Synthesis and characterization of polymer electrolyte membranes based on PVDF and styrene via photoinduced grafting

摘要

This contribution demonstrates the use of a novel photoinduced grafting approach in the fabrication of anhydrous proton conducting poly(vinylidene fluoride) (PVDF) membranes. The process basically involves grafting of styrene onto cast PVDF films under UV light, subsequent sulfonation and triazole doping. Degree of grafting was explored as a function of UV irradiation time, as varied from 0.5 h to 8 h. The synthesized graft copolymers were characterized by ~1H NMR and FT-IR spectroscopic analyses. Their thermal properties were examined by Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC) measurements. To assess the potential of the membranes to be used in fuel cell applications, their ion exchange capacities, water uptakes, and hydration numbers were measured and correlated with degree of grafting. Anhydrous proton conducting properties of 1H-1,2,4-triazole-doped PVDF-g-PSSA polymers were studied. PVDF-g-PSSA(Tri)_2 with a degree of grafting of 50.8 % showed a maximum water-free proton conductivity of approximately 5 × 10~(-2) mS/cm at 150 C.