Wettability changes of TiO2 nanotube surfaces

Abstract

This study examines the effect of environmental and experimental conditions, such astemperature and time, on the wettability properties of titania nanotube (TNT) surfacesfabricated by anodization. The fabricated TNTs are 60–130 nm inner diameter and 7–10 µm height. One-microliter water droplets were used to define the wettability of the TNTsurfaces by measuring the contact angles. A digital image analysis algorithm was developedto obtain contact angles, contact radii and center heights of the droplets on the TNTsurfaces. Bare titanium foil is inherently less hydrophilic with approximately60°–80° contact angle. The as-anodized TNT surfaces are more hydrophilic and annealing furtherincreases this hydrophilic property. Furthermore, it was found that the TNT surfacebecame more hydrophobic when aged in air over a period of three months. It is believedthat the surface wettability can be changed due to alkane contamination and organiccontaminants in an ambient atmosphere. This work can provide guidelines to better specifythe environmental conditions that changes surface properties of TNT surfaces and thereforeaffect their desirable function in specific applications such as orthopedic implants.