POLYMERS

Abstract

A method of preparing a polymer comprises the use of free radical vinyl polymerisation to form carbon-carbon backbone segments of the polymer, wherein the longest chains in the polymer comprise vinyl polymer chains interspersed with other chemical groups and/or chains. The product has the characteristics of a step-growth polymer comprising a mixture of polyfunctional step-growth monomer residues formed by vinyl polymerization.

Claims

1. A method of preparing a polymer comprising the use of free radical vinyl polymerisation to form carbon-carbon backbone segments of the polymer, wherein the longest chains in the polymer comprise vinyl polymer chains interspersed with other chemical groups and/or chains.

2. A method of preparing a polymer comprising the use of free radical vinyl polymerisation to form carbon-carbon segments of step-growth monomer residues.

3. A method as claimed in claim 1 wherein the polymer is a branched polymer and wherein the branch points are in the vinyl polymer chains.

4. A method as claimed in claim 1 comprising the free radical polymerisation of one or more multivinyl monomers.

5. A method as claimed in claim 1 comprising the free radical polymerisation of one or more divinyl monomers.

6. A method as claimed in claim 2 wherein the polymer is a polyester.

7. A method as claimed in claim 6 comprising the free radical polymerization of one or more of a multiacrylate, multimethacrylate or multivinyl multiester, diacrylate, dimethacrylate or divinyl diester.

8. (canceled)

9. A method as claimed in claim 2 wherein the polymer is a polyamide.

10. A method as claimed in claim 9 comprising the free radical polymerization of one or more of a multiacrylamide, multimethacrylamide or multivinyl multiamide, bisacrylamide, bismethacrylamide or divinyl diamide.

11. (canceled)

12. A method as claimed in claim 2 wherein the polymer is a phenylene-containing polymer.

13. A method as claimed in claim 12 comprising the free radical polymerization of one or more multivinylbenzene or divinylbenzene.

14. (canceled)

15. A method as claimed in claim 2 wherein the polymer is a polycarbonate.

16. A method as claimed in claim 15 wherein the multivinyl monomer e.g. divinyl monomer contains one or two carbonate groups between the double bonds.

17. A method as claimed in claim 1 comprising the incorporation of a divinyl monomer and a lesser amount of monovinyl monomer.

18. A method as claimed in claim 1 comprising the incorporation of not only one or more multivinyl monomers but also monovinyl monomers, wherein 10% or more of the vinyl monomers used are multivinyl monomers.

19. A method as claimed in claim 1 comprising the incorporation of a plurality of divinyl monomers.

20. A method as claimed in claim 1 comprising the incorporation of trivinyl monomers and divinyl monomers and/or monovinyl monomers.

21. A polymer obtained by the method of claim 2.

22. (canceled)

23. A branched polymer comprising vinyl polymer chains wherein the vinyl polymer chains comprise residues of vinyl groups of multivinyl monomers, and wherein the longest chains in the polymer are not the vinyl polymer chains but rather extend through the linkages between double bonds of the multivinyl monomers.

24. A step-growth polymer comprising a mixture of polyfunctional step-growth monomer residues formed by vinyl polymerization.

Description

DESCRIPTION OF THE DRAWINGS

[0190] The present invention will now be described in further non-limiting detail and with reference to the drawings in which:

[0191] FIGS. 1 and 2 show free radical mechanisms involved in one embodiment of the present invention;

[0192] FIGS. 3 and 4 show schematic representations of a branched polymer in accordance with one embodiment of the present invention;

[0193] FIG. 5 shows NMR spectra at different stages during the polymerization process in accordance with one embodiment of the present invention;

[0194] FIG. 6 shows examples of some compounds which may be used as divinyl monomers in the present invention;

[0195] FIG. 7 shows examples of some compounds which may be used as chain transfer agents in the present invention;

[0196] FIG. 8 shows a further schematic representation of a branched polymer in accordance with the present invention, highlighting the vinyl polymer chain lengths within the product;

[0197] FIG. 9 shows a mass spectrum of components of a polymer in accordance with an embodiment of the present invention;

[0198] FIG. 10 shows a mass spectrum of polymer species comparative to those of FIG. 9;

[0199] FIG. 11 highlights a polyester chain within a polymer product in accordance with an embodiment of the present invention, and indicates theoretical step-growth synthetic equivalent monomers;

[0200] FIGS. 12 to 16 show NMR spectra of some branched polymer products prepared using trivinyl monomers amongst other reagents; and

[0201] FIG. 17 shows a generic representation of components of a divinyl monomer and a fragment of a polymer of the present invention.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

[0202] With reference to FIG. 1, radical activity is transferred to a chain transfer agent such as dodecanethiol, by reaction with a radical derived from an initiator such as AIBN, or by reaction with a radical derived from a divinyl monomer (e.g. from EGDMA) which has previously reacted with a source of radicals. This results in a chain transfer agent radical [CH.sub.3(CH.sub.2).sub.11S. in FIG. 1] which (FIG. 2) reacts with divinyl monomer in the present invention and results in propagation of the chain.

