Preparation and characterization of plasma treated PP composite electrolyte membranes

Methanol impermeable thin polymer electrolyte membranes were prepared by impregnating Nafion® solution in porous polypropylene (PP) membranes for direct methanol fuel cell application. In order to enhance the impregnation amount and stability of Nafion® molecules, not only the solvent in commercial Nafion® solution was exchanged with ethanol, but the surface and pores of PP membranes were treated with Freon-116 plasma gas. The proton conductivities of the prepared Nafion®/PP composite membranes were about 10 times lower, but the resistance to methanol permeability was about 10 times higher than those of commercial Nafion® membranes. The impregnation features of Nafion® molecules in the plasma treated and non-treated membrane pores were compared by examining the cross-sectional morphologies of membranes.