Proton conducting membranes based on benzimiclazole sulfonic acid doped sulfonated poly(oxadiazole-triazole) copolymer for low humidity operation

This work reports for the first time the preparation of sulphonated poly(oxadiazole-triazole) copolymer membranes doped with amphoteric molecule, 1H-benzimidazole-2-sulphonic acid and their characterisation as proton conductors at 120 degrees C and low humidity. The membranes had not only high proton conductivities, up to 4 x 10(-3) S cm(-1) at 120 degrees C and low relative humidity (5 and 10%), but also had good mechanical properties with a storage modulus of about 3 GPa at 300 degrees C and high thermal stability with T-g up to around 420 degrees C. Because of their superior ion conducting and mechanical properties they have potential as a proton conducting membrane for fuel cell applications, in particular at high temperature and extremely low-humidity conditions.