Conductivity and solvent uptake of proton exchange membrane based on polystyrene(ethylene–butylene)polystyrene triblock polymer

Conducting membranes of polystyrene-block-(ethylene-ran-butylene)-block-polystyrene were obtained by sulphonation of the polymer using chlorosulphonic acid. The membranes were found to have an excellent conductivity in the order of 10−1 S/cm in their fully hydrated condition at room temperature as measured by impedance spectroscopy. This value is several orders higher than what is reported in the literature for hydrocarbon based ionomers. Water and methanol absorption of both non-reinforced and reinforced membranes were studied. Maximum uptake of solvents, wet membrane porosity and uptake of solvent molecules per sulphonic acid group were calculated gravimetrically. Characterization of the membranes was performed by IR, DSC and TGA methods.