Acid-base blend membranes based on Nafion®/aminated SPEEK for reducing methanol permeability

Sulfonated poly(ether ether ketone)s (SPEEKs) were further substituted on the polymer main chain by amino groups to form an acid-basic polymer, and blended with acid polymeric Nafion® to create composite membranes. The acid-base blend membranes containing ionic crosslinking exhibited lower water uptake than recast Nafion®, and the methanol permeability was reduced significantly for various contents of aminated SPEEK, with a maximum proton conductivity of ∼0.063 S cm−1 at 30 °C. The single-cell performance of the blend membranes with various contents of aminated SPEEK showed 20-26 mW cm−2 for S45A47 at 80 °C. Both the power density and open circuit voltage were higher than those of Nafion® 115 and recast Nafion®. The acid-base blend membranes satisfy the requirements for proton exchange membranes in the context of direct methanol fuel cell (DMFC) applications.