Functionalized elastomer containing a nitrogen group
The present invention is directed to a copolymer of a monomer selected from the group consisting of 1,3-butadiene and isoprene, and a monomer of formula I wherein R 1 is phenylene, or a linear or branched alkane diyl group containing 2 to 10 carbon atoms, or a combination of one or more phenylene groups and one or more linear or branched alkane diyl groups containing 1 to 10 carbon atoms; R 2 and R 3 are independently phenyl or a linear or branched alkyl group containing 1 to 10 carbon atoms, or one of R 2 and R 3 is hydrogen and the other is phenyl or a linear or branched alkyl group containing 1 to 10 carbon atoms, or R 2 and R 3 taken together with the nitrogen atom represent a nitrogen containing heterocyclic group containing from 4 to 12 carbon atoms; and R 4 is hydrogen or a linear or branched alkyl group containing 1 to 10 carbon atoms. The invention is further directed to a rubber composition including the copolymer, and a pneumatic tire containing the rubber composition. The invention is further directed to a method of making such a copolymer.
1. A copolymer of 1,3-butadiene and a second monomer of formula I
wherein R 1 is phenylene, or a linear or branched alkane diyl group containing 2 to 10 carbon atoms, or a combination of one or more phenylene groups and one or more linear or branched alkane diyl groups containing 1 to 10 carbon atoms; R 2 and R 3 are independently phenyl or a linear or branched alkyl group containing 1 to 10 carbon atoms, or one of R 2 and R 3 is hydrogen and the other is phenyl or a linear or branched alkyl group containing 1 to 10 carbon atoms, or R 2 and R 3 taken together with the nitrogen atom represent a nitrogen containing heterocyclic group containing from 4 to 12 carbon atoms; and R 4 is hydrogen or a linear or branched alkyl group containing 1 to 10 carbon atoms; wherein the copolymer comprises greater than 80 percent by weight of cis 1,4 microstructure content based on the polybutadiene content of the copolymer.
2. The copolymer of claim 1 , wherein the nitrogen containing heterocyclic group is selected from the group consisting of the structures:
wherein R 5 groups can be the same or different and represent a member selected from the group consisting of linear or branched alkyl groups containing from 1 to about 10 carbon atoms, aryl groups, allyl groups, and alkoxy groups, and wherein Y represents oxygen, sulfur, or a methylene group, and n is an integer from 4 to 12.
3. The copolymer of claim 1 , comprising at least 95 percent by weight of cis 1,4 microstructure content based on the polybutadiene content of the copolymer.
4. The copolymer of claim 1 , comprising from 0.1 to 40 percent by weight of units derived from the second monomer based on the weight of the copolymer.
5. The copolymer of claim 1 , comprising from 0.5 to 20 percent by weight of units derived from the second monomer based on the weight of the copolymer.
6. The copolymer of claim 1 , comprising from 1 to 5 percent by weight of units derived from the second monomer based on the weight of the copolymer.
7. The copolymer of claim 1 , wherein the second monomer is selected from the group consisting of the structures:
8. A rubber composition comprising the copolymer of claim 1 .
9. A pneumatic tire comprising the rubber composition of claim 8 .
10. A method of making a copolymer, comprising the step of polymerizing a first monomer selected from the group consisting of 1,3-butadiene and isoprene and a second monomer of formula I in the presence of an (allyl)(arene)Ni(II) polymerization catalyst
wherein R 1 is phenylene, or a linear or branched alkane diyl group containing 2 to 10 carbon atoms, or a combination of one or more phenylene groups and one or more linear or branched alkane diyl groups containing 1 to 10 carbon atoms; R 2 and R 3 are independently phenyl or a linear or branched alkyl group containing 1 to 10 carbon atoms, or one of R 2 and R 3 is hydrogen and the other is phenyl or a linear or branched alkyl group containing 1 to 10 carbon atoms, or R 2 and R 3 taken together with the nitrogen atom represent a nitrogen containing heterocyclic group containing from 4 to 12 carbon atoms; and R 4 is hydrogen or a linear or branched alkyl group containing 1 to 10 carbon atoms.
11. The method of claim 10 , wherein the second monomer is selected from the group consisting of the structures:
12. The method of claim 10 wherein the polymerization catalyst is of formula II
where BAr F 4 − is tetrakis(3,5-bis(trifluoromethyl)phenyl) borate.
13. The method of claim 10 , wherein the nitrogen containing heterocyclic group is selected from the group consisting of the structures:
wherein R 5 groups can be the same or different and represent a member selected from the group consisting of linear or branched alkyl groups containing from 1 to about 10 carbon atoms, aryl groups, allyl groups, and alkoxy groups, and wherein Y represents oxygen, sulfur, or a methylene group, and n is an integer from 4 to 12.