Potential of mean force between like-charged nanoparticles: Many-body effect

TL;DR

This study investigates the many-body effects on the potential of mean force between like-charged nanoparticles in various salt solutions, revealing how ion concentration and valence influence interactions.

Contribution

It provides a comprehensive analysis of many-body effects on nanoparticle interactions using Monte Carlo simulations and nonlinear Poisson-Boltzmann theory, highlighting the role of ion-binding.

Findings

At high 1:1 salt, PMF is weakly repulsive and additive.

At low 1:1 salt, additive assumption overestimates repulsion.

At low 2:2 salt, many-body PMF can become attractive.

Abstract

Ion-mediated interaction is important for the properties of polyelectrolytes such as colloids and nucleic acids. The effective pair interactions between two polyelectrolytes have been investigated extensively, but the many-body effect for multiple polyelectrolytes still remains elusive. In this work, the many-body effect in potential of mean force (PMF) between like-charged nanoparticles in various salt solutions has been comprehensively examined by Monte Carlo simulation and the nonlinear Poisson-Boltzmann theory. Our calculations show that, at high 1:1 salt, the PMF is weakly repulsive and appears additive, while at low 1:1 salt, the additive assumption overestimates the repulsive many-body PMF. At low 2:2 salt, the pair PMF appears weakly repulsive while the many-body PMF can become attractive. In contrast, at high 2:2 salt, the pair PMF is apparently attractive while the many-body effect can cause a weaker attractive PMF than that from the additive assumption. Our microscopic analyses suggest that the elusive many-body effect is attributed to ion-binding which is sensitive to ion concentration, ion valence, number of nanoparticles and charges on nanoparticles.