Proton conductivity of perfluorinated and nanocomposite ion exchange membranes in aqueous and water-methanol solutions

The proton conductivity of commercial perfluorinated membranes Nafion-115, MF-4SC and synthesized nanocomposite membranes (polyvinylidenefluoride-sulfonated polystyrene, ultra high molecular weight polyethylene-sulfonated polystyrene, polypropylene-sulfonated polystyrene) is studied as a function of concentration of the water-methanol solution sorbed by membranes, by means of contact impedancemetry with the regulated pressure on the electrode-membrane contacts. The optimal experimental conditions are shown to correspond to a pack of several membranes pressed between gold electrodes with the strength of no less than 40 kg/cm 2 . It is found that the specific conductivity of synthesized membranes in water at 24°C is 50–120 mS/cm, which virtually coincides with the corresponding values for Nafion-115 and MF-4SC. As the concentration of the water-methanol solution increases from 0 to 60%, the specific conductivity of Nafion-115 and MF-4SC membranes decreases by 30%. The specific conductivity of synthesized nanocomposite membranes decreases by 40–55% in this concentration range.