WO2015058141A1 - Nucleobase-containing monomers and copolymers - Google Patents

Abstract

The present invention relates to nucleobase-containing monomers and copolymers for making pressure sensitive adhesives or thermoplastics. The monomer has the structure of Formula (I), wherein Y is an acryloyl, methacryloyl, or a styrenic group; R1 is an alkylene having 1 to 18 carbons, or esters or ethers thereof; and B is cytosine or guanine moiety.

Description

iiCLE BASE-CO TA I G MONOMERS AND COPOLYMERS

[0001J This application claims the priority of U.S. Provisional Patent Application

61/892,517, filed October 18, 2013, which is incorporated herein by reference,

FIELD OF THE INVENTION

10002] The resent invention relates to nucleohase ontaining monomers and. copolymers for making pressure sensitive adhesives.

BACKGROUND OF THE INVENTION

| 003] Aery He polymers have advantages and superior qualities to other polymer based adhesives for use m pressure sensitive adhesives (PSA). Acrylics arc transparent and chemically and oxidarively stable. They are less irritating to skin and often used for biomedical applications.

[0004] Supramoiecular polymers describe polymers thai contain noneovaienl interactions such as hydrogen bonding, aromatic stacking, and electrostatics interaction. Synthetic, supramolecular polymers are emerging as versatile and highly useful materials due to die reversible nature of the noncovalent interactions. Commercialized adhesives and coalings generally require a permanent cross-linking mechanism such as covaieu erosslinkiug to obtain sufficient adhesive and cohesive strength, Noncovalent nteract ons can also provide a physically crosslmked polymer network while at the same time being reversible. Supramoieeuiar adhesives and coatings are responsive to heat, moisture, solvent, salt concentration, etc., depending on the specific .noncova!ent interaction. The self-assembly behaviors of supramolecular polymers also contribute to their potential applications as self-healing and mendable materials. [0005] The efficiency of incorporating noneovaient interactions as a reversible crossimking mechan sm for acrylic adhesives has been demonstrated (Cheng ei al., M cromotearies 20 ! 2, 45, 805; Yaraauchi ei ai.₅ Macnw tecules 2003, Id, 1083; Caslifon ei aL J. Adhes. 200 , $5, 1 ), 2- ureido-4[ I Hj-pyrinddinone (UPy) quadruple unit, urethane, and adenine-thymine nuckobase pair provided noneovaient interactions. The strategy invol ves syrrthesixing acrylics with hydrogen, bonding sites or aromatic groups on the polymer side chains. Incorporation of noneo vaient interactions results in enhanced adhesive performance due to the formation of a erossiinked network and increased apparent rnoieeidar weight. Various characterization^ of the stipramoiecular acrylic adhesives revealed their reversibility to heat and solvent. In particular, the adenine-eoniaining acrylics seli-assen hied into phase-separation morpholog driven by the pi -pi stacking of adenine.

[00061 There remains a need for PSAs based on hydrogen, bonding. The reversible nature of noneovaient interaction in hydrogen bonding provides an opportunity to design thermal or solvent reversible adhesiyes and recyclable adhesives materials. Hydrogen bonding introduces physical crosslinks to enhance .mechanical properties, especially cohesive strength of adhesive materials and maintains processibility above the hydrogen bonding dissociation temperature.

SUMMARY OF THE INVENTION

[δ00?| The present invention relates to nucleobase-coniaining monomers (where the mtcleobase is eytosine or guanine) and corresponding copolymers. An object of the present invention is to provide a iiucleobase-containirsg monomers having ihe structure of formula I

Fovrnuia I

wherein Y is an aeryioyl methacryloyl, r a styrerhc group Ri is an alkylene having ! to 18 carbons, preferably 2-6 carbons, or esters or ethers thereof; and B is eytosine or guanine moiety, or protected moieties thereof. Most oreferahiy, the rnors.om.er has the structure of Formula l:A

wherein B! is Formula If or II

Formula II Formula I II

Formula ΪΪ is based on cyiosine; and Formula..!!! is based on. guanine.

