Improvement of sulfonated poly(ether ether ketone)/Y zeolite -SO3H via organo-functionalization method for direct methanol fuel cell

Sulfonated poly (ether ether ketone) (S-PEEK) and sulfonated Y zeolite (S-Y) composite membranes were prepared and characterized to be used as alternative materials for direct methanol fuel cell (DMFC). PEEK was sulfonated with a concentrated sulfuric acid at 60 °C. The degree of sulfonation was determined by the 1H NMR analysis. Organo-functionalized Y Zeolite was prepared by the silanization and graft copolymerization method using poly(2-acrylamido-2-methylpropanesulfonic acid) (pAMPS). The sulfonated Y zeolite was characterized and confirmed by FTIR and XRD. The structures of the composite membranes were characterized by SEM, TGA, and by mechanical properties. SEM results showed the uniform distributions of the sulfonated Y zeolite within the S-PEEK matrix. In this work, the existence of the sulfonated Y zeolite at various amounts (5, 10, and 15%v/v) improved the water uptake, proton conductivity, mechanical properties, methanol permeability, and oxidative stability relative to the pristine S-PEEK membrane. The proton conductivity values of the composite membranes were higher than the commercial perfluorsulfonic acid polymer namely Nafion 117 by an order of magnitude.