Non-Cp type titanium precatalysts for ethylene/norbornene copolymerization

Ethylene/norbornene monomers were homo- as well as copolymerized using titanium-based non-Cp precatalysts [2-(2,6-dialkylphenylamino)-1-phenylethoxy TiCl2] in the presence of methylaluminoxane. The precatalysts polymerized ethylene with moderate activities that increased with increase in temperature reaching a maximum yield of polyethylene at 70 °C. However, these catalysts showed relatively low activity towards norbornene homopolymerization. Precatalysts 1ATiCl2 and 3ATiCl2 were used for ethylene/norbornene copolymerization. The microstructural analysis of these copolymers suggests that these are alternating copolymers with meso (major) and racemic (minor) sequences. Higher norbornene incorporation in the copolymer was obtained with precatalyst 3ATiCl2, which is a more “open” catalyst system. The reactivity ratios for ethylene/norbornene copolymerization suggest that these precatalysts show lesser tendency towards norbornene homopropagation in the copolymerization reactions.