroarylene, a thiol, a silane, or a siloxane, each of which may be substituted; or, each X is independently is a divalent cycle, or heterocycle, each of which may be substituted; or, each X, and one or more of R3, R4, and R5, together with the atoms to which they are attached, are connected to form a heterocycle, which may be substituted; and wherein each X optionally comprises one or more amine, amide, amidine, guanidine, carbamate ester, carbonate diester, ether, ester, thioether, thioester, silane, silyl alkyl ether, or siloxane moieties, or a combination thereof, within its linear or branched carbon chain, or at one of said chain's termini; and N=CR3NR4R5 , R3N=CNR4R5, R3N=CR4NR5, and (N=CR3NR4R5)+, (R3N=CNR4R5)+, (R3N=CR4NR5)+ are each switchable functional groups, wherein R3, R4, and R5 are independently H, a C1 to C10 aliphatic group that is linear, branched, or cyclic;
a CnSim group where n and m are independently a number from 0 to 10 and n + m is a number from 1 to 10, a C5 to C10 aryl group, or a heteroaryl group having from 4 to 10 carbon atoms in the aromatic ring, each of which may be substituted; or, any combination of R3, R4, and R5, together with the atoms to which they are attached, are connected to form a heterocycle, which may be substituted; or, any one of R3, R4, and R5 is repeat unit -(X-N=CR3NR4)m-Z, -(X-N=CNR4R5)m-Z;
or -(X-C=NR3NR4)m-Z, -(X-C=NNR4R5)m-Z; or -(X-NCR4=NR3)m-Z, -(X-NR5CR4=N)m-Z, -(X-NR5C=NR3)m-Z, wherein X and R3, R4, and R5 are as defined above, and Z is a monovalent moiety bonded to the switchable functional group, and is a linear or branched C1-C15 alkyl, a C15-C30 alkyl, a C1-C15 alkenyl, a C15-C30 alkenyl, a alkynyl, a C15-C30 alkynyl, an aryl, a heteroaryl, a thiol, a silane, or a siloxane, each of which may be substituted; or, Z is a monovalent cycle, or heterocycle, each of which may be substituted;
wherein, [X(N=CR3NR4R5)n]m, [X(R3N=CNR4R5)n]m, [X(R3N=CR4NR5)n]m, and [X(N=CR3NR4R5+)n]m, [X(R3N=CNR4R5+)n]m, [X(R3N=CR4NR5+)n]m constitute a chain of repeats units that is linear or branched, each repeat unit in said chain being the same, or different, relative to other repeat units.

6. The composite material of claim 5, wherein the first form of the composite material has the structure of formula 3d, 3d', 3e, 3e', 3f, 3f', or 3f" when Y is absent, p is 1, and R3, R4, or R5 is repeat unit -(X-N=CR3NR4)m-Z, -(X-N=CNR4R5)m-Z; or -(X-C=NR3NR4)m-Z, -(X-C=NNR4R5)m-Z; or -(X-NCR4=NR3)m-Z, -(X-NR5CR4=N)m-Z, -(X-NR5C=NR3)m-Z, the second form of the composite material has the structure of formula 4d, 4d', 4e, 4e', 4f, 4f', or 4f",

7. The composite material of claim 5, wherein the first form of the composite material has the structure of formula 3g, 3h, or 3i when Y is absent, p is 1, and m is 1, the second form of the composite material has the structure of formula 4g, 4h, or 4i,

