A simple approach for fabrication of superhydrophobic titanium surface with self-cleaning and bouncing properties

Abstract

A simple, scalable, rapid and eco-friendly method for the fabrication of superhydrophobic (SHP) titanium surface was developed using rapid breakdown anodization (RBA) for the first time. The desired hierarchical surface morphology for superhydrophobicity is achieved by controlling the RBA process parameters and low surface energy modification by using stearic acid (SA). The prepared samples were characterized using Field emission scanning electron microscope (FESEM), Energy-dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and water contact angle (WCA) measurements. The anodized samples showed islands of TiO2 microclusters with complex hierarchical structures randomly distributed in the passive TiO2 matrix. Ti sample anodized at 30 V was hydrophobic with a WCA of ~ 130° and a sliding angle > 30°, whereas the one anodized at 50 V was superhydrophobic with a WCA of ~ 154° and a sliding angle of 10° after the low surface energy modification. The growth mechanism of RBA leading to the formation of pores and microclusters was understood from the current-time transient data analysis. Our results show that the sustained oxidation of titanium and pore growth by chemical or field-assisted dissolution reactions governed the final morphology of the anodized sample. The superhydrophobic sample exhibited excellent self-cleaning, adhesion (bouncing) properties and abrasion resistance.