Liquid-Liquid Phase Separation in an Elastic Network

TL;DR

This paper demonstrates that stable, tunable liquid droplets can be formed within an elastic network by arresting phase separation, with droplet size controlled by network properties and process conditions, revealing new insights into phase behavior in elastic media.

Contribution

It introduces a method to produce stable, size-tunable droplets through arrested phase separation in elastic networks, highlighting the influence of elasticity on phase behavior.

Findings

Droplets nucleate and stabilize at a size dependent on network cross-linking.

Elasticity alters the threshold for macroscopic phase separation.

Droplet size and polydispersity are influenced by internuclear correlations.

Abstract

Living and engineered systems rely on the stable coexistence of two interspersed liquid phases. Yet surface tension drives their complete separation. Here we show that stable droplets of uniform and tuneable size can be produced through arrested phase separation in an elastic matrix. Starting with an elastic polymer network swollen by a solvent mixture, we change the temperature or composition to drive demixing. Droplets nucleate and grow to a stable size that is tuneable by the network cross-linking density, the cooling rate, and the composition of the solvent mixture. We discuss thermodynamic and mechanical constraints on the process. In particular, we show that the threshold for macroscopic phase separation is altered by the elasticity of the polymer network, and we highlight the role of internuclear correlations in determining the droplet size and polydispersity. This phenomenon has potential applications ranging from colloid synthesis and structural colour to phase separation in biological cells.