8. The composite material of claim 1, wherein the switchable moiety is a guanidine, and the neutral form of the switchable moiety is bound to the polysaccharide via a linker XY; and wherein the first form of the composite material has the structure of formula 5a, 5b, 5c, the second form of the composite material comprising the ionized form of the switchable moiety bound to the polysaccharide via a linker XY has the structure of formula 6a, 6b, 6c, wherein:
n is an integer 1, 2 or 3;
p is an integer between 1 and 4, wherein when Y is absent, p is 1;
m is an integer between 1 and 10 000, wherein m x p is 10 000 of less; or, m is an integer between 1 and 10 000 when Y is absent;
E is O, S, or a combination thereof;
Y is absent, or a divalent moiety bonded to the polysaccharide and X, and is a linear or branched C1-C15 alkylene, a C15-C30 alkylene, a C1-C15 alkenylene, a alkenylene, a C1-C15 alkynylene, a C15-C30 alkynylene, an arylene, a heteroarylene, a thiol, a silane, or a siloxane, each of which may be substituted; or, Y is a divalent cycle, or heterocycle, each of which may be substituted;
each X is a divalent moiety bonded Y, or to the polysaccharide when Y is absent, and the switchable functional group; each X is independently a linear or branched C1-C15 alkylene, a C15-C30 alkylene, a C1-C15 alkenylene, a C15-C30 alkenylene, a alkynylene, a C15-C30 alkynylene, an arylene, a heteroarylene, a thiol, a silane, or a siloxane, each of which may be substituted; or, each X is independently is a divalent cycle, or heterocycle, each of which may be substituted; or, each X, and one or more of.
R6, R7, R8, R9 and R10, together with the atoms to which they are attached, are connected to form a heterocycle, which may be substituted; and wherein each X optionally comprises one or more amine, amide, amidine, guanidine, carbamate ester, carbonate diester, ether, ester, thioether, thioester, silane, silyl alkyl ether, or siloxane moieties, or a combination thereof, within its linear or branched carbon chain, or at one of said chain's termini; and N=CNR6R7NR8R9, R10N=CNR6NR8R9, R10N=CNR6R7NR9, and (N=CNR6R7NR8R9)+, (R10N=CNR6NR8R9)+, (R10N=CNR6R7NR9)+ are each switchable functional groups, wherein R6, R7, R8, R9 and R10 are independently H, a C1 to aliphatic group that is linear, branched, or cyclic; a C n Si m group where n and m are independently a number from 0 to 10 and n + m is a number from 1 to 10, a C5 to C10 aryl group, or a heteroaryl group having from 4 to 10 carbon atoms in the aromatic ring, each of which may be substituted; or, any combination of R6, R7, R8, R9 and R10, together with the atoms to which they are attached, are connected to form a heterocycle, which may be substituted; or, any one of R6, R7, R8, R9 and R10 is repeat unit -(X-N=CNR6R7NR8)m-Z, -(X-N=CNR7NR8R9)m-Z, or -(X-NR6C=NNR8R9)m-Z, -(X-NR6C=NR10NR8)m-Z, -(X-NC=NR10NR8R9)m-Z, wherein X and R6, R7, R8, R9 and R10 are as defined above, and Z is a monovalent moiety bonded to the switchable functional group, and is a linear or branched C1-C15 alkyl, a C15-C30 alkyl, a C1-C15 alkenyl, a C15-C30 alkenyl, a C1-C15 alkynyl, a C15-C30 alkynyl, an aryl, a heteroaryl, a thiol, a silane, or a siloxane, each of which may be substituted; or, Z is a monovalent cycle, or heterocycle, each of which may be substituted;
wherein at least one of R6, R7, R8, R9 and R10 is an electron withdrawing group;
and wherein, [X(N=CNR6R7NR8R9)n]m, [X(R10N=CNR6NR8R9)n]m, [X(R10N=CNR6R7NR9)n]m, [X(N=CNR6R7NR8R9)+n]m, [X(R10N=CNR6NR8R9)+n]m, [X(R10N=CNR6R7NR9)+n]m constitute a chain of repeats units that is linear or branched, each repeat unit in said chain being the same, or different, relative to other repeat units.

