Constraint Release in Entangled Liquid Coacervates Made from Oppositely Charged Polyelectrolytes

Mixtures of oppositely charged polyelectrolytes can phase separate to form a polymer rich coacervate phase, important in many technological applications and biological systems. Many studies focus on formation of the coacervate, but less work has focused on predicting their dynamics. We developed a scaling theory predicting the dynamics of unentangled and entangled liquid coacervates, finding that the structure of asymmetric coacervates results in a dynamic coupling between the high and low charge density polymers. The high charge density polymer can either reptate along the tube formed by other high charge density chains or along the tube formed by low charge density chains. In the latter, topological constraints imposed by the low charge density chains onto the high charge density chains vary with time by reptation of low charge density chains through the process called constraint release. In this work, we develop a scaling model to predict the effects of constraint release on entangled asymmetric coacervates, finding that the dynamic coupling broadens regimes dominated by tube rearrangement as compared to symmetric coacervates. Furthermore, constraint release weakens the concentration dependence of viscosity in regimes dominated by reptation of the high charge density chains.