Corrosion-Resistant Superhydrophobic Coatings on Mg Alloy Surfaces Inspired by Lotus Seedpod

Superhydrophobic surfaces are widely found in nature, inspiring the development of excellent antiwater surfaces with barrier coatings isolating the underlying materials from the external environment. Here, the naturally occurring superhydrophobicity of lotus seedpod surfaces is reported. Protective coatings that mimic the lotus seedpod are fabricated on AZ91D Mg alloy surfaces with the synergistic effect of robust superhydrophobicity and durable corrosion resistance. The predesigned titanium dioxide films are coated on AZ91D by an in situ hydrothermal synthesis technique. Through sonication assisted electroless plating combined with a self-assembling method, the densely packed Cu-thiolate layers are uniformly plated with robust adhesion on the Mg alloy substrate, which function as a superhydrophobic barrier that can hold back the transport of water and corrosive ions contained such as Cl-. Notably, the two extreme wetting behaviors (superhydrophilicity and superhydrophobicity) as well as corrosion resistance and improved corrosion resistance can be easily controlled by removal of the hydrophobic materials (n-dodecanethiol) at elevated temperature (350 degrees C) and modifying them at room temperature for 18 cycles, indicative of exceptional adhesion between the superhydrophobic coating and the underlying AZ91D Mg alloy.