Two Methods Based on Integral Equation Approaches in Analyzing Polyelectrolyte Solutions: Macrophase Separation

• Published in: Polymers Vol. 16; no. 16; p. 2255
• Main Author: Cho, Junhan
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 08.08.2024; MDPI
• Subjects: Adhesive strength; Adhesives; Approximation; charged hard spheres; complex coacervation; Connectivity; Critical point; Energy; Equations of state; Integral equations; Molecular dynamics; molecular equation of state; Phase equilibria; Physical properties; polyelectrolyte solutions; Polyelectrolytes; Salt; Spheres; volumetric properties; molecular equation of state; connectivity; critical behavior; complex coacervation; charged hard spheres; polyelectrolyte solutions; volumetric properties
• ISSN: 2073-4360; 2073-4360
• DOI: 10.3390/polym16162255

To understand the phase behaviors of polyelectrolyte solutions, we provide two analytical methods to formulate a molecular equation of state for a system of fully charged polyanions (PAs) and polycations (PCs) in a monomeric neutral component, based on integral equation theories. The mixture is treated in a primitive and restricted manner. The first method utilizes Blum's approach to charged hard spheres, incorporating the chain connectivity contribution by charged spheres via Stell's cavity function method. The second method employs Wertheim's multi-density Ornstein-Zernike treatment of charged hard spheres with Baxter's adhesive potential. The pressures derived from these methods are compared to available molecular dynamics simulations data for a solution of PAs and monomeric counterions as a limiting case. Two-phase equilibrium for the system is calculated using both methods to evaluate the relative strength of phase segregation that leads to complex coacervation. Additionally, the scaling exponents for a selected solution near its critical point are examined.