[0008] Another object of the present invention .b to provide a copolymer comarning the Rycleobase-e.ontahvi.Rg monomer of Formula I and. a comonomer of Formula IV, V, YF or combinations thereof

[0000J Formula IV is given as_. follows;

Forrnu wherein R.3 is an a!ky! having 1 to 1 carbons., preferably 4-8 carbons, or alcohol or acids thereof; and R4 is hydrogen or an alky! having 1 ιο 3 carbons. More preferably, iU is a buiyl . Preferably. 114 is hydrogen.

[0010] Formula V is given, as follows:

Formula V wherein RS km a^'lk l having to 1.2 carbons, preferably I to 3 carbons, or alcohols or acids thereof; and R6 m hydrog n or an alkyi having I to 3 carbons. Preferably, R5 is a methyl.

Preferably, R6 s hydrogen.

£00 1| Formula VI i g en as fol lows:

Formula wherein R7 is an al^'kylene having 0 to 2 carbons; each of R8 to R12 is independently hydrogen, a halogen, or an alkyi having I to 3 carbons; and R13 is hydrogen or an alkyi having I to 3 carbons, Preferably, R7 has 0 carbon atosn. Preferably; each of RS to R12 is hydrogen.

Preferably, RD is hydrogen. [0012] The copolymer .may be a .random copolymer or a block copolymer. A random copolymer is preferred,. Additionally, the second monomer may contain any combination;; of Formulas IV to VI.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013J Figure 1 shows the chemical, structures of some preferred eomono ers.

[0014] Figure 2 shows the chemical structure of acetyl protected guanine,

[001 S] Figure 3 Is a graph showing the chemical structure and the proton rid carbon B nuclear magnetic resonance spectroscope (N R) analysis of cytosine acrylate (CyA) monomer.

[0016] Figure 4 is a graph showing the chemical structure and the proton FiMR analysis of preferred gwarvme acrylate (G«A) monomer.

[0017] Figure 5 is a graph showing the chemical structure and the NM analysis of polyfcytosiue aoryiate~eo~n-buty| -acrylate) copolymer (abbreviated as po!y(CyA~co~nBA}), [0010] Figure 6 is a graph showing the chemical structure and the NM analysis of poSyiguanme aorylatc-co-n-butyl acrylate) copolymer (abbreviated as poly{GuA-co-nBA)).

[0019] Figure ? is a graph showing thermogravimetnc analysis (TGA) of 15 mo!% CyA- containing poiyacrylate and 8 mol% GiiA-contairhng poiyacrylate, which depict 5·% weight loss temperatures above 300 ^aC in both air and .nitrogen.

[0020] Figure 8 shows pictures - f pol.y(CyA-e»-«B A) with CyA (A) 4 mol%, (B) ! 5 mol%, and (C) 100 mo!%. Corresponding glass transition temperatures for copolymers were -44 ^CC. - 1(5 °C_? and 67 °C for A, B, and (1 respectively.

[0021] Figure 9 shows pictures of poiy(GuA~co~/?BA} iih GuA (A) 2 moi¾, (B) 8 mol¾, and (C) 100%, Corresponding glass transition temperatures for copolymers were -45 ^C'C -22 °C_> and 1. 18 °C tor A_f B, and C, respectively.

[0022] Figure 10 shows the storage and loss modulus master curves of polyacry!ates containing 8 mo!% GuA, 1 1 .mol% CyA. and poly«.BA. [0023| Figure i 1 shows the storage modulus master curves of pol yacryjat.es containing 3 moi% Cm A, 3 moI% t-but l acrylaie, 10 moi% acrylic acid, commercial acrylic PSA sample, and poly«BA,

[0S24] Figure 12 shows the isothermal ffick fhcology res lt of nyc!eohase-c nlairbng acrylics at 130 C for 6 b.

[0020] Figure 1 3 shows variable temperature MR experiments of GcA containing polyaerylaie with a heat ng and coohng cycle.

