Abstract
Three Keggin-type heteropolyanions, namely H3PMo12O40 center dot 13H(2)O, (NH4)(3)PMo12O40 center dot 4H(2)O and H3PW12O40 center dot 13H(2)O were prepared and tested in the ring-opening polymerization reaction of tetrahydrofuran. The effects of the counter-cation (H+, NH4+) and the peripheral atoms (Mo, W) on the polymerization were investigated. It has been found that when the protons of H3PMo12O40 center dot 13H(2)O were replaced by the ammonium cations the polymerization rate decreased dramatically. Whereas, when the peripheral atoms (Mo) were replaced by their homologous (W), the polymerization rate increased twofold. As for the viscosity average molecular weight (M-v) of polymer products, it was found that the high molecular weight (7930) was obtained by using H3PW12O40 center dot 13H(2)O. The molecular weight (M-v) obtained by H3PMo12O40 center dot 13H(2)O and (NH4)(3)PMo12O40 center dot 4H(2)O was 6470 and 6810, respectively.