Effects of contact-line pinning on the adsorption of nonspherical colloids at liquid interfaces

TL;DR

This study investigates how contact-line pinning influences the adsorption dynamics of nonspherical colloids at liquid interfaces, revealing that pinning significantly affects the pathway and timescale of particle adsorption beyond energy minimization.

Contribution

It introduces experimental evidence of contact-line pinning effects on colloid adsorption dynamics at microscale, challenging traditional energy minimization models.

Findings

Particle angle varies linearly with height during adsorption

Contact-line pinning couples translational and rotational motion

Pinning controls the timescale and pathway to equilibrium

Abstract

The effects of contact-line pinning are well-known in macroscopic systems, but are only just beginning to be explored at the microscale in colloidal suspensions. We use digital holography to capture the fast three-dimensional dynamics of micrometer-sized ellipsoids breaching an oil-water interface. We find that the particle angle varies approximately linearly with the height, in contrast to results from simulations based on minimization of the interfacial energy. Using a simple model of the motion of the contact line, we show that the observed coupling between translational and rotational degrees of freedom is likely due to contact-line pinning. We conclude that the dynamics of colloidal particles adsorbing to a liquid interface are not determined by minimization of interfacial energy and viscous dissipation alone; contact-line pinning dictates both the timescale and pathway to equilibrium.