Synthesis of polyolefin elastomers from amine-imine nickel-catalyzed ethylene polymerization

Abstract

The catalytic synthesis of polyolefin elastomers by using ethylene as a sole feedstock is fascinating, while currently reported chain walking catalysts are only limited to α-diimine type. In this contribution, we developed alternative amine-imine nickel catalysts for ethylene polymerization to prepare polyolefin elastomers. The cooperative effect of steric hindrance between the less bulky amine moiety and the bulky imine moiety significantly enhanced the performance of amine-imine nickel-catalyzed ethylene polymerization. The amine-imine nickel catalysts also showed excellent controlled behavior for ethylene polymerization, and living ethylene polymerization was also realized to generate narrowly distributed polyethylenes. The microstructure of the resultant polyethylenes could be tuned by catalyst structure, reaction temperature, and ethylene pressure. The polyethylenes produced by Ni2 with the cyclic amine have higher long-chain branching contents, therefore showing better elastic properties. The strain-at-break value of 888.0 % and the strain recovery value of > 79.0 % are super to most values of polyolefin elastomers generated from α-diimine nickel catalysts.