Effects of Cluster Cohesion on Structure and Dynamics of Ionizable Polymer Melts at High Ion Contents: Molecular Dynamics Simulations Study

Ionic clusters control the structure and dynamics of ionizable polymers. Hence, correlation of cluster cohesion with structure and dynamics is crucial to understand their properties. Here, using atomistic molecular dynamics (MD) simulations, we probe the effects of solvent modified ionic assemblies on the structure and inherent dynamics of polystyrene sulfonate (PSS) melts and dense suspensions in the polyelectrolyte regime. PSS melts at different sulfonation fractions (f=0.20-0.55) are incorporated with THF (0-20%) to modify the cohesion of ionic assemblies. The PSS melt at sulfonation fraction ¦= 0.20 forms intermediate size distinguished clusters while at f ≥ 0.35 there is one large percolating cluster spanning the system. Addition of THF breaks the ionic network and enhances polymer mobility.   Surprisingly, when adding THF, the minimum average distance between sulfur atoms shifted to smaller dimensions which maybe attributed to releasing constraints between ionic groups and enhancing better packing. Correlation of cluster cohesion with structure and dynamics of solvent modified ionizable polymer melts on multi-time-length scales will be discussed.