On the Superhydrophobic Properties of Crystallized Stearic Acid

A surface coating formed by stearic acid (SA) crystals was prepared by repeatedly dipping a silicon substrate into a SA solution and drying it in air. Scanning electron microscopy imaging revealed that the surface roughness of the coating increases with each dip-and-dry cycle. The coating appears as a carpet of hydrophobic 'blades', and is superhydrophobic (after 20 dipping cycles advancing contact angle similar to 160 degrees), even after immersion in water for up to 2 h. This simple method could be applied to large areas, making this an interesting alternative to high-tech surface modification techniques.