Glass Transition in Monolayers of Rough Colloidal Ellipsoids

TL;DR

This study explores how surface roughness in colloidal ellipsoids influences the glass transition, revealing that roughness can eliminate certain glassy states and alter structure-dynamics correlations in monolayer suspensions.

Contribution

It demonstrates that surface roughness significantly modifies the glass transition behavior and structure-dynamics coupling in colloidal ellipsoids, a novel insight into particle shape effects.

Findings

Roughness eliminates orientational glass in monolayers.

Surface roughness destroys two-step glass transition.

Coupling between translational and rotational degrees is induced by roughness.

Abstract

Structure-dynamics correlation is one of the major ongoing debates in the glass transition, although a number of structural features have been found connected to the dynamic heterogeneity in different glass-forming colloidal systems. Here using colloidal experiments combined with coarse-grained molecular dynamics simulations, we investigate the glass transition in monolayers of rough colloidal ellipsoids. Compared with smooth colloidal ellipsoids, the surface roughness of ellipsoids is found to significantly change the nature of glass transition. In particular, we find that the surface roughness induced by coating only a few small hemispheres on the ellipsoids can eliminate the existence of orientational glass and the two-step glass transition found in monolayers of smooth ellipsoids. This is due to the surface roughness-induced coupling between the translational and rotational degrees of freedom in colloidal ellipsoids, which also destroys the structure-dynamics correlation found in glass-forming suspensions of colloidal ellipsoids. Our results not only suggest a new way of using surface roughness to manipulate the glass transition in colloidal systems, but also highlight the importance of detailed particle shape on the glass transition and structure-dynamics correlation in suspensions of anisotropic colloids.