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Communication Dans Un Congrès Année : 2019

Static and dynamic contact lines on a deformable coating of controled thickness

Résumé

Figure: From left to right: (a) drop on a soft substrate (water on PDMS), (b) structure near contact line, (c) non-linear simulations of the shear stress distribution below the contact line, whose intensity is encoded by the colours. Gel layers bound to a rigid substrate are used in cell culture to control differentiation and migration and to lower the friction and tailor the wetting of solids. Their thickness, often considered a negligible parameter, affects cell mechanosensing or the shape of sessile droplets [1]. We show first that the adjustment of thickness provides control over energy dissipation during the spreading of flowing matter on a gel layer [2]. We combine experiments and theory to uncover a scaling law that predicts the dynamic contact angle between the three phases as a function of the properties of the coating and the velocity of the contact line. We also demonstrate that thickness gradients can guide moving droplets. Our study shows that thickness is another parameter, besides surface energy and substrate mechanics, to tune liquid spreading and wetting on compliant coating, with potential applications to dew collection and free-surface film flow control. In a second step, we investigate numerically and theoretically the problem when the slope of the gel surface becomes non-negligible, the material reaching a regime of finite deformations, with non-linearities of geometrical origin. We show that both statics and dynamics are completely modified, a singular force displacing the well-known Neumann balance of forces at contact line [3]. We provide a general framework allowing to develop approximate analytical calculations, and give general laws governing the static and dynamic contact angle in this complex, non-linear regime. [1] J. Dervaux and L. Limat, "Contact lines on soft solids with uniform surface tension: analytical solutions and double transition for increasing deformability", Proc. R. Soc. A 471, 20140813 (2015) [2] M. Zhao, J. Dervaux, T. Narita, F. Lequeux, L. Limat, and M. Roché, "Geometrical control of dissipation during the spreading of liquids on soft solids",
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Dates et versions

hal-02357795 , version 1 (10-11-2019)

Identifiants

  • HAL Id : hal-02357795 , version 1

Citer

Menghua Zhao, Julien Dervaux, Tetsuharu Narita, François Lequeux, Laurent Limat, et al.. Static and dynamic contact lines on a deformable coating of controled thickness. ECS 2019, European Coating Symposium, Wilhelm Schabel; Philip Scharfer, Sep 2019, Heidelberg, Germany. pp.T-12. ⟨hal-02357795⟩
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