Interconversion-controlled liquid-liquid phase separation in a molecular chiral model

TL;DR

This study uses a molecular model to explore how interconversion and force imbalances influence liquid-liquid phase separation, revealing mechanisms for microdomain formation and phase amplification relevant to biological systems.

Contribution

It introduces a chiral off-lattice model to analyze the effects of force imbalance and interconversion on phase separation, providing new insights into fluid morphologies.

Findings

Force imbalance leads to arrested microdomain phase separation.

In equilibrium, phase growth is limited only by system size.

Phase amplification occurs when one phase dominates at steady state.

Abstract

Liquid-liquid phase separation of liquids exhibiting interconversion between alternative states has been proposed as an underlying mechanism for fluid polyamorphism, and may be of relevance to protein function and intracellular organization. However, molecular-level insight into the interplay between competing forces that can drive or restrict phase separation in interconverting fluids remains elusive. Here, we utilize an off-lattice model of enantiomers with tunable chiral interconversion and interaction properties to elucidate the physics underlying the stabilization and tunability of phase separation in fluids with interconverting states. We show that introducing an imbalance in the intermolecular forces between two enantiomers results in nonequilibrium, arrested phase separation into microdomains. We also find that in the equilibrium case, when all interaction forces are conservative, the growth of the phase domain is restricted only by system size. In this case, we observe phase amplification, in which one of the two alternative phases grows at the expense of the other. These findings provide novel insights on how the interplay between dynamics and thermodynamics defines the equilibrium and steady-state morphologies of phase transitions in fluids with interconverting molecular or supramolecular states.