(152af) Random Sulfonated Poly(arylene ether sulfone) and Sulfonated Poly(arylene ether ketone) Membranes for Proton Exchange Fuel Cells

Direct methanol fuel cells (DMFC) are one of the most promising technologies in the clean energy production field. For many decades the preparation of efficient proton exchange membranes has been pursued, and potential candidates have been presented as Nafion^® alternatives. This work discusses the employment of the pre-sulfonation synthesis process and its role in the resulting nanostructure and transport properties for random sulfone or ketone-based polymer synthesis. This process obtained a controlled and reproducible sulfonation process on the prepared polymers. This study showed that more conductive polymer membranes could be achieved for the random sulfone polymers than the random ketone polymers, achieving a proton conductivity of 0.24 S cm^-1 at 80 ^oC. When comparing random sulfone to random ketone polymers, these last presented poor mechanical properties, even when the amount of elastomeric domains (BPA) employed was 50% of the polymer's composition. This lack of mechanical stability from the random ketone polymer was compensated with lower methanol permeability (2x10^-7 cm² s^-1) and outstanding oxidative stability after three days. The selectivity of both polymer series exceeded the reported values for the state-of-the-art Nafion^® 117, and both could be outstanding candidates for DMFC applications.