Phase behaviour of additive binary mixtures in the limit of infinite asymmetry

TL;DR

This paper derives an exact mapping for the phase behavior of highly asymmetric binary mixtures of hard particles, revealing how their demixing transitions relate to effective one-component fluids with adhesive interactions.

Contribution

It introduces an exact mapping between the density functional of a binary mixture and that of an effective one-component fluid in the limit of infinite asymmetry, providing new insights into phase behavior.

Findings

Demixing occurs between solvent-rich and large particle solid phases.

Phase behavior of asymmetric mixtures can be predicted from large component interactions.

Comparison with hard sphere mixtures highlights the role of adhesive potentials.

Abstract

We provide an exact mapping between the density functional of a binary mixture and that of the effective one-component fluid in the limit of infinite asymmetry. The fluid of parallel hard cubes is thus mapped onto that of parallel adhesive hard cubes. Its phase behaviour reveals that demixing of a very asymmetric mixture can only occur between a solvent-rich fluid and a permeated large particle solid or between two large particle solids with different packing fractions. Comparing with hard spheres mixtures we conclude that the phase behaviour of very asymmetric hard-particle mixtures can be determined from that of the large component interacting via an adhesive-like potential.