Ethylene Polymerization and Copolymerization Reactions with a Catalyst Based on the Ti(IV) Complex with a Diolate Ligand

Abstract

A novel catalyst system containing a complex of Ti(IV) with a bidentate diolate ligand and a binary Al(C₂H₅)₂Cl/Mg(C₄H₉)₂ activator at a molar [Al]/[Mg] ratio of ~3 affords the synthesis of high-molecular weight polyethylene and ethylene copolymers with 1-hexene, 1-octene and 1-decene. Kinetic analysis shows that the catalyst contains two families of active centers, unstable and stable. The unstable centers, which dominate at the early stages of the polymerization reactions, produce polymers of high molecular weight and narrow molecular weight distribution (M_w/M_n ~ 2.5), similarly to alkene polymers prepared with several soluble metallocene and post-metallocene catalysts. The stable active centers produce polymers of lower molecular weight and broad molecular weight distribution, which is more typical for polymers produced with heterogeneous catalysts.