FR3061491A1 - FUNCTIONALIZED CELLULOSIC MATERIAL - Google Patents

Abstract

The present invention relates to a functionalized cellulosic material, its method of preparation and its use for the marking of articles containing cellulose.

Description

(57) The present invention relates to a functionalized cellulosic material, its preparation process and its use for marking articles containing cellulose.

(73) Holder (s): UNIVERSITY OF NANTES Public establishment, NATIONAL CENTER OF SCIENTIFIC RESEARCH Public establishment.

© Agent (s): GROSSET FOURNIER AND DEMACHY Limited liability company.

FR 3,061,491 - A1

FUNCTIONALIZED CELLULOSIC MATERIAL

The present invention relates to a functionalized cellulosic material, its preparation process and its use for marking articles containing cellulose.

Cellulose has been the most widely used writing medium since time immemorial. With the advent of inkjet printing, patterns are mostly created by physisorption of polymers on cellulose. The use of nanoparticles, MOFs (metal organic frameworks) or drugs as inks is currently in full swing and has also given promising results. However, the use of small molecules as inks still suffers from problems of stability limited in time linked in particular to the inability of the cellulose to retain these small molecules when brought into contact with a liquid. This then results in the erasure of the pattern or its degradation (for example the loss of spatial resolution).

Paper remains the main material today for applications such as packaging, labeling and making banknotes. In these applications, the current printing techniques (notably by inkjet) do not provide a sufficient level of protection against counterfeiting and many technologies such as holography, bar codes, RFID markings, micro-markers and intaglio printing have been developed for the marking of cellulosic materials.

Covalent printing differs from inkjet printing processes in that small molecules are covalently linked to cellulose. This technique achieves a higher level of security by offering in particular a marking with increased stability (no washing by the solvent).

In the article Redox-responsive, reversibly fluorescent nanoparticles from sustainable cellulose derivivatives (J. Mater. Chem. A, 2014, 2, 13675), Wei Li et al. have developed a cellulosic material comprising a rhodamine derivative.

This material is prepared by adding dithiodipropionic acid on cellulose to give thiol-cellulose in two stages. The thiol function is then reacted with a rhodamine derivative containing an α, β-unsaturated carbonyl function. The principle of labeling of Wei-Li et al. is illustrated in the diagram below:

OH

Cellulose, 1 + HOOC ^^ '- ^ ^SS

COOH

Dithioldipropionic acid, 2

Wei Li et al. also showed in this same article that the materials thus obtained could be colored using an external stimulus such as UV irradiation.

The inventors of the present invention have however demonstrated that the materials described by Wei Li et al. had limited stability. Without wishing to be bound by this theory, it is postulated that the sulfur atom in the beta position of a carbonyl function promotes the degradation of the material by retro-Michael reaction and the elimination of the ink (/.e. Du rhodamine derivative).

Another disadvantage of the method described by Wei Li et al. is due to the fact that the reaction between the thiol function and the alkene function conjugated with a carbonyl function or alkyne conjugated with a carbonyl function occurs spontaneously and it is therefore not possible to spatially control the labeling of the cellulose by the agent printing.

The present invention therefore aims to provide cellulosic materials functionalized by a printing agent (that is to say a group playing the role of an ink) covalently bonded to the cellulose more stable than those proposed. in the prior art. Another object of the present invention is to provide cellulosic materials functionalized by a printing agent covalently bonded to cellulose allowing writing with high spatial resolution.

A first object of the present invention is a cellulosic material C-G-A comprising cellulose covalently functionalized by a printing agent, characterized in that:

a) the cellulose (C) is covalently linked to a group (G) comprising a sulfur atom,

b) the printing agent (A) is covalently linked to said group (G) comprising a sulfur atom by a carbon-sulfur bond with said sulfur atom of said group (G), the sulfur atom n ' not being in the beta position of a carbonyl function.

For the purposes of the present invention, the term "cellulosic material" means a material containing cellulose, optionally in admixture with other substances. The cellulosic material may for example be paper, that is to say a mixture of cellulose and chemical substances, cardboard, fabric such as cotton, or a composite material comprising cellulose such as cellulose mixtures and synthetic polymers.

Within the meaning of the present invention, the stability is determined by the ability of a compound to withstand a washing step in a practical solvent such as water, in neutral or basic acid condition, in particular linked to the retro reaction. -Michael.

Advantageously, the cellulosic material according to the present invention comprises from 0.0001 to 100% by weight of the total weight of the cellulose cellulosic material covalently functionalized by a printing agent.

In the present invention, the cellulose is advantageously functionalized covalently by means of an oxygen atom of the cellulose, for example by means of an oxygen-carbon bond. Advantageously, the cellulose is functionalized by means of a carbonyl function, in particular carbamate, thiocarbamate or ester or of an ether function with the oxygen atom of the cellulose. The degree of functionalization of the cellulose can vary from 1 to 33%, in particular from 5 to 15%. The degree of substitution can be determined by methods known to those skilled in the art, such as elemental analysis. By "degree of functionalization of the cellulose" is meant within the meaning of the present invention the average number of primary alcohols of the cellulose having reacted with the group (G) and / or with the printing agent.

For the purposes of the present invention, the term "printing agent" means a compound capable of leading to a marking which can be detected visually or spectroscopically. The printing agent can be detectable at the wavelengths corresponding to the visible range, at the wavelengths corresponding to the ultraviolet, at the wavelengths corresponding to the infrared, or even under the effect a stimulus, such as a change in polarity of the surrounding environment or a change in temperature.

Advantageously, the printing agent is therefore a photoactive compound such as a fluorophore, a chromophore or a photochromic, thermosensitive such as a thermochrome, sensitive to a change in pH or sensitive to a change in polarity of the surrounding medium.

More preferably, the printing agent is a rhodamine derivative, a coumarin derivative, a hydrophobic derivative or a chromene derivative.

The printing agent can in particular be chosen from the following agents:

The present invention therefore relates to a cellulosic material C-G-A as defined above in which the cellulose functionalized covalently by a printing agent corresponds to the following formula (I):

in which :

m is 1, 2 or 3,

L represents a single bond or a spacer,

Y represents NR ^a , O or S, where

R ^a is H, alkyl to C _6, aryl, heteroaryl or (alkyl -C ₆₎ -aryl,

X represents a single bond, O or NR ^C , where

R ^c is H, alkyl, Ct to C ₆ alkyl, aryl, (C Ch -C ₆₎ -aryl, or C = Y is CH ₂ and X is a single bond,

U represents C 1 to C 10 alkyl, aryl (C ₆ to C ₆ alkyl),

Z is H, Ci to Cio alkyl, aryl or (alkyl -C ₆₎ -aryl or pattern:

o

OH in which Y ’, X’ and U ’, identical or different respectively from Y, X and U, have the definition given for Y, X and U,

V represents H, alkyl to C _1o, aryl or (alkyl -C ₆₎ -aryl,

Phore represents a printing agent as defined above, excluding a compound in which X represents a single bond and U represents an alkyl having 2 carbon atoms in the chain linking C = Y and the atom of sulfur, and / or X 'represents a single bond and U' represents an alkyl having 2 carbon atoms in the chain linking C = Y 'and the sulfur atom.

In the present invention, cellulose is represented as follows:

OH

OH

The number n of glucose units of cellulose essentially depends on the type of cellulose used and / or the cellulose material. The value of n will therefore depend on the cellulosic material used. Typically, n is from 15 to 15,000.

In cellulosic materials, the Phore printing agent can be linked to cellulose by one, two or three carbon-sulfur bonds.

Advantageously, m is worth 1 or 2.

The compounds according to the present invention have the following formula when m = 1:

When m = 2, the compounds according to the present invention have the following formula:

Phore

When m = 3, the compounds according to the present invention have the following formula:

For the purposes of the present invention, the term "spacer" means a group which makes it possible to bind the printing agent to the rest of the molecule. The spacer may in particular be necessary for synthetic reasons, for example to introduce the double bond or the triple bond useful for the photo-thiol-ene or photo-thiol-yne reaction. The nature of the spacer is not essential in the present invention but it must be chosen so as not to alter the properties of the printing agent and / or the stability of the cellulosic material CGA, in particular of formula (I ).

