Fabrication and electrochemical properties of SPVdF-co-HFP/SPES blend proton exchange membranes for direct methanol fuel cells

Sulfonated poly (vinylidene fluoride-co-hexafluoropropylene) (SPVdF-co-HFP)/sulfonated poly (ether sulfone) (SPES) blend polymer electrolyte membranes (PEMs) were fabricated effectively as an alternative PEM for direct methanol fuel cell (DMFC) applications. In order to prepare PEMs with improved proton conductivity PVdF-co-HFP and PES were preferred and sulfonated using chlorosulfonic acid and sulfuric acid respectively. The presence of sulfonic acid groups were confirmed by FT-IR spectroscopy. TGA results showed that SPVdF-co-HFP/SPES blend membranes were superior than control one. Atomic force microscopy images of the blend PEMs clearly showed that the surface roughness and nodule size are increased. The influential characteristics of the PEMs, such as, water uptake, swelling ratio, ion exchange capacity, proton conductivity, methanol crossover, selectivity ratio were characterized with respect to the control membrane. Though, the tensile strength and elongation at break slightly decreases by the addition of hydrophilic SPES, the water uptake and proton conductivity of SPVdF-co-HFP/SPES blend membranes were increased and found to be higher than that of the pure SPVdF-co-HFP. Selectivity ratio of the prepared blend PEMs were in the range of 1.709 x 10(4) to 2.193 x 10(4) S cm(-3) s which is much higher than that of Nafion 117 (0.214 x 10(4) S cm(-3)s) membrane. (C) 2016 Elsevier Ltd. All rights reserved.