Interactions between Rigid Polyelectrolytes Mediated by Ordering and Orientation of Multivalent Nonspherical Ions in Salt Solutions

Multivalent ions in solutions with polyelectrolytes (PEs) 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 rigid 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.

Automated summary

Multivalent ions in polyelectrolyte solutions cause electrostatic correlations that can alter ion distributions and interactions. Our simulations demonstrate that ion shape and concentration, in addition to valency, can control rigid like-charged polyelectrolyte interactions. We show a correlation between the orientation of aspherical ions and the induced polyelectrolyte attraction through multivalency. This external control over interaction type, strength, and range can guide the self-assembly of like-charged polyelectrolytes.