Copolymerization of propylene oxide with carbon disulfide was studied by using a catalyst consisting of diethylzinc (ZnEt2) and various electron donors. Tertiary amines, tertiary phosphines, and hexamethylphosphoric triamide were the effective donors for the copolymerization, but ZnEt2–water, alcohol, and primary or secondary amines having high activities for the homopolymerization of propylene oxide were not effective for the copolymerization of propylene oxide and carbon disulfide. The copolymers obtained were of low molecular weight and had a monomer unit ratio (CS2/PO) of 0.5–0.7. In addition, a considerable amount of 1,3‐oxathioran‐4‐methyl‐2‐thion was isolated as a by‐product.

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Polymerization of epichlorohydrin (ECH) and copolymerization of propylene oxide–allyl glycidyl ether were studied by using a catalyst consisting of aluminum alkyl–strong phosphoric acid–Lewis base. This system showed high polymerization activity for alkylene oxides, and it was elucidated by x‐ray diffraction analysis that the resultant ECH polymer was completely amorphous. The polymerization was presumed to be of the coordinated anionic type. The physical properties of the vulcanized polymers were studied.

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