sPEEK based composite membranes for direct ethanol fuel cell applications

In this paper, sulfonated poly(ether ether ketone) (sPEEK) based composite membranes are discussed. The inorganic matrix consisted of silica: Aerosil (R) 380, tetraethoxysilane (TEOS), or a combination of both to obtain an interconnected silica network. The ion exchange capacity (IEC) was determined and these values coincided with the predicted IEC values. Uptake in water and 2 M ethanol was performed and an optimum was obtained. TEOS promoted the uptake due to its hydrophilicity. Proton conductivity values of the composite membranes and the polymeric reference were similar, although the IEC was lower. The stability of the composite membranes could be improved by adding an imidazole based functional silane to the composite system. This stability increased with increasing imidazole content resulting in remarkably lower ethanol permeability. (C) 2009 Elsevier B.V. All rights reserved.