Gel transitions in colloidal suspensions

TL;DR

This paper applies mode coupling theory to colloidal suspensions with short-range attractions, predicting gelation through ergodicity breaking and providing a detailed phase diagram and asymptotic model for low-temperature dynamics.

Contribution

It extends phase diagram calculations with new data for shorter attraction ranges and develops an asymptotic model capturing low-temperature nonergodicity transitions.

Findings

Nonergodicity transition line remains unimpeded by gas-liquid critical curve at low temperatures.

Asymptotic model accurately describes low-temperature gelation behavior.

Critical nonergodicity parameters align with recent experimental observations.

Abstract

The idealized mode coupling theory (MCT) is applied to colloidal systems interacting via short-range attractive interactions of Yukawa form. At low temperatures MCT predicts a slowing down of the local dynamics and ergodicity breaking transitions. The nonergodicity transitions share many features with the colloidal gel transition, and are proposed to be the source of gelation in colloidal systems. Previous calculations of the phase diagram are complemented with additional data for shorter ranges of the attractive interaction, showing that the path of the nonergodicity transition line is then unimpeded by the gas-liquid critical curve at low temperatures. Particular attention is given to the critical nonergodicity parameters, motivated by recent experimental measurements. An asymptotic model is developed, valid for dilute systems of spheres interacting via strong short-range attractions, and is shown to capture all aspects of the low temperature MCT nonergodicity transitions.