Proton conducting membranes based on electrolyte filled microporous matrices

Polysulfone and microglass fiber fleeces were used as microporous supports for electrolyte based composites. The membranes were prepared by impregnating the matrix with various inorganic acids as well as with a 5 wt.% Nafion® solution. Among the various combinations of microporous supports and electrolytes both types of fleece filled with 5 mol/dm3 H2SO4 and the microglass fiber fleece impregnated with Nafion® (∼26 wt.% uptake) exhibit a resistance similar to that of Nafion®-117 (0.530 Ω cm2), whereas the polysulfone fleece soaked in Nafion® shows a distinctively higher ohmic resistance. With regard to the material properties, the polysulfone/H2SO4 composite exhibits a specific conductivity higher than Nafion®-117 but still more than an order of magnitude lower than expected on the basis of the porosity of the support (83%) and the specific conductivity of the acid. Therefore, the uptake of electrolyte seems to depend strongly on the surface characteristics of the microporous support.