Preparation of Catalysts for the Alternating Copolymerization of Propylene Oxide and Carbon Dioxide

Abstract

The alternating copolymerization of propylene oxide and carbon dioxide was conducted at 60°C with some new types of catalysts. The catalysts employed were metal oxides-supported diethylzinc (A), metal salts of acetic acid (B), the reaction products of zinc hydroxide and dicarboxylic acids (C), and metal oxides-supported zinc, cobalt and aluminum halides (D). In the case of the copolymerization with the A-series catalysts, the activity increased to a great extent with an increase in the pore diameters of metal oxides. Among the B-series catalysts, only cobalt and zinc acetates gave the alternating copolymer. The addition of acetic acid to these systems hardly diminished the copolymer yield, but the number average molecular weight of the copolymer decreased in proportion to the concentration of acetic acid. In the case of the copolymerization with the C-series catalysts, the activity was strongly dependent upon dicarboxylic facids used Aliphatic dicarboxylic acids, especially glutaric acid, showed very high activities. On the other hand, the D-series catalysts also showed considerably high activity, although none of these metal halides showed any activity without supporting on metal oxides. A plausible mechanism for the alternating copolymerization with these catalysts was proposed.