Effects of Ionic Clusters on Dynamics of Sulfonated Polystyrene Blends: Computational Insight

Ionizable polymers have an immense potential to enhance a broad range of technologies from clean energy to water purification and biotechnology, where their structure and dynamics determine their function. Here we follow the formation of ionic-non-ionic interfaces in blends of short 20-mers of polystyrene (PS) and polystyrene sulfonates (SPS) using molecular dynamics simulations with the overarching goal of correlating the degree of phase segregation induced by the ionic groups and their dynamics. Blends of 1:1 made by merging dilute implicit solvent solutions and compressing the systems to melt densities were followed for times up to 1000 ns and the static and dynamic structure factors were extracted and correlated with the distribution of ionic clusters. We find that for these low Mw, local phase segregation dominates the structure. Even though small clusters are formed and slow the motion of the molecules, both the PS and PSS chains remain dynamic.