A series of cross-linked poly(vinyl alcohol)-sulfonated poly(ether sulfone) blend membranes were prepared. The studies of physico-chemical properties revealed that the reported membranes are promising candidate for PEMFC applications.

A series of composite membranes based on sulfonated poly (arylene ether sulfone) (SPAES) embedded with powdered silicotungstic acid (STA) was synthesized. SPAES was synthesized by direct aromatic nucleophilic polymerization and then solution blended with STA. Fourier-transform infrared spectroscopy analysis showed that the sulfonic acid groups on the polymer backbone interacted with the tungstic oxide in STA. The composite membranes exhibited a low Heteropolyacid extraction after treatment with water at 60 1C for 24 h. The composite membranes were characterized for water uptake, ionexchange capacity (IEC), hydrolytic stability, proton conductivity and thermal stability in order to evaluate the suitability of these membranes for fuel cells. The proton conductivity of the membranes increased with increasing STA content. With an increase in the STA content, the conductivity of the composite membranes at 30 1C increased from 0.079 to 0.109 S cm À1 , whereas the parent membrane exhibits a proton conductivity of 0.073 S cm À1 . The composite membranes not only had good proton conductivity but also showed excellent thermal stability and mechanical strength. This study shows that the composite membranes based on SPAES and STA can be viable candidates for electrolyte membranes.

A new hyperbranched sulfonated poly(arylene aliphatic ketones) (HB‐SPAAK) has been synthesized and loaded with titania nanoparticles to obtain HB‐SPAAK/TiO2 nanocomposites for thermally stable proton‐conducting electrolyte membrane fuel cell (PEMFC) applications. The synthesis of HB‐SPAAKs was carried out through the polycondensation reaction of different aliphatic and aromatic acids with simultaneous loss of H2O, trifluromethane sulfonic acid used as catalyst. The long chain hyperbranched polymers and TiO2‐loaded nanocomposites were characterized by FT‐IR, 1H‐NMR, SEM and HR‐TEM. Proton conductivity (PC), swelling ratio, water uptake and oxidative stability. The SEM image of TiO2 NPs and HB‐SPAAKs/TiO2 nanocomposites membrane clearly showed the spherical of TiO2 and porous structure of HB‐SPAAKs with a pore diameter of 2–50 μm. TEM image reveals the uniform particle size distribution of TiO2 nanoparticles having a nanosize of 100 nm. TiO2 loaded polymer nanocomposites showed lower values of W/U and S/R when compared to the unmodified HB‐SPAAK, while 3% TiO2 loaded HB‐SPAAKs exhibited a threefold increment of proton conductivity of 1.439 × 10−2 S cm−1 compared to HB‐SPAAKs (0.41 x 10−2 S cm−1) and lower than that of Nafion 117 (0.1003 S cm−1 at 80°C). The 5% TiO2 NPs‐embedded with HB‐SPAAKs nanocomposites membranes also presented admirable oxidative stability with a degradation value of 13.8% during immersion in Fenton reagent for 8 h at 70°C.

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Flexible organic–inorganic polymer nanocomposite membranes with uniformly distributed metal oxide nanoparticles were prepared using sulfonated poly(ether ether ketone) (SPEEK) as a base material and praseodymium oxide (PSO) as an inorganic additive. The degree of sulfonation of SPEEK was determined by proton nuclear magnetic resonance (NMR) analysis and found to be 60%. The characteristic properties of the polymer nanocomposite membranes were examined by thermogravimetric analysis, X-ray diffraction, ion exchange capacity, water uptake ability, and proton conductivity. The incorporation of metal oxide into the polymer matrix was confirmed by scanning electron microscope with energy dispersive X-ray spectroscopy and X-ray diffraction analyses. The nanocomposite membrane exhibits good thermal stability when compared to that of the pristine membrane and SPEEK with 10 wt% of PSO loading was found to be stable up to 450°C. The assessment of polymer electrolyte membrane is accomplished by fabricating membrane electrode assemblies of pure SPEEK and SP-PSO-10 membranes and the latter produced maximum peak power density of 622 mW cm−2. The constructed SPEEK/PSO nanocomposite membranes offered superior physicochemical properties while applying these materials in an H2-O2 fuel cell.

A novel polymer containing an azo based ionic diol has been successfully fabricated as an electrolyte membrane to yield a good fuel cell performance in the whole range of current density.