Local influence of boundary conditions on a confined supercooled colloidal liquid

TL;DR

This study investigates how boundary conditions and confinement affect the dynamics of colloidal particles in a supercooled liquid, revealing confinement as the main factor slowing particle motion and boundary effects causing slight mobility gradients.

Contribution

It provides new insights into how boundary conditions influence particle mobility in confined colloidal suspensions, modeling behaviors relevant to glass-forming systems.

Findings

Confinement significantly slows particle motion.

Proximity to stuck boundary particles further reduces mobility.

Particle mobility shows a slight gradient due to boundary asymmetry.

Abstract

We study confined colloidal suspensions as a model system which approximates the behavior of confined small molecule glass-formers. Dense colloidal suspensions become glassier when confined between parallel glass plates. We use confocal microscopy to study the motion of confined colloidal particles. In particular, we examine the influence particles stuck to the glass plates have on nearby free particles. Confinement appears to be the primary influence slowing free particle motion, and proximity to stuck particles causes a secondary reduction in the mobility of free particles. Overall, particle mobility is fairly constant across the width of the sample chamber, but a strong asymmetry in boundary conditions results in a slight gradient of particle mobility.