Hydrodynamics in Semidilute Polyelectrolyte Solutions and Complex Coacervates

Abstract: It is generally assumed that hydrodynamics in dense polyelectrolyte (PE) solutions, such as semidilute PE solutions and PE complex coacervates, is heavily screened and inconsequential. Here, using mesoscale molecular dynamics that explicitly accounts for hydrodynamics, we show that segmental dynamics in the subdiffusive regime show strong signatures of hydrodynamic interactions that persist well beyond the correlation length of semidilute PE solutions with moderately short chains. The strong hydrodynamic effects are also observed in coacervate systems containing moderately short chains, even with PE concentration as high as $30\%$. Our work fills a gap in the existing simulation literature on dense PE solutions and hints at the importance of hydrodynamics in the transport and rheological properties in broader polymer/polyelectrolyte solution systems.