Complex coacervation: A field theoretic simulation study of polyelectrolyte complexation

TL;DR

This study employs field theoretic simulations with complex Langevin sampling to analyze phase behavior and structure in salt-free polycation-polyanion mixtures, revealing the impact of charge density and molecular weight on complex coacervation.

Contribution

It introduces a field theoretic simulation approach to explore the equilibrium phase behavior and structure of polyelectrolyte complexes beyond mean-field approximations.

Findings

Demixing phase transition to form coacervates observed in strongly charged systems

Charge density and molecular weight significantly influence complexation behavior

Spinodal and binodal boundaries of phase diagram characterized

Abstract

Using the complex Langevin sampling strategy, field theoretic simulations are performed to study the equilibrium phase behavior and structure of symmetric polycation-polyanion mixtures without salt in good solvents. Static structure factors for the segment density and charge density are calculated and used to study the role of fluctuations in the electrostatic and chemical potential fields beyond the random phase approximation. We specifically focus on the role of charge density and molecular weight on the structure and complexation behavior of polycation-polyanion solutions. A demixing phase transition to form a ``complex coacervate'' is observed in strongly charged systems, and the corresponding spinodal and binodal boundaries of the phase diagram are investigated.