High styrene high vinyl styrene-butadiene rubber and methods for preparation thereof
A process for polymerization of a polymer containing monomeric units derived from a styrene monomer and a 1,3-butadiene monomer includes polymerizing the monomeric units in the presence of an initiator, a first polar agent, and a second polar agent. The first polar agent includes a structure (I): R 1′ R 2′ N-Q-NR 3′ R 4′ ; and the second polar agent comprises a structure (II): R 1′ , R 2 ′, R 3′ , and R 4′ are each independently selected from the group consisting of an alkyl group and hydrogen; Q contains an alkylene group; R 1 and R 2 are each independently an alkyl group; and R 3 , R 4 , R 5 , R 6 , R 7 and R 8 are each independently selected from the group consisting of an alkyl group and hydrogen. Polymers prepared by the above process are described, as are compositions containing such a polymer, and articles containing at least one component formed from such a composition.
1. A process for polymerization of a polymer comprising monomeric units derived from a styrene monomer and a 1,3-butadiene monomer, the process comprising:
polymerizing the monomers in the presence of an initiator, a first polar agent, and a second polar agent;
wherein the first polar agent comprises a structure (I):
R 1′ R 2′ N-Q-NR 3′ R 4′ (I);
wherein the second polar agent comprises a structure (II):
wherein R 1′ , R 2′ , R 3′ , and R 4′ are each independently selected from the group consisting of an alkyl group and hydrogen;
wherein Q comprises an alkylene group;
wherein R 1 and R 2 are each independently an alkyl group;
wherein R 3 , R 4 , R 5 , R 6 , R 7 and R 8 are each independently selected from the group consisting of an alkyl group and hydrogen; and wherein the polymer comprises a vinyl content from greater than 30 to about 80 weight percent, based on toatle amount of polymerized 1, 3-butadiene.
2. The process as in claim 1 wherein R 1′ , R 2′ , R 3′ , and R 4′ are each independently selected from the group consisting of hydrogen and a C 1 -C 4 alkyl group.
3. The process of claim 1 wherein the alkylene group comprises a structure —(CH 2 ) n —, wherein n is an integer equal to or greater than 2.
4. The process of claim 1 wherein R 1 and R 2 are each independently a C 1 -C 4 alkyl group.
5. The process of claim 1 wherein R 3 , R 4 , R 5 , R 6 , R 7 and R 8 are each independently selected from the group consisting of hydrogen and a C i -C 4 alkyl group.
6. The process of claim 1 wherein a molar ratio of the second polar agent to the first polar agent is between about 0.01 and about 10.
7. The process of claim 1 wherein the first polar agent comprises tetramethylethylenediamine.
8. The process of claim 1 wherein the second polar agent comprises ditetrahydrofurylpropane.
9. The process of claim 1 wherein the polymer comprises a styrene content from about 20 to about 80 weight percent.
10. The process of claim 1 wherein the polymer has a molecular weight distribution from about 1.05 to about 1.8.
11. The process of claim 1 wherein the polymer has a number-average molecular weight greater than or equal to about 100,000 g/mole.
12. The process of claim 1 wherein the polymer has a weight-average molecular weight greater than or equal to about 180,000 g/mole.
13. The process of claim 1 wherein the polymer has only one glass transition temperature (Tg), which is about −50° C. to about 20° C.
14. The process of claim 1 wherein a molar ratio of the first polar agent to active initiator is greater than about 0.3.
15. The process of claim 1 wherein a molar ratio of the second polar agent to active initiator is greater than about 0.3.
16. The process of claim 1 wherein the polymerization is run at a temperature of between about 10° C. and about 80° C.
17. The process of claim 1 wherein the initiator comprises n-butyl lithium.
18. The process of claim 1 wherein the polymerizing takes place in a hydrocarbon solvent.