Controlled Ethylene Polymerization Catalyzed by Cp$\rm{{_{2}^{\ast}}}$ZrBu2/[Ph3C] [B(C6F5)4]/iBu4Al2O above Room Temperature

The ternary system composed of CpZrBu2 (Cp*=Me5Cp), [CPh3][B(C6F5)4], and tetraisobutyldialuminoxane (TIBAO) catalyzed the polymerization of ethylene in a controlled fashion at temperatures up to 60 °C. The consumption of ethylene remained constant during the polymerization process, the molecular weight of the polyethylene increased linearly with time, and polydispersity indexes down to 1.3 were obtained. Characterization of the polyethylene by 13C-NMR and FT-IR spectroscopy did not indicate any branching or CC linkages, even for polymer produced at 40 °C or above. The linear and saturated polymer structure is due to the absence of β-hydride transfer, β-hydride elimination and chain walking during the polymerization. The absence of termination reactions is consistent with the system's demonstrated controlled polymerization.