When L is a spacer, it is for example chosen from the group consisting of:

• (alkyl -C ₆₎ -C and m is 3 or (alkyl -C ₆₎ -CH and m is 2 or (C, to C ₆₎ -CH ₂ - and m is 1, • ( alkyl to C ₆₎ or -0 (alkyl -C ₆₎ -OCH ₂ - and m is 1, • (alkyl -C ₆₎ -NH (CH ₂₎ - and m is 1, • ( alkyl -C ₆₎ -N (CH _{2) 2} - and m is 2, • (alkyl -C ₆₎ -COOCH ₂ - and m is 1, or • (alkyl -C ₆₎ -CON (CH _{2) 2} - and m is 2, • (alkyl -C ₆₎ -NHCO- (C₁-C ₆₎ - and m is 1, • (alkyl -C ₆₎ -NHCO- ( C ₂ -C ₆ alkylene) - and m is 1, • (C ₁ -C ₆ alkyl) -NHCOO- and m is 1, • (C ₁ -C ₆ alkyl) -NHCOOCH ₂ - and m is 1, • (alkyl -C ₆₎ -NHCO- (C₁-C ₆₎ COO- and m is 1.

• (C, to C ₆₎ -NHCO- (C₁-C ₆₎ -COOCH ₂ - and m is 1.

For example, when the print agent is:

O.

the printing agent can be linked to the rest of the molecule by a spacer L and the LPhore group can therefore represent a group chosen from:

For the purposes of the present invention, "X represents a single bond" means that the group C = Y is linked directly to the group U.

For the purposes of the present invention, the term "C 1 to C ₁₀ alkyl" means an acyclic carbon chain, saturated, linear or branched, comprising 1 to 10 carbon atoms. These are methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl and decyl groups. The definition of propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl and decyl includes all possible isomers. For example, the term butyl includes n-butyl, isobutyl, sec-butyl and terf-butyl.

For the purposes of the present invention, the term "aryl" means an aromatic unicycle comprising from 5 to 6 carbon atoms, which can itself be fused with a second saturated, unsaturated or aromatic ring. The term aryl includes, without limitation, phenyl and its derivatives in which one or more hydrogen atoms have been replaced by a group independently selected from alkyl, halogen, alkyl-halogen, hydroxyl, alkoxy, amino, amido, nitro , cyano, trifluoromethyl, carboxylic acid or carboxylic ester and naphthyl. Examples of substituted aryls include, without restriction, 2-, 3- or 4 (N, N-dimethylamino) -phenyl, 2-, 3- or 4-cyanophenyl, 2-, 3- or 4-nitrophenyl, 2-, 3or 4-fluoro-, chloro-, bromo- or iodo-phenyl, 2-, 3- or 4-methoxyphenyl.

For the purposes of the present invention, the term “(C ₆ -C ₆ ) alkyl-aryl, a group comprising an acyclic carbon chain, saturated, linear or branched, comprising 1 to 6 carbon atoms as defined above linked to an aryle. An example of (C 1 -C ₆ alkyl) -aryl is in particular the benzyl group.

For the purposes of the present invention, the term “heteroaryl” means an unsaturated, mono or polycyclic aromatic ring of 5 to 10 members in which one or more of the CH groups have been replaced by one or more heteroatoms. Among the heteroaryls, mention may in particular be made of pyridyl, pyrrolyl, furyl and pyrimydinyl groups. thienyl, imidazolyl and pyrrolyl.

The presence of a sulfur atom in beta position of a carbonyl function leading to the formation of less stable cellulosic materials, are therefore excluded from the present invention the compounds in which -C (= Y) -U-S-represents:

Alk 'Alk where -CH (Alk) -C (Alk') (Alk ”) - represents a C ₂ to C ₁₀ alkyl chain as defined above.

The cellulosic material of formula (I) can be obtained according to the method described below by photo-thiol-ene reaction with a terminal alkene or photo-thiol-yne with a terminal alkyne (or true alkyne). For the purposes of the present invention, the term "terminal alkene or terminal alkyne" means that the double bond or the triple bond does not have any substituent at one of its ends. A terminal alkene will therefore have, at one of its ends, a CH ₂ group and a terminal alkyne a CH group.

The present invention therefore advantageously relates to a cellulosic material of formula (I) in which V represents H.

The cellulosic material of formula (I) can be obtained according to the method described below using a cellulosic material containing a symmetrical disulfide group.

Advantageously, the present invention therefore relates to a cellulosic material of formula (I) in which U and U ’are identical, X and X’ are identical and Y and Y ’are identical.

Advantageously, the present invention relates to a cellulosic material of formula (I) in which U represents C-ι, C ₃ or C ₄ alkyl.

Preferably, U represents C ·, alkyl.

In another embodiment, the present invention relates to a cellulosic material in which the cellulose functionalized covalently by a printing agent is obtained by photo-thiol-ene reaction, said cellulosic material corresponding to the following formula (la):

in which :

m, L, Y, X, U, V and Phore are as defined for formula (I), and

Z is H, alkyl Ch -C ₁₀ aryl or (C, to C ₆₎ aryl.

In one embodiment, the present invention relates to a cellulosic material in which the cellulose functionalized covalently by a printing agent is obtained by photo-thiol-yne reaction, said cellulosic material corresponding to the following formula (Ib):

in which :

Z represents a pattern:

and m, L, Y, X, U, Y ’, X’, U ’, V and Phore are as defined for formula (I).

Advantageously, the present invention relates to a cellulosic material as described above, in particular of formula (I), (la) or (lb), in which the cellulose (C) is covalently linked to the group (G) comprising an atom sulfur via an ester, carbamate, thiocarbamate or ether bond, of formula (M):

in which :

C = Y represents C = O and X represents a single bond, or

C = Y represents C = O and X represents NR ^C , where R ^c represents H, Cf to C ₆ alkyl, aryl, (C-ι to C ₆ alkyl) -aryl, or

C = Y represents C = S and X represents NR ^C , where R ^c represents H, C 1 to C ₆ alkyl, aryl, (C 1 to C ₆ alkyl) -aryl, or

C = Y represents CH ₂ and X represents a single bond, and m, L, U, Z, V and Phore are as defined in formula (I), (la) or (lb).

excluding a compound in which X represents a single bond and U represents an alkyl having 2 carbon atoms in the linking chain C = Y and the sulfur atom, and / or X 'represents a single bond and U 'represents an alkyl having 2 carbon atoms in the chain linking C = Y' and the sulfur atom.

More advantageously, the present invention relates to a cellulosic material as described above, in particular of formula (1-1), in which the cellulose (C) is covalently linked to the group (G) comprising a sulfur atom by l 'via an ester, carbamate, thiocarbamate or ether bond, of formula (1-1-a):

in which :

C = Y represents C = O and X represents a single bond, or

C = Y is C = O and X is NR ^C wherein R ^G is H, alkyl to C _6, aryl, _(Ci-C6) -aryl, or

Y represents C = C = S and X represents NR ^C wherein R ^c is H, alkyl to C _6, aryl, _(Ci-C6) -aryl, or

C = Y represents CH ₂ and X represents a single bond,

U is alkyl to C _10, m, L, Z, V and Phore are as defined in formula (I), excluding a compound wherein X represents a single bond and U is alkyl having 2 carbon atoms in the chain linking C = Y and the sulfur atom, and / or X 'represents a single bond and U' represents an alkyl having 2 carbon atoms in the chain linking C = Y 'and the atom sulfur.

