Competing interactions in arrested states of colloidal clays

TL;DR

This study combines experiments, theory, and simulations to understand the arrested states in colloidal clays, revealing the role of screened Coulomb repulsion and distinguishing between gel and glass states based on their response to dilution.

Contribution

It provides a comprehensive analysis of arrested states in colloidal clays, highlighting the stabilizing role of electrostatic interactions and differentiating gel and glass states through experimental and theoretical methods.

Findings

Arrested state is stabilized by screened Coulomb repulsion (Wigner glass)

Dilution causes melting of high-concentration disconnected state

Theoretical models match experimental structure factors and confirm electrostatic interactions

Abstract

Using experiments, theory and simulations, we show that the arrested state observed in a colloidal clay at intermediate concentrations is stabilized by the screened Coulomb repulsion (Wigner glass). Dilution experiments allow us to distinguish this high-concentration disconnected state, which melts upon addition of water, from a low-concentration gel state, which does not melt. Theoretical modelling and simulations reproduce the measured Small Angle X-Ray Scattering static structure factors and confirm the long-range electrostatic nature of the arrested structure. These findings are attributed to the different timescales controlling the competing attractive and repulsive interactions.