Block sulfonated poly(arylene ether ketone) containing flexible side-chain groups for direct methanol fuel cells usage

A series of novel block sulfonated poly(arylene ether ketone)s containing side-chain groups were synthesized by condensation polymerization and grafting reactions. The structures of the oligomer and the polymers were investigated by 1H NMR after each step. The synthetic process was simple and efficient, and the phase separation of the block polymers between the hydrophobic and the hydrophilic components became more apparent. The thermal stability of the membranes was studied by TGA. The proton conductivity of the Block-15 membrane reached up to 0.246 S cm−1 at 80 °C, which was high enough for practical use. Furthermore, the block membranes showed very strong mechanical properties, water uptake, and resistance to methanol permeability. This study shows that a combination of side chain and block structures are a simple and effective approach to increase the nanophase separation and improve the performance of the proton exchange membranes in fuel cells.