Ethylene/α-olefin copolymerization with bis(β-enaminoketonato) titanium complexes activated with modified methylaluminoxane

Abstract

Copolymerizations of ethylene with α-olefins (i.e., 1-hexene, 1-octene, allylbenzene, and 4-phenyl-1-butene) using the bis(β- enaminoketonato) titanium complexes [(Ph)NC(R2)CHC(R 1)O]2TiCl2 (1a: R1 = CF3, R2 = CH3; 1b: R1 = Ph, R2 = CF 3; and 1c: R1 = t-Bu, R2 = CF3), activated with modified methylaluminoxane as a cocatalyst, have been investigated. The catalyst activity, comonomer incorporation, and molecular weight, and molecular weight distribution of the polymers produced can be controlled over a wide range by the variation of the catalyst structure, α-olefin, and reaction parameters such as the comonomer feed concentration. The substituents R1 and R2 of the ligands affect considerably both the catalyst activity and comonomer incorporation. Precatalyst 1a exhibits high catalytic activity and produces highmolecular-weight copolymers with high α-olefin insertion. © 2005 Wiley Periodicals, Inc.