On hydrophilicity improvement of the porous anodic alumina film by hybrid nano/micro structuring

In both, laboratory and industry, tremendous attention is paid to discover an effective technique to produce uniform, controllable and (super) hydrophilic surfaces over large areas that are useful in a wide range of applications. In this investigation, by combing porous anodic alumina (PAA) film with nano-structures and microarray of aluminum, the hydrophilicity of hybrid nano-micro structure has been significantly improved. It is found some factors can affect the hydrophilicity of film, such as the size and aspect ratio of microarray, the thickness of nano-PAA film etc. Comparing with pure nano-PAA films and microarray, the hybrid nano-micro structure can provide uniform surface with significantly better hydrophilicity. The improvement can be up to 84%. Also, this technique exhibits good stability and repeatability for industrial production. By optimizing the thickness of nano-PAA film and aspect ratio of micro-structures, super-hydrophilicity can be reached. This study has obvious prospect in the fields of chemical industry, biomedical engineering and lab-on-a-chip applications. (C) 2017 Elsevier B.V. All rights reserved.