Superhydrophilicity of anodic aluminum oxide films: From honeycomb to bird's nest

An electrochemical method has been used to prepare different kinds of surfaces including honeycomb-like and bird's nest-like surfaces on anodic aluminum oxide (AAO) films. The relationship between the morphology and wettability of the AAO films was investigated by scanning electron microscopy and the measurement of water contact angles. The results show that the bird's nest-like structure is necessary for superhydrophilic property, which provide direct experimental evidences for the 3D capillary theory concerning superhydrophilicity. It is expected that this investigation will be devoted to guiding the fabrication of superhydrophilic and superhydrophobic surfaces. (C) 2009 Elsevier B.V. All rights reserved.