Extreme Superomniphobicity of Multiwalled 8 nm TiO₂ Nanotubes

Abstract

We report unprecedented superomniphobic characteristics of nanotube-structured TiO(2) surface fabricated by electrochemical etching and hydrothermal synthesis process, with the wettability contact angles for water and oil both being ∼174° or higher. A tangled forest of ∼8-nm-diameter, multiwalled nanotubes of TiO(2) was produced on the microtextured Ti surface, with the overall nanotube length controlled to 150 nm by adjusting the processing time. Wettability measurements indicate that the nanotube surface is extremely nonwettable to both water and oil. The contact angle of the 8 nm TiO(2) nanotube surface after perfluorosilane coating is extremely high (178°) for water droplets indicating superhydrophobic properties. The contact angle for oil, measured using a glycerol droplet, is also very high, about 174°, indicating superoleophobic characteristics. These dual nonwetting properties, superomniphobic characteristics, are in sharp contrast to the as-made TiO(2) nanotubes which exhibit superhydrophilic properties with a contact angle of essentially ∼0°. Such an extreme superomniphobic material made by a simple and versatile method can be useful for a variety of technical applications. It is interesting to note that all three properties can be obtained with identical nanotube structures. A nanometer-scaled structure introduced by hydrothermally grown TiO(2) nanotubes is an effective air trapping nanostructure in enhancing the amphiphobic (superomniphobic) wettability.

Theoretical and Experimental Approaches of Liquid Entry Pressure Determination in Membrane Distillation Processes

“…It should be also noted that there are some recent investigations aiming at developing new MD membrane materials and modifying microfiltration membranes in order to obtain improved non-wettability characteristics of membrane surfaces that may find MD applications in the future. These include, for example, migrating fluorinated surface modifying macromolecules to the top of the membrane surface [11], CF 4 plasma surface modification [12], and creating superomniphobic characteristics of nanotube-structured TiO 2 surfaces [13].…”

Synthetic Methods for Titanium Dioxide Nanoparticles: A Review

“…Direct oxidation of the titanium metal with hydrogen peroxide has also been found to lead to the formation of TiO 2 nanorods. The TiO 2 can be obtained by placing a cleaned Ti metal plate in a 50 mL solution of 30 wt% H 2 O 2 at 353 K for 72 h [33]. Formation of crystalline TiO 2 occurs via mechanism of dissolution precipitation and this phase can be controlled by addition of NaX (X = F…”

“…The colloidal TiO 2 nanoparticles can be prepared in a short period of time (within 5-60 min) compared to several hours needed for the conventional methods of forced hydrolysis at high temperatures (~195°C) [41]. TiO 2 nanotubes which are open-ended and multi-walled with diameters of 8-12 nm and lengths between 200 and 1000 nm were also prepared using this method [33]. TiO 2 nanoparticles in the anatase phase were prepared by Baldassari et al [42] using microwave-assisted hydrolysis of titanium tetrachloride (TiCl 4 ) in a dilute acidic aqueous medium.…”

Strong Amphiphobic Porous Films with Oily-self-cleaning Property beyond Nature

“…There are very few reports on oil repellency in air, 3 because the lower surface tension of oil makes the lyophobicity harder achieve than in the case of water. 4 Therefore, it is urgent, necessary, and challenging to design and fabricate superhydrophobic surfaces with antioily contamination for industrial applications.To achieve these properties, improving the oleophobicity of superhydrophobic surfaces is of utmost significance. It is well known that wettability is governed by both the chemical composition and geometric structure of a solid surface.…”

“…There are very few reports on oil repellency in air, 3 because the lower surface tension of oil makes the lyophobicity harder achieve than in the case of water. 4 Therefore, it is urgent, necessary, and challenging to design and fabricate superhydrophobic surfaces with antioily contamination for industrial applications.…”