Potential of mean force and the charge reversal of rodlike polyions

TL;DR

This paper presents a model analyzing how electrostatic interactions can cause charge reversal in polyion solutions, showing salt concentration effects and kinetic limitations on overcharging.

Contribution

It introduces a simple model to calculate the potential of mean force and explores conditions leading to charge reversal and overcharging in polyelectrolyte solutions.

Findings

Electrostatic interactions can induce strong attraction and overcharging.

Small salt concentrations promote charge reversal.

High salt concentrations hinder charge reversal.

Abstract

A simple model is presented to calculate the potential of mean force between a polyion and a multivalent counterion inside a polyelectrolite solution. We find that under certain conditions the electrostatic interactions can lead to a strong attraction between the polyions and the multivalent counterions, favoring formation of overcharged polyion-counterion complexes. It is found that small concentrations of salt enhance the overcharging, while an excessive amount of salt hinders the charge reversal. The kinetic limitations to overcharging are also examined.