Arrested state of clay-water suspensions: gel or glass?

TL;DR

This study investigates the aging process of charged clay-water suspensions using scattering techniques, revealing two distinct arrested states—gel-like at low concentrations and glass-like at high concentrations—based on volume fraction changes.

Contribution

It provides the first direct experimental evidence of two different arrested states in a single colloidal system, distinguished by concentration and aging behavior.

Findings

Inhomogeneous arrested state at low concentrations.

Homogeneous arrested state at high concentrations.

Evolution of static structure factor with aging time.

Abstract

The aging of a charged colloidal system has been studied by Small Angle X-rays Scattering, in the exchanged momentum range Q=0.03 - 5 nm-1, and by Dynamic Light Scattering, at different clay concentrations (Cw =0.6 % - 2.8 %). The static structure factor, S(Q), has been determined as a function of both aging time and concentration. This is the first direct experimental evidence of the existence and evolution with aging time of two different arrested states in a single system simply obtained only by changing its volume fraction: an inhomogeneous state is reached at low concentrations, while a homogenous one is found at high concentrations.