Colloidal stabilization via nanoparticle haloing

TL;DR

This paper uses numerical simulations to explore how charged nanoparticles can stabilize colloidal suspensions by inducing effective repulsive interactions, with results matching experimental observations and revealing reentrant gelation at higher concentrations.

Contribution

It introduces a detailed numerical analysis of nanoparticle-induced stabilization mechanisms in colloids, employing advanced Monte Carlo methods and theoretical comparisons.

Findings

Small nanoparticle concentrations stabilize colloids via repulsion.

Higher concentrations lead to reentrant gelation due to attraction.

Simulation results align with experimental and theoretical models.

Abstract

We present a detailed numerical study of effective interactions between micron-sized silica spheres, induced by highly charged zirconia nanoparticles. It is demonstrated that the effective interactions are consistent with a recently discovered mechanism for colloidal stabilization. In accordance with the experimental observations, small nanoparticle concentrations induce an effective repulsion that counteracts the intrinsic van der Waals attraction between the colloids and thus stabilizes the suspension. At higher nanoparticle concentrations an attractive potential is recovered, resulting in reentrant gelation. Monte Carlo simulations of this highly size-asymmetric mixture are made possible by means of a geometric cluster Monte Carlo algorithm. A comparison is made to results obtained from the Ornstein-Zernike equations with the hypernetted-chain closure.