PVDF-g-PSSA and Al2O3 composite proton exchange membranes

Poly(vinylidene fluoride) grafted polystyrene sulfonated acid (PVDF-g-PSSA) membranes doped with different amount of Al2O3 (PVDF/Al2O3-g-PSSA) were prepared based on the solution-grafting technique. The microstructure of the membranes was characterized by IR-spectra and scanning electron microscope (SEM). The thermal stability was measured by thermal gravity analysis (TGA). The degree of grafting, water-uptake, proton conductivity and methanol permeability were measured. The results show that the PVDF-g-PSSA membrane doped with 10% Al2O3 has a lower methanol permeability of 6.6 × 10−8 cm2 s−1, which is almost one-fortieth of that of Nafion-117, and this membrane has moderate proton conductivity of 4.5 × 10−2 S cm−1. Tests on cells show that a DMFC with the PVDF/10%Al2O3-g-PSSA has a better performance than Nafion-117. Although Al2O3 has some influence on the stability of the membrane, it can still be used in direct methanol fuel cells in the moderate temperature.