[0028] Figure 14 shows variable temperature FT!R experiments of GuA containing

polyacrylaie,

[0027] Figure 1 S shows variable temperature FUR -experiments of CyA. containing oly aery I ate,

[0028] Figure ] 6 shows dynamic mechanica; analysis of poiyacryUues containing S nxd%, 1 i mol¾ oiOuA and I 5 mol¾, 29 mol% CyA,

DE AILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

1 0293 The present invention relates ta monom rs having guamme or cytokine moiety as part of the monomer, and io . cop lyme s containing the monomer .for supranwlecular adhesive* and coatings. In an embodiment ihe monomer has tbe structure of Formula !l

FonnuJa I

wherein Y is an aeryloya meihacryioyi₅ or a styrenic group; R 1. is an aikyiene having 1 to 18 carbons, preferably 2-6 carbons, or esters or ethers thereof; and B is eytosine or guanine moiety. In certain embodiments, the cvtosme or guanine m iety may con a a protecting group, such as acetyl, t-btuyloxycarbonyL trifluoroaeetyi, benzyl iriphenylmeihyl, benzyloxycarbon l, or combinations thereof. In. a preferred embodiment, the monomer has the structure of Formula L wherein B is Formula VII or VIII

Formula VI! Formula VIH

or protected forms thereof In protected the -NI¾ of either .Formula VI! or Vlli contains the protecting group. For example, when Formulas VII and VII I are protected with the acetyl group,, ihe results are Formulas II and HI, respectively. In the most preferred embodiments, tbe monomer has the structure of Formula I . as defined above. 0030J In another embodiment, the nucleobase-eontakung monomer may be made by a two step process. First, the guanine (G) or eyioslne (€) is protected. The protected Q or C Is then reacted with a compound having the sirueiure of Formula IX by Michael addition

Formula IX

wherein Y and R.l are as described above. Alter Michael addition, the protecting group -ma be removed or remain with the C or G moiety ,

[0031] For -e am le, the compound of Formula I A may be synthesized b protecting lbs ¾ ^•of guanine or cytokine with an acetyl group to obtain, the compounds of Formula II or III. The protection reaction for guanine s preferably carried out with excess acetyl anhydride in dimethylaeetamide (DMAc) at reftuxiug temperature (about 150 .1 ?0¾> for about 2-8 hours.

H e compound of Formula II or III is thee reacted with 1 , 4_>-bu(amedioj osacrykue in a Michael addition to f m the compound of Formula IA. lite Michael additional reaction is preferably carried out in the presence of a solvent, a polymerization inhibitor, and an organic base. The solvent may be, bat is not limited !.o, dlmethylsuli xide (DMSO), dimethyl formamide (DMF), dimethylaeetamide (DMAc), or combinati ns ihereof, with DMSO being the preferred solvent. The polymerization Inhibitor may be, but is not limited to, huty!aied hydroxyioluene ( Si I f), hydroqmnone, or combinations thereof, with. BHT being the preferred polymerisation inhibitor. The base may be, but is not. limited to, trieih.ylami.ne (TEA), potassium carbonate, potassium tett- butoxiiie, or combinations thereof, with TEA being the preferred base.

[0032] !n another embodiment, the present invention relates to copolymer containing a nucleobase-containiog mo omer (where the nucleohase is cytokine or guanine) and a

conioriomer (the cornooomer may Include one or several different, types o comonomers), ^'The copolymers are useful in making adhesive compositions .and thermoplastics. The nocieohase containing monomer has the stnfctute^'of Formula I as noted above. The comonomer has the structure of Formula fV, V, \ or combinations thereof Preferably, the copolymer contains about 0.1-20 moi %, more preferably about 2-8 mo! % and 80-99. mole % of the conionomer, more preferably about 92-98 moi %.

