Proton Conducting Properties of Sulfonated Poly(etheretherketone) Composite Membranes with Layered Tin Phosphate Hydrates at Intermediate Temperatures

Abstract

Sulfonated poly(etheretherketone) (SPEEK)/layered tin phosphate hydrate membranes were prepared with a SnP content of 0–50 vol %, and their chemical stability and proton conductivities at were investigated. In the membranes with 25–50 vol % SnP, improved heat resistance, water insolubility, and lower water uptake were confirmed. It is suggested from the results of thermogravimetry–differential thermal analysis and diffuse reflectance Fourier transform infrared spectroscopy that hydrogen bonds were formed at the SPEEK/SnP interfaces and that these bonds are responsible for the improved stability. Proton conductivity was dependent on the absorbed water amount and increased with increasing SnP content in the membranes with 25–50 vol % SnP. The membrane with 50 vol % SnP showed a high conductivity of at under saturated water vapor pressure and a smaller dependence of conductivity on the relative humidity at than the membrane with 25 vol % SnP. The SPEEK/SnP composites have a promising potential as membranes usable at .