9. The composite material of claim 8, wherein the first form of the composite material has the structure of formula 5d, 5d', 5d", 5e, or 5e' when Y is absent, p is 1, and R6, R7, R8, R9 or R10 is repeat unit -(X-N=CNR6R7NR8)m-Z, -(X-N=CNR7NR8R9)m-Z, or -(X-NR6C=NNR8R9)m-Z, -(X-NR6C=NR10NR8)m-Z, -(X-NC=NR10NR8R9)m-Z, the second form of the composite material has the structure of formula 6d, 6d', 6d", 6e, or 6e'

10. The composite material of claim 8, wherein the first form of the composite material has the structure of formula 5f, 5g, or 5h when Y is absent, p is 1, and m is 1, the second form of the composite material has the structure of formula 6f, 6g, or 6h,

11. The composite material of claim 1, wherein the switchable moiety is a pyridine, and the neutral form of the switchable moiety is bound to the polysaccharide via a linker XY; and wherein the first form of the composite material has the structure of formula 7, (7); and the second form of the composite material comprising the ionized form of the switchable moiety bound to the polysaccharide via a linker XY has the structure of formula 8, wherein:
n is an integer 1, 2 or 3;
o is an integer 1, 2 or 3;
p is an integer between 1 and 4, wherein when Y is absent, p is 1;
m is an integer between 1 and 10 000, wherein m x p is 10 000 of less; or, m is an integer between 1 and 10 000 when Y is absent;
E is O, S, or a combination thereof;
Y is absent, or a divalent moiety bonded to the polysaccharide and X, and is a linear or branched C1-C15 alkylene, a C15-C30 alkylene, a C1-C15 alkenylene, a alkenylene, a C1-C15 alkynylene, a C15-C30 alkynylene, an arylene, a heteroarylene, a thiol, a silane, or a siloxane, each of which may be substituted; or, Y is a divalent cycle, or heterocycle, each of which may be substituted;
each X is a divalent moiety bonded Y, or to the polysaccharide when Y is absent, and the switchable moiety; each X is independently a linear or branched C1-C15 alkylene, a C15-C30 alkylene, a C1-C15 alkenylene, a C15-C30 alkenylene, a C1-alkynylene, a C15-C30 alkynylene, an arylene, a heteroarylene, a thiol, a silane, or a siloxane, each of which may be substituted; or, each X is independently is a divalent cycle, or heterocycle, each of which may be substituted; or, each X, and one or two of R1 and R2, together with the atoms to which they are attached, are connected to form a heterocycle, which may be substituted;
wherein each X optionally comprises one or more amine, amide, amidine, guanidine, carbamate ester, carbonate diester, ether, ester, thioether, thioester, silane, silyl alkyl ether, or siloxane moieties, or a combination thereof, within its linear or branched carbon chain, or at one of said chain's termini; and is a switchable functional group, wherein R15 is H, a C1 to C10 aliphatic group that is linear, branched, or cyclic, a C n Si m group where n and m are independently a number from 0 to 10 and n + m is a number from 1 to 10, a C5 to C10 aryl group, or a heteroaryl group having 4 to 1 0 ring atoms, each of which may be substituted; or any two of R15, together with the atoms to which they are attached, are connected to form a cycle, or heterocycle, each of which may be substituted; or any one of R15 is repeat unit wherein X and R15 are as defined above, q is integer 1 or 2, and Z is a monovalent moiety bonded to the switchable functional group, and is a linear or branched C1-C15 alkyl, a C15-C30 alkyl, a C1-C15 alkenyl, a C15-C30 alkenyl, a C1-C15 alkynyl, a C15-C30 alkynyl, an aryl, a heteroaryl, a thiol, a silane, or a siloxane, each of which may be substituted; or, Z is a monovalent cycle, or heterocycle, each of which may be substituted;

wherein, constitute a chain of repeat units that is linear or branched, each repeat unit in said chain being the same, or different, relative to other repeat units.

12. The composite material of claim 11, wherein the first form of the composite material has the structure of formula 7a when Y is absent, p is 1, and R15 is repeat unit the second form of the composite material has the structure of formula 8a, (8a).