[0203] A schematic representation of the resultant branched polymer is shown in FIGS. 3 and 4. Where DDT is used as the chain transfer agent the circle represents a moiety which comprises a dodecyl chain. Although the polymer is built up by vinyl polymerisation, nevertheless the chemistry of the longest chains in the product is determined by the other functional groups present in the divinyl monomer, and accordingly in some embodiments the longest chains may be polyesters.

[0204] One advantage of the present invention is that the vinyl functionality of the monomers can react completely. Experimental proof of this has been obtained by NMR analysis: in FIG. 5, the top NMR spectrum, in respect of a sample at the start of the reaction, shoes .sup.1H NMR due to the presence of double bond hydrogens. After reaction, the NMR trace (bottom) shows no detectable double bond signals.

[0205] FIG. 8 shows a branched polymer made from the divinyl monomer EGDMA and chain transfer agent DDT (shown as spheres). Thick lines indicate the CC bonds which were double bonds in the monomer. The numerals indicate the vinyl polymer chain lengths. It can be seen that there are 13 chains of length 1, five chains of length 2, six chains of length 3, one chain of length 4 and one chain of length 5.

[0206] The product shown in FIG. 8 is consistent with the discussion above which refers to some standard systems having (n+1) chain transfer agent residues per n divinyl monomer residues, and average vinyl polymer chain lengths of 2n/(n+1). The ratio of chain transfer residues to divinyl monomer residues is 26:25 i.e. (n+1):n, such that the number of chain transfer residues per divinyl monomer residue is 26/25=1.04.

[0207] The average polymer chain length is [(113)+(25)+(36)+(41)+(51)]/(13+5+6+1+1)=50/26=1.923 i.e. 2n/(n+1). All vinyl groups have reacted, i.e. the conversion is 100%. Each vinyl residue is directly vinyl polymerised to on average 48/50=0.96 other divinyl monomer residues.

[0208] The step-growth monomer residues formed by vinyl polymerisation in the present invention, would, if formed by analogous step-growth polymerisation, be derived from a mixture of synthetic equivalents (see FIG. 11) including some polyfunctional (at least trifunctional) synthetic equivalents (e.g. polyacids or polyols) in order to form a branched architecture. This would correspond to a step-growth system of A.sub.n+B.sub.m monomers where at least one of n or m is greater than 2 and the other is 2 or greater, e.g. a system of A.sub.2+B.sub.3 monomers or A.sub.3+B.sub.2 monomers. Such a system would be synthetically complex, stoichiometrically challenging, and beset with other difficulties including issues of gelation.

Example 1EGDMA as Divinyl Monomer and DDT as Chain Transfer Agent

[0209] Thus, in one embodiment, the divinyl monomer is EGDMA, the chain transfer agent is DDT, and a small amount of AIBN is used to provide a source of radicals. The reaction may be carried out in toluene, or other solvents.

[0210] Different ratios of chain transfer agent to divinyl monomer were investigated. A summary of the results is shown in the following table.

[0211] EGDMAMonomer

[0212] DDTCTA

[0213] AIBNThermal initiator

[0214] TolueneSolvent (wt. 50%)

Standard Conditions:

[0215] Oil bath at 70 C. [0216] Reaction time24 hrs [0217] Mass of AIBN was based on 1.5% mol of double bonds in monomer

TABLE-US-00009 Number of repeat units EGDMA:DDT per EGDMA DDT in final object (mol (mol Gel polymer Vinyl Mw Mn based on eq.) eq.) formation product.sup.a conversion.sup.a (kg/mol).sup.b (kg/mol).sup.b a.sup.d Mw 1 0.5 Yes 1 1 Yes 1 2 No 1:1 >99% 26.6 8.8 3.02 0.28 66 1 2 No 1:1 >99% 19.4 5.35 3.6 0.234 48 1 1.33 No 1:0.95 >99% 144.0 12.7 11.4 0.3 360 1.sup.c 1.33.sup.c No.sup.c 1:1.05.sup.c >99%.sup.c 157.4 4.4 35.6 0.287 393 1.sup.e 1.33.sup.e No.sup.e 1:1.sup.e >99%.sup.e 228.55.sup.e 2.83.sup.e 80.84.sup.e 0.339.sup.e 570.sup.e 1 1.25 No 1:1 >99% 216.86 10.19 21.27 0.299 541 1 1.11 No 1:1.05 >99% 3,484.0 52.96 65.79 0.368 8,700 .sup.adetermined by .sup.1H NMR (400 MHz) in CDCl.sub.3. .sup.bdetermined by triple detection GPC .sup.cscale-up reaction (3 time the previous scale) .sup.dMark-Houwink parameter: [] = KM.sup.a .sup.eReaction carried out in ethyl acetate at 50 wt % solid content

[0218] From these results it can be seen that, for these reagents, gelation can be avoided by the use of more equivalents of the chain transfer agent DDT than the brancher EGDMA, and that the final product contains about the same amount of chain transfer agent as brancher.

[0219] It can also be seen that changing the amount of chain transfer agent can affect the degree of polymerisation. For example, if just enough chain transfer agent is used to avoid gelation, a high molecular weight product can be obtained. The skilled person is able to tailor the product accordingly.