|0 33| The eomonomers are we!l-krio n In the and may be obtained using previously described methods, indeed, the second comooomers are available commercially from many sources. For example, baty! acryiate has CAS Number 141 -32-2 and is available from Dow; butyl meihacry!a!s has CAS Numbe 97-88-1 and. is available from Dow; 2-eihy!hexyl methacrylate has CAS Number 6S§^»S4*6 and is available from Sigma A!drich; 2- drvihexyl acryiate has CAS Number 103- i 1 --? and is available from Sigma Aldrich methyl acryiate has CAS Number 96-33-3 and Is available from Dow; and methyl methacrylate has CAS Number 8(1-62-6 and is available from Sigma Aidnch, Styrene and its iunctionalked monomers are also available through. S m Aidnch. Speci.be examples of the second monomer may be, but are not limited- to, acrylates or methaerylates, such as methyl acryiate, methyl methacrylate, ethyl acryiate, ethyl methacrylate, isopropyl aerylate, isopropyl nie hacrylate, o-bniyl acryiate, n -bu l methacryl te, i -but l acryiate, i~buiy1 methacrylate, t-butyl acryiate, t-butyl methacrylate, bexyi acryiate, hexylmethseryiate ethylhexyl acryiate, exhyihexyl rnethaer iate, 3 ,3 dimethySbuty! methacrylate, lanryi. acryiate; styrene and functionalized slyrenes, such as bromostyrene, ehlorostyrenes, hutoxystyrenes, butylsiyrenes, methylstyrenes, and pro ylsiryrenes. The preferred second eomomorsers are u-butyl acryiate, n-butyl methacrylate, 2-edrylhexyl acryiate, iso-octyl acryiate, methyl acryiate, methyl methacrylate, vinyl acetate, styrene, 2-hydrox.y ethyl acryiate, or combinations thereof The structures of some of hos second comouomers are shown in. Figure L The most preferred second eomonomer is n-butyS aery l e, n-buty! meihaeryhue, or combinations thereof

[0034] The nucleobase-eontamin monomer and epmpm>nier are reacted to form the copolymer of the present invention. Preferably, the reaction lakes place In a solvent with the presence of an initiator. Preferably, the reaction is carried out at 60-70 under inert gas (such as nitrogen or argon) or at reflux. Solid weight percent initiator to monomer .ratio, and reaction time cart- be used to control the molecular weighlof copolymer. Preferably, pol mer tion takes place with about 40-60% solvent by weight and about 0.05 -1 mol¾ initiator. The solvent can be, but is not limited to, dim tnylformgmide (DMP), dimetyl sulfoxide (DMSO), ethyl acetate, methanol, isopropauol, ioxane, with a DMP and DMSO being the preferred solvents. The initiator can be, bni. is not limited to, azobisisobui.yronit.rile ίΛΙΒΝΙ 4,4'~Aiⁱ;obis(4-eyanovaieric acid), and organic peroxides, such as di-tert-buiyl peroxide and benzoyl peroxide, with AIBN being the preferred initiator,

03δ] 1 n a preferred embodiment, the copolymer contains the monomer of Formula lA and « -butyl acrylaie. In another preferred embodiment, the copolymer contains the monomer of Formula I A and ethylhexyl acrylaie. Formula IA can be obtained, fo example, by Michael addition of 1 , -butanedioI diacrylate with aceiyl-proiected guanine or cytosme. The reaction preferably takes place in DMSO wit TEA and Biff at room temperature. Preferably, 1 , 4- butanediol diacrylate is used at two equivalents to one equivalent of the acetyl -protected guanine or eytosine.

[0036] In yet another embodiment, the present invention provides a horaopoiymer containing the monomer of Formula L The homopolymer can be synthesized by reacting the monomer in the presence of AlBN in DMSO at 6i 7(fC unde Inert gas. f G037J Without, further description, if is believed that one f ordinary skill in the art can, using th preceding description and the following, illustrative example, make and utilize the compounds of the present invention and practice the claimed methods. The following example is given to illustrate the present invention, it should be understood that the invention is not to be limited to the specific conditions or details described m the example

Exa p

|0 3SJ We describe herein tor the first time the synthesis and cbaraeterization of cyiosine and giianine-eontaining acrylics as suprarnoleenlar adbesives and coatings.. Michael addition afforded the synthesis of novel cyiosine and guanine acryiate monomer, offering an efficient, route lor producing bio-inspired polymers through tree radical copoiymenzation. We probed the effect of incorporating cyiosme and guanine on the physical properties and adhesive performance f polyacr late s.. Ultimately,, our invention broadens erosalinking methods in adhesive fabrication and introduces ihermoreversibiHty to adhesive performance,

mm Meth ds

[0040] Synthesis of4-{(3~(N.2~Ac iyk ^~ ^P^^a ^^a y)^^ Acryiate (CyA)

