Properties of composite membranes based on sulfonated poly(ether ether ketone)s (SPEEK)/phenoxy resin (PHR) for direct methanol fuel cells usages

A series of proton exchange composite membranes were prepared by solution method through blending of methyl substituted highly sulfonated poly (ether ether ketone)s (SPEEK) with phenoxy resin (PHR) containing methyl groups and biphenyl structure, to improve the selective permeability and the mechanical properties. The physical and electrochemical properties of the composite membranes were characterized in detail as a function of weight fraction of PHR. The composite membranes exhibited moderated swelling properties and ion exchange capacities for electro-membrane applications. The membranes blended with PHR showed good methanol resistance property and excellent proton conductive capability (0.031-0.0627 S/cm). The methanol diffusion coefficients of composite membranes (10.3 × 10^-7 to 5.4 × 10^-7 cm²/s) were much lower than that of pure SPEEK membranes (1.47 × 10^-6 cm²/s), the blends selectivity for application to the DMFC was impacted by PHR. The membranes also obtained better mechanical properties and were strong and tough enough to be used as functional proton exchange membrane materials. The composite membranes showed good potential usage in direct methanol fuel cells (DMFCs).