AVS 59th Annual International Symposium and Exhibition
    Surface Science Tuesday Sessions
       Session SS-TuP

Paper SS-TuP17
Photo-patternable Superhydrophobic Porous TiO2 Films Prepared by Hydrothermal Treatment

Tuesday, October 30, 2012, 6:00 pm, Room Central Hall

Session: Surface Science Poster Session
Presenter: S. Nishimoto, Okayama University, Japan
Authors: S. Nishimoto, Okayama University, Japan
M. Becchaku, Okayama University, Japan
Y. Kameshima, Okayama University, Japan
M. Miyake, Okayama University, Japan
Correspondent: Click to Email
In recent years, highly porous TiO2 surfaces prepared by hydrothermal treatment using aqueous alkaline solutions have attracted great interest due to their unique architectures, which include TiO2 nanotubes and nanowires. These nanostructured surfaces can potentially be used as filtration membranes, high-surface-area electrodes, and photocatalysts for environmental purification. In addition to these applications, porous TiO2 surfaces are considered to be suitable for use as functional surfaces that undergo photostimulated wettability conversion that changes them from being superhydrophobic to being superhydrophilic. However, to the best of our knowledge, no studies have been conducted on potential applications of such superhydrophobic-superhydrophilic surfaces. In this paper, we report the preparation of superhydrophobic TiO2 surfaces by hydrothermally treating Ti plates with concentrated NaOH solution and then washing them in deionized water and HCl and subjecting them to heat treatment and surface modification with octadecylphosphonic acid (ODP). Rough nanostructured anatase TiO2 surfaces with many pores were prepared by the hydrothermal treatment. Surface modification with self-assembled monolayers (SAMs) of ODP made the surface superhydrophobic with a static water contact angle (CA) of about 174°. This superhydrophobic surface could be converted into a superhydrophilic surface with a water CA of nearly 0° by irradiating it with ultraviolet light as the result of photocatalytic decomposition of the ODP SAM. Thus, the large wettability contrast of the surface, with a water CA difference of over 170°, would allow this photostimulated wettability conversion porous films to be used in many applications including offset printing, cell growth, spotting of biomolecules fluidic microchips, site-selective immobilization of functional materials, and so on.