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Proc Natl Acad Sci U S A. 2017 Sep 26;114(39):10373-10378. doi: 10.1073/pnas.1705181114. Epub 2017 Sep 11.

Arresting dissolution by interfacial rheology design.

Author information

1
Department of Materials, ETH Zürich, CH-8093 Zürich, Switzerland.
2
Department of Chemical Engineering, KU Leuven, University of Leuven, B-3001 Heverlee, Belgium.
3
LadHyX and Department of Mechanics, Ecole Polytechnique, CNRS, 91128 Palaiseau Cedex, France.
4
Institute of Material Science, Nestle Research Center, CH-1000 Lausanne 26, Switzerland.
5
Department of Materials, ETH Zürich, CH-8093 Zürich, Switzerland; jan.vermant@mat.ethz.ch.

Abstract

A strategy to halt dissolution of particle-coated air bubbles in water based on interfacial rheology design is presented. Whereas previously a dense monolayer was believed to be required for such an "armored bubble" to resist dissolution, in fact engineering a 2D yield stress interface suffices to achieve such performance at submonolayer particle coverages. We use a suite of interfacial rheology techniques to characterize spherical and ellipsoidal particles at an air-water interface as a function of surface coverage. Bubbles with varying particle coverages are made and their resistance to dissolution evaluated using a microfluidic technique. Whereas a bare bubble only has a single pressure at which a given radius is stable, we find a range of pressures over which bubble dissolution is arrested for armored bubbles. The link between interfacial rheology and macroscopic dissolution of [Formula: see text] 100 [Formula: see text]m bubbles coated with [Formula: see text] 1 [Formula: see text]m particles is presented and discussed. The generic design rationale is confirmed by using nonspherical particles, which develop significant yield stress at even lower surface coverages. Hence, it can be applied to successfully inhibit Ostwald ripening in a multitude of foam and emulsion applications.

KEYWORDS:

Ostwald ripening; emulsions; foams; interfacial rheology; yield stress

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