Experimental (for Approximately a 5 g Scale Reaction)

[0220] In a typical experiment, 55.9 mg of AIBN (0.3406 mmol, 1.5% vs. double bonds) were placed in a single neck 25 mL round bottomed flask. EGDMA (2.14 mL, 11.352 mmol, 0.75 eq), DDT (3.62 mL, 15.13 mmol, 1 eq) and Toluene (6.14 mL, 50 wt % vs. EGDMA and DDT) were added to the reactor and the mixture was purged by argon sparge for 15 minutes under stirring. The reactor was then placed in a preheated oil-bath at 70 C. for up to 24 hours. The resulting crude material was analysed by .sup.1H NMR and showed no evidence of remaining double bonds after 2.5 hours. Further purification of the product was performed by evaporating the toluene on a rotary evaporator, dissolving the resulting mixture in THF and precipitating in methanol at room temperature (THF:methanol=1:10 v/v). The resulting white precipitate was isolated and dried under vacuum at 40 C. (yield 85%).

Example 2EGDMA as Divinyl Monomer and Benzyl Mercaptan as Chain Transfer Agent

[0221]

TABLE-US-00010 EGDMA:benzyl Benzyl mercaptan in Vinyl Mw Mn EGDMA Mercaptan Gel final polymer Con- (kg/ (kg/ (mol %) (mol %) formation product.sup.a version.sup.a mol).sup.b mol).sup.b a.sup.d 1 1 Yes 1 0.5 Yes l.sup.c 2.sup.c No.sup.c 1:1.1.sup.c 100%.sup.c 16.9.sup.c 3.1.sup.c 5.5.sup.c 0.288.sup.c 1 1.33 Yes 1 2 No 1:1.02 100% Details as Example 1, except: .sup.cReacted for 72 hours Purification by precipitation was carried out using THF and ethanol at 0 C. to produce a white precipitate.

Example 3EGDMA as Divinyl Monomer and 2-Naphthalenethiol as Chain Transfer Agent

[0222]

TABLE-US-00011 2- EGDMA: 2- Naphthalene- Gel Reaction naphthalenethiol EGDMA thiol form- Time Vinyl in final polymer (mol %) (mol %) ation (hrs) conversion product 2 1 Yes 1 1 1 No 24 Unable to Unable to determine.sup.a determine.sup.a 1 1 No 48 Unable to Unable to determine.sup.a determine.sup.a Details as Example 1 except: .sup.aUnable to analyse as it seems to be immiscible in chosen solvents: CDCl.sub.3, toluene and CDCl.sub.3, DMF and THF.

Example 4EGDMA as Divinyl Monomer and a Dendron Thiol as Chain Transfer Agent

[0223] ##STR00001##

TABLE-US-00012 G1- DBOP EGDMA:DBOP EGDMA Thiol in final Mw Mn (mol (mol Gel polymer Vinyl (kg/ (kg/ %) %) formation product.sup.a conversion.sup.a mol).sup.b mol).sup.b .sup.d 1 2.5 No 1:1 86% 6.7 3.1 2.15 0.168 Details as Example 1.

Example 5PEGDMA (Approximately 875 g Mol.SUP.1.) as Monomer

[0224]

TABLE-US-00013 No. of repeat PEG- PEGDMA:DDT units per dimeth- Gel in final Vinyl Mw Mn object acrylate DDT for- polymer con- (kg/ (kg/ based (mol %) (mol %) mation product.sup.a version.sup.a mol).sup.b mol).sup.b a.sup.c on Mw 1 2 Yes 1 1.33 Yes 1 4 No 1:1.2 >99% 22.6 6.4 3.55 21 1 4 No 1:1.1 >99% 1 3.33 No 1:1.1 >99% 1 2.89 No 1:1.1 >99% 54.7 4.7 11.6 51 1 2.5 No 1:1.1 >99% 2,200 61 36.5 2037 M.sub.R.U. 1080 g/mol Details as Example 1 except: .sup.cMark-Houwink parameter: [] = KM.sup.a

Example 6PEGDMA (Approximately 3350 g Mol.SUP.1.) as Divinyl Monomer and DDT as Chain Transfer Agent

[0225]

TABLE-US-00014 No. of repeat PEG- PEGDMA:DDT units per dimeth- Gel in final Vinyl Mw Mn object acrylate DDT for- polymer con- (kg/ (kg/ based (mol %) (mol %) mation product.sup.a version.sup.a mol).sup.b mol).sup.b a.sup.c on Mw 1 1 Yes 1 4 No 1:1.3 100% 93.6 8.8 10.6 26 1 2.5 No 1:1.3 >99% 103.8 7.7 13.4 29 1 2 No 1:1.1 100% 106.7 9.5 11.2 30 Details as Example 5 except: M.sub.R.U. 33500 g/mol

Examples 7 and 8Polymerisations of EGDMA with DDT, or PEGDMA (Mw 875) with DDT, at a Higher Temperature

[0226]

TABLE-US-00015 EGDMA:DDT in final EGDMA DDT Gel polymer Vinyl Mw Mn (mol %) (mol %) formation product.sup.a conversion.sup.a (kg/mol).sup.b (kg/mol).sup.b a.sup.d 1 1 Yes 1 1.33 No 1:1 >99% PEGDMA:DDT PEG- in final dimethacrylate DDT Gel polymer Vinyl Mw Mn (mol %) (mol %) formation product.sup.a conversion.sup.a (kg/mol).sup.b (kg/moI).sup.b a.sup.d 1 2 Yes 1 2.5 No 1:1.1 >99% 1,600 28.9 55.3
Details as Examples 1 and 5 except:
Oil bath at 85 C. rather than 70 C.

