Communication Dans Un Congrès Année : 2021

Wetting at the nanoscale: molecular desorption induced by a moving contact line

Résumé

It is well established that the wetting properties of a surface by a given liquid largely depend on the topographic and chemical nature of the substrate, down to the nanometer scale. The coupling with the liquid can also trigger a modification of the substrate properties leading to complex situations of adaptative wetting [1]. The interplay between the substrate modification and the dynamics of the drop is an open question in wetting science, which requires new specific experiments at the molecular scale. Atomic force microscopy (AFM) is a unique tool to study the dynamics of contact line or nanomeniscus at the nanometer scale. The monitoring of the capillary force exerted by the liquid on a nanoneedle carved at the apex of the AFM tip allows measurement of surface energy, pinning on individual defects [2] or dissipation in a nanomeniscus [3]. In a recent study [4], we monitored the change of surface wettability when the tip is continuously dipped and withdrawn from the liquid a large number of times. We demonstrate that this leads to a change of the wettability of the surface while keeping the topography intact. Since the initial surface can be recovered when left in air, we interpret this behavior as a desorption of airborne contaminants by the liquid. Interestingly, using specific experiments, we unambiguously demonstrate that the desorption of physically sorbed molecules is induced at the contact line. The mechanism of molecules desorption is directly determined by the capillary force exerted at the contact line on the molecules. We also emphasize the potential of AFM to clearly decorrelate the effects of topographical and chemical defects and monitor, with a subsecond time resolution, the dynamics of molecules adsorption on a surface. References: [1] Butt, H.-J. et al., Langmuir 34 (2018) 11292. [2] Delmas M. et al., Phys. Rev. Lett. 106 (2011) 136102. [3] Mortagne C. et al., Phys. Rev. Fluid 2 (2017) 102201. [4] Franiatte S. et al., Phys. Rev. Lett. 107 (2011) 065501.

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hal-04756912 , version 1 (28-10-2024)

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  • HAL Id : hal-04756912 , version 1

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Sylvain Franiatte, Philippe Tordjeman, Thierry Ondarçuhu. Wetting at the nanoscale: molecular desorption induced by a moving contact line. Fluids and Complexity, • Céline Cohen - InPhyNi, Université de Nice-Sophia Antipolis ; Philippe Thomen - InPhyNi, Université de Nice-Sophia Antipolis; Rudy Valette - CEMEF, MINES-ParisTech, Nov 2021, Nice, France. ⟨hal-04756912⟩
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