Equilibrium route to colloidal gellation: mixtures of hard sphere-like colloids

TL;DR

This paper investigates how binary mixtures of large size ratio hard sphere-like colloids undergo equilibrium gelation driven by depletion interactions, revealing conditions where gellation occurs without phase separation.

Contribution

It introduces a theoretical framework to compute binodals and non-ergodicity lines, showing that physical gellation can happen without fluid-phase separation in such mixtures.

Findings

Gellation can occur without phase separation in large size ratio colloidal mixtures.

Oscillations in the depletion potential are key to this behavior.

The results are relevant for all simple mixtures with non-ideal depletants.

Abstract

The binodals and the non-ergodicity lines of a binary mixture of hard sphere-like particles with large size ratio are computed for studying the interplay between dynamic arrest and phase separation in depletion-driven colloidal mixtures. Contrarily to the case of hard core plus short range effective attraction, physical gellation without competition with the fluid-phase separation can occur in such mixtures. This behavior due to the oscillations in the depletion potential should concern all simple mixtures with non-ideal depletant, justifying further studies of their dynamic properties.