Removal of the thiocarbonylthio or thiophosphorylthio end group of polymers and further functionalization thereof
View Patent ↗A method of free radical polymerization and for cleaving a thio group from the resulting polymer is provided. The method comprises forming a mixture of one or more monomers, at least one free radical source and a chain transfer agent, wherein the chain transfer agent comprises a thio moiety. The mixture is polymerized, and the resulting polymer is mixed with a free radical source, and a monomer having little or no homopolymerizability under cleavage conditions. The thio moiety on the polymer is replaced with a group of interest.
1. A method of free radical polymerization comprising (1) forming a mixture of one or more monomers, at least one free radical source and a chain transfer agent, wherein the chain transfer agent comprises a thio group; (2) subjecting the mixture to polymerization conditions, wherein a resulting polymer comprises thio groups; (3) contacting the resulting polymer with a free radical source and a monomer having a propagation rate constant (k p ) less than 2000 under cleavage reaction conditions; and (4) activating the free radical source to generate radicals, wherein at least 50% of the thio groups are replaced with a group of interest other than hydrogen.
2. The method of claim 1 , wherein the monomer contacting the resulting polymer has a k p of less than 1000.
3. The method of claim 1 , wherein the monomer contacting the resulting polymer has a k p of less than 500.
4. The method of claim 1 , wherein the monomer contacting the resulting polymer with has a k p of less than 300.
5. The method of claim 1 , wherein the free radical source is introduced continuously throughout the cleavage reaction.
6. The method of claim 1 , wherein the monomer with a k p less than 2000 is selected from the group consisting of maleimide, N-substituted maleimides, maleic anhydride, maleic acid, fumaric acid, maleic esters, fumaric esters, allyl and methallyl compounds, vinyl ethers, vinyl sulphonates, vinyl phosphonates, 1,3-butadiene derivatives, itaconic acid, α-alkylstyrene, α-ethylacrylate, cis and trans stilbene, and combinations thereof.
7. The method of claim 1 , wherein the monomer with a k p less than 2000 is selected from the group consisting of maleimide, N-phenylmaleimide, N-methylmaleimide, N-ethylmaleimide, N-benzylmaleimide, N-propylmaleimide, N-(4-ethylphenyl)maleimide, N-(4-acetylphenyl) maleimide, N-(para-tolyl)-maleimide, N-cyclohexyl maleimide N-dodecyl maleimide, N-tert-butyl maleimide, N-isopropyl maleimide, N-(2-hydroxyethyl) maleimide, N-(3-hydroxypropyl) maleimide, di-n-butyl maleate, di-n-amyl maleate, diethyl maleate, diisoamyl maleate, dimethyl maleate, diphenyl maleate, and di-n-propylmaleate, di-n-amyl fumarate, diethyl fumarate, diisoamyl fumarate, diisobutyl fumarate, diisopropyl fumarate, dimethyl fumarate, diphenyl fumarate, di-n-propyl fumarate, (meth)allylsulfonate, (meth)allylglycidylether, (meth)alkylvinylether, (meth)allylbutyl ether, (meth)allylethyl ether, (meth)allylmethyl ether, and combinations thereof.
8. The method of claim 1 , wherein the monomer with a k p less than 2000 is selected from the group consisting of N-phenylmaleimide, N-methylmaleimide, N-ethylmaleimide, N-benzylmaleimide, N-propylmaleimide, and combinations thereof.
9. The method of claim 1 , wherein at least one of the one or more monomers in the monomer mixture is an acrylate.
10. The method of claim 1 , wherein all of the monomers in the monomer mixture are acrylates.
11. The method of claim 1 , wherein cleavage reaction conditions comprise a molar ratio of between 0.5:1 and 10:1 for the monomer having a k p less than 2000 to the thio groups in the polymers for which cleavage is desired.
12. The method of claim 1 , wherein cleavage reaction conditions comprise a molar ratio of between 1.0:1 and 5:1 for the monomer having a k p less than 2000 to the thio groups in the polymers for which cleavage is desired.
13. The method of claim 1 , wherein cleavage reaction conditions comprise a molar ratio of between 1.5:1 to 3:1 for the monomer having a k p less than 2000 to the thio groups in the polymers for which cleavage is desired.
14. A polymer formed by the method of claim 1 .
15. The polymer of claim 14 , wherein said polymer is a block copolymer.
16. The polymer of claim 14 , wherein said polymer is a random copolymer.
17. The method of claim 1 , wherein at least 85% of the thio groups are replaced with a moiety comprising the radicals generated in step (4).
18. The method of claim 1 , wherein at least 95% of the thio groups are replaced with a moiety comprising the radicals generated in step (4).
