Viscoelastic properties of attractive and repulsive colloidal glasses

TL;DR

This study uses numerical simulations to analyze how short-range attractive colloids transition into glassy states, revealing distinct microscopic mechanisms for viscosity increase near repulsive and attractive glass transitions.

Contribution

It provides a detailed numerical investigation of the shear viscosity and elastic moduli near dynamical arrest in attractive colloids, highlighting different fluctuation controls for repulsive and attractive glasses.

Findings

Viscosity diverges with a power law near the glass transition.

Density fluctuations near the first peak control viscosity in repulsive glasses.

Larger wavevector fluctuations dominate near attractive glasses.

Abstract

We report a numerical study of the shear viscosity and the frequency dependent elastic moduli close to dynamical arrest for a model of short-range attractive colloids, both for the repulsive and the attractive glass transition. Calculating the stress autocorrelation functions, we find that density fluctuations of wavevectors close to the first peak in the structure factor control the viscosity rise on approaching the repulsive glass, while fluctuations of larger wavevectors control the viscosity close to the attractive glass. On approaching the glass transition, the viscosity diverges with a power law with the same exponent as the density autocorrelation time.