The reaction behavior of water in tetrahydrofuran polymerization initiated by a heteropolyacid

H3PW12O40 in the presence of ethylene oxide was studied.The variation of components during polymerization was monitored by gas chromatography.Most of water was converted in the earlier stage of the polymerization into ethylene glycol

which was consumed in the subsequent reaction process through chain transfer reaction.Water could not take part in the initiation reaction to start a polymer chain and might reduce the activity of the polymerization.Low molecular weight glycol such as ethtlene or butylene or butylene glycol has a similar effect with water on controlling the molecular weight of the polymer.The molecular weight of the product can be predicted by an equation based upon concentrations of molecular weight controller and heteropolyacid

and conversion of polymerization.