Copolymerization with saturated epoxides

TMO Copolymerization With Saturated Epoxides. Copolymerizing TMO with ethylene oxide (EO) in an 80 20 weight ratio with the chelate catalyst gave a water-soluble product (90% of the total) which contained only 8% TMO (Run 2, Table II). On the basis of an ideal copolymerization, the EO is estimated to enter the copolymer in this fraction approximately 70 times more readily than does the TMO. This result confirms that alkylene oxides polymerize much more readily than oxetanes with the chelate catalyst. A small amount (10% of the Total) of a water-insoluble copolymer containing 44% TMO was obtained. This result indicates that the chelate catalyst contains some sites which give more favorable copolymerization. One possible explanation is that the unfavorable copolymerization of TMO at the major sites is due to steric hindrance which reduces the ability of TMO to coordinate at this site. 

Given the high activity and selectivity of catalyst 4 and the variety of commercially available epoxides, we explored the versatility of 4 as a catalyst for the alternating copolymerization of other aliphatic epoxides. The copolymerizations of aliphatic epoxides with saturated and unsaturated hydrocarbon chains were examined flrst, and the results are shown in Table I. 

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