Parameterization of a Coarse Grained Model for Perfluorosulfonic Acid Polymer

A step-by-step approach was used to build coarse-grained (CG) models for hydrated perfluorosulfonic acid (PFSA) polymer membranes. The intramolecular bond potentials are described by using harmonic potentials and the parameters are determined by reproducing the bond and angle distributions obtained from all-atom molecular dynamics simulations. The nonbonded interaction is described by using Lennard-Jones function. LJ 12-4 function is used for the pairs involving water, while the LJ 9-6 and LJ 7-6 is used for any other pairs. Density, surface/interfacial tension and radial distribution function data are used for nonbonded parameter fitting. Comparison between the CG and AA simulations of PFSA membrane with different water contents has confirmed that the CG model can reasonably represent the density and structure properties of the membranes. The developed CG model will be useful in simulating PFSA membranes at a large-scale system