Abstract: The copolymerization of chloromethylthiirane(CMT) with epichlorohydrin(ECH) was investigated by using rare earth coordination catalysts for the first time.It has been discovered that rare earth coordination catalysts,especially Nd (acac)₃-Al(i-Bu)₃ and Nd(naph)₃-Al(i-Bu)₃ are highly active catalysts for the copolymerization giving rather high molecular weight([η]=0.16 dL/g) alternate-rich copolymer in fairly high yield(～60%),and the catalytic efficiency of Nd(acac)₃-Al(i-Bu)₃ reached 10000 g copolymer/mol Nd.The characteristics of the copolymerization of CMTand ECHwith Na(acac)₃-Al(i-Bu)₃ had been studied in detail.The reactivity ratio of CMT(1) and ECH(2) was obtained to be 0.22(r₁) and 0.097(r₂) from the sulfur contents of the copolymers determined by oxygen combustion method.The structure and the molecular weight of copolymer were characterized by IR,¹³C NMR,GPC and VPO.

Key words: Rare earth coordination catalysts, Chloromethylthiirane(CMT), Epichlorohydrin(ECH), Ring-opening copolymerization, Reactivity ratio determination