Monomer. A suspension of N4-aceiyIcytosine (5.0 g₅ 0,03 ol), TEA (1.5 mL, 0.01 mol.}₅ BHT (0,6 g). and ! ,4-hutanediol diacrylaie (12 M L, 0.06 moi.) in DMSO ( 100 mL) was stirred at room temperature lor ^'24 h. Solution was poured into water (500 ml.) and washed with .hexane to remove excess 1 ,4-buta.oe iot diaerylatc. The water layer was extracted with dicWoromeihane (3 * 100 mL), The combined extracts were dried over gSO_¾ filtered, and concentrated in a vacuum evaporator to remove all the solvents. The evaporation, residue was purified using chromatography with CHC -MeOB (20:1 ) on silica gel. Cyiosme acryiate monomer was stored with solvent to prevent autopolytncrisatk upon drying. O erall yield was 53%, melting at 69,9- 723 °C.

|0041] S m-heste of 4f(3~{Nj~Aceiyigiimmi~9~yi}ppopa^ Acryl ie (QuA)

Monomer, A sus ension of guanine (20 g) and excess acetic anhydride (40 ml.) in N,N- dimetl Saceiamide (200 ml) was re!luxed until the solution turned clear. Reaction -mixture wa .filtered hot and cooled to room temperature. The precipitated: solid was iiltered and washed: it evhanol, yielding N2-seeiyigiranine, The same procedure s cylosme aeryiate synthesis was followed to produce guanine acrylate. Colum chromatography separated 9- and 7- isomers with a total 70% yield. Evaporation of einent yielded two while solids respectively. The 9-isomer^!s melting point is 145 ,7- 149.9 *€> 9- isomer was used throughout the polymer synthesis.

f0042] Sj ikesb qfNtici obase*Can(ami.ng Cop lym rs Poiy(GuA-a m¾A} and poly(CyA- co-rsBA) were- prepared using solution tree radical copoSymerizaiion in DMSO or N.N- dimeihyiibforamide (DMF) with Λ1.ΒΝ as . initiator, Typical synthesis was conducted as ib! lows. A round-bottomed flask, was charged with GuA, AIB (0 J mol¾), and DMF (20 wi%) and sparged with j ibr 20 min. The reaction roixttrre was stirred at 65 °C for 24 h. The solution was concentrated and precipitated in MeOH and water mixture. The precipitates were collected and dried under reduced pressure (22 rnmlig for 24 h. Ful l removal of solvent was confirmed by T N R.

fO043J Amfyticai M thods. II NMR and ^: 'C NMR spectra spectroscopy was performed on a Varian Unity 400 at 400 MHz in deuterated chloroform or DMSO. Size exclusion

chromatography (SEC) was performed using a Waters size exclusion chromatograph. T h instrument was equipped with an auto sampler, three 5 urn PLgel Mixed-C columns, a Waters 2410 refractive index (RI) detector operating at 880 mm a Wyatt Technologies rn.ini.DAWN muitwangle laser light scattering (MALLS) detector operating at 690 nm, and a Vlseotek 270 viscosity detector with a rlow rate of ! mLAnm at 50 °C in DMF with 0.05 M lithium bromide (UBrV Reported molecular weights are relative to polystyrene. Prior to SEC analysis, all polymers were analyzed by DLS to confirm no aggregation in the utilized SEC solvent. DSC was performed inder a nitrogen flush of 50 nd min at a heating rate οΠ Ο °C/mln on a TA instruments Q 1000 DSC, which was calibrated using indium (mp™ 156,60 ) and zinc (mp ~ 41 ,47 ^sCj standards. Glass transition temperatures were measured as the midpoint of the transition in the second heating ramp. Dynamic mechanical analysis (DMA) was conducted o a TA Insimments QSO0 Dynamic Mechanical Analyzer in tensio mode at a frequency of I ¾ an oscillatory amplitude of 15 urn, and a static force of 0. 1 R The temperature ramp was 3 ^'' J/min, Polymers were dissolved in CHCh MeOJ 1 mixture and cast into a Ί eflon® Petri dish, followed by slow evaporation of the solvent and drying the Elm In vacuo. Disposable 25 mm diameter aluminum parallel plates were used ibr rheometry. All measurements were strain- controlled at a constant nominal: strain value within, the linear viseoelastie range, determined with strain sweeps. Master curves were obtained iron.- temperature/frequency sweep measu eme ts using time-temperature superposition (TTS)_> which were described with the ilHams-Landel- Ferry equation. O^* curves were used as the reference curves for TTS,

