Depelopment of supported catalysts for living polymerization of olefins and its application to gas-phse polymerization

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The living polymerization, therefore, has attracted much attention and several papers have reported on the living polymerization of propene by homogeneous catalytic systems. There are, however, few examples for living polymerization of propene by supported single-site catalytic systems, which should be very important from the practical point of view. We have previously found that living polymerization of propene proceeded in heptane at 0℃ by a chelating (diamide) dimethyltitaniumcomplex (1) activated with trialkylaluminum-free modified methylaluminoxane (dMMAO), which is easily soluble in hydrocarbons.We prepared supported dMMAOs using silica gel, alumina and magnesia by the reaction of the support and dMMAO in heptane and conducted propene polymerization with 1 to clarify the supporting effects of dried MMAO. The supported systems conducted living polymerization of propene at 0℃ without any induction period regardless of the metal oxides for dried MMAO. The propagation rate constants (k_p) of these systems and the molecular weight distribution (M_w/M_n) of the produced polymer depended on the metal oxide employed. The k_p value increased with the increase in Lewis acidity of MMAO on the support and the broadening (M_w/M_n) was ascribed to the distribution of Lewis acidity caused by the heterogeneity of the supported cocatalyst. The systems gave atactic polypropylene regardless of the metal oxides for dried MMAO.We also conducted propene polymerization with ansa-fluorenylamidodimethyltitanium (2), which conducts living polymerization of propene when activated with dMMAO, in place of 1. Although the 2-supported dMMAO systems of silica-gel and alumina showed very high initial activity, the system deactivated and chain transfer also occurred. The results indicated that the combination of the complex and the supported activator was very important for the living polymerization with supported catalytic systems.