“…Aiming for better water retention other approaches have also been explored [12]. LT-PEM are mostly based on a stable fluorinated or polyaromatic backbone polymer, e.g., poly(ethylene-alt-tetrafluoroethylene) (ETFE) [13,14,15,16], poly (vinylidene fluoride) (PVDF) [17,18,19] or poly(ether ether ketone) (PEEK) [20,21,22,23]. Protogenic functional groups such as sulfonic acid groups are attached to these matrices [24,25,26,27,28,29].…”