Boundary mobility controls glassiness of confined colloidal liquids

TL;DR

This study investigates how boundary mobility influences the dynamics and glassy behavior of confined colloidal liquids, revealing that boundary interactions significantly affect system dynamics and challenge existing descriptive measures.

Contribution

It demonstrates that boundary mobility controls the dynamics and anisotropy in confined colloidal glasses, highlighting the importance of boundary interactions in glassy systems.

Findings

Gradients in dynamics depend on boundary mobility

Boundary interactions induce anisotropic motions

Conventional measures may not fully describe confined glasses

Abstract

We use colloidal suspensions encapsulated in emulsion droplets to model confined glass-forming liquids with tunable boundary mobility. We show dynamics in these idealized systems are governed by physical interactions with the boundary. Gradients in dynamics are present for more mobile boundaries, whereas for less mobile boundaries gradients are almost entirely suppressed. Motions in a system are not isotropic, but have a strong directional dependence with respect to the boundary. These findings bring into question the ability of conventional quantities to adequately describe confined glasses.