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Article Dans Une Revue Proceedings of the National Academy of Sciences of the United States of America Année : 2018

Geometrical control of dissipation during the spreading of liquids on soft solids

Résumé

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. Here we show that the adjustment of coating thickness provides control over energy dissipation during the spreading of flowing matter on a gel layer. We combine experiments and theory to provide an analytical description of both the statics and the dynamics of the contact line between the gel, the liquid and the surrounding atmosphere. We extract from this analysis a hitherto unknown 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. Finally, we show that droplets moving on vertical substrates coated with gel layers having linear thickness gradients drift towards regions of higher energy dissipation. Thus thickness control opens the opportunity to design a priori the path followed by large droplets moving on gel-coated substrates. Our study shows that thickness is another parameter, besides surface energy and sub-strate mechanics, to tune the dynamics of liquid spreading and wetting on a compliant coating, with potential applications in dew collection and free-surface flow control. Wetting | Soft Materials |
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Dates et versions

hal-01836567 , version 1 (12-07-2018)

Identifiants

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Menghua Zhao, Julien Dervaux, Tetsuharu Narita, Francois Lequeux, Laurent Limat, et al.. Geometrical control of dissipation during the spreading of liquids on soft solids. Proceedings of the National Academy of Sciences of the United States of America, 2018, 115 (8), pp.1748-1753. ⟨10.1073/pnas.1712562115⟩. ⟨hal-01836567⟩
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