Preparation and Properties of Sulfonated Poly(arylene ether sulfone)/Modified Phosphotungstic Acid Composite Proton Exchange Membranes

In the present study, SPAES/PWA -funtionalized silica membranes with various weight ratio of PWA/silica were prepared and their microstructure, chemical stabilities and proton conductivity at high temperature were investigated. The SPAES-PWA in situ composite membrane has better mechanical properties compare with the pure SPAES membrane due to the strong hydrogen bonding interactions of the PWA and the polymeric matrix. However, the SPAES-silica-SO₃H in situ composite membrane has worse mechanical properties than the pure SPAES membrane. These results indicate that a hydrophilic substance such as -SO₃H creates void spaces and limits the stress transfer of silica particles. In addition, the tensile strength of the SPAES-PWA-silica-SO₃H sol-gel composite membranes is greater than that of the pure SPAES membrane and the SPAES-PWA-silica-SO₃H in situ composite with the same inorganic particle content. Proton conductivity depends strongly on the sulfonic acid content; so, when the silica content is increased, the proton conductivity (under conditions of low humidity) is also increased. On account of their well-connected silica network and PWA, the composite membranes have higher levels of proton conductivity, better mechanical properties, and lower water uptake levels than the in situ membrane. This composite membrane is therefore a suitable candidate for PEMFC applications.