Superhydrophobie Active

Abstract : A droplet of water on a lotus leaf stays spherical as a bead, and rolls very easily without leaving any trace behind; the leaf is thus protected from water and stays dry. This property is called superhydrophobicity, or « Lotus effect ». This thesis is about studying remarkable surperhydrophobic behaviors in nature and understanding their origins to inspire the creation of new materials.A part of this thesis is dedicated to an unusual spider, the Diving Bell spider, which has everything of a terrestrial spider, especially its structure and respiratory system, but that lives its entire life under water. To breath oxygen in the gas form, it constructs itself a bell of air under water by accumulating bubbles that it pulls from the water surface, thanks to its superhydrophobic abdomen. We are interested in the coupling of the superhydrophobic properties of its abdomen and the dynamic of the air cavities pulled by the spider when it leaves an air/water interface.We also design new sensitive and active water repelling materials, inspired by living superhydrophobic sur- faces in nature. It is now well established that the rugosity of a surface plays a crucial role in its wetting properties. The goal is therefore to tune a generally fixed rugosity. A way to do so, is to make the textures with a material that we can modify the mechanical properties of, for example its elasticity. To take it a step further, it is an interesting challenge to create surfaces of which one can modify the structure of the textures by applying external stimuli, so as to tune their wetting properties. Finally, we show that the behavior of a non-wetting drop on such surfaces can depend on its rheological properties, and especially viscosity.
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Submitted on : Wednesday, October 22, 2014 - 11:58:24 AM
Last modification on : Thursday, July 4, 2019 - 11:00:05 AM
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Raphaële Thévenin. Superhydrophobie Active. Physique [physics]. Ecole polytechnique, 2014. Français. ⟨pastel-01074498⟩

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