More advantageously, the present invention relates to a cellulosic material as described above, in particular of formula (1-1), in which the cellulose (C) is covalently linked to the group (G) comprising a sulfur atom by l 'via an ester, carbamate, thiocarbamate or ether bond, of formula (1-1-a):

in which :

C = Y represents C = O and X represents a single bond, or

C = Y represents C = O and X represents NR °, where R ^c represents H, C to C _s alkyl, aryl, 5 (C to C ₆ alkyl) -aryl, or

C = Y represents C = S and X represents NR ^C , where R ^c represents H, C ₆ to C ₆ alkyl, aryl, (C ₆ to C ₆ alkyl) -aryl, or

C = Y represents CH ₂ and X represents a single bond,

U represents C alkyl! at C ₁₀ ,

V represents H, m, L, Z, and Phore are as defined in formula (I), excluding a compound in which X represents a single bond and U represents an alkyl having 2 carbon atoms in the chain linking C = Y and the sulfur atom, and / or X 'represents a single bond and U' represents an alkyl having 2 carbon atoms in the chain linking C = Y 'and the sulfur atom.

Even more advantageously, the present invention relates to a cellulosic material as described above, in particular of formula (1-1), in which the cellulose (C) is covalently linked to the group (G) comprising a sulfur atom by via an ester, carbamate, thiocarbamate or ether bond, of formula (1-1-b):

in which :

C = Y represents C = O and X represents a single bond, or

C = Y is C = O and X is NR ^C wherein R ^G is H, alkyl to C _6, aryl, _(Ci-C6) -aryl, or

Y represents C = C = S and X represents NR ^G, wherein R ^G is H, alkyl to C _6, aryl, _(Ci-C6) -aryl, or

C = Y represents CH ₂ and X represents a single bond,

U is alkyl Ci-Ci _0,

Z represents H or a motif:

V represents H, m, L, Y ', X', U 'and Phore are as defined in formula (I), excluding a compound in which X represents a single bond and U represents an alkyl having 2 carbon atoms in the linking chain C = Y and the sulfur atom, and / or X 'represents a single bond and U' represents an alkyl having 2 carbon atoms in the linking chain C = Y 'and l sulfur atom.

In a particular embodiment, the present invention relates to a cellulosic material as described above, in particular of formula (I), (la), (Ib) or (1-1) in which the cellulose (C) is bound covalently to the group (G) comprising a sulfur atom via an ester bond, of formula (I-2):

in which :

m, L, Z, U, V and Phore are as defined in formula (I),

X represents a single bond, excluding a compound in which U represents an alkyl having 2 carbon atoms 10 in the linking chain C = O and the sulfur atom, and / or U 'represents an alkyl having 2 carbon atoms in the chain linking C = O and the sulfur atom.

In an advantageous embodiment of this particular embodiment, the present invention relates to a cellulosic material of formula (1-2), in which the cellulose (C) is covalently linked to the group (G) comprising a sulfur atom via an ester bond, of formula (1-2-2):

in which :

m, L, Z, V and Phore are as defined in formula (I),

X represents a single bond,

U represents C- alkyl | to C- | Q, excluding a compound in which U represents an alkyl having 2 carbon atoms in the chain linking C = O and the sulfur atom, and / or U 'represents an alkyl having 2 atoms of carbon in the chain linking C = O and the sulfur atom.

In another advantageous embodiment of this particular embodiment, the present invention relates to a cellulosic material as described above, in which the cellulose (C) is covalently linked to the group (G) comprising a sulfur atom via an ester bond, of formula (1-2-2):

in which :

m, L, Z, and Phore are as defined in formula (I),

X represents a single bond,

U represents C1-C10 alkyl,

V represents H, excluding a compound in which U represents an alkyl having 2 carbon atoms in the chain linking C = O and the sulfur atom, and / or U 'represents an alkyl having 2 carbon atoms in the chain linking C = O and the sulfur atom.

In a more particular embodiment, the present invention relates to a compound of formula (I-3):

in which :

m, L and Phore are as defined in formula (I),

X represents a single bond,

U represents alkyl in

Z represents H, and

V represents H.

The present invention therefore relates in particular to a compound of formula (I-3) below:

The present invention relates in particular to the following compounds, preferably those in which Y represents Ο, X represents a single bond and U represents a C 1 alkyl

OH η

OH η

The present invention also relates to the use of a cellulosic material as defined above for the covalent labeling of a material comprising cellulose.

Advantageously, the present invention relates to the use of a cellulosic material as defined above for anti-counterfeiting marking. More advantageously, the printing agent is an invisible compound in the visible domain and can be viewed under the influence of an external stimulus. In particular, the printing agent is a compound visible under UV illumination.

The cellulosic material according to the present invention is obtained from a cellulosic material comprising cellulose covalently functionalized by groups comprising a disulfide S-S function.

As has been shown by the inventors, the compounds in which the sulfur atom is in the beta position of a carbonyl function are less stable due to the potential reaction of retro-Michaël.

A second object of the present invention therefore relates to a cellulosic material comprising cellulose functionalized covalently by groups comprising a disulfide function SS, characterized in that the sulfur atom is not in the beta position of a carbonyl function .

For the purposes of the present invention, the term "cellulose covalently functionalized by groups comprising a disulfide SS function" means that part of the hydroxyl functions of D-glucose constituting the cellulose fibers is linked via a covalent bond to a group containing a sulfur-sulfur bond. Said covalent bond is in particular an O-C bond.

In the remainder of the present application, the materials will be described as comprising a group containing an S-S bond linked at each of its ends to a hydroxyl group belonging to two different cellulose fibers. However, it is likely that a group containing a sulfur-sulfur bond can be linked to two hydroxyl functions belonging to the same cellulosic fiber. It is also possible that a group containing a sulfur-sulfur bond is linked to a single hydroxyl function.

The present invention relates in particular to a cellulosic material comprising cellulose functionalized covalently by groups comprising a disulfide S-S function as defined above and corresponding to the following formula (II):

in which ;

Y and Y ', identical or different, represent NR ^a , O or S, where R ^a represents H, C alkyl! to C ₆ , aryl, heteroaryl or (C1 to C ₆ alkyl) -aryl,

X andX ', identical or different, represent a single bond, O or NR ^b , or C = Y and C = Y' represent CH ₂ and X and X 'represent a single bond,

U represents alkyl CL to C-io aryl (C! -C _6), where

R ^b is H, alkyl CL -C ₆ alkyl, aryl, (C ₆ -C CL) -aryl.

excluding a compound in which X represents a single bond and U represents an alkyl having 2 carbon atoms in the linking chain C = Y and the sulfur atom and / or X 'represents a single bond and U' represents an alkyl having 2 carbon atoms in the chain linking C = Y 'and the sulfur atom.

The present invention relates to a cellulosic material of formula (II) in which the group comprising an S-S disulfide function is symmetrical.

Advantageously, the present invention therefore relates to a cellulosic material of formula (IIa) below:

in which U, X and Y are as defined in formula (II).

Advantageously, the present invention relates to a cellulosic material as described above, in particular of formula (II) or (IIa), in which the cellulose (C) is covalently linked to the group (G) comprising a sulfur atom by l 'via an ester, carbamate, thiocarbamate or ether bond, of formula (11-1):

in which :

U, Y ’, X’ and U ’are as defined in formula (II) or (IIa),

C = Y represents C = O and X represents a single bond, or

C = Y represents C = O and X represents NR ^C , where R ^c represents H, C alkyl! to C ₆ , aryl, (C1 to C ₆ alkyl) -aryl, or

Y represents C = C = S and X represents NR ^C wherein R ^c is H, alkyl to C _6, aryl, _(Ci-C6) -aryl, or

C = Y represents CH _{2 and} X represents a single bond, excluding a compound in which X represents a single bond and U represents an alkyl having 2 carbon atoms in the linking chain C = Y and the sulfur atom and / or X represents a single bond and U 'represents an alkyl having 2 carbon atoms in the chain linking C = Y' and the sulfur atom.

