Hybrid Network Sulfonated Polynorbornene/Silica Membranes with Enhanced Proton Conductivity by Doped Phosphotungstic Acid

A series of novel hybrid sulfonated polynorbornene-silica (PBN–SiO 2 ) proton conducting membranes doped with different weight ratio of phosphotungstic acid (PWA) were prepared by the casting procedure. The proton conductivity of the composite membranes containing 40 wt.% PWA reached the maximum of 6.1 × 10 –2 S cm –1 and increased gradually with PWA content and temperature elevating, while the methanol permeabilities (3.52–9.39 × 10 –7 cm 2 s –1 ) of these membranes were much lower than that of Nafion 117 (2.36 × 10 –6 cm 2 s –1 ). The membranes also exhibited excellent thermally stable and mechanical properties, which imply that the PBN–SiO 2 –PWA membranes are promising materials in the direct methanol fuel cells (DMFC) applications.