M. He, Y.L. Song
Institute of Chemistry, Chinese Academy of Sciences,
Keywords: super-hydrophobic, aluminum, condensation
Summary:As an important engineered metal, aluminum is widely used in aircrafts, cooling systems and thermal managements . Superhydrophobicity of engineered aluminum surface, especially to condensed microdroplets  is still a great challenge nowadays. Here, hierarchical porous structures were facilely fabricated on aluminum by integrating breath figures  and chemical bath deposition  (Fig. 1). Typically, polystyrene (PS)/chloroform solution (1 wt.%) was dropped on an aluminum surface to form breath figures followed by etching with alkali aqueous (0.1 mol/L) to obtain ordered micropores on the aluminum surface. Then the porous PS film was removed and the chemical bath deposition was carried out on the aluminum surface to form nanopores when the aluminum was immersed in hot water (70 oC). The morphology of porous PS and hierarchical porous aluminum surface was showed in Fig. 2 a and b. It can be seen from the scanning electron microscope (SEM) images that the aluminum surface is covered by micropores and nanopores. After being modified with 1H, 1H, 2H, 2H- Perfluorodecyltrimethoxysilane, the hierarchical porous aluminum surface was superhydrophobic to condensed microdroplets which were spherical on the surface (Fig. 2 b and c). More importantly, condensed microdroplets self-removed from the surface as soon as they coalesced due to the hierarchical porous structures [5,6], indicating efficient condensation. This facile method of fabricating hierarchical porous aluminum surface will throw new light on highly efficient condensation and anti-frost/ice in many fields.