[0045] We propose the synthesis and investigation of a wide variety of guanine and cytosine- contaimng monomers and polymers. These proposed giranine cytosine-containiag monomers provide facile synthesis to incorporate the nudeobase in an adhesive formulation, offering reversible eross nking sites to increase the apparent molecular weight and enhance mechanical strength. We can also time the ! (see Formula 1) spacer length between mieieoha.se motif to polymer backbone, which is critical far iniermoleetdar recognition. Fo each guanine/eytosine* containin m nomer, a wide variety of commercially available eomonomers can serve as the polymer matrix to maintain the tackiness and lower the cost. Currently, we e on die s nthesis and characterization oC gsianine/cyfosine acr !ate monomers with 1 ,.4-buisnediof spacer and acrylic copolymers for adhesives fabrication to examine structure--pn)peity relationships with nueleobase incorporation. Available comenomers tor reversible adhesive formulation include, but arc not limited to, s-butyl acrylate, 2-ethylhexyl acryiate, toe-oct i acryiate, methyl acryiate, methyl meihaerylatc, vinyl acetate, styrene, and 2-dwdroxy ethyl acryiate (Figure 1 ).

[0048} Among the four nueleohases in DN A structure, thymine and cytosine arc pyrini dincs: adenine and guanine are purines, Despite the structural similarity, their properties arc proven to be significant different comparing A to G; Tto ( Michael addition of excess diacrylate arid aceiyl-proteeted guanine and cytosine yielded cytosine and guanine-eontaimng acrylic monomers- Unlike adenine ami thymine, unprotected cytosine and guanine showed low reactivit in DMSO due to their lower solubility. Protection groups are preferred to achieve over 50 ¾ yield of the monomer synthesis. Protected guanine reacted with diacry late on both 7- and 9- position due to taatomerfoation (see Figure 2 for position labels for acetyl protected guanine). Surprisingly, crystallization of cytosine acrylic monomer required weeks compared to thymine acryiate's immediate crystallization daring solvent removal, which led to autopolymerlzaiion Issues. Conventional free radical co olymers zation of eytoslne guanine acryiate (CyA/GuA) and nBA afforded the synthesis of random copolymers with a series of different, mieleobase contents, homopolyo^e of cytosine acryiate, and homopelymer of f?-buty.l acryiate. With protection group, cytosine and guanine monomer still, showed lower solubility in organic solvent compare to their thymine and adenine analog. Λ DMF and DMSO mixture solvent with specific ratio was required to obtain a homogeneous polymerization solution with specific monomer feed ratio. olyOuA and poiyCyA homopoiymers were synthesize in DMSO. DMF SEC confirmed nucloohase-contairiing copolymers with hig molecular weights were achieved. Tabic 1 lists molecular weights of several copolymers ana poly«BA examples (relative to polystyrene standard ). We can Ume the nueieobase composition and .molecular weight of copolymer through varying the monomer feed ratio, initiator concentration, and solution concentration.

Table 1. Relative molecular weight to polystyrene standard of nucleohase-containing acrylics

Wi t

10 mo! CyA 62k !42k 2.29

2 mol% GnA 37k 84k 2.29

f¾04?J Polymer morphology and behavior changes significantly with increasing nueleobase content in a copolymer. Figure 8 shows pictures of cytosine-containmg polyscrylates wit 4 mol%, 15 raol , and 100 mol% eytosine incorporation. They were tacky liquid, free standing iii.ro, and brittle dust respectively. The glass transition temperature increased with more nueleobase content, which was attributed to additional chain mobility restriction from,

imermotecttiar and intramolecular physical erosslinkmg. Guanine-eontaimng polyacrylates showed a similar trend in Figure 0. Both homopolynrers exhibited higher glass transition temperature compared to their thymine and adenine analogs. PolyGuA T_a was 1 18 °C\ 50 °C higher than po!yfademne acrylaie); poiyCyA T^'s_, was < ? X 20 °C higher than polyithymine acryiate), Guanine and eytosine displayed enhanced ability to tune the copolymer properties with sower nueieobase content compared to their thymine and adenine analogs, Polyacrvlates gamed mechanical strength with nueieobase incorporation. Guanine and cytokine provided hydrogen bondin sites on. polymer side chains, which led to erossbnked networks and incre sed apparent molecular w ight.

