Comment on "Faceting and Flattening of Emulsion Droplets: A Mechanical Model"

TL;DR

This paper demonstrates that the elastic model with intrinsic curvature for shape-shifting droplets is mathematically equivalent to a phase-transition mechanism, challenging claims about the underlying process of droplet deformation.

Contribution

It reveals the mathematical equivalence between the elastic and phase-transition models of droplet deformation, questioning the uniqueness of the proposed mechanism.

Findings

Models are mathematically equivalent, making them indistinguishable experimentally.

Surface tension and intrinsic curvature interplay can mimic phase transitions.

Claims of a single underlying mechanism are not supported without detailed comparison.

Abstract

Garc\'ia-Aguilar et al. [Phys. Rev. Lett 126, 038001 (2021)] have shown that the deformations of "shape-shifting droplets" are consistent with an elastic model, that, unlike previous models, includes the intrinsic curvature of the frozen surfactant layer. In this Comment, we show that the interplay between surface tension and intrinsic curvature in their model is in fact mathematically equivalent to a physically very different phase-transition mechanism of the same process that we developed previously [Phys. Rev. Lett. 118, 088001 (2017); Phys. Rev. Res. 1, 023017 (2019)]. The mathematical models cannot therefore distinguish between the two mechanisms, and hence it is not possible to claim that one mechanism underlies all observed shape-shifting phenomena without a much more detailed comparison of experiment and theory.