13. The composite material of claim 11, wherein the first form of the composite material has the structure of formula 7b when Y is absent, p is 1, and m is 1, the second form of the composite material has the structure of formula 8b,

14. The composite material of claim 5, wherein the neutral form of the switchable moiety is bound to the polysaccharide via a linker XY; and wherein the first form of the composite material has the structure of formula 9a, 9b, 9c, or 9d, the second form of the composite material comprising the ionized form of the switchable moiety bound to the polysaccharide via a linker XY has the structure of formula 10a, 10b, 10c, or 10d, wherein:
n is an integer 1, 2 or 3;
p is an integer between 1 and 4, wherein when Y is absent, p is 1;
m is an integer between 1 and 10 000, wherein m x p is 10 000 of less; or, m is an integer between 1 and 10 000 when Y is absent;
E is O, S, or a combination thereof;
Y is absent, or a divalent moiety bonded to the polysaccharide and X, and is a linear or branched C1-C15 alkylene, a C15-C30 alkylene, a C1-C15 alkenylene, a alkenylene, a C1-C15 alkynylene, a C15-C30 alkynylene, an arylene, a heteroarylene, a thiol, a silane, or a siloxane, each of which may be substituted; or, Y is a divalent cycle, or heterocycle, each of which may be substituted;
each X is a divalent moiety bonded Y, or to the polysaccharide when Y is absent, and the switchable moiety; each X is independently a linear or branched C1-C15 alkylene, a C15-C30 alkylene, a C1-C15 alkenylene, a C15-C30 alkenylene, a C1-alkynylene, a C15-C30 alkynylene, an arylene, a heteroarylene, a thiol, a silane, or a siloxane, each of which may be substituted; or, each X is independently is a divalent cycle, or heterocycle, each of which may be substituted; or, each X, and one or two of R1 and R2, together with the atoms to which they are attached, are connected to form a heterocycle, which may be substituted;

wherein each X optionally comprises one or more amine, amide, amidine, guanidine, carbamate ester, carbonate diester, ether, ester, thioether, thioester, silane, silyl alkyl ether, or siloxane moieties, or a combination thereof, within its linear or branched carbon chain, or at one of said chain's termini; and R11, R12, R13, and R14 are each independently H, a C1 to C10 aliphatic group that is linear, branched, or cyclic; a CnSim group where n and m are independently a number from 0 to 10 and n + m is a number from 1 to 10, a C5 to C10 aryl group, or a heteroaryl group having from 4 to 10 carbon atoms in the aromatic ring, each of which may be substituted; or, any combination of R11, R12, R13, and R14, together with the atoms to which they are attached, are connected to form a cycle or heterocycle, each of which may be substituted; or any one of R11, R12, R13, and R14 is repeat unit -(X-Im)m-Z, wherein X is as defined above, Im is an optionally substituted imidazole ring, and Z is a monovalent moiety bonded to the switchable functional group, and is a linear or branched alkyl, a C15-C30 alkyl, a C1-C15 alkenyl, a C15-C30 alkenyl, a C1-C15 alkynyl, a C15-C30 alkynyl, an aryl, a heteroaryl, a thiol, a silane, or a siloxane, each of which may be substituted; or, Z is a monovalent cycle, or heterocycle, each of which may be substituted;
wherein, the repeat unit [X(Im)n]m and [X(Im)+n]m constitute a chain of repeat units that is linear or branched, each repeat unit in said chain being the same, or different, relative to other repeat units.

15. The composite material of claim 14, wherein the first form of the composite material has the structure of formula 9e, 9f, 9g, or 9h when Y is absent, p is 1, and m is 1, the second form of the composite material has the structure of formula 10e, 10f, 10g, or 10h,

16. The composite material of claim 15, wherein the first form of the composite material has the structure and the second form of the composite material has the structure

17. The composite material of any one of claims 1-16, wherein the polysaccharide is cellulose nanocrystal (CNC), cellulose, dextran, cotton, starch, chitin, chitosan, or any combination thereof.

18. The composite material of any one of claims 1-17, wherein said first form of the composite material is neutral and hydrophobic, and the second form of the composite material is ionized and hydrophilic.

