Connectivity dynamics in the vitrification of colloidal liquids

TL;DR

This paper investigates how microscopic connectivity changes in charged colloidal liquids lead to vitrification, extending elastic models to quantitatively predict the dramatic increase in viscosity near the glass transition.

Contribution

It provides the first direct measurement of connectivity dynamics in colloidal liquids approaching vitrification and extends Dyre's elastic model to include particle-level dynamics.

Findings

Connectivity dynamics correlate with viscosity increase

Extended elastic model accurately predicts relaxation slowdown

Quantitative agreement between model and experiments

Abstract

While various structural and dynamical precursors to vitrification have been identified, a predictive and quantitative description of how subtle changes at the microscopic scale give rise to the steep growth in macroscopic viscosity is missing. It was proposed that the presence of long-lived bonded structures within the liquid may provide this connection. Here we directly observe and quantify the connectivity dynamics in liquids of charged colloids en-route to vitrification. Based on these data, we extend Dyre's elastic model for the glass transition to account for particle-level dynamics; this results in a parameter-free expression for the slowing down of relaxations in the liquid that is in quantitative agreement with our experiments.