ALTERNATING ETHYLENE-STYRENE COPOLYMERIZATION WITH A METHYLALUMINOXANE-FREE HALF-TITANOCENE CATALYST

Copolymerization of ethylene and styrene in the presence of the cataly tic system eta(5)-C(5)Me(5)-Ti(CH(2)Ph)(3)-B(C6F5)(3) has been investi gated. Independently from the feed composition, basically alternating ethylene-styrene copolymers are obtained, together with some polyethyl ene and syndiotactic polystyrene, from which the former can be separat ed by solvent extraction. NMR analysis of suitably C-13-enriched end g roups shows that the regiospecificity of styrene insertion in the init iation step is largely secondary. A tentative explanation for the pref erentially alternating comonomer incorporation is proposed.