Arresting bubble coarsening: A two-bubble experiment to investigate grain growth in presence of surface elasticity

TL;DR

This study investigates how surface elasticity influences bubble coarsening, combining experiments and modeling to predict relationships between surface properties and bubble size evolution, with implications for foam stability.

Contribution

It introduces a modified Gibbs criterion to explain how surface elasticity can arrest bubble coarsening, advancing understanding of foam stability mechanisms.

Findings

Surface elasticity can significantly slow down or arrest bubble coarsening.

Predicted relationships between surface tension, elasticity, and bubble size ratios.

Modified Gibbs criterion explains the conditions for coarsening arrest.

Abstract

Many two-phase materials suffer from grain-growth due to the energy cost which is associated with the interface that separates both phases. While our understanding of the driving forces and the dynamics of grain growth in different materials is well advanced by now, current research efforts address the question of how this process may be slowed down, or, ideally, arrested. We use a model system of two bubbles to explore how the presence of a finite surface elasticity may interfere with the coarsening process and the final grain size distribution. Combining experiments and modelling in the analysis of the evolution of two bubbles, we show that clear relationships can be predicted between the surface tension, the surface elasticity and the initial/final size ratio of the bubbles. We rationalise these relationships by the introduction of a modified Gibbs criterion. Besides their general interest, the present results have direct implications for our understanding of foam stability.