Chemically reactive and aging macromolecular mixtures II: Phase separation and coarsening

TL;DR

This paper develops a thermodynamically consistent kinetic model to analyze how phase separation, chemical reactions, and aging influence the behavior of complex macromolecular mixtures, highlighting the impact of gelation and Brownian motion on domain coarsening.

Contribution

It introduces a novel kinetic framework and numerical algorithm to study the interplay of phase separation, chemical reactions, and aging in inhomogeneous macromolecular systems.

Findings

Gelation significantly limits diffusive transport.

Brownian motion coalescence dominates coarsening in gel-rich systems.

Atypical domain growth rates emerge due to size-dependent diffusivities.

Abstract

In a companion paper, we put forth a thermodynamic model for complex formation via a chemical reaction involving multiple macromolecular species, which may subsequently undergo liquid-liquid phase separation and a further transition into a gel-like state. In the present work, we formulate a thermodynamically consistent kinetic framework to study the interplay between phase separation, chemical reaction and aging in spatially inhomogeneous macromolecular mixtures. A numerical algorithm is also proposed to simulate domain growth from collisions of liquid and gel domains via passive Brownian motion in both two and three spatial dimensions. Our results show that the coarsening behavior is significantly influenced by the degree of gelation and Brownian motion. The presence of a gel phase inside condensates strongly limits the diffusive transport processes, and Brownian motion coalescence controls the coarsening process in systems with high area/volume fractions of gel-like condensates, leading to formation of interconnected domains with atypical domain growth rates controlled by size-dependent translational and rotational diffusivities.