PhD defence: Structure and Stability of Bicontinuous Colloid-Stabilized Emulsions: Insights from X-ray Scattering and Microscopy

PLEASE NOTE: If a candidate gives a layman's talk, the livestream will start fifteen minutes earlier.

Manufacturing industries often depend on chemical solvents and energy-intensive processes. Climate change, however, calls for more sustainable and cleaner ways to fabricate products for daily life. One promising solution are emulsions: mixtures of two liquids like oil and water, that can enable reactions and separations without solvents or energy-demanding steps. Because emulsions typically consist of separate droplets, substances are restricted in their movements between them, which limits their efficiency in industrial processes.

A more advanced emulsion type, called bijels, forms an interwoven network of oil and water channels instead of droplets. This network is held together by a dense layer of nanoparticles with stabilising molecules, which allows for efficient transport of chemical substances. Their complex fabrication and tendency to break down, tough, still prevent bijels from being widely used.

In this thesis, we first unravel how bijels form using advanced X-ray techniques. By analysing how rapidly liquid networks grow and how nanoparticles organize out of a liquid mixture, we reveal how nanoparticles and stabilising molecules influence the formation and structure of bijels. These insights contribute to improve the fabrication methods.

We then focus on strengthening bijels. Microscopy studies show that liquids, especially water, tend to leave the network over time. By slowing this process, the bijel lifetime extends from hours to several weeks. Additionally, by growing a solid coating on the particles, we can control the strength and porosity of those networks. Together, these fundamental insights into bijel formation, stabilisation and strengthening open up new ways to design robust, particle-laden materials for sustainable, industrial applications.