Sulfonated poly(arylene ether sulfone) (SPAES) copolymer with degree of sulfonation of 1.0 was synthesized and characterized. A series of SPAES-TiO2 hybrid membranes with various contents of nano-sized TiO2 particles were prepared and characterized through sol-gel reactions. Scanning electron microscopy (SEM) images indicated the TiO2 particles were well dispersed within polymer matrix. These composite membranes were evaluated for proton exchange membranes (PEMs) in direct methanol fuel cell (DMFC). These membranes showed good thermal stability and mechanical properties. It was found that the water uptake of these membranes increased with the increase of the TiO2 contents in the hybrid membranes. Meanwhile

the introduction of inorganic particles increased the proton conductivity and reduced the methanol permeability. The proton conductivities (0.118-0.162 S/cm) of SPAES-TiO2 hybrid membranes with 8% TiO2 particles are much higher than those of Nafion 117 membrane (0.095-0.117 S/cm) and pure SPAES membrane (0.100-0.124 S/cm) with degree of sulfonation of 1.0 at all temperatures (25-100°C). Especially

the methanol diffusion coefficient (8.4× 10-7 cm2/s) of SPAES-TiO2 hybrid membranes with 8% TiO2 is much lower than that of Nafion 117 membrane (2.1 ×10-6 cm2/s). SPAES-TiO2 hybrid membranes were therefore proposed as candidates of material for PEM in DMFC.