Interactions between polyelectrolytes mediated by ordering and orientation of multivalent non-spherical ions in salt solutions

TL;DR

This study uses molecular dynamics simulations to show how ion shape, concentration, and valency influence the interactions between like-charged polyelectrolytes, enabling external control over their assembly.

Contribution

It reveals how multivalent non-spherical ions' shape and orientation can be used to modulate polyelectrolyte interactions, a novel approach to controlling self-assembly.

Findings

Ion shape and concentration affect PE-PE interactions.

Orientational ordering of ions correlates with attraction.

Interaction properties can be externally tuned.

Abstract

Multivalent ions in solutions with polyelectrolytes (PE) induce electrostatic correlations that can drastically change ion distributions around the PEs and their mutual interactions. Using coarse-grained molecular dynamics simulations, we show how in addition to valency, ion shape and concentration can be harnessed as tools to control like-charged PE-PE interactions. We demonstrate a correlation between the orientational ordering of aspherical ions and how they mediate the effective PE-PE attraction induced by multivalency. The interaction type, strength, and range can thus be externally controlled in ionic solutions. Our results can be used as generic guidelines to tune the self-assembly of like-charged polyelectrolytes by variation of the characteristics of the ions.