Multiphase coexistence in polydisperse colloidal mixtures

TL;DR

This paper investigates the phase behavior of polydisperse colloidal mixtures with complex depletion agents using free-volume and fundamental measure theories, revealing the possibility of multiple stable critical points in the phase diagram.

Contribution

It introduces a theoretical framework combining free-volume and fundamental measure theories to analyze phase diagrams of polydisperse colloidal mixtures with arbitrary-shaped depletion agents.

Findings

Complex phase diagrams with two stable critical points can be engineered by tuning polymer distributions.

The approach accounts for particle geometry and polydispersity in phase behavior predictions.

The method extends understanding of multiphase coexistence in colloidal systems.

Abstract

We study the phase behavior of mixtures of monodisperse colloidal spheres with a depletion agent which can have arbitrary shape and can possess a polydisperse size or shape distribution. In the low concentration limit, considered here, we can employ the free-volume theory and take the geometry of particles of the depletion agent into account within the framework of fundamental measure theory. We apply our approach to study the phase diagram of a mixture of (monodisperse) colloidal spheres and two polydisperse polymer components. By fine tuning the distribution of the polymer it is possible to construct a complex phase diagram which exhibits two stable critical points.