Novel silica/poly(2,6-dimethyl-1,4-phenylene oxide) hybrid anion-exchange membranes for alkaline fuel cells: Effect of heat treatment

A series of silica/poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) anion exchange hybrid membranes are prepared. PPO is modified by bromination, hydroxylation and quaternization in sequence. Subsequent sol–gel reaction with monophenyl triethoxysilane (EPh) and tetraethoxysilane (TEOS), followed by heat treatment at 120–140 °C for different times, yields the hybrid membranes. Results show that the physico-chemical properties of the membranes, including ion exchange property, hydrophilicity, OH− conductivity and tensile property, can be easily controlled by adjusting the heating temperature and time. The membranes have proper conductivity (up to 0.0085 S/cm) and favorable tensile properties. The tensile strength (TS) can be higher than 20 MPa and the elongation at break (Eb) is in the range of 5.5–19.5%. Besides, the chemical stability in alkali conditions and thermal stability are comparable to those of anion-exchange membranes based on (partially) fluorinated-polymer. Hence, the hybrid membranes are suitable for potential application in alkaline fuel cells.