Tetrahydrofuran was polymerized using a heteropolyacid

H3PW12O40 (PW12 ) in low concentration (molar ratio of PW12/THF2.5×10-3 ) as the initiator and ethylene oxide as the polymerization promoter

which effectively increased the rate and conversion of the polymerization.Water was used to control the molecular weight of the product.The polymerization proceeded well even when the molar ratio of H 2O/PW 12 reaches 30.The yield reached 50%～60% per cycle and the average molecular weight could be controlled around 2000.The products were found to be polyether glycol with hydroxyl groups at both ends.The melting point was lower by ～ 10℃ as compared with polytetramethylene ether glycol having the same molecular weight.The concentration of active species maintained unchanged throughout the polymerization

whith indicated the absence of chain termination.