Atomistic Simulations of Side-Chain Architecture and Head-Group Chemistry in Tailored Perfluorinated Anion-Exchange Membranes

Anion-exchange membranes (AEMs) are critical to the performance and durability of alkaline fuel cells, requiring an optimal balance between high hydroxide conductivity and chemical stability. In this study, we present a molecular-level investigation of four perfluorinated AEMs with systematically varied cationic head groups and pendant chain lengths to elucidate structure-transport relationships. Classical molecular dynamics simulations were performed at 300 and 353 K to examine the impact of targeted chemical modifications on microphase separation, hydration morphology, and hydroxide-ion transport. Structural and dynamical properties were characterized using radial distribution functions, mean square displacement, radius of gyration, end-to-end distance, intrachain cationic head spacing, and structure factor analysis. Spatial distribution functions further revealed the preferential organization of hydroxide ions and water around cationic sites, providing insights into ion-polymer interactions. The cluster lifetime, residence time of hydrated structure around hydroxyl ions, and Onsager coefficients demonstrate that subtle variations in pendant chain architecture and headgroup chemistry significantly influence membrane morphology and hydroxide conductivity.