Polyelectrolyte Adsorption on Charged Substrate

TL;DR

This study investigates how polyelectrolytes adsorb onto charged substrates with high dielectric constants, revealing a first-order transition and deriving a new scaling law for the adsorption layer thickness.

Contribution

It combines Monte-Carlo simulations and analytical methods to characterize the adsorption transition and introduces a new scaling law for layer thickness.

Findings

Adsorption transition is first-order at low ionic strength.

Monomer density correlates linearly with surface charge density.

A new scaling law for adsorption layer thickness is verified.

Abstract

The behavior of a polyelectrolyte adsorbed on a charged substrate of high-dielectric constant is studied by both Monte-Carlo simulation and analytical methods. It is found that in a low enough ionic strength medium, the adsorption transition is first-order where the substrate surface charge still keeps repulsive. The monomer density at the adsorbed surface is identified as the order parameter. It follows a linear relation with substrate surface charge density because of the electrostatic boundary condition at the charged surface. During the transition, the adsorption layer thickness remains finite. A new scaling law for the layer thickness is derived and verified by simulation.