More advantageously, the present invention relates to a cellulosic material as described above, in particular of formula (11-1), in which the cellulose (C) is covalently linked to the group (G) comprising a sulfur atom by via an ester, carbamate, thiocarbamate or ether bond, of formula (11-1-a):

in which :

Y ’, X’ and U ’are as defined in formula (II) or (lia),

C = Y represents C = O and X represents a single bond, or

C = Y is C = O and X is NR ^G, wherein R ^c is H, alkyl to C _6, aryl, _(Ci-C6) -aryl, or

C = Y represents C = S and X represents NR ^C , where R ^c represents H, C-ι to C ₆ alkyl, aryl, (C-ι to C ₆ alkyl) -aryl, or

C = Y represents CH ₂ and X represents a single bond,

U is alkyl to C _10, excluding a compound wherein X represents a single bond and U represents an alkyl having 2 carbon atoms in the chain linking C = Y and sulfur atom and / or X 'represents a single bond and U' represents an alkyl having 2 carbon atoms in the chain linking C = Y 'and the sulfur atom.

In a particular embodiment, the present invention relates to a cellulosic material as described above, in particular of formula (11-2):

in which :

U and U ’are as defined in formula (II) or (IIa),

X and X 'represent a single bond, excluding a compound in which U represents an alkyl having 2 carbon atoms in the linking chain C = O and the sulfur atom and / or U' represents an alkyl having 2 carbon atoms in the chain linking C = O and the sulfur atom.

In an advantageous embodiment of this particular embodiment, the present invention relates to a cellulosic material as described above of formula (II-2-a):

in which :

X and X ’represent a single bond

U and U ', identical or different, represent C1 to C10 alkyl, with the exclusion of a compound in which U represents an alkyl having 2 carbon atoms in the chain linking C = O and the sulfur atom and / or U 'represents an alkyl having 2 carbon atoms in the chain linking C = O and the sulfur atom.

In particular, the present invention relates to a cellulosic material chosen from the group consisting of:

η (11-2-3-1)

OH η

(11-2-3-5)

More particularly, the cellulosic material corresponds to the formula (ll-2-a-1):

The present invention also relates to the use of a cellulosic material comprising cellulose functionalized covalently by groups comprising a disulfide function SS as defined above for the covalent fixing of a printing agent comprising an alkene function or alkyne not conjugated to a carbonyl group, said covalent attachment resulting from a photo-thiol-ene or photo10 thiol-yne type reaction between said alkene function or said alkyne function not conjugated to a carbonyl group and the thiyl radical generated by said SS disulfide function.

By “alkene or alkyne function not conjugated to a carbonyl group”, is meant within the meaning of the present invention that the double bond is not in position 2,3 of a carbonyl function. Are therefore excluded from the scope of the present invention the printing agents in which is present an α, β-unsaturated ketone function, α amide, β-unsaturated or an α, β-unsaturated ester.

Within the meaning of the present invention, the term “resulting from a photothiol-ene or photo-thiol-yne type reaction between said alkene function or said alkyne function not conjugated to a carbonyl group and the thiyl radical generated by said disulfide function SS ”the fact that the bond between sulfur and the carbon atom of the bond of the cellulosic material is formed directly from the disulfide function.

Advantageously, the use of a thiol (SH) to form the C-S bond with the alkene function or the alkyne function is therefore excluded from the present invention. The inventors of the present invention have indeed demonstrated that the use of an S-S disulfide makes it possible to reduce the energy supply necessary for the formation of the C-S bond. The lower energy required by this reaction makes it possible, among other advantages, to make the preparation of the material less costly but also to limit the degradation of the cellulose, in particular to limit its coloring during the photo-thiol-ene or photo reaction. -thiol-yne.

By “photocatalysed” is meant within the meaning of the present invention that the thiyl radical is generated by subjecting the cellulose functionalized by the disulfide function SS to a source of energy sufficient to generate a radical S *, in particular ultraviolet irradiation . The photo-thiol-ene or photo-thiol-yne reaction is a reaction well known to those skilled in the art and has been described in numerous books and reviews, for example Hoyle, C.E .; Bowman, C. N. Angew. Chem. Int. Ed. 2010, 49, 1540, Hoyle, C. E .; Lowe, A. B .; Bowman,

C. N. Chem. Soc. Rev. 2010, 39, 1355, Lowe, A. B. Polym. Chem. 2010, 1, 17, Lowe, A. B. Pofymer 2014, 55, 5517.

Advantageously, the present invention relates to the use of a cellulosic material comprising cellulose covalently functionalized by groups comprising a disulfide function SS of formula (II), (11a), (11-1), (11-1 -a), (ll-2) or (ll-2-a), in particular of formula (ll-2-a-1), (ll-2-a-2), (II-2-a-3) , (ll-2-a-4), (ll-2-a-5), (ll-2-a6), preferably (II-2-a-1), for the covalent attachment of an agent d printing comprising an alkene or alkyne function not conjugated to a carbonyl group, said covalent attachment resulting from a photo-thiol-ene or photo-thiol-yne type reaction between said alkene function or said alkyne function not conjugated to a carbonyl group and the thiyl radical generated by said disulfide function SS.

The printing agent comprising an alkene or alkyne function not conjugated to a carbonyl group is in particular a compound of formula (III):

Phore

m in which L, Z, V and Phore are as defined in formula (I), p is 0 and is a triple bond, or p is 1 22222.- and is a double bond,

The compound of formula (III) is a printing agent linked either directly or through a spacer L to a double bond or a triple bond.

In one embodiment, the compound of formula (III) is a printing agent comprising a double bond of formula (Ilia) below:

Phore

m in which:

Phore, L, Z, m and V are as defined in formula (III).

In another embodiment, the compound of formula (III) is a printing agent comprising a triple bond of formula (IIIb) below:

Phore

in which :

Phore, L and V are as defined in formula (III).

Advantageously, the printing agent of formula (III) is chosen from the group consisting of:

A third object of the present invention relates to a process for the preparation of a CGA cellulosic material as defined above, comprising the reaction of cellulose functionalized by a group comprising a disulfide function SS as defined above, with an agent for printing comprising an alkene function or an alkyne function not conjugated to a carbonyl group in a photo-thiol-ene or photo-thiol-yne type reaction between said alkene function or said alkyne function and the thiyl radical generated by said disulfide function SS .

The process according to the present invention essentially contains a step of adding a thiyl radical S 'generated from a disulfide SS to a double bond or to a triple bond not conjugated to a carbonyl function, none of the atoms of sulfur constituting the disulfide function not being in the beta position of a carbonyl function.

The method according to the present invention has the following advantages compared to those described in the prior art:

(1) the reaction being carried out using disulfide, the energy required for the reaction is low and the cellulose is not altered during this step, (2) the double bond not being conjugated to a function carbonyl, the addition of the sulfur atom to the double bond occurs only under specific reaction conditions (ultraviolet irradiation). It is thus possible to control the reaction spatially by limiting the area where the irradiation is applied, (3) the spatial control of the reaction makes it possible to obtain a high resolution, (4) the product obtained being devoid of an atom of sulfur in beta position of a carbonyl function, it does not give rise to degradation by retro-Michaël reaction.

Advantageously, the present invention relates to a process for the preparation of a compound of formula (I) below:

in which m, L, Y, X, U, Z, V and Phore are as defined above, comprising a photo-thiol-ene or photo-thiol-yne type reaction between a compound of formula (II):

in which Y, X, U, Y ’, X’ and U ’are as defined above, and a compound of formula (III) as defined above.

In one embodiment, the compound of formula (III) is a printing agent comprising a double bond of formula (Ilia) as defined above. From the compound of formula (Ilia), the method according to the present invention makes it possible to obtain a cellulosic material of formula (la).

In another embodiment, the compound of formula (III) is a printing agent comprising a triple bond of formula (IIIb) as defined above. From the compound 10 of formula (IIIb), the method according to the present invention makes it possible to obtain a cellulosic material of formula (Ib).

The reaction conditions used to carry out the thiol-ene reaction and the thiol-yne reaction can be determined experimentally according to the product desired by a person skilled in the art.

Advantageously, the thiol-ene or thiol-yne reaction is carried out in the presence of a radical initiator. These include 2,2-dimethoxy-2-phenylacetophenone.

Advantageously, the thiol-ene or thiol-yne reaction is carried out in a polar solvent, in particular in DMSO.

