Synthesis of Proton-conducting Electrolytes Based on Poly(vinylidene fluoride-co-hexafluoropropylene) via Atom Transfer Radical Polymerization:

The preparation of poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) grafted poly (styrene sulfonic acid) (PVDF-HFP-g-PSSA) copolymer as proton-conducting electrolytes by atom transfer radical polymerization of styrene sulfonic acid at the secondary halogenated sites of PVDF-HFP was demonstrated. The structure of the PVDF-HFP-g-PSSA copolymers was verified by Fourier transform infrared spectra, proton nuclear magnetic resonance spectra and X-ray photoelectron spectroscopy. The PVDF-HFP-g-PSSA copolymer membranes showed ion exchange capacity values ranging from 0.045 to 0.272 mEq g-1, the water uptake varied from 13.7 to 26.8 wt.% and the proton conductivities varying from 1.85 2 10-4 to 9.8 2 10-4 S cm-1, all of which could be modulated by control of the polymerization time. All the membranes exhibited decomposition temperature up to around 350 °C as revealed by thermogravimetric analysis. The incorporation of poly(styrene sulfonic acid) into PVDF-HFP chains resulted in melting at higher tempera...