• Open Access

Dynamic Solid Surface Tension Causes Droplet Pinning and Depinning

M. van Gorcum, B. Andreotti, J. H. Snoeijer, and S. Karpitschka
Phys. Rev. Lett. 121, 208003 – Published 16 November 2018
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Abstract

The contact line of a liquid drop on a solid exerts a nanometrically sharp surface traction. This provides an unprecedented tool to study highly localized and dynamic surface deformations of soft polymer networks. One of the outstanding problems in this context is the stick-slip instability, observed above a critical velocity, during which the contact line periodically depins from its own wetting ridge. Time-resolved measurements of the solid deformation are challenging, and the mechanism of dynamical depinning has remained elusive. Here we present direct visualisations of the dynamic wetting ridge formed by water spreading on a PDMS gel. Unexpectedly, it is found that the opening angle of the wetting ridge increases with speed, which cannot be attributed to bulk rheology, but points to a dynamical increase of the solid’s surface tensions. From this we derive the criterion for depinning that is confirmed experimentally. Our findings reveal a deep connection between stick-slip processes and newly identified dynamical surface effects.

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  • Received 20 July 2018
  • Revised 15 October 2018

DOI:https://doi.org/10.1103/PhysRevLett.121.208003

Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.

Published by the American Physical Society

Physics Subject Headings (PhySH)

  1. Physical Systems
Fluid DynamicsCondensed Matter, Materials & Applied Physics

Authors & Affiliations

M. van Gorcum1,*, B. Andreotti2, J. H. Snoeijer1, and S. Karpitschka3

  • 1Physics of Fluids Group, Faculty of Science and Technology, Mesa+ Institute, University of Twente, 7500 AE Enschede, Netherlands
  • 2Laboratoire de Physique Statistique, UMR 8550 ENS-CNRS, Université Paris-Diderot, 24 rue Lhomond, 75005 Paris, France
  • 3Max Planck Institute for Dynamics and Self-Organization (MPIDS), 37077 Göttingen, Germany

  • *Corresponding author. m.vangorcum@utwente.nl

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Issue

Vol. 121, Iss. 20 — 16 November 2018

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