Wettability Switch of Anodic Titanium Dioxide Nanotubes with Various Diameters

Abstract

Surface topography and physicochemical properties such as adhesion, cohesion and wettability is presumed to alter/facilitate the protein binding, cell adhesion and proliferation, thereby reducing post-operative complications with increased lifespan of biomedical implants.1 Current study examines the ageing behaviour of titanium dioxide (TiO2) nanotubes with various diameters and their switch in wettability by gaseous plasma treatment.Self-organized TiO2 nanotube layers were fabricated according to the electrochemical anodization method published earlier.2 The ethylene glycol based electrolytes were used for growing the nanostructures which contains specific amount of water and specific concentration of hydrofluoric acid. Anodization parameters such as applied voltage as well as experimental time were optimized to get desired diameters (15nm, 50nm and 100nm) of TiO2 nanotubes. As-anodized surfaces are hydrophilic and tend to age with time to more hydrophobic. Water contact angle measurements were performed during seven weeks period to study ageing behaviour as well as switch in wettability after gaseous plasma treatment. All the contact angle measurements were performed with demineralized water. The contact angle was measured by fitting the water drop on the surface. Surface wettability indeed switched after plasma treatment as the surface became hydrophilic. Changes in wettability after ageing were explained by organic contamination from ambient atmosphere, while hydrophilic character was obtained after plasma treatment due to removal of these contaminants. Moreover storing the samples in sealed container also influenced on their ageing profile.This current work provides solution and guidelines by which switch in wettability of TiO2 nanotubes can be achieved and can be employed in medical applications where hydrophilic character is desired for specific application, such as orthopedic implants.