Ti(IV) Complexes with OSSO-Type Diol Ligands as Catalysts for Synthesis of Ultrahigh-Molecular-Weight Polyethylene and Ethylene–Propylene Copolymers

Abstract

A series of novel complexes of titanium(IV) with OSSO-type ligands were synthesized. In the presence of Al/Mg activators such as {Et₂AlCl+Bu₂Mg} and {Et₃Al₂Cl₃+Bu₂Mg}, all the synthezed compounds catalyzed the polymerization of ethylene (with activity up to 2554 kg_PE mol_M^–1 h^–1 atm^–1). The otained ultrahigh-molecular-weight polyethylene (UHMWPE) samples had a molecular weight up to 7.6×10⁶ Da and exhibited high melting points (up to 143°C) and high crystallinity (up to 84%). It was demonstrated that these polymers can be processed by a solvent-free method into high-strength/high-modulus oriented films (with breaking strength up to 2.2 hPa and elastic modulus up to 127.7 hPa). The synthesized compounds further manifested themselves as efficient pre-catalysts (as indicated by their catalytic activity up to 408 kg_copolymer mol_M^–1 h^–1 atm^–1) for the preparation of ethylene–propylene copolymers with high propylene incorporation (up to 37%).