The microstructure and wettability of the TiOx films synthesized by reactive DC magnetron sputtering

Different chemical state of titanium oxide films were deposited on commercially pure Ti (CP Ti) by reactive DC magnetron sputtering under different oxygen flow rates to examine a possibility of their applications to endovascular stents. The chemical composition and crystal structure of the obtained films were analyzed by XPS and XRD, respectively. In dependence on the deposition parameters employed, the obtained films demonstrated different mixture of anatase TiO2, Ti2O3, TiO and Ti. The wettability of the films was measured by the water contact angle variation. By formation of titanium oxide film on CP Ti, contact angle was decreased. In order to modify and control the surface wettability, the resultant TiOx films were etched subsequently by different plasma. The wettability was influenced by etched process according to the decreased contact angle values of etched TiOx film. Furthermore, TiOx films became highly hydrophilic by ultraviolet (UV) irradiation, and returned to the initial relatively hydrophobic state by visible-light (VIS) irradiation. The wettability of the TiOx film was enabled to convert between hydrophilic and hydrophobic reversibly by alternative UV and VIS irradiation. By adjusting deposition parameter and further modification process, the wettability of the TiOx films can be changed freely in the range of 0–90°.