The polymerization of tetrahydrofuran ( T H F) initiated by heteropolyacid H3 P W12 O40( P W12) in low concentration could be effectively promoted by propylene oxide( P O) . The polymerization conversion reached 50 % ～60 % after a reaction time around 5 h . Wateror butylene glycol was used to controlthe molecular weightofthe productin the rangeof 1000 ～3000 . The polymerization started upon addition of P Oand stopped with completeconsumption of P O,but it would start again when a new portion of P O was added . Theaverage hydroxyl end group functionality of polyether glycol is close to 2 . The ratio ofprimary and secondary hydroxyl end groups is close to one ,and the percentage of thehydroxyl group attached to P O moietiesatthe polymerchain endsis higherthan 50 % ofthetotal hydroxyl end groups. All the obtained results inferred that T H F polymerizationpromoted by P Oproceeded quite similar to that promoted by ethylene oxide,i.e., P O wasnecessary in theinitiation of T H Fpolymerization to startthe propagation ofchains,and withthe complete consumption of P Othe propagating chains transformed into dormant species,which can be re initiated by the addition ofa supplementary portion of P O.
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