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

Xi Zhang,Ya-Zhou Shi,Xiao-Long Zhu,Jin-Si Zhang,Zhi-Jie Tan

doi:10.1038/srep23434

Xi Zhang, Ya-Zhou Shi + Show 3 more

Open Access

https://doi.org/10.1038/srep23434

Copy DOI

Journal: Scientific reports	Publication Date: Mar 21, 2016
Citations: 26	License type: CC BY 4.0

Affiliation: Wuhan University, Jianghan University

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.

Highlights

Ion-mediated interaction is important for the properties of polyelectrolytes such as colloids and nucleic acids
The counterion condensation (CC) theory has been extended for many-body like-charged rods to show the non-additivity of the potential of mean force (PMF) between charged rods, while the theory always predicts an effective attraction between rods even at low monovalent salt[37]
In analogy to 1:1 salt, we have examined how the charge density on nanoparticles affects the many-body effect on PMF between nanoparticles in 2:2 salt solutions, and we use different charges of Z = − 20e and − 28e on each nanoparticle to calculate the PMFs for two-body, three-body and four-body systems

Summary

Introduction

Ion-mediated interaction is important for the properties of polyelectrolytes such as colloids and nucleic acids. Such many-body effect on enhancing attractive PMF at low 2:2 salt is coupled to divalent ion-binding to nanoparticles.

Results

Conclusion