"Petal Effect" on Surfaces Based on Lycopodium: High-Stick Surfaces Demonstrating High Apparent Contact Angles

Wetting properties of lycopodium-based surfaces are reported. The surfaces demonstrate high apparent contact angles accompanied by high adhesion of water droplets, similar to the recently reported biological interfaces (rosea Rehd) showing the "petal effect". Apparent contact angles depended strongly on the droplet volume. Vertical vibration of droplets deposited on the lycopodium-based reliefs promoted wetting transition. Semiquantitative analysis of the observed wetting transition taking into account the hierarchical topography of the relief is presented. We relate the high adhesion of droplets to the partial filling of pores constituting the relief.