Anionic polysulfone based membranes for AMFC

Alkaline membrane fuel cells (AMFCs) can be considered a valid alternative to overcome polymer electrolyte fuel cells (PEFCs) limitations such as a difficult oxygen reduction reaction (ORR), higher fuel cross-over, high CO poisoning and use of precious metal catalysts. In this context, the development of anion exchange membrane (AEM) with good hydroxyl conductivity and polymer stability, is a key factor for (AMFC) applications. Polysulfone-based AEMs have been widely studied due to their good solubility in aprotic polar solvents, high thermostability, high chemical and mechanical resistance, and easy film preparation. In this work, a series of quaternary ammonium-functionalized polysulfones were successfully synthesized by chloromethylation two-step method. Different functionalization degrees from 60 to 150% of original chloromethylated polysulfone connecting triethylamine and trimethylamine were investigated, in order to point out the optimal functionalization degree for greater efficiency in fuel cell. 1H-NMR spectroscopy confirmed that ammonium-polysulfones were successfully synthesized to the desired degree of functionalization. Using a doctor-blade casting method anionic membranes were prepared starting from each obtained polymer with a good homogeneity of thickness. The resulting membranes were chemical-physical and electrochemical characterized to evaluate the key parameters such as ion exchange capacity, water retention and anion conductivity as a function of the functionalization degree and the used quaternary agents.