Interplay of Polymer Structure, Solvent Ordering, and Charge Fluctuations in Polyelectrolyte Solution Thermodynamics

Abstract

We develop a polymer field-theoretic model that incorporates explicit treatment of semiflexibility and polar solvents, providing a framework to determine the impact of solvent ordering and concentration fluctuations on the thermodynamic behavior of polyelectrolyte solutions. We study the effect of dipole ordering on the electrostatic potential near a charged surface and the phase behavior of oppositely charged symmetric polyelectrolytes. The phase diagrams, incorporating quadratic-order concentration fluctuation corrections, are determined using different approximations of the chain structure factor for semiflexible polymers. While wormlike-chain statistics provides the most broadly accurate prediction for phase behavior, a Gaussian-rigid interpolation remains an adequate approximation for quadratic-order fluctuation corrections for many experimentally relevant systems. However, our theory provides the basis for predicting the impact of higher-order concentration fluctuations, which requires chain statistics that cannot be rendered from existing approximate methods.