Functionalized Polysulfones as an Alternative Material to Improve Proton Conductivity at Low Relative Humidity Fuel Cell Applications

Polysulfones (udel) was chemically functionalized by bonded functional groups to the main chain through chemical reaction and investigated for use as proton-conducting fuel-cell membranes. The resulting ionomers were cast into membranes and properties such as thermal stability, ion-exchange capacity, proton conductivity and water sorption were evaluated. The modified polymers were characterized by nuclear magnetic resonance (NMR) and infrared spectroscopy (FT-IR). Thermo gravimetric analysis (TGA) show that these membranes are thermally stable up to 480°C in dry air, which implying that they have a good potential to be used as the membranes for high-temperature PEM fuel cells. Under anhydrous circumstances, ionic conductivity of the membrane hit the highest point value of 7.94 10-5 at 160 °C related with the activation energy of 11.6 kJ mol-1 for proton transport. The surface morphology of the formed membrane was examined using atomic force microscopy and scanning electron microscopy.Keywords: Proton conducting materials, relative humidity, Polysulfone, Chloromethyl benzoic acid, imidazol-1-yl 4-methylbenzoate