Alkoxylation of epoxidized polyisoprene by opening of oxirane rings with alcohols

Alkoxylation of epoxidized polyisoprene catalyzed by cerium ammonium nitrate (CAN) was achieved under very mild conditions both in melt and in solution. The cleavage of the epoxidized units with alcohols leads to the formation of alkoxyalcohol units and epoxide rearrangement units in the case of 20 and 38% epoxidized 1,4-polyisoprenes. For higher percentage of epoxidation (72%), cyclization of epoxidized units is observed, which dramatically reduces the alcohol grafting percentage onto the polymer chains. The glass transition temperature increase with the percentage of alkoxylation is attributed to both alkoxy and hydroxyl groups formed after the ring opening of the epoxidized units. However, size-exclusion chromatography analysis of the modified polymers showed a decrease in the number-average molecular weight and an increase in the weight-average molecular weight, which can be interpreted as the degradation and crosslinking of the polymer chains, respectively. (C) 2004 Society of Chemical Industry.