A study on the minute change of the alumina surface structure according to the anodizing conditions for the production of a robust wettability-modified surfaces

The anodizing method of aluminum has been loved by the industry by forming a mechanically and chemically robust Al 2 O 3 layer on the surface of aluminum, and various researches have been reported to expand the applicability. In particular, superhydrophilic/superhydrophobic surface modification through anodization can take advantage of change in wettability and at the same time secure surface robustness, thus it can be said to be a very promising technology in the industry. In this study, changes in the surface structure of the Al 2 O 3 layer according to the anodizing conditions were observed, and changes in mechanical robustness and wettability were closely analyzed. Through the minute change of anodization condition, conventional nanoporous structures and novel nanofibrous structures were fabricated. The nanofibers could form in two different shapes depending on the current density. To characterize their surface properties, mechanical and wetting properties were measured. The nanoporous structures were found to have excellent mechanical properties . The nanofibrous structures were found to be advantageous as they maximized the wetting properties, resulting in either a slippery or sticky superhydrophobic surface. The investigation of structural diversification and surface properties offers a guideline to choosing the optimal anodization condition depending on the application. • Diverse AAO morphologies were obtained under different anodization conditions. • Fabrication conditions for nanoporous and nanofibrous structures were minutely investigated. • At lower volage, nanofibers were formed with long stretched shapes. • Maximized wetting properties were realized based on alumina nanofibrous structures.