La magnétisante histoire de la goutte fakir ou étude des propriétés de mouillage de surfaces superhydrophobes à géométrie magnétiquement modulable

Abstract : During this thesis, we have developped superhydrophobic surfaces whose wettability can be controlled by an external magnetic stimulus. Formulating a network of elastomeric and magnetic micro-pillars with high aspect ratio allows the orientation of the pillars through magnetic forces, hence an adaptable surface roughness. Moreover, modulating the geometry, elasticity and magnetization of pillars allowed us to highlight the following conclusions.We have seen first that in agreement with the literature, without magnetic field, the wetting hysteresis increased with the surface fraction. However, it remains constant varying the elasticity of pillars. This conclusion is confusing, because at the pillar scale, there is indeed a difference of mobility between rigid and flexible pillars due to the force exerted by the triple line.We then demonstrated that the deflexion of the pillars can change significantly the sliding angle due to the applied magnetic field. Moreover, sliding of the droplet on such a surface is promoted when pillars are deflected against the slope.Finally, we managed to control the displacement of a droplet on a surface which is tilted with an angle below the sliding angle : it moves forward from the surface only if magnetic actuation is applied. This surfaces will be an attractive source of study in order to understand how to modulate wetting and liquid flow in fakir state.
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Blandine Bolteau. La magnétisante histoire de la goutte fakir ou étude des propriétés de mouillage de surfaces superhydrophobes à géométrie magnétiquement modulable. Chimie théorique et/ou physique. Sorbonne Université, 2018. Français. ⟨NNT : 2018SORUS062⟩. ⟨tel-02163924⟩

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