Paper MN-TuM3
Development of Superhydrophobic Biomimetic Surfaces with Hierarchical Roughness

Tuesday, October 21, 2008, 8:40 am, Room 206

Superhydrophobic plant surfaces, e.g. the Lotus leaves, and theoretical calculations show that a hierarchical surfaces roughness is beneficial for superhydrophobicity. Biomimetic hierarchical surface structures were produced by multiple replication of a microstructured silicon master surface. Replicas are made in a two step process, in which a two-component silicon molding mass was applied into the micropatterned Si surfaces, followed by a filling of the mold with an epoxy resin. On these different nanostructures have been applied by physical vapor deposition of hydrophobic n-hexatriacontane (C₃₆H₇₄), and octacosn-1-ol. These organic molecules are able to self assembles on the substrates into three-dimensional crystals, and their shape, size and chemistry is comparable to those structures, found on water repellent surfaces. The surfaces created are fully characterized by SEM and AFM and attempted to separate out the effect of hierarchical structures on the hydrophobicity. We show how static contact angles, hysteresis and tilt angles vary with microstructure, nanostructure and hierarchical structure. We also study the effect of droplet size on contact angle by evaporation using droplets on the surfaces.