Computational Modeling of Hydrated Polyamine-Based Anion Exchange Membranes via Molecular Dynamics Simulation

Abstract

The present study aims to investigate static and dynamic properties of polyamine-based anion exchange membranes (AEMs) using all-atom molecular dynamics simulations. The effects of the hydration level, degree of amination, and temperature on the properties of AEMs were systematically explored. The phase segregation and the formation of interconnected hydrophilic channels were visualized for different simulated membranes. Additionally, the variation of the diffusion coefficients of both water molecules and hydroxide anions as a function of the aforementioned parameters were computed, and the mechanical properties of the different membranes were studied. The results revealed that increasing the degree of amination and water uptake facilitates the transport of water and anionic species. However, this comes at the expense of the mechanical stability of the membrane due to water-induced plasticization, potentially leading to its irreversible deformation under operating conditions. We then demonstrate that a promising compromise solution between high conductivity and mechanical stability can be achieved by limiting the degree of amination to about 30%. These results furnish valuable insights into the development of improved AEMs.