Et3Al and Et2Zn cooperatively enhanced Ti catalyzed ethylene coordinative chain transfer polymerization

Developing olefin polymerization catalytic systems for both high activity and high chain transfer efficiency by using coordinative chain transfer polymerization (CCTP) is critical for the controlled synthesis of various novel high-value polyolefin materials. While the limited choice of chain transfer agents (CTAs) makes it a challenge to achieve highly efficient CCTP as well as chain propagation due to their competition during the polymerization. Here we report using the combination of R3Al 3 Al and R2Zn 2 Zn in equal amount for tetradentate amine-bis(phenolate) Ti complex and tridentate ketoiminate Ti complex catalyzed ethylene polymerization and observed significantly enhanced CCTP catalytic performance in terms of activity, chains/cat, fill ratio, and k ct / k p vs. using R3Al 3 Al as CTA. The role of R3Al 3 Al and R2Zn 2 Zn during ethylene polymerization were probed by preliminary control experiments studies and a possible mechanistic scenario was proposed.