Critical behavior in colloid-polymer mixtures: theory and simulation

TL;DR

This study combines theoretical and simulation approaches to analyze the critical behavior of colloid-polymer mixtures, confirming Ising universality and highlighting the effects of long-range fluctuations on phase separation.

Contribution

It applies hierarchical reference theory and simulations to accurately characterize critical phenomena in colloid-polymer mixtures, bridging one- and two-component models.

Findings

Critical exponents align with 3D Ising model

Simulations confirm Ising universality class

Discrepancy in critical point location between models

Abstract

We extensively investigated the critical behavior of mixtures of colloids and polymers via the two-component Asakura-Oosawa model and its reduction to a one-component colloidal fluid using accurate theoretical and simulation techniques. In particular the theoretical approach, hierarchical reference theory [Adv. Phys. 44, 211 (1995)], incorporates realistically the effects of long-range fluctuations on phase separation giving exponents which differ strongly from their mean-field values, and are in good agreement with those of the three-dimensional Ising model. Computer simulations combined with finite-size scaling analysis confirm the Ising universality and the accuracy of the theory, although some discrepancy in the location of the critical point between one-component and full-mixture description remains. To assess the limit of the pair-interaction description, we compare one-component and two-component results.