Elastic instability and contact angles on hydrophobic surfaces with periodic textures

Surface textures are used to impart advanced wetting properties to surfaces. However, understanding the surface response in relation to the nature of the texture is still a challenge. Here we have measured advancing and receding contact angles on model hydrophobic surfaces with cylindrical pillars as a function of the pillar spacing. We show that the dependences of both advancing and receding contact angles upon spacing are well accounted for by a simple model of the instability of the triple line, following the line elasticity theory by Joanny and de Gennes (J. Chem. Phys., 81 (1984) 552). This result demonstrates the prominent role of the triple-line elasticity in determining the wetting properties of textured surfaces. Copyright (C) EPLA, 2012