Anion Exchange Ionomers: Impact of Chemistry on Thin‐Film Properties

Ionomer thin-films (i.e., 20–100 nm) on supports serve as model systems to understand ionomer-catalyst interfacial behavior well the confinement-driven deviation in properties from bulk membranes. While ionomer have been examined for proton exchange ionomers, thin-film of anion ionomers (AEIs) remain largely unexplored. More importantly, delineating convoluted impact chemistry and confinement morphology hydration is interest advancing field functional ionic interfaces. In this work, these aspects are studied by using AEIs different backbones (perfluorinated, aliphatic, aromatic) side chains (various lengths, single versus dual groups). Quartz-crystal microbalance spectroscopic ellipsometry used analyze density coupled with calculated free volume fraction provide insights their gas transport properties. AEI side-chain's chemical character plays a key role how modulates (in bulk). The results elucidate effects backbone, side-chain anion/cation type changes swelling. This study also provides new tuning functionalities at interfaces via chemistry, which can benefit design development electrode-ionomers alkaline membrane-based energy systems.