Surfactantless synthesis of amphiphilic cationic block copolymers

Abstract

The present invention is directed to a method of producing an amphiphilic block copolymer, including the steps of: (1) preparing a first aqueous polymerization medium which is comprised of (a) 4-vinylpyridine,(b) a trithiocarbonate RAFT agent, and an emulsifier, wherein the emulsifier is prepared in-situ within the aqueous polymerization medium by the reaction of a latent surfactant with a surfactant activator;(2) polymerizing the 4-vinylpyridine within the first aqueous polymerization medium in the presence of a first free radical initiator to produce a poly(4-vinylpyridine);(3) protonating the poly(4-vinylpyridine) to form a protonated poly(4-vinylpyridine) RAFT macroinitiator;(4) preparing a second aqueous polymerization medium which is comprised of the protonated poly(4-vinylpyridine) RAFT macroinitiator and a monomer containing ethylenic unsaturation but is exclusive of a surfactant; and(5) polymerizing the protonated poly(4-vinylpyridine) RAFT macroinitiator and monomer containing ethylenic unsaturation within the second aqueous medium in the presence of a second free radical initiator and a temperature less than 100° C. to produce an amphiphilic block copolymer of the 4-vinylpyridine and monomer containing ethylenic unsaturation.

Description

Claims

1. A method of producing an amphiphilic block copolymer, comprising the steps of: (1) preparing a first aqueous polymerization medium which is comprised of (a) 4-vinylpyridine,(b) a trithiocarbonate RAFT agent, and an emulsifier, wherein the emulsifier is prepared in-situ within the aqueous polymerization medium by the reaction of a latent surfactant with a surfactant activator;(2) polymerizing the 4-vinylpyridine within the first aqueous polymerization medium in the presence of a first free radical initiator to produce a poly(4-vinylpyridine);(3) protonating the poly(4-vinylpyridine) to form a protonated poly(4-vinylpyridine) RAFT macroinitiator;(4) preparing a second aqueous polymerization medium which is comprised of the protonated poly(4-vinylpyridine) RAFT macroinitiator and a monomer containing ethylenic unsaturation but is exclusive of a surfactant; and(5) polymerizing the protonated poly(4-vinylpyridine) RAFT macroinitiator and monomer containing ethylenic unsaturation within the second aqueous medium in the presence of a second free radical initiator and a temperature less than 100° C. to produce an amphiphilic block copolymer of the 4-vinylpyridine and monomer containing ethylenic unsaturation.

2. The method of claim 1, wherein the trithiocarbonate RAFT agent is of the structural formula:

3. The method of claim 2 wherein Y represents a functional group selected from the group consisting —C(R′)2CN, —C(CH3)2Ar, —C(CH3)2COOR″, —C(CH3)2CONHR″, —C(CH3)2CH2C(CH3), —CH(CH3)Ar, —CH2Ar, —C(CH3)3, —CR′2COOH, —C(R′)(CN)—(CH2)n—COOH, and —C(R′)(CN)—(CH2)n—OH; wherein R′ represents a linear or branched hydrocarbon containing from 1 to 12 carbon atoms; wherein Ar represents an unsubstituted or substituted phenyl, napthyl, anthracenyl, pyrenyl or pyridyl group; and wherein n represents an integer from 1 to 8.

4. A free radical control agent according to claim 1 wherein R1 is (CH2)m where m ranges from 1 to 4.

5. A free radical control agent according to claim 1 wherein Y represents a function group selected from the group consisting of benzyl, picolyl, and t-butyl.

6. The method of claim 2, wherein R1 is (CH2)9, R2 and R3 are hydrogen, R4 is —COOH, Y is benzyl, and the free radical control agent is S-benzyl-S′-(11-undecanoic acid) trithiocarbonate.

7. The method of claim 2, wherein R1 is CH2, R2 is (CH2)8, R3 is hydrogen, R4 is —OH, Y is benzyl, and the free radical control agent is S-benzyl-S′-(2-hydroxydecyl) trithiocarbonate.

8. The method of claim 2, wherein R1 is CH2, R2 is (CH2)8, R3 is hydrogen, R4 is —OH, Y is 4-picolyl, and the free radical control agent is S-(4-Picolyl)-S′-(2-hydroxydecyl)trithiocarbonate.

9. The method of claim 2, wherein the at least one monomer is butadiene and the amphiphilic block copolymer is poly(4-vinylpyridene-b-butadiene).

10. The method of claim 1 wherein the at least one monomer comprises butadiene and styrene and the amphiphilic block copolymer is poly (4-vinylpyridene-b-styrenebutadiene).

11. The method of claim 1 wherein the amphiphilic block copolymer is in the form of a stable latex that does not contain additional surfactant.

12. A polymer produced using the method of claim 1, wherein the monomer is selected from the group consisting of styrene, substituted styrene, alkyl acrylate, substituted alkyl acrylate, alkyl methacrylate, substituted alkyl methacrylate, acrylonitrile, methacrylonitrile, acrylamide, methacrylamide, N-alkylacrylamide, N-alkylmethacrylamide, N,N-dialkylacrylamide, N,N-dialkylmethacrylamide, isoprene, 1,3-butadiene, ethylene, vinyl acetate, vinyl chloride, and vinylidene chloride.

13. A polymer produced using the method of claim 1, wherein the monomer is selected from the group consisting of styrene, 1,3-butadiene, and isoprene.

14. A tire comprising the polymer of claim 12.

15. A tire comprising the polymer of claim 13.