Example 9: Divinyl Benzene as Divinyl Monomer and DDT as Chain Transfer Agent

Experimental

[0227] In a typical experiment, 75.7 mg of AIBN (0.4608 mmol, 1.5% vs. double bonds) were placed in a single neck 25 mL round bottomed flask. DVB (2.19 mL, 15.36 mmol, 1 eq), DDT (3.68 mL, 15.36 mmol, 1 eq) and Toluene (5.91 mL, 50 wt % vs. DVB and DDT) were added to the reactor and the mixture was purged by argon sparge for 15 minutes under stirring. The reactor was then placed in a preheated oil-bath at 70 C. for up to 24 hours. Further purification of the product was performed by evaporating the toluene on a rotary evaporator, dissolving the resulting mixture in THF and precipitating in methanol at room temperature (THF:methanol=1:10 v:v).

TABLE-US-00016 DVB:CTA in final DVB DDT Solid Gel polymer Vinyl Mw Mn (eq.) (eq.) content Formation product.sup.a conversion.sup.a (kg/mol).sup.b (kg/mol).sup.b .sup.b .sup.c 1 1 50 wt % No 0.92:1.0 99% 69.8 1.5 45.2 0.263 1 2 50 wt % No 0.57:1.0 >99% 1.02 0.8 1.24 0.643 1 1 70 wt % Yes 1 1 60 wt % Yes 1 1 55 wt % No 0.86:1 99% 113.4 2 56.7 0.26 .sup.adetermined by .sup.1H NMR (400 MHz) in CDCl.sub.3. .sup.bdetermined by triple detection GPC .sup.cMark-Houwink parameter: [] = KM.sup.a

Example 10: Divinylbenzene as Divinyl Monomer and Benzyl Mercaptan as Chain Transfer Agent

Experimental

[0228] In a typical experiment, 18.9 mg of AIBN (0.1152 mmol, 1.5% vs. double bonds) were placed in a single neck 25 mL round bottomed flask. DVB (1.094 mL, 7.68 mmol, 0.5 eq), benzyl mercaptan (1.803 mL, 15.36 mmol, 1 eq) and Toluene (3.364 mL, 50 wt % vs. DVB and benzyl mercaptan) were added to the reactor and the mixture was purged by argon sparge for 15 minutes under stirring. The reactor was then placed in a preheated oil-bath at 70 C. for up to 24 hours. Further purification of the product was performed by evaporating the toluene on a rotary evaporator, dissolving the resulting mixture in THF and precipitating in methanol at room temperature (THF:methanol=1:10 v:v).

TABLE-US-00017 Benzyl DVB:CTA in DVB mercaptan Gel final polymer Vinyl Mw Mn (eq.) (eq.) Formation product.sup.a conversion.sup.a (kg/mol).sup.b (kg/mol).sup.b .sup.b .sup.c 1 1 Yes 1 2 No 99% 0.6 0.5 1.2 1.2 1 1.33 No 99% 3.63 0.78 4.652 0.194 1 1.25 No 99% 6.175 0.71 8.72 0.171 1 1.11 No 99% 28.7 0.91 31.65 0.209 .sup.adetermined by .sup.1H NMR (400 MHz) in CDCl.sub.3. .sup.bdetermined by triple detection GPC .sup.cMark-Houwink parameter: [] = KM.sup.a

Example 11: Bisacrylamide as Divinyl Monomer and Thioglycerol as Chain Transfer Agent

Experimental

[0229] In a typical experiment, 16.0 mg of AIBN (0.0973 mmol, 1.5% vs. double bonds) were placed in a single neck 10 mL round bottomed flask. Bisacrylamide (0.5 g, 3.243 mmol, 0.5 eq), thioglycerol (TG; 0.56 mL, 6.5 mmol, 1 eq) and ethanol (1.49 mL, 50 wt % vs. bisacrylamide and TG) were added to the reactor and the mixture was purged by argon sparge for 15 minutes under stirring. The reactor was then placed in a preheated oil-bath at 70 C. for up to 24 hours. The product was obtained by removing the ethanol on a rotary evaporator.