The reaction is carried out at a wavelength providing sufficient energy to lead to the formation of the thiyl radical. Typically, this wavelength is from 250 to 450 nm.

Advantageously, the thiol-ene or thiol-yne reaction is carried out at a wavelength of 250 to 450 nm in the presence of a radical initiator. More advantageously, the photo-thiol-ene or photo-thiol-yne reaction is carried out at a wavelength of approximately 400 nm and 2,2-dimethoxy-2-phenylacetophenone as a radical initiator.

Thanks to the process according to the present invention, the printing agent can be covalently grafted onto the cellulosic material with excellent spatial resolution.

The printing agent can in particular be grafted onto a cellulosic material in a covalent manner with excellent spatial resolution and on a surface determined by the use of a mask.

By "mask" is meant in the sense of the present invention any device making it possible to define the surface exposed to the wavelength necessary to carry out the photothiol-ene or photo-thiol-yne reaction. Said mask makes it possible to introduce onto the surface of a cellulosic material such as fabric, paper or cardboard an image, a writing or any other form.

In one embodiment, the present invention relates to a process for the preparation of a cellulosic material C-G-A as defined above comprising the steps of:

a) impregnation of the cellulosic material comprising cellulose functionally covalently by groups comprising a disulfide function SS, in particular of formula (II), with a solution containing a printing agent comprising an alkene or alkyne function not conjugated to a group carbonyl, in particular of formula (III) and advantageously a radical initiator,

b) affixing a mask having the desired shape to the part of the surface of the cellulosic material on which the printing agent is to be grafted,

c) irradiation at a wavelength making it possible to initiate the thiol-ene or thiol-yne reaction of the part of the surface of the cellulosic material for a sufficient time to obtain the grafting of the printing agent comprising an alkene function or alkyne not conjugated to a carbonyl group, in particular of formula (III) on cellulose covalently functionalized by groups comprising a disulfide function SS, in particular of formula (11),

d) washing the cellulose material, in particular to remove excess reagents.

The cellulosic material comprising cellulose covalently functionalized by groups comprising an S-S disulfide function as defined above can be prepared by various methodologies known to those skilled in the art from cellulose.

Said methodologies are, for example, the alkylation of cellulose with a halogenated derivative, nucleophilic substitution under Mitsunobu conditions, acylation with a carboxylic acid in the presence of a catalyst or acylation with an activated derivative of a carboxylic acid such as an acyl chloride or a carboxylic anhydride. Other alkylation and / or acylation methodologies can be used without departing from the scope of the present invention.

Advantageously, the cellulose can be functionalized by using, as acylating agent, a carboxylic acid in the presence of an acid catalyst.

It has thus been demonstrated by the inventors that the acylation of cellulose with a carboxylic acid comprising a disulfide function SS in the presence of a catalytic amount of a strong acid makes it possible to obtain a cellulosic material with a degree high substitution while avoiding browning of the cellulosic material (in particular paper).

A fourth object of the present invention relates to a process for the preparation of a compound of formula (II), (11a), (11-1), (11-1-a), (II-2) or (H-2 -a), in particular of formula (ll-2-a-1), (II-2-a-2), (ll-2-a-3), (II-2-a-4), (ll- 2-a-5), (ll-2-a-6), preferably (ll-2-a-1), as defined above:

comprising a step of bringing the cellulose into contact with:

a compound of formula (IVa):

Y a compound of formula (IVb):

a compound of formula (IVc):

in which :

Y, Y ', X, X', U and U 'are as defined for formula (II), (lia), (11-1), (11-1-a), (II-2) or ( II-2a), in particular of formula (ll-2-a-1), (ll-2-a-2), (ll-2-a-3), (ll-2-a-4), (ll -2-a-5), (ll-2-a-6), preferably (ll-2-a-1), and

GP and GP ’, identical or different from each other, represent OH or a leaving group such as halogen, acyl or sulfonate, under conditions capable of leading to an acylation and / or an alkylation of the cellulose.

For the purposes of the present invention, the term “leaving group” means a functional group capable of promoting a nucleophilic substitution reaction.

Such groups are, for example, but not limited to, activated esters (e.g. hydroxybenzotriazole / carbodiimide system, carboxylic anhydrides, acyl chlorides), alkyl halides and alkyl sulfonates.

In one embodiment, Y and Y ’are identical, X and X’ are identical, U and U ’are identical and the method comprises bringing the cellulose into contact with:

e) a compound of formula (IVa-1):

or

f) a compound of formula (IVc-1):

According to an advantageous embodiment, the cellulose is linked to the group comprising a disulfide function SS via an ester function and the method comprises a step of contacting between cellulose and a carboxylic acid of formula (IVa1- 1):

in which X and U are as defined in one of the formulas (II), (lia), (11-1), (ll-1-a), (II-

2) or (ll-2-a), in particular of formula (ll-2-a-1), (ll-2-a-2), (ll-2-a-3), (ll-2-a -4), (ll-2-a-5), (II-2a-6), preferably (ll-2-a-1), in the presence of a strong acid, especially a sulfonic acid.

For the purposes of the present invention, the term "strong acid" means an organic or mineral acid, preferably organic, having a pKa in water ranging from -1 to 2. The strong acid is in particular a sulfonic acid, in particular para-toluene sulfonic acid.

In one embodiment, the cellulose is pretreated so as to improve its functionalization. Preferably, the pretreatment is carried out with a base solution, in particular of sodium hydroxide, in particular at 10 mol%.

A fifth object of the present invention relates to a process for the preparation of a cellulosic material comprising cellulose covalently functionalized by a printing agent, characterized in that the cellulose (C) is covalently linked to a group ( G) comprising a sulfur atom, the printing agent (A) is covalently linked to said group (G) comprising a sulfur atom by a CS bond with said sulfur atom, the sulfur atom being not in the beta position of a carbonyl function, comprising the steps of:

(a) reaction between cellulose and a compound comprising a disulfide function SS, characterized in that the sulfur atom is not in the beta position of a carbonyl function, in particular of formula (IV) as defined above above, said compound being capable of forming a covalent bond with at least one oxygen atom of the cellulose, in order to obtain cellulose functionalized by a group comprising a disulfide function SS, in particular of formula (II), (11a), ( 11-1), (11-1 -a), (II-2) or (ll-2-a), in particular of formula (ll-2-a-1), (ll-2-a-2) , (ll-2-a-3), (ll-2-a-4), (ll-2-a-5), (ll-2-a-6), preferably (ll-2-a- 1), (b) reaction of the cellulose functionalized with a group comprising a disulfide function SS, in particular of formula (II), (IIa), (11-1), (11-1-a), (II-2) or (ll-2-a), in particular of formula (ll-2-a-1), (ll-2-a-2), (ll-2-a-3), (ll-2-a- 4), (ll-2-a-5), (ll-2-a-6), preferably (ll-2-a-1) with a printing agent comprising an alkene function or a alkyne function not conjugated to a carbonyl group, in particular of formula (III) in a photo-thiol-ene or photo-thiol-yne type reaction between said alkene function or said alkyne function and the thiyl radical generated by said disulfide function SS, to obtain a cellulosic material comprising cellulose covalently functionalized by a printing agent, characterized in that the cellulose (C) is covalently linked to a group (G) comprising a sulfur atom, the agent d impression (A) is covalently linked to said group (G) comprising a sulfur atom by a CS bond with said sulfur atom, the sulfur atom not being in the beta position of a carbonyl function.

The present invention therefore relates to a process for the preparation of a cellulosic material C-G-A as defined above in which the cellulose is covalently functionalized by a printing agent corresponding to the following formula (I):

in which :

m is 1, 2 or 3,

L represents a single bond or a spacer,

Y represents NR ^a , O or S, where

R ^a represents H, C 1 to C ₆ alkyl, aryl, heteroaryl or (C 1 to C ₆ alkyl) -aryl, X represents a single bond, O or NR ^C , where

R ^c is H, alkyl to C _6, aryl, _(Ci-C6) -aryl, or C = Y is CH ₂ and X is a single bond,

U is alkyl to C ₁₀ aryl- (C, to C _6),

Z is H, Ci to Cio alkyl, aryl or (alkyl -C ₆₎ -aryl or pattern:

in which Y ’, X’ and U ’, identical or different respectively from Y, X and U, have the definition given for Y, X and U,

V is H, Ci-Cio alkyl, aryl or (alkyl -C ₆₎ -aryl.