[0048] Figure 1.0 shows the rheological characterisat on of guanine and eytosme co ol ers using time- temperate re superposition. The master curves of storage and loss modulus versus frequency for 8 mol% GuA polyaerylate, 1 1 rooi% CyA polyaerylate and homopolymer

polywBA were referenced to 25^C'C and overlaid. ^'N cieobasc-eontaining poiyaerylatea exhibited slower molecular dynamics compared to polyoBA, Nueieobase incorporation also contributed to higher shear modulus over the entire ireomency range tested. The master curves -demonstrate a marked improvement of cohesive strength upon Introduction of nueieobase into polyacryiates. |OO40| Isothermal theological experiments at 1 0 *C and thermal gravimetric analysis confirm the melt stability of GuA and CyA-containing acrylics, which, indicate their potential for hot melt adheshves iab icatioft (Figures 7 and 12), Figure 16 shows the thermodynamic

.mechanical, properties of solvent casted eytosme and guanme-coniaining polyacryiates films. Storage modulus of both polyacry iates exhibited one step decrease with increasing temperature, CyA polyaerylate displayed similar phase-mixing morphology to its thymine analogy resulting ^•from the relative small aromatic pyrimfdine ring, GuA acrylate^!s morphology, however_* differed from its adenine analog in spite of their similar purine ring.. Tan delta curves revealed broad glass transition resulting from the dynamic hydrogen bonding. The mechanical strength of Guanine and eytosine acrylics decreased gradually as temperature increased and a 99.00% loss of shear strength occurred below 65 ^fiC, Variable MR and PUR experiments in Figure 13- 15 show the thermally reversible nature of hydrogen bonding. Our results demonstrate the thermal responsiveness of hydrogen bonding-erosshnked aeryhcs tor thermally reversible adhesive applications.

Although certain, presently preferred embodiments of the invention have been specifically .descri e , herein, .t will be apparent to those skilled in the art to which the invention pertains that variations and modifications of the various embodiments shown and described herein may be made withou departing from the spirit and scope of the invention Accordingly, it is intended that tbc invention be limited only to the extent required by the appended claims and the applicable rules of law.

Claims

What is cla med is

Λ nueleoba&e-coniainlng m nomer having the structure of Formula I

Form la 3

wherein Y is a Y is m aeryloyh tnethacrykryh or a styrenic group; R.1 is an alky!ene a ing 1 to 18 carbons, or esters or ethers thereof; md B is eyiosine or guanine moiety or protected versions thereof

The m ome of claim I _;, wherein B lias ihe structure of Formula VII or V III

Formula VII Formula VIII

or protected Forms thereof.

The monomer of cl aim I , wherein B has ihe structure of Formula II or III

orju Formula lil

4, The monomer of cluim, j , having the sirii tur o f Fom la 1A

F rm la ΪΑ

wherein Bi is Formula II or

Formula III.

5. A copolymer comprising

a. the mscieobase-contakimg monomer of claim Ϊ ; and

b. a omonpmer having the structure of^'Formuia IV, V. VI, or corabmaisons thereof

F3

Formula V

wherein RJ is an alkyl having 1 to 16 carbons or alcohol or acids thereof; and R4 is hydrogen or n alkyl having 1 io 3 carbons;

Formula V

wherein R5 is an alkyl. having 1 io 1 2 carbons or alcohols or acids there f; and R6 is hydrogen or an alkyl having I to 3 carbons;

Formula V!

wherein R? is an alkylene having 0 to 3 carbons; each of :8 to RI 2 s independently hydrogen, a halogen, or an alkyl having 1 to 3 carbons; and R33 is hydrogen or an alky! having 1 to 3 carbons.

The copolymer of claim 5 , wherein B has the structure of Formula VII or VII !

Formula VH Formula VIE

protected forms thereof.

