Synthesis of ethylene-norbornene-1-octene terpolymers with high 1-octene contents, molar masses, and tunable values, in high yields using half-titanocene catalysts

Terpolymerizations of ethylene (E) and norbornene (N) with 1-octene (O) using different aryloxo- or ketimide-modified half-titanocene catalysts, Cp′TiCl 2 (O-2,6- i Pr 2 C 6 H 3 ) [Cp′ = indenyl ( 1 ), C 5 Me 5 (Cp*, 2 ), t BuC 5 H 4 ( 3 )] and Cp′TiCl 2 (N&z.dbd;C t Bu 2 ) [Cp′ = t BuC 5 H 4 ( 4 ), Cp ( 5 )], in the presence of MAO cocatalysts were investigated. The microstructures, termonomer contents, and molecular weights of the resultant terpolymers, and their thermal properties were determined. The ketimide-modified Cp′TiCl 2 (N&z.dbd;C t Bu 2 ) ( 4 and 5 ) exhibited higher catalytic activities and yielded higher molecular weight terpolymers, poly(E- ter -N- ter -O)s, than the aryloxo-modified Cp′TiCl 2 (O-2,6- i Pr 2 C 6 H 3 ) ( 1-3 ); the 1-octene incorporation is often higher than that prepared using ansa -metallocenes, noticeably reaching 13.5 mol%. Terpolymers prepared using ketimide-modified Cp′TiCl 2 (N&z.dbd;C t Bu 2 ) possessed significantly higher M n values than the E/N copolymers; the same trend is observed in the terpolymers prepared using the Cp*-aryloxo analogue ( 2 ). This has been demonstrated to be correlated with the lower propensity of catalysts 4 and 5 to provide β-H elimination, which occurred at the last-inserted E unit, as suggested through the analysis of the vinyl end groups observed in the 1 H NMR spectra. This unique behaviour is quite different from that of well-developed ansa -metallocenes. Thus, poly(E- ter -N- ter -O)s with high O contents, molar masses, and T g values from 23 °C to 153 °C were obtained in high yields using 2 , 4 , and 5 half-titanocene catalysts. Synthesis of unique poly(E- ter -N- ter -O)s using half-titanocene catalysts: 1-octene does not behave as a chain termination/transfer agent unlike ansa -metallocenes.