Phore represents a printing agent as defined above, comprising the steps of:

(a) reaction between cellulose and:

i. a compound of formula (IVa):

ii. a compound of formula (IVb):

iii. a compound of formula (IVc):

in which :

Y, Y ’, X, X’, U and U ’are as defined for formula (I),

GP and GP ’, identical or different from each other, represent a leaving group such as OH, halogen, acyl or sulfonate, to give a cellulosic material of formula (II):

(b) photo-thiol-ene or photo-thiol-yne type reaction between the compound of formula (II) and a compound of formula (III):

in which :

in which L, Z, V and Phore are as defined in formula (I), p is 0 and ΞΞΞ is a triple bond, or p is 1 '££££ - and is a double bond, to give a material cellulosic of formula (I) as defined above.

excluding a compound in which X represents a single bond and U represents an alkyl having 2 carbon atoms in the linking chain C = Y and the sulfur atom, and / or X 'represents a single bond and U 'represents an alkyl having 2 carbon atoms in the chain linking C = Y' and the sulfur atom.

In one embodiment, the method according to the present invention is implemented in order to obtain a cellulosic material of formula (I), characterized in that Y and Y ’represent O,

X and X ’represent a single bond, U and U’ represent C1 alkyl, GP and GP ’represent OH and in that the strong acid is a sulfonic acid, in particular paratoluene sulfonic acid.

The present invention relates in particular to the following objects:

1. A cellulosic material C-G-A comprising cellulose covalently functionalized by a printing agent, characterized in that:

a) the cellulose (C) is covalently linked to a group (G) comprising a sulfur atom,

b) the printing agent (A), in particular a photoactive compound such as a fluorophore, a chromophore or a photochromic, thermosensitive such as a thermochromic, sensitive to a variation of pH or sensitive to a variation of polarity of the medium surrounding, is covalently linked to said group (G) comprising a sulfur atom by a carbon-sulfur bond with said sulfur atom of said group (G), the sulfur atom not being in the beta position of a function carbonyl.

2. Cellulosic material C-G-A according to the object, corresponding to the following formula (I):

in which :

m is 1, 2 or 3,

L represents a single bond or a spacer,

Y represents NR ^a , O or S, where

R ^a represents H, C alkyl! -C _{6 alkyl,} aryl, heteroaryl or (C! -C ₆₎ -aryl, X represents a single bond, O or NR ^C wherein

R ^c represents H, C alkyl! to C ₆ , aryl, (C1 to C ₆ alkyl) -aryl, or C = Y represents CH ₂ and X represents a single bond,

U represents C1 to C10 alkyl, aryl- (C ₁ to C _e alkyl),

Z is H, alkyl to C _1o, aryl or (alkyl -C ₆₎ -aryl or pattern:

n in which Y ’, X’ and U ’, identical or definition given for Y, X and U, different respectively from Y, X and U, have the

V represents H, C1 to C10 alkyl, aryl or (C ₄ to C ₆ alkyl) -aryl,

Phore represents a printing agent as defined in object 1, excluding a compound in which X represents a single bond and U represents an alkyl having 2 carbon atoms in the chain F = C and Y 'sulfur atom, and / or X' represents a single bond and U 'represents an alkyl having 2 carbon atoms in the chain linking C = Y' and the sulfur atom.

3.

at Cio,

Cellulosic material according to object 2, characterized in that U represents C1 alkyl, especially Ci.

Cellulosic material according to one of objects 2 or 3, characterized in that U and U ’are

4.

identical, X and X ’are identical and Y and Y’ are identical.

5. Cellulosic material comprising cellulose covalently functionalized by groups comprising a disulfide S-S function, characterized in that the sulfur atom is not in the beta position of a carbonyl function.

6.

Cellulosic material according to object 5, corresponding to formula (II):

in which :

Y and Y ', identical or different, represent NR ^a , O or S, where R ^a represents H, C alkyl! -C _e, aryl, heteroaryl or (C! -C ₆₎ -aryl,

X and X ', identical or different, represent a single bond, O or NR ^b , or C = Y and C = Y' represent CH ₂ and X and X 'represent a single bond,

U represents C1 to C10 alkyl, aryl- (Ct to C ₆ alkyl), where

R ^b represents H, C ₆ -C ₆ alkyl, aryl, (C 1 -C ₆ alkyl) -aryl.

excluding a compound in which X represents a single bond and U represents an alkyl having 2 carbon atoms in the linking chain C = Y and the sulfur atom and / or X 'represents a single bond and U' represents an alkyl having 2 carbon atoms in the chain linking C = Y 'and the sulfur atom.

7. Cellulosic material according to object 6, characterized in that U represents C ₁₀ to C ₁₀ alkyl, in particular Ch.

8. Cellulosic material according to one of objects 6 or 7, characterized in that U and U ’are identical, X and X’ are identical, Y and Y ’are identical.

9. Use of a cellulosic material according to one of objects 5 to 8, for the covalent fixing of a printing agent comprising an alkene or alkyne function not conjugated to a carbonyl group, said covalent fixing resulting from a reaction of photo thiol-ene or photo-thiol-yne type between said alkene function or said alkyne function not conjugated to a carbonyl group and the thiyl radical generated by said disulfide function SS.

10. Use according to object 9, characterized in that the printing agent comprising an alkene or alkyne function not conjugated to a carbonyl group corresponds to formula (III):

(Z) P

Phore.

(H) p in which:

m is 1 to 3,

L represents a single bond or a spacer,

Z represents H, C alkyl! to C _1o , aryl or (C 1 to C ₆ alkyl) -aryl,

V represents H, alkyl to C _10, or aryl (C₁-C ₆₎ aryl,

Phore represents a printing agent, p is 0 and ~ E == is a triple bond, or p is 1 and is a double bond.

11. Method for preparing a cellulosic material according to one of claims 5 to

8, comprising the steps of:

(a) covalent functionalization of the cellulose with a group comprising an S-S disulfide function, in particular chosen from:

• a compound of formula (IVa):

PG '

GP a compound of formula (IVb):

• a compound of formula (IVc):

in which :

Y, Y ’, X, X’, U and U ’are as defined for formula (I), and

GP and GP ', identical or different from each other, represent OH or a leaving group such as halogen, acyl or sulfonate, under conditions capable of forming a covalent bond between the cellulose and said group comprising a disulfide function SS to obtain a cellulosic material according to one of objects 5 to 8.

12. Process for the preparation of a cellulosic material according to one of objects 1 to 4, comprising the reaction of cellulose functionalized with a group comprising a disulfide function SS as defined in one of objects 5 to 8, with a printing agent comprising an alkene function or an alkyne function not conjugated to a carbonyl group, in particular according to object 10, in a photo-thiol-ene or photothiol-yne type reaction between said alkene function or said alkyne function and the thiyl radical generated by said disulfide function SS.

13. Process for the preparation of a cellulosic material according to one of objects 1 to 4, comprising the steps of:

(a) covalent functionalization of the cellulose with a group comprising an S-S disulfide function, in particular chosen from:

• a compound of formula (IVa):

• a compound of formula (IVb):

• a compound of formula (IVc):

in which :

Y, Y ’, X, X’, U and U ’are as defined for formula (I), and

GP and GP ', identical or different from each other, represent OH or a leaving group such as halogen, acyl or sulfonate, under conditions capable of forming a covalent bond between the cellulose and said group comprising a disulfide function SS to obtain a cellulosic material according to one of objects 5 to 8, (b) reaction between the cellulosic material according to one of objects 8 to 8 and a printing agent comprising an alkene function or an alkyne function not conjugated to a carbonyl group, in particular according to object 10, in a photo-thiol-ene or photo-thiol-yne type reaction between said alkene function or said alkyne function and the thiyl radical generated by said disulfide function SS, in order to obtain a material cellulosic according to one of objects 1 to 4.

