Novel aromatic proton-exchange polyelectrolytes via polyacylation of pre-sulfonated monomers

Disodium 2,2'-di(sulfopropyloxy)-biphenyl as a novel sulfonated aromatic diarene monomer has been facilely synthesised via one-step etherification in high yield and successfully applied in polyacylation under mild conditions for the first time. Proton-exchange membranes of the resulting side-chain-type sulfonated aromatic polyketones exhibit proton conductivity higher than Nafion (R) while maintaining a low swelling ratio, which may be ascribed to the microstructure of Nafion-like ionic clusters as observed by atomic force spectrometry. This work demonstrates that polyacylation directly from pre-ionised monomers offers a novel and powerful tool to advanced aromatic proton-exchange polyelectrolytes for fuel cells.