Polymer synthesis by solid-acid catalyst based on heteropolyacid ammonium salt

Ring-opening polymerizations of four kinds of monomers such as glycidyl phenyl ether, oxetane (OX), ε-caprolactone (CL), and 2,2-dimethyltrimethylene carbonate were performed with a silica-supported catalyst based on heteropolyacid ammonium salt, (NH₄)₃PW₁₂O₄₀/SiO₂. Preparation of the catalyst was done by an impregnation of (NH₄)₃PW₁₂O₄₀ onto SiO₂ in aqueous ammonia, followed by its calcination. Selectivities for skeletal isomerizations of 1-butene exhibited a strong acidity of the (NH₄)₃PW₁₂O₄₀/SiO₂. Among four monomers, the OX and CL were the promising monomers for this polymerization system. The resulting poly(OX) and poly(CL) with number-average molecular weight (M _n) of 2900–6500 and 5500–8600 were obtained in 65–80 and 93–96 % yields, respectively. Furthermore, copolymerization of OX and CL successfully proceeded, affording poly(OX-co-CL) with compositions of OX:CL = 63:37, 50:50, and 37:63 having M _n = 2400–3800 in 64–84 % yields.