TABLE-US-00018 Bisacryl- amide:CTA Bisacryl- 1- in final Vinyl Mn amide Thioglycerol Gel polymer conver- Mw (kg/ (eq.) (eq.) Formation product.sup.a sion.sup.a (kg/mol).sup.b mol).sup.b .sup.b .sup.c 1 2 No 1.6 1.3 1.23 .sup.adetermined by .sup.1H NMR (400 MHz) in CDCl.sub.3. .sup.bdetermined by triple detection GPC .sup.cMark-Houwink parameter: [] = KM.sup.a

Example 12: PEGDMA (875 g/Mol) as Divinyl Monomer and Thioglycerol as Chain Transfer Agent

Experimental

[0230] In a typical experiment, 19.3 mg of 4, 4-azobis(4-cyanovaleric acid) (ACVA; 0.0687 mmol, 1.5% vs. double bonds) were placed in a single neck 10 mL round bottomed flask. PEGDMA (2 g, 2.29 mmol, 1 eq), 1-thioglycerol (TG; 0.824 g, 7.62 mmol, 3.33 eq) and anhydrous ethanol (3.58 mL, 50 wt % vs. PEGDMA and TG) were added to the reactor and the mixture was purged by argon sparge for 15 minutes under stirring. The reactor was then placed in a preheated oil-bath at 70 C. for up to 24 hours. Further purification of the product was performed by concentrating on a rotary evaporator and precipitating in hexane at room temperature.

TABLE-US-00019 PEGDMA:TG in final Vinyl Mw Mn PEGDMA TG Gel polymer con- (kg/ (kg/ (eq.) (eq.) Formation product.sup.a version.sup.a mol).sup.b mol).sup.b .sup.b .sup.c 1 5 No 1:2.5 >99% 10.2 0.1 98.4 / 1 3.33 No 1:1.75 >99% 415.3 6.05 68.65 / 1 2.5 Yes All reaction performed in ethanol at 50 wt % .sup.adetermined by .sup.1H NMR (400 MHz) in CDCl.sub.3. .sup.bdetermined by triple detection GPC .sup.cMark-Houwink parameter: [] = KM.sup.a

Example 13: PEGDMA (875 g/Mol) as Divinyl Monomer with Mixed Chain Transfer Agents (DDT and Thiolglycerol)

Experimental

[0231] In a typical experiment, 11.3 mg of AIBN (0.0686 mmol, 1.5% vs. double bonds) were placed in a single neck 25 mL round bottomed flask. PEGDMA (2 g, 2.76 mmol, 1 eq), DDT (0.578 g, 2.86 mmol, 1.25 eq), 1-thioglycerol (TG; 0.309 g, 2.86 mmol, 1.25 eq) and toluene (8.34 mL, 50 wt % vs. PEGDMA, TG and DDT) were added to the reactor and the mixture was purged by argon sparge for 15 minutes under stirring. The reactor was then placed in a preheated oil-bath at 70 C. for up to 24 hours. Further purification of the product was performed by evaporating the toluene on a rotary evaporator, dissolving the resulting mixture in chloroform and precipitating in petroleum ether at 0 C. (CHCl.sub.3:petroleum ether=1:10 v:v).

TABLE-US-00020 % of % of 1- DDT in Thio- Gel final glycerol For- poly- in final Vinyl Mw Mn Brancher DDT TG ma- mer polymer conver- (kg/ (kg/ (eq.) (eq.) (eq.) tion product.sup.a product.sup.a sion.sup.a mol).sup.b mol).sup.b .sup.b .sup.c 1 1.25 1.25 No 26 74 >99% 76.12 3.2 23.6 / 1 1.25 1.25 No 24 76 >99% 9.3 0.51 18.19 / 1 1.875 0.625 No 51 49 >99% 28.25 2.45 11.55 / 1 1.5 1 No 32 68 >99% 131 3.82 34.4 / 1 1.25 1.25 No 30 70 >99% 1,040 11.8 88.3 0.462 1 1.5 1 No 37 63 >99% 395 2.73 144 0.392 1 1.875 0.625 No 55 45 >99% 348 7.46 46.6 0.381 1 1.75 0.75 No 50 50 >99% 964 19.3 50 0.473 .sup.adetermined by .sup.1H NMR (400 MHz) in CDCl.sub.3. .sup.bdetermined by triple detection GPC .sup.cMark-Houwink parameter: [] = KM.sup.a

Example 14: Incorporation of a Monovinyl Monomer (Benzyl Methacrylate) into the System (EGDMA as Divinyl Monomer and DDT as Chain Transfer Agent)

Experimental

[0232] In a typical experiment, 49.7 mg of AIBN (0.303 mmol, 1.5% vs. EGDMA double bonds) were placed in a single neck 25 mL round bottomed flask. EGDMA (1.903 mL, 10.09 mmol, 0.75 eq), Benzyl methacrylate (BzMA; 0.456 mL, 2.691 mmol, 0.2 eq), DDT (3.222 mL, 13.453 mmol, 1 eq) and toluene (6 mL, 50 wt % vs. EGDMA, BzMA and DDT) were added to the reactor and the mixture was purged by argon sparge for 15 minutes under stirring. The reactor was then placed in a preheated oil-bath at 70 C. for up to 24 hours. Further purification of the product was performed by evaporating the toluene on a rotary evaporator, dissolving the resulting mixture in THF and precipitating in methanol at room temperature (THF:methanol=1:10 v:v).

