Proton conducting composite membranes from sulfonated polyethersulfone Cardo and phosphotungstic acid for fuel cell application

A new kind of inorganic–organic composite membranes based on sulfonated polyethersulfone Cardo (SPES-C) with embedded phosphotungstic acid (PWA) was prepared. The composite membranes were characterized by using FT-IR, XRD, TGA and SEM techniques. FT-IR and XRD measurements confirmed the presence of PWA particles into the polymer matrix. FT-IR spectra indicated the existence of a specific interaction between PWA particles and SPES-C polymer. TGA results showed that the composite membranes were thermally stable up to approximately about 200 °C. SEM micrographs verified that nano-scale PWA particles were homogeneously distributed into the polymer matrix. By incorporation PWA into SPES-C polymer the proton conductivity of the composite membranes was enhanced. It was 4.5 × 10−2 S cm−1 at 90 °C and 6.7 × 10−2 S cm−1 at 110 °C, while the conductivity of Nafion® 115 membrane was 4.1 × 10−2 S cm−1 and 4.7 × 10−2 S cm−1 at 90 °C and 110 °C, respectively.