Claims
- 1. A process for the preparation of block polymers by the sequential polymerization of at least one conjugated diene monomer to form a diene polymer block and copolymerization of a vinyl aromatic monomer and an isopropenyl aromatic monomer to form a vinyl aromatic monomer-isopropenyl aromatic monomer polymer block, the polymerization being conducted in a solvent, the solvent comprising the isopropenyl aromatic monomer, the isopropenyl aromatic monomer being present in an excess of at least 2 moles per liter of reaction mixture, polymerization being initiated by a lithium based polymerization initiator, maintaining the monomeric components at a temperature between about 20.degree. centigrade and about 160.degree. centigrade during the formation of the vinyl aromatic monomer-isopropenyl aromatic monomer polymer block to thereby provide a diene-vinyl aromatic monomer-isopropenyl aromatic monomer block copolymer wherein the ratio of vinyl aromatic monomer to isopropenyl aromatic monomer is from about 50 to 1 to about 1 to 50, with the further limitation that the molecular weight of the block copolymer as determined by gel permeation chromatography is from about 5,000 to 800,000 molecular weight units.
- 2. The process of claim 1 wherein the block copolymer contains from about 2 to 40 weight percent of diene monomer forming the diene polymer block.
- 3. The process of claim 1 wherein the block copolymer contains from about 50 to 98 weight percent of diene monomer forming the diene polymer block.
- 4. The process of claim 1 wherein the block copolymer contains from about 40 to 50 weight percent of diene monomer forming the diene polymer block.
- 5. The process of claim 1 wherein the diene monomer is butadiene.
- 6. The process of claim 1 wherein the diene monomer is isoprene.
- 7. The process of claim 1 wherein the diene monomer is a mixture of butadiene and isoprene.
- 8. The process of claim 1 wherein the lithium based polymerization initiator is polyfunctional.
- 9. The process of claim 8 wherein the lithium based initiator is difunctional.
- 10. The process of claim 1 wherein the lithium based initiator is monofunctional.
- 11. The process of claim 1 wherein the diene block is formed prior to the vinyl aromatic monomer-isopropenyl aromatic monomer block.
- 12. The process of claim 1 including the step of adding the vinyl aromatic monomer to the isopropenyl aromatic monomer in a continuous manner during the formation of the vinyl aromatic monomer-isopropenyl aromatic monomer block.
- 13. The process of claim 1 including the step of adding the vinyl aromatic monomer to the isopropenyl aromatic monomer in a discontinuous manner during polymerization of a vinyl aromatic monomer-isopropenyl aromatic monomer block.
- 14. The process of claim 1 including the steps of forming a living block copolymer of vinyl aromatic monomer-isopropenyl aromatic random copolymer block-diene polymer block wherein lithium terminates the diene block configuration and subsequently contacting the living block copolymer with a coupling agent.
- 15. The process of claim 1 wherein the vinyl aromatic monomer is styrene.
- 16. The process of claim 1 wherein the isopropenyl aromatic monomer is .alpha.-methylstyrene.
- 17. The process of claim 1 wherein the vinyl aromatic monomer is styrene and the isopropenyl aromatic monomer is .alpha.-methylstyrene.
- 18. The process of claim 1 wherein all monomers and solvent are in admixture prior to addition of the initiator.
- 19. A block copolymer of the formula AB(BA).sub.n wherein n has a value of 0 or greater; A represents a block of a random copolymer of vinyl aromatic monomer and isopropenyl aromatic monomer wherein the ratio of vinyl aromatic monomer to isopropenyl aromatic monomer is from about 50 to 1 to about 1 to 50; B is a diene polymer block wherein the diene is selected from the group consisting of 1,3-butadiene and isoprene and mixtures thereof containing from 0 to 40 weight percent aromatic monomer copolymerizable therewith and having a 1,2-vinyl content of not greater than 25 percent wherein the ratio of vinyl aromatic and isopropenyl aromatic block to diene block varies from about 50 to 1 to 1 to 50, the molecular weight of the block copolymer as determined by gel permeation chromatography is from about 5,000 to about 800,000 molecular weight units.
- 20. The block copolymer of claim 19 wherein the vinyl aromatic monomer is styrene.
- 21. The block copolymer of claim 19 wherein the isopropenyl aromatic monomer is .alpha.-methylstyrene.
- 22. The block copolymer of claim 19 wherein the vinyl aromatic monomer is styrene and the isopropenyl aromatic monomer is .alpha.-methylstyrene.
- 23. The block copolymer of claim 19 wherein the diene monomer is butadiene.
- 24. The block copolymer of claim 19 wherein the diene monomer is isoprene.
- 25. The block copolymer of claim 19 wherein the diene monomer is a mixture of butadiene and isoprene.
- 26. The block copolymer of claim 19 wherein the ratio of A to B is from about 90 to 10 to 10 to 90.
- 27. The block copolymer of claim 19 wherein the A block contains vinyl aromatic monomer and isopropenyl aromatic monomer in the ratio of from about 1 to 0.5 to 1 to 2.5.
- 28. The block copolymer of claim 19 wherein n is 1 or greater.
- 29. The block copolymer of claim 28 wherein n is about 1.
- 30. The block copolymer of claim 19 wherein the molecular weight is about 20,000 to 500,000 molecular weight units.
Parent Case Info
This application is a continuation-in-part of the copending Application Ser. No. 248,623, filed Mar. 27, 1981, abandoned, which is a continuation in part of the Application Ser. No. 176,884, filed Aug. 11, 1980, now abandoned.
US Referenced Citations (5)
Foreign Referenced Citations (1)
Number |
Date |
Country |
1264741 |
Feb 1972 |
GBX |
Continuation in Parts (2)
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Number |
Date |
Country |
Parent |
248623 |
Mar 1981 |
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Parent |
176884 |
Aug 1980 |
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