Effect of alkaline treatment of PVDF membranes on preparation of proton exchange membranes with high conductivity

Fuel Cell is a new type of power source with high power density and little pollution. Proton exchange membrane is a key component of the fuel cell. Poly(vinylidene fluoride) grafted polystyrene sulfonated acid (PVDF-g-PSSA), a kind of proton exchange membrane, with high proton conductivity has been prepared by solution grafting on alkaline treated poly(vinylidene fluoride) membrane. PVDF membranes treated with alkaline solutions were studied by FTIR, FT-Raman spectroscopy and electron spin resonance (ESR). The vibrational spectra showed the existence of conjugated C=C bonds in the treated membranes. Free radicals were observed in the membranes from the ESR spectra, the concentrations of which were in the 10¹⁶ spin/g order of magnitude. The structure modification of the alkaline treated PVDF membrane could improve the grafting on the membrane and played an important role in increasing the conductivity of PVDF-g-PSS A membrane to a high value of 6.40 × 10^-2 S/cm.