CO-POLYMERIZATION OF CARBON-DIOXIDE AND PROPYLENE-OXIDE WITH SUPPORTED DIETHYLZINC CATALYSTS

In the reported experiments, diethylzinc was allowed to react with various metal oxides in n-heptane at 60 degree C, and the copolymerization of propylene oxide and carbon dioxide was investigated at 60 degree C in solution in dioxane with reaction products as catalysts. An alternate copolymer was obtained with every catalyst, but the yield of copolymer and the number-average molecular weight depended significantly on the supporting materials. In a kinetic study of the copolymerization we found that the catalytic efficiency (number of propagating species per number of zinc supported) was only a few percent with every catalyst. The copolymerization was also examined by using several kinds of silica, whose pore diameters are markedly different, as supports. The results obtained strongly suggested that only the active species existing in large pores act as the propagation species.