Synthesis and characterization of fluorosulfonyl imide isatin biphenylene block copolymer for PEMFC

114Random and block copolymers successfully synthesized from isatin, biphenyl and 2.2′-biphenol with super acid catalyst. Block copolymer membranes show higher proton conductivity than random copolymers. The block copolymer showed the IEC value 1.45 meq./g, water uptake 19.14% and the proton conductivity 78.89 mS/cm at 80 °C under 90% RH. Block copolymer membrane showed a greater dependence of proton conductivity on the relative humidity, and had higher conductivity and cell performance than that of random copolymer with similar IEC value. These results showed that the morphology of polymer matrix greatly affected the cell performance and membrane with well-separated hydrophilic/hydrophobic phase is very important in the fuel cell application. This research demonstrated the possibility of promising BPIIB membranes for excellent proton conductivity and cell performance.