A proton-exchange membrane prepared by the radiation grafting of styrene and silica into polytetrafluoroethylene films

A polytetrafluoroethylene (PTFE) based organic–inorganic hybrid proton-exchange membrane was prepared from simultaneous radiation grafting of styrene (St) into porous PTFE membrane with the in situ sol–gel reaction of tetraethoxysilane (TEOS) followed by sulfonation in fuming sulfonic acid. The effect of radiation on the sol–gel reaction was studied. The results show that radiation promotes the sol–gel reaction with the help of St at room temperature. Incorporated silica gel helps to produce higher degree of grafting (DOG). SEM analysis was conducted to confirm that the inorganic silicon oxide was introduced to produce hybrid membrane in this work. The proton conductivity of membrane evaluated using electrochemical impedance spectroscopy is much higher (14.3×10−2 S cm−1) than that of Nafion® 117 at temperature of 80 °C with acceptable water uptake 51 wt%.