TABLE-US-00021 Brancher:MonoVM:CTA Gel in Vinyl Mw Mn EGDMA BzMA DDT For- purified con- (kg/ (kg/ (eq.) (eq.) (eq.) mation product.sup.a version.sup.a mol).sup.b mol).sup.b .sup.b .sup.c 1 0.267 1.33 No 1:0.2:1 >99% 94.1 10.6 8.9 0.275 .sup.adetermined by .sup.1H NMR (400 MHz) in CDCl.sub.3. .sup.bdetermined by triple detection GPC .sup.cMark-Houwink parameter: [] = KM.sup.a

Example 15: BDME as Stimuli-Responsive (Acid-Cleavable) Divinyl Monomer and DDT as Chain Transfer Agent

Experimental

[0233] In a typical experiment, 26.7 mg of AIBN (0.163 mmol, 1.5% vs. double bonds) were placed in a single neck 10 mL round bottomed flask. BDME (1.71 g, 5.44 mmol, 1 eq), DDT (1.47 g, 7.29 mmol, 1.33 eq) and toluene (3.69 mL, 50 wt % vs. BDME and DDT) were added to the reactor and the mixture was purged by argon sparge for 15 minutes under stirring. The reactor was then placed in a preheated oil-bath at 70 C. for up to 24 hours. Further purification of the product was performed by evaporating the toluene on a rotary evaporator, dissolving the resulting mixture in THF and precipitating in ethanol at 0 C. (THF:ethanol=1:10 v:v).

TABLE-US-00022 BDME:DDT in final BDME DDT Gel polymer Vinyl Mw Mn (eq.) (eq.) Formation product.sup.a conversion.sup.a (kg/mol).sup.b (kg/mol).sup.b .sup.b .sup.c 1 1.33 No 0.99:1 >99% 20.5 7.4 2.76 0.341 .sup.adetermined by .sup.1H NMR (400 MHz) in CDCl.sub.3. .sup.bdetermined by triple detection GPC .sup.cMark-Houwink parameter: [] = KM.sup.a

Example 16Experiments, Using Degradable Monomers, to Help Elucidate the Polymerisation Mechanisms and Structures within the Products

[0234] To establish the mechanistic basis of the polymerisation/telomerisation, two reactions were conducted under near-identical conditions. The first utilised an acid sensitive divinyl monomerBDMEas in Example 15 above and shown in FIG. 9. The resulting polymer was then treated with acid to cleave all of the diacetal units within what could conventionally be termed a step-growth polymer backbone and yield a distribution of vinyl oligomers that are representative of the free radical telomerisation during the synthesis. The acid degradation was achieved as follows:

[0235] THF (9 mL) was added to 1 mL of the crude product (before purification) of the reaction described above. Then, trifluoroacetic acid (TFA; 10 L, 2 eq vs BDME) was added to the solution and stirred for 72 hours at room temperature. Basic alumina (2 g) was added to the reaction mixture followed by filtration with a 200 nm syringe filter. The solvent was evaporated on a rotary evaporator and the resulting product was analysed by GPC and MALDI-TOF mass spectroscopy.

[0236] The GPC analysis showed very low molecular weight species that were difficult to study using the available analytical instrument. In order to generate accurate analytical data, the sample was subjected to MALDI-TOF mass spectrometry, yielding the mass spectrum shown in FIG. 9.

[0237] The species present are polymethacrylic acid oligomers and telomers with a single CTA at one end of the chain and are generated during the cleavage as follows:

##STR00002##

[0238] The MALDI-TOF spectrum (negative ion) clearly indicates that a distribution of telomers and oligomers are present with a chain length of up to 18 units. These correspond to polyacid monomer residues within the branched polyacetal structure. MALDI-TOF and other mass spectrometry techniques are well known to not fully represent the concentration of the different species present within the analysis sample and the purification of the sample will have disproportionately removed different species within the mixture. For example, the units relating to reaction of the CTA radical with a single vinyl group (n=1) are not readily observable. Additional signals are present due to oxidation of thio-ethers resulting from the presence of the CTA within the distribution of species. This is as expected by those skilled in the art.

[0239] The type of structures present in such systems would be impossible to replicate using step growth polymerisation methods. In this case, polycondensation of polyacid mixtures and ethylene glycol would likely lead to gelation at low conversions due to the components being so highly functional (e.g. 18-acid functional) To compare with conventional free radical polymerisation conditions, a model reaction using a mono-vinyl monomer (methyl methacrylateMMA) was conducted as follows, strongly replicating the BDME conditions but in the absence of divinyl monomer.

[0240] Methyl methacrylate (2.27 g, 22.7 mmol, 1 eq) was purged with nitrogen for 15 minutes. 1-Dodecanethiol (3.06 g, 15.13 mmol, 1.33 eq), AIBN (0.0559 g, 0.341 mmol) and toluene (6.16 mL) were added to the 25 mL round-bottomed flask and purged with nitrogen for 5 minutes. The reaction flask was heated in an oil bath at 70 C. and stirred for 24 hours and then cooled. The reaction mixture was concentrated by rotary evaporation and the resulting product was analysed by GPC and MALDI-TOF mass spectroscopy.

