Numerical analysis of Pickering emulsion stability: insights from ABMD simulations

TL;DR

This study uses dissipative particle dynamics simulations to analyze the stability mechanisms of Pickering emulsions at a mesoscopic level, focusing on droplet coalescence influenced by nanoparticle properties and collision speed.

Contribution

It introduces a mesoscopic simulation approach to understand how nanoparticle shape, contact angle, and collision dynamics affect Pickering emulsion stability.

Findings

Stabilization depends on collision speed and interfacial rheology.

Slow coalescence reveals nanoparticle mobility and caging effects.

Interparticle interactions and hydrodynamics influence emulsion stability.

Abstract

The issue of the stability of Pickering emulsions is tackled at a mesoscopic level using dissipative particle dynamics simulations within the Adiabatic Biased Molecular Dynamics framework. We consider the early stage of the coalescence process between two spherical water droplets in decane solvent. The droplets are stabilized by Janus nanoparticles of different shapes (spherical and ellipsoidal) with different three-phase contact angles. Given a sufficiently dense layer of particles on the droplets, we show that the stabilization mechanism strongly depends on the collision speed. This is consistent with a coalescence mechanism governed by the rheology of the interfacial region. When the system is forced to coalesce sufficiently slowly, we investigate at a mesoscopic level how the ability of the nanoparticles to stabilize Pickering emulsions is discriminated by nanoparticle mobility and the associated caging effect. These properties are both related to the interparticle interaction and the hydrodynamic resistance in the liquid film between the approaching interfaces.