Integral equation theory of flexible polyelectrolytes. II. Primitive model approach

Abstract

The multicomponent Polymer Reference Interaction Site Model is solved numerically for solutions of linear flexible polyelectrolytes in the Primitive Model approach with an explicit description of the counterions and salt ions. All the ionic species interact via bare Coulomb and hard sphere potentials. The wormlike chains modeled as connected interacting charged sites are characterized by their persistence length. The hypernetted chain integral equation is used as the closure relation. The structural and thermodynamic properties of semidiluted polyelectrolyte solutions are presented. The model gives the pair correlation functions for monomer–monomer, monomer–ion, and ion–ion pairs. From the monomer–counterion correlations information on the ionic condensation around flexible chains is deduced. The ion-averaged monomer–monomer potential obtained from the monomer–monomer correlations presents a classical screened Coulomb behavior at low coupling and reveals an attractive character at high electrostatic coupling.