Polynuclear Olefin Polymerization Catalysis: Proximity and Cocatalyst Effects Lead to Significantly Increased Polyethylene Molecular Weight and Comonomer Enchainment Levels

Weight watching: In ethylene polymerization, approximately 70 fold increases in molecular weight are achieved with C1-Zr2 compared to ethylene-bridged C2-Zr2 (see scheme). With MAO as the cocatalyst, approximately 600 fold increases in polyethylene (PE) molecular weight are achieved with C2-Zr2Cl4 and C1-Zr2Cl4 compared to a mononuclear analogue. These results support the argument that Zr–Zr proximity significantly influences chain-transfer rates, and such effects are highly cocatalyst-sensitive.