Effects of Cocatalysts on Propene Polymerization with [t‐BuNSiMe2(C5Me4)]TiMe2

Propene polymerization was conducted using t‐BuNSiMe₂(C₅Me₄)]TiMe₂ combined with various cocatalysts at 0°C, and kinetic profiles were investigated under atmospheric pressure of propene in a semibatch system. Dried methylaluminoxane (MAO), which was free of Me₃Al, was found to be more active than the standard MAO system, resulting in a steady polymerization rate and giving higher molecular‐weight polypropenes. Sampling experiments during the polymerization showed an almost linear relationship between the number‐average molecular weight, M̄_n, and polymerization time while retaining a narrow molecular‐weight distribution, whereas the results of batch polymerization with different monomer concentrations and post‐polymerization indicated that chain transfer reactions occurred to a minor degree under these polymerization conditions. Additive effects of trialkylaluminium on the dried MAO system showed that the polymer yield was increased by the addition of i‐Bu₃Al and Oct₃Al and decreased by Me₃Al and Et₃Al. All of the trialkylaluminium compounds increased the number of polymer chains (N), and the Et₃Al system showed the highest N value with the lowest M̄_n value.