Tuesday, November 6, 2007
331f

Fabrication Of Non-Ageing Superhydrophobic Surfaces By Packing Flower-Like Hematite Particles

Anmin Cao, Liangliang Cao, and Di Gao. Chemical and Petroleum Engineering, University of Pittsburgh, 1249 Benedum Hall, 3700 O' Hara street, Pittsburgh, PA 15261

Superhydrophobic surfaces, characterized by a water contact angle of greater than 150º, have attracted considerable interest for applications in self-cleaning products and hydrodynamic drag reduction. However, ageing—deterioration of superhydrophobicity over time—is a major obstacle that hinders the practical application of artificial superhydrophobic surfaces. Here we demonstrate the fabrication of non-ageing superhydrophobic surfaces by packing flower-like micrometer-sized hematite (α-Fe2O3) particles. Although hematite is intrinsically hydrophilic, the nanometer-sized protrusions on the particles form textures with overhanging structures that prevent water from entering into the textures and induce a macroscopic superhydrophobic phenomenon. These superhydrophobic surfaces do not age even in extremely oxidative environments—they retain the superhydrophobicity after being stored in ambient laboratory air for 4 months, heated to 800ºC in air for 10 hours, and exposed to ultraviolet ozone for 10 hours. We anticipate that the demonstrated approach of packing flower-like particles could be applied to a variety of materials for fabrication of non-ageing superhydrophobic surfaces.