Molecular Dynamics Simulation of Ion Conduction in Sulfonated Poly(ether ether ketone) Membrane

Molecular dynamics (MD) simulation technique was used to investigate the effect of degree of sulfonation (DS) on the structural and transport properties of sulfonated poly(ether ether ketone) (SPEEK) membrane at different temperatures. Simulations were performed for the cell containing SPEEK membrane, hydronium ions and water molecules. By analyzing the pair correlation function (PCF), it was found that with increasing the degree of sulfonation, the distance between sulfonic acid groups and the distance between sulfonic acid groups and hydronium ions are decreased. Furthermore, the PCF analysis of water-hydronium pair shows that water molecules and hydronium ions are located at far distances from each other. However, the diffusion coefficient and ionic conductivity of hydronium ions increase due to the greater number of the hydronium ions at high DS conditions. Simulated ionic conductivities follow experimental data qualitatively, but due to simulation conditions, some differences between simulation results and experiment are observed.

Keywords:

molecular dynamics simulation , sulfonated poly(ether ether ketone)(SPEEK) , ion conductivity