Silica nanoparticle-based films on titanium substrates with long-term superhydrophilic and superhydrophobic stability

We report the fabrication of stable superhydrophilic and superhydrophobic surfaces on titanium substrates using simple methods. Sandblasting the titanium surface to generate microscale roughness, followed by dip-coating in a colloidal silica nanoparticle solution to generate nanoscale roughness and a hydrophilic surface chemistry, produces a superhydrophilic surface. Further chemical modification with a several-nanometer-thick low surface energy fluorinated carbon film renders the surface superhydrophobic. The wettability of these superhydrophilic and superhydrophobic surfaces display a high degree of stability, as both surfaces retain their wetting properties for at least 54 days under multiple wetting/de-wetting cycles. Furthermore, the superhydrophilic surfaces retain their wetting properties in excess of 25 months after storage in ambient atmosphere. Due to their long-term wetting stability and ease of fabrication, these surfaces have potential applications in a variety of fields, including biomedical fields where titanium is widely used. (C) 2013 Elsevier B.V. All rights reserved.