19. The composite material of any one of claims 1-18, wherein the composite material converts to, or is maintained in, said second, ionized form when the switchable moiety is exposed to an ionizing trigger at an amount sufficient to maintain said switchable moiety in its ionized form; and, wherein the composite material converts to, or is maintained in, said first form when said ionizing trigger is removed or reduced to an amount insufficient to maintain said switchable moiety in its ionized form.

20. The composite material of claim 19, wherein the ionizing trigger is an acid gas.

21. The composite material of claim 20, wherein the acid gas is CO2, COS, CS2, or a combination thereof

22. The composite material of claim 19, wherein the ionizing trigger is removed or reduced by exposing the composite material to: (i) an at least partial vacuum;
(ii) heat; (iii) a flushing inert gas (iv) a liquid substantially devoid of an ionizing trigger;
or, (v) any combination thereof; in the presence or absence of agitation.

23. The composition material of claim 22, wherein the inert gas is N2, Ar or air.

24. The composite material of claim 23, wherein exposing to heat is heating to <= 60 °C, <= 80 °C, or <= 150 °C.

25. The composite material claim 19, wherein the ionizing trigger is a Bronsted acid sufficiently acidic to ionize said switchable moiety from its neutral form;
or, any Bronsted base sufficiently basic to de-ionize said switchable moiety from its ionized form.

26. A method for switching a composite material of any one of claims 1 - 25 between its first form and second form, comprising:
exposing the neutral and hydrophobic composite material to (i) an aqueous liquid, or (ii) a non-aqueous liquid and water, to form a mixture, and exposing said mixture to an ionizing trigger, thereby protonating the switchable moiety and rendering the composite material ionized and hydrophilic; and/or exposing the neutral and hydrophobic composite material to an aqueous carbonated liquid to form a mixture, wherein the carbonated liquid protonates the switchable moiety to render the composite material ionized and hydrophilic;
and optionally, separating the ionized hydrophilic composite material from the mixture.

27. A method for switching a composite material of any one of claims 1 - 25 between its second form and first form, comprising:
exposing an ionized hydrophilic composite material to: (i) an at least partial vacuum; (ii) heat; (iii) a flushing inert gas; (iv) a liquid substantially devoid of an ionizing trigger; or, (v) any combination thereof; in the presence or absence of agitation, thereby expelling the ionizing trigger from the switchable moiety and rendering the composite material neutral and hydrophobic; and optionally, separating the neutral and hydrophobic composite material from the mixture.

28. The method of claims 26 or 27, wherein the ionizing trigger is an acid gas.

29. The method of claim 28, wherein the acid gas is CO2, COS, CS2, or a combination thereof.

30. The method of claim 27, wherein the inert gas is N2, Ar or air.

31. The method of claim 27, wherein exposing to heat is heating to <=
60 °C, <= 80 °C, or <= 150 °C.

32. Use of the composite material of any one of claims 1-25, for manipulating and/or controlling dispersibility, for example, CNC dispersibility.

33. Use of the composite material of any one of claims 1-25, as a separation membrane.

34. Use of the composite material of any one of claims 1-25, for formation of a membrane comprising a chiral nematic liquid crystalline structure.

35. Use of the composite material of any one of claims 1-25, as an absorbent.

36. Use of the composite material of any one of claims 1-25, as a drying agent.

37. Use of the composite material of any one of claims 1-25, as a flocculent.

38. Use of the composite material of any one of claims 1-25, for water or wastewater treatment.

39. The use of claim 38, wherein water or wastewater treatment comprises removal of organic contaminants or metal contaminants.

40. Use of the composite material of any one of claims 1-25, for cleaning a surface.

41. Use of the composite material of any one of claims 1-25, for formation of a switchable fabric.

42. Use of the composite material of any one of claims 1-25, for formation of a switchable filter paper.

43. Use of the composite material of any one of claims 1-25, for stabilizing an emulsion.

44. Use of the composite material of any one of claims 1-25, as a switchable viscosity modifier.

45. Use of the composite material of any one of claims 1-25, for use in chromatography.