Proton‐conductive membranes based on vanadium substituted heteropoly acids with Keggin structure and polymers

In this article, novel proton‐conducting composite membranes SPEEK/PW₁₁V and PVA/SiW₁₁V were synthesized from vanadium substituted heteropoly acids (H₄PW₁₁VO₄₀·8H₂O and H₅SiW₁₁VO₄₀·15H₂O, abbreviated as PW₁₁V and SiW₁₁V) and polymers (SPEEK or PVA) at the weight ratio 70 : 30. The membranes were characterized by the infrared spectroscopy, X‐ray powder diffraction, and scanning electron microscopy, which confirmed the maintenance of the Keggin framework and dispersion homogeneously in the polymer matrix without long‐range ordering. Their proton‐conducting properties were investigated with electrochemical impedance spectroscopy. The results show that the respective proton conductivities of SPEEK/PW₁₁V and PVA/SiW₁₁V membranes were in the order of 10^?2 and 10^?4 S cm^?1 at ambient temperature. The temperature dependence of the two composite membrane electrolytes exhibit Arrhenius behavior, and the observed activation energies to be 15.82 kJ mol^?1 for SPEEK/PW₁₁V and 14.40 kJ mol^?1 for PVA/SiW₁₁V, which indicates that the proton conduction complies with the Grotthuss mechanism. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42204.