Perylene-based sulfonated aliphatic polyimides for fuel cell applications: Performance enhancement by stacking of polymer chains

Aliphatic-type sulfonated polyimides with different aliphatic chain lengths consisting of perylenediimide units have been facilely synthesized via mild polyacylation of a sulfonated diarene monomer and aliphatic perylenediimide dicarboxylic acid monomers. The membranes were prepared by casting from DMSO solutions. The obtained flexible and tough membranes exhibited distinct micro-phase separation and excellent proton conductivity while maintaining relative low linear swelling ratio. For example, the proton conductivity of 162.2 mS/cm was obtained for membrane AL-SPI-10 (IEC = 1.73 mmol/g) at 80 °C with the lower linear swelling ratio of 27%. Moreover, The maximum power densities for the fuel cell based on AL-SPI-5 and AL-SPI-10 reached 931.88 mW/cm2 and 773.51 mW/cm2 at 80 °C, respectively, The high performance of the membrane may be ascribed to the self-assembly behavior driven by the strong π-π interactions of the perylenediimide units and the hydrophilic interactions of the sulfonated groups.