Function of chloride and effect of various alkylaluminiums, Cl/Al molar ratio, solvents on cyclization in situ of isoprene polymerization catalyzed by Nd Al bimetallic complex were studied. The structure of cyclized products was characterized by means of IR and 1H NMR. The results indicated that in the course of isoprene polymerization with rare earth catalytic system, the function of alkylchloride introduced is terminating cis polymerization and generating cationic species with alkyl aluminums to initiate cyclization in situ . Soluble cyclized polyisoprene was obtained with fragments of cyclopolyisoprene.
