Ion correlation driven like-charge attraction in multivalent salt solutions
Abstract
The electrostatic double layer force is key to determining the stability and self-assembly of charged colloids and many other soft matter systems. Fully understanding the attractive force between two like-charged surfaces remains a great challenge. Here we apply the modified Gaussian renormalized fluctuation theory to study ion correlation-driven like-charge attraction in multivalent salt solutions. The effects of spatially varying ion correlations on the structure of overlapping double layers and their free energy are self-consistently accounted for. In the presence of multivalent salts, increasing surface charge or counterion valency leads to a short-range attraction. We demonstrate that although both overcharging and like-charge attraction are outcomes of ion correlation, there is no causal relationship between them. Our theory also captures the non-monotonic dependence of like-charge attraction on multivalent salt concentration. The reduction of attraction at high salt concentrations could be a contributing factor towards the reentrant stability of charged colloidal suspensions. Our theoretical predictions are consistent with the observations reported in experiments and simulations.
Cite
@article{arxiv.2306.10137,
title = {Ion correlation driven like-charge attraction in multivalent salt solutions},
author = {Nikhil R. Agrawal and Ravtej Kaur and Carlo Carraro and Rui Wang},
journal= {arXiv preprint arXiv:2306.10137},
year = {2024}
}