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

• Published in: The European physical journal. E, Soft matter and biological physics Soft matter and biological physics, 2009-08, Vol.29 (4), p.391-397
• Main Authors: Peters, A. M., Pirat, C., Sbragaglia, M., Borkent, B. M., Wessling, M., Lohse, D., Lammertink, R. G. H.
• Format: Article
• Language: English
• Subjects: Biological and Medical Physics; Biophysics; Chemistry; Complex Fluids and Microfluidics; Complex Systems; Exact sciences and technology; Fluid Dynamics; General and physical chemistry; Nanotechnology; Physics; Physics and Astronomy; Polymer Sciences; Regular Article; Soft and Granular Matter; Solid-liquid interface; Surface physical chemistry; Surfaces and Interfaces; Thin Films
• ISSN: 1292-8941; 1292-895X
• DOI: 10.1140/epje/i2009-10489-3

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.