Hydrodynamics in Semidilute Polyelectrolyte Solutions and Complex Coacervates

TL;DR

This study demonstrates that hydrodynamic interactions significantly influence segmental dynamics in dense polyelectrolyte solutions and coacervates, challenging the assumption that such effects are negligible in these systems.

Contribution

It provides the first mesoscale simulation evidence that hydrodynamics affect dynamics in semidilute PE solutions and coacervates with moderately short chains.

Findings

Hydrodynamic interactions persist beyond the correlation length in semidilute PE solutions.

Strong hydrodynamic effects are observed in coacervates with 30% PE concentration.

Segmental dynamics show signatures of hydrodynamics in the subdiffusive regime.

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.