Regular Article - Soft Matter
Active spheres induce Marangoni flows that drive collective dynamics
Technical University Dresden, Zellescher Weg 19, 01069, Dresden, Germany
2 Max Planck Institute for Intelligent Systems, Heisenbergstr. 3, 70569, Stuttgart, Germany
3 Física Teórica, Universidad de Sevilla, Apdo. 1065, 41080, Sevilla, Spain
4 Instituto Carlos I de Física Teórica y Computacional, 18071, Granada, Spain
Accepted: 21 December 2020
Published online: 8 March 2021
For monolayers of chemically active particles at a fluid interface, collective dynamics is predicted to arise owing to activity-induced Marangoni flow even if the particles are not self-propelled. Here, we test this prediction by employing a monolayer of spherically symmetric active particles located at an oil–water interface with or without addition of a nonionic surfactant. Due to the spherical symmetry, an individual particle does not self-propel. However, the gradients produced by the photochemical fuel degradation give rise to long-ranged Marangoni flows. For the case in which surfactant is added to the system, we indeed observe the emergence of collective motion, with dynamics dependent on the particle coverage of the monolayer. The experimental observations are discussed within the framework of a simple theoretical mean-field model.
© The Author(s) 2021
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