Coexistence diameter in two-dimensional colloid-polymer mixtures

TL;DR

This study investigates the critical behavior of two-dimensional colloid-polymer mixtures, revealing a violation of the expected coexistence diameter law and showing that particle shape alone does not induce a Yang-Yang anomaly.

Contribution

It demonstrates the violation of the rectilinear coexistence diameter law in 2D non-spherical colloid-polymer mixtures and shows the absence of a significant Yang-Yang anomaly.

Findings

Diameter exhibits t ln(t) singularity near critical point

No detectable t^2b term, indicating weak or no Yang-Yang anomaly

Particle shape alone does not cause pronounced Yang-Yang anomaly

Abstract

We demonstrate that the law of the rectilinear coexistence diameter in two-dimensional (2D) mixtures of non-spherical colloids and non-adsorbing polymers is violated. Upon approach of the critical point, the diameter shows logarithmic singular behavior governed by a term t ln(t), with t the relative distance from the critical point. No sign of a term t^2b could be detected, with b the critical exponent of the order parameter, indicating a very weak or absent Yang-Yang anomaly. Our analysis thus reveals that non-spherical particle shape alone is not sufficient for the formation of a pronounced Yang-Yang anomaly in the critical behavior of fluids.