Control of polymer topology through transition-metal catalysis: synthesis of functional olefin copolymers using a chain walking catalyst

摘要

Tremendous amount of efforts have been devoted into the design of new polymer architectures and topologies because of their importance to polymer properties. We have been exploring new strategies for controlling polymer branching topology through transition-metal catalysis. In one example, polyethylene (PE) branching topology was controlled by ethylene pressure (PE) in ethylene polymerization using the Brookhart's Pd-bisimine catalysts. By controlling the competition between monomer insertion and catalyst isomerization (chain walking), PEs were synthesized with a broad spectrum of topologies, ranging from linear to hyperbranched to dendritic.2a, b To broaden the scope of this strategy, we report here the control of the branching topology of ethylene polar copolymers through copolymerization using the chain walking catalyst (Scheme 1).