Eur. Phys. J. E (2009) 29: 391-397
https://doi.org/10.1140/epje/i2009-10489-3

Regular Article

Cassie-Baxter to Wenzel state wetting transition: Scaling of the front velocity

¹ Membrane Technology Group, Faculty of Science and Technology, Mesa+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500, AE Enschede, The Netherlands
² Physics of Fluids, Faculty of Science and Technology, Mesa+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500, AE Enschede, The Netherlands
³ Laboratoire de Physique de la Matière Condensée et Nanostructures, Université de Lyon, Univ. Lyon I, CNRS, UMR 5586, 69622, Villeurbanne, France
⁴ Department of Physics, University of Rome Tor Vergata, Via della Ricerca Scientifica 1, 00133, Rome, Italy
⁵ Impact, Institute on Mechanics, Processes and Control Twente, University of Twente, P.O. Box 217, 7500, AE Enschede, The Netherlands

^* e-mail: r.g.h.lammertink@utwente.nl

Received: 6 April 2009
Accepted: 8 July 2009
Published online: 9 August 2009

Abstract

We experimentally study the dynamics of water in the Cassie-Baxter state to Wenzel state transition on surfaces decorated with assemblies of micrometer-size square pillars arranged on a square lattice. The transition on the micro-patterned superhydrophobic polymer surfaces is followed with a high-speed camera. Detailed analysis of the movement of the liquid during this transition reveals the wetting front velocity dependence on the geometry and material properties. We show that a decrease in gap size as well as an increase in pillar height and intrinsic material hydrophobicity result in a lower front velocity. Scaling arguments based on balancing surface forces and viscous dissipation allow us to derive a relation with which we can rescale all experimentally measured front velocities, obtained for various pattern geometries and materials, on one single curve.