Preparation and properties of sulfonated poly(phthalazinone ether sulfone ketone)/zirconium sulfophenylphosphate/PTFE composite membranes

Porous polytetrafluoroethylene (PTFE) membranes were used as support material for sulfonated poly(phthalazinone ether sulfone ketone) (SPPESK)/zirconium sulfophenyl phosphate (ZrSPP)/PTFE composite membranes. The membranes were prepared via a spray painting method. Membranes were characterized by thermal gravimetric analysis (TGA) and scanning electron microscopy (SEM). The composite membranes exhibited good thermal stabilities. SEM micrographs confirmed that the pores of the PTFE were filled entirely with SPPESK and ZrSPP. The resulting composite membranes were mechanically durable, dimensionally stable in alternating wet/dry environments, and had lower methanol permeabilities compared with the unsupported SPPESK/ZrSPP composite membranes reported in our previous work. The water uptake of these membranes was also lower than previous SPPESK/ZrSPP composite membranes. The proton conductivity of PTFE supported SPPESK (DS 81%)/ZrSPP(10 wt%) composite membrane was as high as 0.24 S/cm at 120 °C. Thus, the composite membranes exhibited good thermal stabilities, proton conductivities, and good methanol resistance, indicating that these composite membranes could serve as effective alternative membranes for direct methanol fuel cells (DMFCs).