14. Use of a cellulosic material according to one of objects 1 to 4 for covalent anti-counterfeiting marking.

Description of the figures:

Figure 1 shows the XPS scanning spectrum ((a)) and the high resolution C1s spectrum of the filter paper ((b)); the XPS scanning spectrum ((c)) and the high resolution S2p spectrum ((d)) of cellulose after reaction with dithiodiglycolic acid. Cellulose has a characteristic peak at 286.4 eV corresponding to the C-0 bonds and two peaks of lesser intensity at 284.8 and 287.9 eV for the C-C and O-C-O bonds respectively. The C1s spectrum of cellulose after reaction with dithiodiglycolic acid has a new peak at a high binding energy (289.1 eV), corresponding to the ester bond created.

Figure 2 shows the high resolution XPS C1s spectrum of the cellulose on which Callyloxycoumarin is grafted (Figure on the left (a)) and propargyloxycoumarin (Figure on the right (b)).

Figure 3 shows the high resolution spectrum C1s of the cellulose on which allyl rhodamine B is grafted. The full scanning spectrum of the patterned area showed the presence of the N1s peak at 399.7 eV, while the spectra at High resolution of the C1s region showed a significant increase in the maximum count for CC links at 284.7 eV. These two observations confirm the successful introduction of the dye on the cellulosic material.

Figure 4 shows a labeling of cellulose paper with a printing agent according to Wei Li et al. (3) and a printing agent according to the present invention not conjugated to a carbonyl function (4). In the case of the prior art, the marking is extremely weak and very diffuse.

Figure 5 shows a labeling of cellulose paper with a coumarin-based printing agent obtained by thiol-ene reaction (Cell-TEC) and by thiol-yne reaction (Cell-TYC). In both cases, an impression is obtained with high spatial resolution and high intensity.

Figure 6 shows a photograph of the cellulose on which rhodamine B is grafted under acidic conditions ((a)) and basic conditions ((b)).

EXAMPLES:

General procedure for the pretreatment of cellulose

Four pieces of filter paper are immersed in a freshly prepared 10% NaOH solution (300 mL). The solution is stirred overnight on an orbital shaker. The cellulose samples are washed three times with 50 mL of ethanol and stored in ethanol.

EXAMPLE 1:

Grafting of dithiodiglycolic acid or dithiodipropionic acid on cellulose

A pretreated filter paper (about 145 mg, 0.90 mmol glucose units), washed twice with 10 ml of toluene is immersed in anhydrous toluene (20 ml). A catalytic amount of p-toluene sulfonic acid (20 mg) is added and the reaction medium is stirred for 5 minutes. The dithioglycolic acid (3 equivalents per glucose unit) is then added to the solution and the mixture is stirred for 16 hours at reflux under a nitrogen atmosphere.

The functionalized filter paper (1) is washed sequentially with ethanol, methanol, acetone and CH ₂ CI ₂ in an ultrasonic bath. The sample is then dried under reduced pressure and stored under a nitrogen atmosphere.

According to the same methodology, the filter paper functionalized with dithiodipropionic acid is prepared.

EXAMPLE 2:

Synthesis of 7-propargyloxycoumarin

Anhydrous potassium carbonate (3.41 mmol) was added to a solution of 7hydroxycoumarin (2.28 mmol) in acetonitrile (25 mL) under an inert atmosphere.

Propargyl bromide (2.72 mmol) is added to the solution which is stirred for 12 hours at 60 ° C.

At the end of the reaction, the solution is filtered and concentrated under reduced pressure. The solid residue is purified by recrystallization from hexane (90%) to give colorless crystals.

EXAMPLE 3 Synthesis of printing agents comprising a double or a triple bond

Synthesis of 7-allyloxycoumarin

A solution of umbelliferone (5 mmol), potassium carbonate (5 mmol) and allyl bromide (5 mmol) in 50 mL of acetone is brought to reflux for 5 hours. After filtration, the 7-allyloxycoumarin is recovered and purified by crystallization from ethanol (90% to give colorless crystals.

Synthesis of aminoethyl rhodamine B:

A solution of rhodamine B (2 mmol) in ethanol (25 ml) was treated with ethylenediamine (3 mmol) with vigorous stirring at room temperature. After being stirred for 12 h at 80 ° C, the clear solution was cooled to room temperature and the volatiles were removed under reduced pressure. The resulting solid was diluted with water (25 ml), extracted with CH ₂ CI ₂ (3 x 100 ml), washed with water (50 ml), dried over anhydrous MgSO4 and concentrated under reduced pressure. Purification by flash chromatography (2% MeOH-CH ₂ CI ₂ ) gives aminoethyl rhodamine B (75%) in the form of a light purple solid.

Synthesis of diallyl-rhodamine B

Aminoethyl rhodamine B (1 mmol) and Et ₃ N (3.6 ml) in chloroform (25 ml) under nitrogen were added and the resulting mixture was stirred for 20 minutes. Then 3bromoprop-1-ene (7.1 mmol) was added at room temperature and the reaction mixture was further stirred for 12 h at 75 ° C. After cooling to room temperature, water (12 ml) was added to the crude mixture. The organic layer was separated, dried over anhydrous MgSO ₄ and concentrated in vacuo. The crude was purified by flash chromatography (10% EtOAc-petroleum ether) to give the expected rhodamine derivative (50%) as a pale orange solid.

EXAMPLE 3 Thiol-ene and thiol-yne reaction with chromophores as a printing agent

Thiolene reaction on cellulosic paper with 7-allyloxycoumarin

Cellulose paper grafted with dithiodiglycolic acid (70 mg), a mixture of 7-allyloxycoumarine (30 mg) and 2,2-dimethoxy2-phenylacetophenone (5 mg) in DMSO (500 mg) was added dropwise μΙ). Then, the paper was irradiated with blue light (10 W, Amax = 400 nm) for 150 min. Finally, the piece of paper was sequentially washed with water, MeOH, acetone and CH ₂ CI ₂ in an ultrasonic bath, dried under vacuum and stored under nitrogen.

Thiol-yne reaction on cellulosic paper with 7-propargyloxycoumarin

Was added dropwise to cellulose paper grafted with dithiodiglycolic acid (70 mg), a mixture of 7-propargyloxycoumarine (30 mg) and 2,2dimethoxy-2-phenylacetophenone (5 mg) in DMSO ( 500 μΙ). Then, the paper was irradiated with blue light (10 W, Amax = 400 nm) for 150 min. Finally, the piece of paper was sequentially washed with water, MeOH, acetone and CH ₂ CI ₂ in an ultrasonic bath, dried under vacuum and stored under nitrogen.

Thiol-ene reaction on cellulose paper with diallyl-rhodamine B

A mixture of diallyl rhodamine B (40 mg) and 2,2-dimethoxy2-phenylacetophenone (5 mg) in DMSO (500 μΙ) was added dropwise on cellulose paper grafted with dithiodiglycolic acid (70 mg ). Then, the paper was irradiated with blue light (10 W, Amax = 400 nm) for 150 min. Finally, the piece of paper was sequentially washed with water, MeOH, acetone and CH ₂ CI ₂ in an ultrasonic bath, dried under vacuum and stored under nitrogen.

EXAMPLE 3 Thiol-ene and thiol-yne reaction with an apolar group as a printing agent

Thiol-ene reaction on cellulose paper with allylpentafluorophenyl ether:

F

F

F

F

Was added dropwise to cellulose paper grafted with dithiodipropionic acid (70 mg), a mixture of allylpentafluorophenyl ether (30 mg) and 2,2-dimethoxy-2phenylacetophenone (5 mg) in DMSO (500 μΙ). Then, the paper was irradiated with blue light (10 W, Amax = 400 nm) for 150 min. Finally, the piece of paper was sequentially washed with water, MeOH, acetone and CH ₂ CI ₂ in an ultrasonic bath, dried under vacuum and stored under nitrogen.

