The Implications of Cation Clustering in Anion Exchange Membranes on Conductivity and Mechanical Properties

Anion exchange membranes (AEMs) contain cations that act as dipoles. The dipoles interact with each other and give rise to clustering in the AEM and this clustering can affect the ionic conductivity and mechanical properties of the polymer. Polymers designed to have dispersed cations can, when wet, have their cations cluster as the material undergoes an order-disorder transition at some temperature at which the system has enough energy to reorganize. Clustering is often unavoidable in AEMs and imposes a limit on the increase in conductivity that can be achieved by increasing IEC. Above a certain IEC AEMs do not show increased ionic conductivity only increased swelling on exposure to higher RH. Understanding these phenomena is essential to designing high performance AEMs. Here we propose an AEM based on a scalable random copolymer with rapidly deployed photo-crosslinking to lock the morphology in place to avoid cation clustering.