The polymerzation of tetrahydrofuran (THF) initiated by heteropolyacid—H3PW12O40 in low concentration could be promoted by oxetane (OX)

but the polymerization stopped at lower conversion than that promoted by oxiranes. The chain structure analysis by NMR spectra showed that OX was more reactive toward polymerization than oxiranes and more than 80% of OX were consumed through copolymerization

but not initiation. By stepwise addition of OX the conversion of THF polymerization could be increased higher than 50%.The percentage of the hydroxyl group attached to OX moieties at the polymer chain-ends was higher than 50% of the total hydroxyl end-groups

inferring that polymerization proceeded quite similar to that promoted by ethylene oxide and each chain wasstarted with the OX moiety.