A facile synthesis of proton-conducting organic–inorganic membranes

•Hybrid proton conducting membranes based on PEG, sulfonic acid units and silica was reported.•The membranes were prepared in one step at room temperature by sol–gel process.•All materials are homogenous, transparent, and highly flexible with good mechanical and thermal properties.•Proton conductivities were measured by impedance technique and conductivity was evaluated to be close to 10−2 S cm−1 at 20 °C.

Hybrid organic–inorganic proton conducting membranes based on arylsulfonic acid (Ar-SO3H) groups and poly(ethylene glycol) (PEG) units were easily obtained in one step synthesis by co-hydrolysis and polycondensation of 2-(4-Chlorosulfonylphenyl)ethyl trimethoxysilane and bis-silylated polyethylene oxide. The hydrolysis of SO2Cl groups into SO3H was achieved during the sol–gel process by the in situ generated HCl acting as catalyst for the hydrolysis and polycondensation reactions. All membranes were characterized by 1H, 13C and 29Si MAS solid-state NMR, elementary analysis, Scanning Electron Microscopy (SEM) and X-ray photoelectron (XPS) spectroscopy. Their thermal and thermomechanical properties were investigated by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA), respectively.. The thermomechanical and conductive properties were found to be dependent on the PEG chain length and the PMMA amount. The proton conductivities of these materials were found to be approximately 10−2 S cm−1 at 20 °C.

Graphical abstractWe report here, by sol−gel process, the one pot synthesis of highly flexible and proton-conducting organic–inorganic membranes.Figure optionsDownload full-size imageDownload high-quality image (198 K)Download as PowerPoint slide