Novel sulfonated polyimides proton-exchange membranes via a facile polyacylation approach of imide monomers

A novel perylenebisimides monomer N, N'-Di(4-phenoxyphenyl)perylene-3,4,9,10-tetracarboxylic diimide (PBI-1) was successfully synthesized by direct imidization of 4-phenoxyaniline with 3,4,9,10-Perylenetetracarboxylic dianhydride (PTDA). Then a series of sulfonated polyimides with different ion exchange capacities (IECs) was obtained from a facile polyacylation reaction of PBI-1 with a side-chain-type sulfonated aromatic monomer, disodium 2,2-di(sulfopropyloxy)-biphenyl (SBP) and 4,4-oxydibenzoic acid under mild conditions. The obtained membrane shows good hydrophilic characteristic and high proton conductivity with a relatively low linear swelling ratio due to the pi-conjugation derived from the flat perylene structure. Consequently, this material proved to be promising as a proton exchange membrane.