[0241] The MALDI-TOF mass spectrum (positive ion-sodium adducts comprise the main distribution) of this product is seen in FIG. 10.

[0242] As can be readily seen, the telomerisation/oligomerisation of MMA under identical conditions generates a near identical distribution of identifiable species. Structures up to 18 monomer units are seen through the free radical polymerisation of MMA under these conditions and such species were seen in the homopolymerisation of the divinyl monomer BDME.

Example 17Reactions Using Trivinyl Monomer TMPTMA

Experimental (for Approximately a 5 g Scale Reaction)

[0243] In a typical experiment, 43.7 mg of AIBN (0.266 mmol, 1.5% vs. double bonds) were placed in a single neck 25 mL round bottomed flask. Trimethylolpropane trimethacrylate (TMPTMA) (1.887 mL, 5.91 mmol, 0.4 eq), DDT (3.539 mL, 14.78 mmol, 1 eq) and Toluene (5.769 mL, 50 wt % vs. TMPTMA and DDT) were added to the reactor and the mixture was purged by nitrogen sparge for 15 minutes under stirring. The reactor was then placed in a preheated oil-bath at 70 C. for up to 24 hours. The resulting crude material was analysed by .sup.1H NMR and showed no evidence of remaining double bonds after 24 hours. Further purification of the product was performed by evaporating the toluene on a rotary evaporator, dissolving the resulting mixture in THF and precipitating in methanol (MeOH) at room temperature. The product was collected by removing the supernatant and was rinsed with fresh MeOH. Finally, the resulting polymer was dried under vacuum at 40 C. for 12 hours. After purification, the polymer was collected with a yield of 73% (m.sub.polymer/m.sub.DDT+TMPTMA). The purified product was further analysed by GPC and .sup.1H NMR.

[0244] Trivinyl monomer was homopolymerized, and was also copolymerised with divinyl monomer and with monovinyl monomer. It was possible to incorporate various functionalities e.g. tertiary amine functionality and epoxy functionality, thereby facilitating further reaction possibilities.

DEAEMA: 2-(diethylamino)ethyl methacrylate
GlyMA: Glycidyl methacrylate

[0245] The ratios in the first column indicate the relative molar amounts of reagents used in the reaction.

[0246] Proton NMR spectra of some of the products are shown in FIGS. 12 to 16:

[0247] FIG. 12homopolymerisation of trivinyl monomer;

[0248] FIG. 13polymerisation of trivinyl monomer with epoxy-functional monovinyl monomer;

[0249] FIG. 14polymerisation of trivinyl monomer with tertiary amine-functional monovinyl monomer;

[0250] FIG. 15comparison of spectra of FIGS. 12 and 13;

[0251] FIG. 16comparison of spectra of FIGS. 13 and 14.

TABLE-US-00023 NMR Mw Mn MH conv. (kg/mol) (kg/mol) Trivinyl monomer [DDT]:[TMPTMA] 4:1 >99% 9.76 1.86 5.24 0.179 3:1 >99% 20.04 1.53 13.07 0.261 2.5:1 >99% 239.90 4.04 59.34 0.313 2:1 >99% 1,080 15.22 70.97 0.332 Trivinyl + divinyl monomer [DDT]:[TMPTMA]: [EGDMA] 5:1:0.5 >99% 11.08 0.97 11.48 0.254 5:1:1 >99% 25.15 1.21 20.79 0.177 5:1:1.5 >99% 93.14 3.34 27.89 0.297 5:1:2 >99% 279.22 6.49 43.00 0.318 Trivinyl + monovinyl monomer [DDT]:[TMPTMA]: [BzMA] 2.2:1:0.1 >99% 428.83 7.12 60.24 0.308 2.2:1:0.45 >99% 417.23 8.34 50.04 0.332 Trivinyl + monovinyl monomer [DDT]:[TMPTMA]: [BzMA] 2:1:0.6 >99% 1,347 20.92 64.41 0.324 2:1:1 >99% 726.14 18.61 39.01 0.311 Trivinyl + monovinyl monomer (tertiary amine functionality) [DDT]:[TMPTMA]: [DEAEMA] 2:1:0.15 >99% 682.43 17.35 39.32 0.305 2:1:0.6 >99% 560.65 62.91 8.91 0.322 2:1:0.8 >99% 228.63 31.37 7.29 0.319 Trivinyl + monovinyl monomer (epoxy functionality) [DDT]:[TMPTMA]: [GlyMA] 2:1:0.2 >99% 3,168 1,518 2.088 0.538 2:1:0.8 >99% 978.4 416.3 2.35 0.43 2:1:1 >99% 810.9 291.9 2.778 0.428

Example 18

[0252] The polymer products can have various properties depending on the functional groups within the monomers and other components. For example, degradable, biodegradable, compostable or responsive properties can be incorporated.

