Issue
EPL
Volume 81, Number 2, January 2008
Article Number 26006
Number of page(s) 5
Section Condensed Matter: Structural, Mechanical and Thermal Properties
DOI http://dx.doi.org/10.1209/0295-5075/81/26006
Published online 20 December 2007
EPL, 81 (2008) 26006
DOI: 10.1209/0295-5075/81/26006

Impalement of fakir drops

M. Reyssat1, J. M. Yeomans2 and D. Quéré1

1  Physique et Mécanique des Milieux Hétérogènes, UMR 7636 du CNRS, ESPCI - 75005 Paris, France
2  The Rudolf Peierls Centre for Theoretical Physics, University of Oxford - 1 Keble Road, Oxford OX1 3NP, UK


received 7 September 2007; accepted in final form 19 November 2007; published January 2008
published online 20 December 2007

Abstract
Water drops deposited on hydrophobic materials decorated with dilute micro-posts generally form pearls. Owing to the hydrophobicity of the material, the drop sits on the top of the posts. However, this "fakir state" is often metastable: if the drop impales inside the texture, its surface energy is lowered. Here we discuss the transition between these two states, considering the drop size as a parameter for inducing this transition: remarkably, it is found that a drop impales when it becomes small, which is interpreted by considering its curvature. This interpretation allows us to propose different recipes for avoiding this detrimental effect.

PACS
68.08.-p - Liquid-solid interfaces.
68.08.Bc - Wetting.

© EPLA 2008