19. A method of cleaving at least a portion of a thiocarbonylthio group from an end of a polymer, the method comprising forming a mixture of the polymer, at least one free radical source, and a monomer with propagation rate constant (k p ) less than 2000, and subjecting the mixture to cleavage reaction conditions.
20. The method of claim 19 , wherein the source of free radicals is selected from the group consisting of peroxides, hydroperoxides, peresters, peracids, percarbonates and azo compounds.
21. The method of claim 19 , wherein an additional reagent is added which interacts in a redox reaction with the free radical source to liberate radicals.
22. The method of claim 19 , wherein cleavage reaction conditions comprise a molar ratio of between 0.5:1 and 10:1 for the monomer having a k p less than 2000 to the thio groups in the polymers for which cleavage is desired.
23. The method of claim 19 , wherein cleavage reaction conditions comprise a molar ratio of between 1.0:1 and 5:1 for the monomer having a k p less than 2000 to the thio groups in the polymers for which cleavage is desired.
24. The method of claim 19 , wherein cleavage reaction conditions comprise a molar ratio of between 1.5:1 to 3:1 for the monomer having a k p less than 2000 to the thio groups in the polymers for which cleavage is desired.
25. The method of claim 19 , wherein the monomer has a k p less than 1000.
26. The method of claim 19 , wherein the monomer has a k p less than 500.
27. The method of claim 19 , wherein the monomer has a k p less than 300.
28. The method of claim 19 , wherein the monomer with a k p less than 2000 is selected from the group consisting of maleimide, N-substituted maleimides, maleic anhydride, maleic acid, fumaric acid, maleic esters, fumaric esters, allyl and methallyl compounds, vinyl ethers, vinyl sulphonates, vinyl phosphonates, 1,3-butadiene derivatives, itaconic acid, α-alkylstyrene, α-ethylacrylate, cis and trans stilbene, and combinations thereof.
29. The method of claim 19 , wherein the monomer with a k p less than 2000 is selected from the group consisting of maleimide, N-phenylmaleimide, N-methylmaleimide, N-ethylmaleimide, N-benzylmaleimide, N-propylmaleimide, N-(4-ethylphenyl)maleimide, N-(4-acetylphenyl) maleimide, N-(para-tolyl)-maleimide, N-cyclohexyl maleimide N-dodecyl maleimide, N-tert-butyl maleimide, N-isopropyl maleimide, N-(2-hydroxyethyl) maleimide, N-(3-hydroxypropyl) maleimide, di-n-butyl maleate, di-n-amyl maleate, diethyl maleate, diisoamyl maleate, dimethyl maleate, diphenyl maleate, and di-n-propylmaleate, di-n-amyl fumarate, diethyl fumarate, diisoamyl fumarate, diisobutyl fumarate, diisopropyl fumarate, dimethyl fumarate, diphenyl fumarate, di-n-propyl fumarate, (meth)allylsulfonate, (meth)allylglycidylether, (meth)alkylvinylether, (meth)allylbutyl ether, (meth)allylethyl ether, (meth)allylmethyl ether, and combinations thereof.
30. The method of claim 19 , wherein the monomer with a k p less than 2000 is selected from the group consisting of N-phenylmaleimide, N-methylmaleimide, N-ethylmaleimide, N-benzylmaleimide, N-propylmaleimide, and combinations thereof.
31. The method of claim 19 , wherein said polymer is a block copolymer.
32. The method of claim 19 , wherein the polymer is a random copolymer.
33. The method of claim 19 , wherein at least 85% of the thio groups are replaced with a moiety other than hydrogen.
34. The method of claim 19 , wherein at least 95% of the thio groups are replaced with a moiety other than hydrogen.
35. The method of claim 19 , wherein the free radical source is introduced continuously throughout the cleavage reaction.
36. A method of free radical polymerization comprising (1) forming a mixture of one or more acrylate monomers, at least one free radical source and a chain transfer agent, wherein the chain transfer agent comprises a thiocarbonylthio group; (2) subjecting the mixture to polymerization conditions, wherein a resulting polymer comprises thiocarbonylthio groups; and (3) contacting the resulting polymer with a free radical source and a monomer having a propagation rate constant (k p ) less than 2000 under cleavage reaction conditions.
37. The method of claim 36 , wherein the monomer having a k p less than 2000 is selected from the group consisting of N-phenylmaleimide, N-methylmaleimide, N-ethylmaleimide, N-benzylmaleimide, N-propylmaleimide, and combinations thereof.
38. The method of claim 36 , wherein the free radical source is an initiator.