The yield of copolymerization of tetrahydrofuran(THF) and epichlorohydrin(ECH

10%

by wt.) using a binary catalyst of fuming sulfuric acid(21% or 28%) and perchloric acid or sodium perchlorate is higher than 60%. The average molecular weight of the product can be controlled in the range of 1000-2000 by varying the catalyst system. The hydroxyl functionality of the product is equal to 2

and the end-groups are predominantly primary hydroxyls(around 70-80%).