Organic–inorganic hybrid proton-conducting electrolyte membranes based on sulfonated poly(arylene ether sulfone) and SiO2–SO3H network for fuel cells

A series of novel organic–inorganic hybrid proton exchange membranes (PEMs) were prepared from the sulfonated poly(arylene ether sulfone) with 4-amino phenyl pendant groups (Am-SPAES), (3-isocyanatopropyl) triethoxysilane (ICPTES), and 3-(trihydroxysilyl) propane-1-sulfonic acid with covalent bonds to form network using a sol-gel method. The obtained cross-linked hybrid membranes (Am-SPAES/I-SiO2-S) displayed excellent solvent resistance and thermal and mechanical stability. The Am-SPAES/I-SiO2-S membranes with cross-linking network exhibited a higher proton conductivity (0.043 S cm−1 at 20°C) than PEMs without covalent bonds (Am-SPAES/SiO2-S) and the swelling ratio maintained below 17.00% even at 100°C. Most importantly, all of the obtained membranes showed considerably lower methanol permeability than that of Nafion 117. In addition, the chemical structures and morphologies of the hybrid membranes were characterized by Fourier transform infrared spectroscopy and scanning electron microscopy, respectively.