Fri August 24th 2018
11:30 – 12:30
Seminar Particle-stabilized sprouting drops: alone and in pairs
Paul Clegg


A layer of colloidal particles will become irreversibly trapped at a fluid–fluid interface if they exhibit partial wettability with both fluid phases. When the interfaces are densely coated with particles, they behave like rigid elastic sheets with moduli that are proportional to the underlying interfacial tension. The interfaces are permeable, a characteristic that can, for example, lead to compositional ripening of particle-stabilized emulsions.
Here we show that when particle-stabilized water drops are created in a bath of toluene with ethanol, millimetre-scale tubes are observed to sprout from the top of the drops. [1] Growth is driven by the ethanol partitioning from the toluene into the water which leads to an internal overpressure. Vertical growth occurs over many minutes; finally the tube buckles when it can no longer support its own weight. This novel growth behaviour can be controlled by varying the concentration or the nature of the alcohol [2] or by changing the concentration of particles in the bath.
When two such drops, with differing chemical composition, are in close proximity further solvent exchange is also driven by this composition difference. We show how this can lead to complex self-assembly behaviour of spontaneously formed tiny droplets within the bath phase. [3]
[1] Graužinytė, M., Forth, J., Rumble, K. A, & Clegg, P. S. (2015). Angewandte Chemie (Int. Ed.), 54, 1456–1460.
[2] Rumble, K. A., Stoev, I. D., French, D. J., Abou-Hassan, A., & Clegg, P. S. (2017). Langmuir, 33, 4235–4241.
[3] Otero, J., Meeker, S., & Clegg, P. S. (2018). Soft Matter, 14, 3783–3790.
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The 32nd International Conference on High-Speed Imaging and Photonics ICHSIP-32

Max Planck Gesellschaft
Centre for Scientific Computing