^'The copolymer of claim 5, wherein B has the structure of Formula H or J I

Formula If Formula

The^■ c l mer of claim 5, wherein She nucleobase monomer has ihe structure of Formula lA

wherein Bl is Formula II or III

^•o: inul orro s

9, The copolymer of claim 5, wherein the comonom^'er is o-b ty! aery late, n-hutyl :methacrykte, 2-eihylhexyl aery late, iso-octyl aery late, methyl acrylate, methyl methaoyiat vinyl acetate, styrsne. 2-hydroxy ethyl acrylaie_: or combinations thereof,

10 The copol me of claim 5, where n the eoraonomer is n~bu†yl aery l re, n~butyl rrsethacrylaie, or combinations thereo

] I . The copolymer of claim 5, where n the nudeobase monomer is present at about 0.1 -

12. The copolymer of claim S, wherein the eomonomer is present ai about O- 9. mo! %,

13. The copolymer of claim I , wherein, the copolymer is a .random copolymer or a block copolymer.

14. A. method tor makin an a hesive comprising the ste of coppolymenang the nueleoba3e--coniaining monomer of claim 1 , and a eom-onomer havin the struct re of Formula IV, V, V], or eombma!irrnx thereof

3

Formula IV

wherein R3 is an alkyl h&\½g. l to 16 carbons or alcohol or acids thereof; and R4 is hydrogen or an alkyl having I to 3 carbons;

Formula V

wherein R5 is an a!kyi having I io 1.2 carbons or alcohols or acids thereof; and R6 hydrogen or an alkyl having I to 3 carbons:

F rmula I

wherein IT? s an a!kylene having ϋ to 3 carbons; each of 118 to R12 is independently hydrogen, a halogen, or an alk l having ί to 3 carbons; a d 13 is hydrogen or an ailcyi having I to 3 carbons.

15, ^'The method of chu 14, wherein the copo!ymeri tag step occurs in a solvent and an initiator,

16, The method of claim 15, wherein the solvent is dimethyl sulfoxide (D O) ethyl acetate, methanol, isopropanol dioxane, or combinations he eof

17, The method of claim 1 5, wherein the initiator is azobislsobutyroniirhe (AIBN), 4,4*- A2ohis(4-cyanovaleric acid), and organic peroxides, or combinations thereof i 8, The method of claim 1 , wherein wherein copolymers are synthesized by reacting the monomer in presence of AIBN in DMSO at 60-70 °C under inert gas with constant stirring.

1 . The .method of claim 14_* wherein the nudeobase-eontai ng monomer has the structure

Of ΡΛΎ ϊά' )A

.formula 1A

wherein Bl Is Formul II or II

Formula 0 Formula Ilf,

20, The method of claim 1.4, h rein the comonomer s n-butyl acryiate, « -butyl meihacrylate, 2-ethyihex.yl aery te. iso-oeiyl acryiate, methyl acrytaie, methyl methacryiate, vinyl acetate_* styrene, 2 -hydroxy ethyl acfy!ate, or combinations thereof

21. An adhesive comprising the copolymer of claim.5,

The adhesive of caim 21, wherein. B has the structure of Formula VII or VI !

Formula VII

or protected, forms thereof

2.3. The adhesive ofdaim 21. wherein B has the structure of Formula II or II S

24. The d esive of clam 21, wherein the nucleobase monomer has the structure of F rmal

wherein Bl is Formula fi or 111

Formula 1 ! 'ormu!a III,

25, The adhesive of claim 1, wherein the comonomer is n~hu£y1 actylate, sv^'bmyl methacrykte, 2-ehyIhcxyi acry ie, iso-octyl actylate, methyl aerylate, methyl methacrylate. vinyl acetate, st rene,, 2-hydroxy ethyl acry ie, or mmbinai ns thereof,

26. The adhesive of claim 21, wherein the eomoiiomer is n-butyl aery late, n-buty).

methaerylate, or combinations thereof. 27, The adhesi ve of claim 21 , wherein the rmdeobase monomer is present at abcrui 0. i -20 mo I %.

28, The adhesive of claim 2 i , where n the eomoixsrner present ai about 80-99.9 mol %.

29, The adhesive of claim 21 , wherein the copolymer is a random copolymer or a block copolymer.