Synthesis and Characterization of Novel Ion-Conducting Membranes Based on Poly(ether sulfone) and Protic Ionic Liquid

Concerns about environmental preservation instigate new investigations on alternative energy sources, such as proton exchange membrane fuel cells (PEMFCs). In order to avoid efficiency loss in PEMFC systems, at temperatures above 100 degrees C and minimize catalyst poisoning, anhydrous conditions are proposed, with substitution of water molecules by protic ionic liquids (PILs) as conducting medium for ions. PILs also feature excellent thermal stability. In this work, poly(ether sulfone) (PES), diethylmethylamine triflate ([dema][TfOH]) and titania (TiO2) or zirconia (ZrO2) based membranes were obtained and characterized, so that the filler effect on ion conductivity and polymer/PIL compatibility could be evaluated. XRD and TGA results indicated higher PES chain organization induced by the oxide networks, with thermal stability over 200 degrees C. These networks also contribute to better PIL retention in the membranes, as shown by TD-NMR, and help improve ion conductivity, reaching values 160% higher than those found in samples containing just PIL.