COMPARATIVE EXAMPLE:

Synthesis of methacrylamide-rhodamine B

To a solution of aminoethyl rhodamine B (1 mmol) and triethylamine (2.4 mmol) in CH ₂ CI ₂ (3.5 ml) under nitrogen at 0 ° C, a solution of methacryloyl chloride (2 mmol) in CH ₂ CI ₂ (2 ml). The reaction mixture is allowed to warm to room temperature and stirred further for 18 h. The crude solution was washed with water (3x10 ml), saturated Na ₂ CO _{3 solution} (3x10 ml), brine (10 ml), dried over anhydrous MgSO ₄ and concentrated under reduced pressure. The residue was quickly purified on a pad of silica gel (AcOEt) to give a purple solid (yield 55%).

Thiol-ene reaction on cellulose paper with methacrylamide-rhodamine B

A mixture of methacrylamide-rhodamine B (40 mg) and 2,2-dimethoxy-2-phenylacetophenone (5 mg) in DMSO (500 μl) was added dropwise on cellulose paper grafted with dithiodiglycolic acid (70 mg). Then, the paper was irradiated with blue light (10 W, Amax = 400 nm) for 150 min. Finally, the piece of paper was sequentially washed with water, MeOH, acetone and CH ₂ CI ₂ in an ultrasonic bath, dried in vacuo and stored under nitrogen.

EXAMPLE 4 List of compounds synthesized from the thiol-yne or thiolene reaction:

Claims (14)

1. Cellulosic material C-G-A comprising cellulose covalently functionalized by a printing agent, characterized in that: a) the cellulose (C) is covalently linked to a group (G) comprising a sulfur atom, b) the printing agent (A), in particular a photoactive compound such as a fluorophore, a chromophore or a photochromic, thermosensitive such as a thermochromic, sensitive to a variation of pH or sensitive to a variation of polarity of the medium surrounding, is covalently linked to said group (G) comprising a sulfur atom by a carbon-sulfur bond with said sulfur atom of said group (G), the sulfur atom not being in the beta position of a function carbonyl. 2. C-G-A cellulosic material according to claim 1, corresponding to the following formula (I): in which : m is 1, 2 or 3, n is 15 to 15,000 L represents a single bond or a spacer, Y represents NR ^a , O or S, where R ^a represents H, C ·, C ₆ alkyl, aryl, heteroaryl or (C ₁ -C ₆ alkyl) -aryl, X represents a single bond, O or NR ^C , where R ^c is H, alkyl to C ₆ alkyl, aryl alkyl, (Ct -C ₆₎ -aryl, or C = Y is CH ₂ and X is a single bond, U represents C1 to C10 alkyl, aryl- (Ct to C ₆ alkyl), Z represents H, alkyl Ci-C ™, aryl or (alkyl -C ₆₎ -aryl or pattern: in which Y ’, X’ and U ’, identical or different respectively from Y, X and U, have the definition given for Y, X and U, V represents H, alkyl to C _10, or aryl (C₁-C ₆₎ aryl, Phore represents a printing agent as defined in claim 1, with the exclusion of a compound in which X represents a single bond and U represents an alkyl having 2 carbon atoms in the linking chain C = Y and l sulfur atom, and / or X 'represents a single bond and U' represents an alkyl having 2 carbon atoms in the chain linking C = Y 'and the sulfur atom. 3. Cellulosic material according to claim 2, characterized in that U represents C-ι to Cio alkyl, in particular CL. 4. Cellulosic material according to one of claims 2 or 3, characterized in that U and U 'are identical, X and X ’are identical and Y and Y’ are identical. 5. Cellulosic material comprising cellulose covalently functionalized by groups comprising a disulfide S-S function, characterized in that the sulfur atom is not in the beta position of a carbonyl function. 6. Cellulosic material according to claim 5, corresponding to formula (II): in which : Y and Y ′, which may be identical or different, represent NR ^a , O or S, where R ^a represents H, C ₆ to C ₆ alkyl, aryl, heteroaryl or (C 1 to C ₆ alkyl) -aryl, X and X ', identical or different, represent a single bond, O or NR ^b , or C = Y and C = Y' represent CH ₂ and X and X 'represent a single bond, U is alkyl to C _10l aryl- (C Ch -C _6), where R ^b is H, alkyl Ch -C ₆ aryl, (Ci-C ₆₎ aryl. excluding a compound in which X represents a single bond and U represents an alkyl having 2 carbon atoms in the linking chain C = Y and the sulfur atom and / or X 'represents a single bond and U' represents an alkyl having 2 carbon atoms in the chain linking C = Y 'and the sulfur atom. 7. cellulosic material according to claim 6, characterized in that U is alkyl to C _10, in particular Cl. 8. Cellulosic material according to one of claims 6 or 7, characterized in that U and U ’are identical, X and X’ are identical, Y and Y ’are identical. 9. Use of a cellulosic material according to one of claims 5 to 8, for the covalent fixation of a printing agent comprising an alkene or alkyne function not conjugated to a carbonyl group, said covalent fixation resulting from a reaction of photo-thiol-ene or photo-thiol-yne type between said alkene function or said alkyne function not conjugated to a carbonyl group and the thiyl radical generated by said disulfide function SS. 10. Use according to claim 9, characterized in that the printing agent comprising an alkene or alkyne function not conjugated to a carbonyl group corresponds to formula (III): (Z) p Phore (H) p in which: m is 1 to 3, L represents a single bond or a spacer, Z represents H, C 1 to C 10 alkyl, aryl or (C 1 to C ₆ alkyl) -aryl, V represents H, alkyl Ci-Ci ₀ aryl or (alkyl -C ₆₎ -aryl, Phore represents a printing agent, p is 0 and is a triple bond, or p is 1 and is a double bond. 11. Process for the preparation of a cellulosic material according to one of claims 5 to 8, comprising the steps of covalent functionalization of the cellulose with a group comprising a disulfide S-S function, in particular chosen from: • a compound of formula (IVa): Y ' PG ' GP a compound of formula (IVb): • a compound of formula (IVc): in which : Y, Y ', X, X', U and U 'are as defined in claim 2, and GP and GP', identical or different from each other, represent OH or a leaving group such as halogen , acyl or sulfonate, under conditions capable of forming a covalent bond between the cellulose and said group comprising a disulfide function SS to obtain a cellulosic material according to one of claims 5 to 8. 12. Process for the preparation of a cellulosic material according to one of claims 1 to 4, comprising the reaction of cellulose functionalized with a group comprising a disulfide function SS as defined in one of claims 5 to 8, with a printing agent comprising an alkene function or an alkyne function not conjugated to a carbonyl group in a photo-thiol-ene or photo-thiol-yne type reaction between said alkene function or said alkyne function and the thiyl radical generated by said function disulfide SS. 13. Process for the preparation of a cellulosic material according to one of claims 1 to 4, comprising the steps of: (a) covalent functionalization of the cellulose with a group comprising an S-S disulfide function, in particular chosen from: • a compound of formula (IVa): Τί • a compound of formula (IVb): • a compound of formula (IVc): in which : Y, Y ’, X, X’, U and U ’are as defined for formula (I), and GP and GP ', identical or different from each other, represent OH or a leaving group such as halogen, acyl or sulfonate, under conditions capable of forming a covalent bond between the cellulose and said group comprising a disulfide function SS to obtain a cellulosic material according to one of claims 5 to 8, (b) reaction between the cellulosic material according to one of claims 5 to 8 and a printing agent comprising an alkene function or an alkyne function not conjugated to a carbonyl group in a photo-thiol-ene or photo-thiolyne type reaction between said alkene function or said alkyne function and the thiyl radical generated by said disulfide function SS, in order to obtain a cellulosic material according to one of claims 1 to 4 . 14. Use of a cellulosic material according to one of claims 1 to 4 for covalent anti-counterfeiting marking. 1/3 (a) is