Fabrication of Superhydrophobic Surface on Anodized Aluminum Through a Wet-Chemical Route

Abstract

Fabrication of superhydrophobic surfaces on anodized aluminum substrates by wet-chemical grafting using cost-effective chemicals through a simple immersion process is described. Formation of formate-alumoxane is possible by treating the anodized and sealed aluminum substrate with formic acid at around 50°C. On treatment with sodium salts of higher-order carboxylic acids (stearic acid, lauric acid, and palmitic acid), the formate ions are replaced by higher-order carboxylates. A possible bonding mechanism of the longer chain carboxylic acid with aluminium surfaces has been suggested based on infrared reflection–absorption spectroscopy and X-ray photoelectron spectroscopy studies. The as-prepared superhydrophobic aluminum substrates exhibited a static water contact angle of up to 167° with a sliding angle of 6°, with decent resistance against abrasion in addition to good UV, environmental and thermal stabilities. Aluminium substrates of any size, shape, and surface finish can be easily rendered robust and superhydrophobic without the use of expensive chemicals and sophisticated machinery.