Anion Exchange Membranes Based on Reactive Block Copolymers

The unmet needs for polymeric AEMs include high hydroxide conductivity, chemical stability under strongly basic conditions, and sufficient mechanical properties to withstand the temperature and humidity fluctuations in a fuel cell. This presentation will include our most recent findings from an effort to develop cation-containing polymers based on phosphonium and ammonium derivatives of styrene using co-polymerization of reactive, ion-containing block copolymers with a small molecule ``matrix'' monomer. By creating polymer membranes with co-continuous cation-containing domains in a cross-linked matrix, we hope to demonstrate high conductivity simultaneously with the robust mechanical properties required in the fuel cell environment. Morphological data from SAXS and TEM, mechanical property measurements, in- and through-plane charge transport measurements, and the results of fuel cell testing will be presented. It was found that the surface transport characteristics of these materials differ from the through-plane properties, that chemical crosslinks may not produce membranes with the required toughness, and that a polymerization technique that is highly sensitive to reaction kinetics is not ideal for the production of AEMs.