Reactivity of Heteropolymolybdates and Heteropolytungstates in the Cationic Polymerization of Styrene

摘要

The two heteropolyacids H3PW12O40 and H3PMo12O40, and their homologous salts (NH4)3PW12O40, and (NH4)3PMo12O40 were prepared and tested in the cationic polymerization of styrene. The results showed that the heteropolytungstates were more reactive than the heteropolymolybdates. It has been found that the yield and the viscosity average molecular weight (Mv) of polystyrene are directly proportional to the acidity strength of the heteropolyanions (H3PW₁₂O₄₀ > H₃PMo₁₂O₄₀ > (NH₄)₃PW₁₂O₄₀ > (NH₄)₃PMo₁₂O₄₀). The highest yield (68.0%) and M_v (7,930) were obtained by using H₃PW₁₂O₄₀. In addition, H₃PW₁₂O₄₀ polymerized the styrene under mild conditions and was recyclable, and could behave as a truly heterogeneous catalyst.