Numerical simulations of self-diffusiophoretic colloids at fluid interfaces

TL;DR

This study uses numerical simulations to explore how active colloids behave at fluid interfaces, revealing that they experience a net torque influenced by contact angle and surface properties, which impacts their potential applications.

Contribution

It introduces a mesoscopic numerical approach to analyze active colloids at fluid interfaces and uncovers the torque effects independent of viscosity contrast.

Findings

Active colloids experience a net torque at fluid interfaces.

Torque depends on contact angle and surface properties.

Results inform self-assembly and emulsion stabilization strategies.

Abstract

The dynamics of active colloids is very sensitive to the presence of boundaries and interfaces which therefore can be used to control their motion. Here we analyze the dynamics of active colloids adsorbed at a fluid-fluid interface. By using a mesoscopic numerical approach which relies on an approximated numerical solution of the Navier-Stokes equation, we show that when adsorbed at a fluid interface, an active colloid experiences a net torque even in the absence of a viscosity contrast between the two adjacent fluids. In particular, we study the dependence of this torque on the contact angle of the colloid with the fluid-fluid interface and on its surface properties. We rationalize our results via an approximate approach which accounts for the appearance of a local friction coefficient. By providing insight into the dynamics of active colloids adsorbed at fluid interfaces, our results are relevant for two-dimensional self assembly and emulsion stabilization by means of active colloids.