Polyelectrolyte stars in planar confinement

TL;DR

This study uses molecular dynamics simulations and theory to explore how multiarm polyelectrolyte stars behave near planar walls, revealing three key mechanisms that generate repulsive forces.

Contribution

It introduces a new mechanism involving rod compression near walls, distinct from star-star interactions, advancing understanding of polyelectrolyte star confinement.

Findings

Identified three mechanisms for star-wall repulsion.

Discovered a novel compression mechanism absent in star-star interactions.

Quantified the effects of confinement on polyelectrolyte conformations.

Abstract

We employ monomer-resolved Molecular Dynamics simulations and theoretical considerations to analyze the conformations of multiarm polyelectrolyte stars close to planar, uncharged walls. We identify three mechanisms that contribute to the emergence of a repulsive star-wall force, namely: the confinement of the counterions that are trapped in the star interior, the increase in electrostatic energy due to confinement as well as a novel mechanism arising from the compression of the stiff polyelectrolyte rods approaching the wall. The latter is not present in the case of interaction between two polyelectrolyte stars and is a direct consequence of the impenetrable character of the planar wall.