Particle-Size Effects in the Formation of Bicontinuous Pickering Emulsions

TL;DR

This study shows that nanoparticles create more robust bicontinuous emulsions (bijels) than microparticles, allowing formation at slower heating rates due to their smaller disruptive curvature, with implications for formulation flexibility.

Contribution

The paper introduces the concept of mechanical leeway, explaining how nanoparticles enable bijel formation under less restrictive conditions compared to microparticles.

Findings

Nanoparticles allow bijel formation at heating rates 100 times slower than microparticles.

Nanoparticles benefit from smaller driving forces towards disruptive curvature.

The concept of mechanical leeway can be applied to other formulations with restrictive parameters.

Abstract

We demonstrate that the formation of bicontinuous emulsions stabilized by interfacial particles (bijels) is more robust when nanoparticles rather than microparticles are used. Emulsification via spinodal demixing in the presence of nearly neutrally wetting particles is induced by rapid heating. Using confocal microscopy, we show that nanospheres allow successful bijel formation at heating rates two orders of magnitude slower than is possible with microspheres. In order to explain our results, we introduce the concept of mechanical leeway i.e. nanoparticles benefit from a smaller driving force towards disruptive curvature. Finally, we suggest that leeway mechanisms may benefit any formulation in which challenges arise due to tight restrictions on a pivotal parameter, but where the restrictions can be relaxed by rationally changing the value of a more accessible parameter.