(488c) Arresting Dissolution By Interfacial Rheology Design

A strategy to halt dissolution of particle coated air bubbles in water based on interfacial rheology design will be presented. Whereas previously a dense monolayer was believed to be required for such an “armored bubble” to resist dissolution, in fact engineering a two-dimensional yield stress interface suffices to achieve such performance at sub-monolayer particle coverages. We use a suite of interfacial rheology techniques to characterize the behavior of spherical PS-PVP particles at an air-water interface as a function of surface coverage. Spherical 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. This pressure window is dictated by the particle surface coverage and the yield stress of the interface. The link between interfacial rheology and macroscopic dissolution of ∼100μm bubbles coated with ∼1μm PS-PVP particles is presented and discussed. The results imply a generic design rationale that can be applied to successfully inhibit Ostwald ripening in a multitude of foam and emulsion applications.