Faceting and flattening of emulsion droplets: a mechanical model

TL;DR

This paper presents a comprehensive mechanical model explaining the morphological transformations of cooled emulsion droplets with frozen interfaces, accounting for experimental observations and highlighting the roles of gravity and spontaneous curvature.

Contribution

It introduces a new mechanical model that quantitatively explains the faceting and flattening transitions of emulsion droplets, integrating effects of gravity and interface curvature.

Findings

The model accurately predicts the scaling behavior of faceting transitions.

Gravity and spontaneous curvature are key factors in transition pathways.

Experimental observations are quantitatively explained by the model.

Abstract

When cooled down, emulsion droplets stabilized by a frozen interface of alkane molecules and surfactants have been observed to undergo a spectacular sequence of morphological transformations: from spheres to faceted icosahedra, down to flattened liquid platelets. While generally ascribed to the interplay between the elasticity of the frozen interface and surface tension, the physical mechanisms underpinning these transitions have remained elusive, despite different theoretical pictures having been proposed in recent years. In this article, we introduce a comprehensive mechanical model of morphing emulsion droplets, which quantitatively accounts for various experimental observations, including the scaling behavior of the faceting transition. Our analysis highlights the role of gravity and the spontaneous curvature of the frozen interface in determining the specific transition pathway.