[0253] By way of example, FIG. 17 shows schematically a divinyl monomer and a fragment of a polymer made from it. In this divinyl monomer, A and L could be any substituent, E and J could be any linker (e.g. an ester), and G could be additional linking chemistry (of course there could just be one linking moiety). M denotes CTA, T initiator fragment and Q and X terminating groups from chain transfer. Degradable components could be introduced via for example E, J or G, or alternatively or additionally M or Q.

[0254] Accordingly, the products of the present invention may be biodegradable.

Example 19Dilution Experiments

[0255] In contrast to the experimental procedures for some of the Examples described above which refer to a solids weight % of 50%, a series of experiments was carried out with a solids weight % of 10%, using EGDMA as DVM and DDT as CTA. Attempts were made to carry out the reaction using lower amounts of CTA per equivalents DVM. It was found that gels formed if 0.4 equivalents or fewer of CTA were used per 1 equivalent DVM. The gel point was found to be between 0.4 and 0.5. Non-gelled products were formed in the following cases:

TABLE-US-00024 .sup.1H NMR (CDCl.sub.3) Vinyl EGDMA:DDT GPC (THF) Gel Con- in Mw Mn DDT For- % version final (kg/ (kg/ Entry (equiv.) mation Yield (%) product mol) mol) dn/dc 1 0.45 No 75 >99 0.95:1 6119 418.1 14.6 0.374 0.1099 2 0.5 No 82 >99 1.65:1 1223 40.22 30.4 0.261 0.108 3 0.75 No 59 >99 1.52:1 51.3 3.62 14.2 0.229 0.1182 4 1 No 53 >99 1.3:1 14.02 2.34 5.99 0.206 0.1051 5 1.33 No 59 >99 1:1 5.74 0.686 8.374 0.193 0.1103 DVM:EGDMA Solvent:ethyl acetate Solid wt % = 10% AIBN %: 1.5% DDT equivalents are per 1 equivalent EGDMA Entries 1 and 2 were purified by precipitation into MeOH at 0 degrees C. Entries 3 to 5 were purified by precipitation into MeOH at room temperature

[0256] Of note is that non-gelled products were formed when as little as 0.45 equivalents of CTA were used per equivalent of DVM (reaction time: 24 hours).

[0257] The appearances and textures observed in the products were as follows:

Entry 1: white crunchy powder
Entry 2: white fine powder
Entry 3: white solid
Entry 4: clear, sticky, hard liquid
Entry 5: clear, sticky, soft liquid

[0258] Further experiments were carried out at solid weight % of 10, 25 and 50:

TABLE-US-00025 .sup.1H NMR (CDCl.sub.3) EGDMA:DDT GPC (THF) Reactn Vinyl in Mw Mn EGDMA DDT Solid Time Yield Conv. final (kg/ (kg/ Entry (equiv.) (equiv.) wt. % (hrs) (%) (%) product mol) mol) dn/dc 1 1 1.33 10 24 59 >99 1:1 5.74 0.686 8.374 0.193 0.1103 2 1 1.33 25 24 73 >99 0.91:1 14.75 0.658 22.43 0.215 0.0976 3 1 1.33 50 24 67 >99 1:1 229 2.83 80.8 0.339 0.0883 Entry 1: clear, sticky, soft liquid Entry 2: turbid, soft liquid Entry 3: clear, sticky, hard liquid

Example 20Kinetics of Polymerisation with Varying Amounts of AIBN

[0259] The polymerisations proceeded more slowly but still effectively even at low concentrations of initiator:

TABLE-US-00026 .sup.1H NMR (CDCl.sub.3) Actual Ratio of EGDMA:DDT Theoretical Theoretical Gel Reaction @ Vinyl Conv EGDMA:DDT Entry EGDMA (equiv.) DDT (equiv.) Formation Time (hrs) % AIBN t = 0 (%) in final product 1 1 1.33 No 24 1.5 >99 1:1 2 1 1.33 No 24 0.15 1:1.36 99 0.92:1 3 1 1.33 No 24 0.05 1:1.33 94 0.97:1 4 1 1.33 No 48 0.05 1:1.33 99 TBC GPC (THF) Mw Mn Entry (kg/mol) (kg/mol) dn/dc 1 229 2.83 80.84 0.339 0.0883 2 182.71 1.84 99.3 0.329 0.0966 3 81 1.72 46.96 0.319 0.0979 4 TBC TBC TBC TBC TBC .sup.1H NMR (CDCl.sub.3) EGDMA + DDT EGDMA + DDT EGDMA + DDT System at 1.5% System at 0.15% System at 0.05% AIBN AIBN AIBN Reaction Vinyl Conversion Vinyl Conversion Vinyl Conversion Sample Time (hr) (%) (%) (%) 1 0 0 0 0 2 0.5 48 8 3 1 83 20 4 1.5 98 33 5 2 >99 45 6 2.5 >99 53 7 3 >99 59 23 8 3.5 >99 68 9 4 >99 74 10 5 >99 82 11 6 >99 86 45 12 24 >99 99 94 13 48 N/A N/A N/A EGDMA + DDT System at 0.05% AIBN (2) Vinyl Conversion Sample (%) 1 0 2 3 4 5 6 7 16 8 9 10 11 39 12 95 13 99