Complex coacervation in polyelectrolytes from a coarse-grained model
Jack F. Douglas, Marat Andreev, Juan J. DePablo, Vivek Prabhu, Matthew Tirrell
Polyelectrolyte coacervation refers to the formation of distinct liquid phases that arise when polyelectrolytes are mixed under appropriate polymer and salt concentrations. Molecular-level studies of complex polyelectrolyte coacervation have been limited. In this work, a coarse-grained model of the polymers and the corresponding counter-ions is proposed. The model is used to simulate coacervation as a function of polymer length and overall salt concentration. The results of simulations in different ensembles reproduce a number of phenomena observed in experiments, including the destabilization of the coacervate region by increasing ionic strength or by decreasing molecular weight. The results of the model are also shown to compare favorably with experimental measurements of dynamic modulus.