The feasibility of poly(vinyl alcohol)(PVA)/sulfosuccinic acid(SSA)/heteropolyacid (HPA) composite membranes was investigated to apply for direct methanol fuel cells (DMFC). The composite membranes were prepared by the solution casting method and their properties were examined. The FTIR spectra showed that the Keggin unit of HPA was preserved in the composite membranes and that specific interactions were involved between PVA and HPA. The composite membranes showed uniform distribution of PWA particles in the PVA/SSA/PWA composite membranes by FE‐SEM. The HPA bleeding out was observed to decrease with increasing HPA concentration. The proton conductivity of PVA/SSA/HPA composite membranes improved at low HPA concentration (5‐10 wt.%), while those properties decreased as HPA concentration increased over 10 wt.%.

Binary composite membranes were prepared by the solution casting method from sulfonated poly(etheretherketone) (SPEEK) and organic additives such as hydroxyquinolinesulfonicacid (HQS), 4-tertiary butylpyridine (TBP), imidazole and succinimide. Ternary composite membranes were prepared from SPEEK, inorganic phosphotungstic acid (PWA) and the same organic additives. The acid base interaction characteristics of the composite membranes were not observed by ATR-FTIR analysis. TGA results showed that the thermal stability of the composite membranes was enhanced in the temperature range up to about 400 o C by the addition of the organic additives. The acid-base interaction between SPEEK and the organic additives of HQS, TBP and imidazole decreased the water uptake, methanol permeability and proton conductivity of the binary and ternary composite membranes. However, the addition of succinimide did not decrease the water uptake, proton conductivity and methanol permeability of the composite membranes. The composite membranes containing succinimide made little acid-base interaction but made hydrogen bonding with SPEEK. The hydrogen bonding proved to be weaker than the acid-base interaction. The selectivity of the composite membranes increased by the addition of PWA, and the selectivities of the composite membranes containing succinimide were higher than those of the other composite membranes.