Quantitative Morphological Optimization of Bicontinuous Pickering Emulsions via Interfacial Curvatures

TL;DR

This study uses advanced imaging techniques to analyze the interfacial curvatures of bicontinuous Pickering emulsions, revealing their evolution over time and providing a new way to optimize their structure beyond porosity alone.

Contribution

It introduces a curvature-based characterization method for bijels and demonstrates their temporal evolution, offering new insights for structural optimization.

Findings

Interfacial curvatures vary with time up to 60 minutes after formation.

Curvature analysis provides additional parameters for bijel optimization.

Bijel structure evolution challenges previous assumptions about stability.

Abstract

Bicontinuous Pickering emulsions (bijels) are a physically interesting class of soft materials with many potential applications including catalysis, microfluidics and tissue engineering. They are created by arresting the spinodal decomposition of a partially-miscible liquid with a (jammed) layer of interfacial colloids. Porosity $L$ (average interfacial separation) of the bijel is controlled by varying the radius ($r$) and volume fraction ($\phi$) of the colloids ($L \propto r/\phi$). However, to optimize the bijel structure with respect to other parameters, e.g. quench rate, characterizing by $L$ alone is insufficient. Hence, we have used confocal microscopy and X-ray CT to characterize a range of bijels in terms of local and area-averaged interfacial curvatures. In addition, the curvatures of bijels have been monitored as a function of time, which has revealed an intriguing evolution up to 60 minutes after bijel formation, contrary to previous understanding.