Synthesis and characterization of sulfonated PEEK-WC-PES copolymers for fuel cell proton exchange membrane application

In this work we have developed new sulfonated cardo (lactonic group) PEEK-WC-PES random copolymers with different molar ratio. The degree of sulfonation was determined from elemental analysis and ion-exchange capacity (IEC). Sulfonation levels from 0.64 to 1 were easily achieved by varying and controlling the reaction conditions. Proton conductivity was evaluated by impedance spectroscopy (EIS). Activation energy for proton transport, determined by conductivity measurements ranged between 11 and 15 kJ mol(-1), suggesting a vehicular proton transport mechanism. The membrane with better performance in single fuel cell was PEEK-SWC-PES 70:30 with maximum power and current densities of 93.6 mW cm(-2) and 340 mA cm(-2), respectively.