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Article history: Received 6 April 2011 Received in revised form 5 December 2011 Accepted 5 December 2011 Available online 13 December 2011
2. Experimental section
2.1. Reagentsห้องสมุดไป่ตู้
Dopamine hydrochloride was purchased from Aladdin Chemistry Co. Ltd. Titanium tetrachloride was purchased from China National Medicines Corporation Co. Ltd. All other reagents were obtained from Shanghai Reagent Co. Ltd.
Keywords: Titanium dioxide Thin films Polydopamine Contact angle Hydrophilic conversion Wetting Glass substrate
abstract
Titanium oxide (TiO2) nanofilm was prepared by a simple method of sol–gel deposition on the glass substrate, which was pre-modified with a polydopamine (PDA) film. The as-prepared TiO2 nanofilm was analyzed by X-ray diffraction, scanning electron microscopy, and atomic force microscopy. The thickness of TiO2 film can be controlled by the thickness of PDA film, which was dependent on the polymerization time. The mechanism of wettability conversion on TiO2 film was investigated by means of contact angle measurements in different experimental conditions. The results demonstrated that humidity was the major factor for converting the hydrophobic surface of TiO2 film into hydrophilic surface under ultra-violet (UV) irradiation. And atmospheric oxygen played dominant role in reconverting the hydrophilic surface of TiO2 film into hydrophobic surface when it was stored in the dark. The TiO2 nanofilm showed reversible hydrophobic/hydrophilic conversion in the condition of alternating between UV irradiation and storage in the dark.
This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution
⁎ Corresponding author. Tel.: + 86 791 87046351; fax: + 86 791 87046320. E-mail address: zlz@ (L. Zheng).
0040-6090/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.tsf.2011.12.017
Longzhen Zheng ⁎, Qiang Liu, Leyan Xiong, Yindi Li, Kui Han, Wen Liu, Kun Tao, Shaoming Yang, Jian Xia
Department of Chemistry and Chemical Engineering, East China Jiao Tong University, Nanchang, Jiangxi 330013, PR China
platform for secondary reactions, leading to tailoring of the coatings for diverse functional uses. For example, the outer hydroxyl groups of the PDA film can chelate with metal ions of inorganic oxide to generate oxide film [15].
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Thin Solid Films 520 (2012) 2776–2780
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Thin Solid Films
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1. Introduction
Titania (TiO2) film has been received special attention in the past few years due to its outstanding properties and widespread potential applications. Applications of TiO2 film in photodegradation of organic pollutants [1], hybrid solar cells [2], gas sensors [3], and anti-fogging mirrors [4] were reported. Numerous methods have been developed to fabricate TiO2 film, such as chemical vapor deposition [5], sputtering technique [6], hydrothermal process [7] and electron beam evaporation [8]. However, a large apparatus was needed and the operation process was complicated in these methods. Recently, the simple sol–gel method has attracted attention again for the preparation of TiO2 film due to its easy operation. The sol–gel solution of TiO2 can be coated onto a substrate by dip-coating [9], electrostatic sol spray deposition [10], and aerosol pyrolysis [11].
In the present manuscript, PDA film was first polymerized on glass substrate and then used as a template for the preparation of TiO2 nanofilm. The thickness of TiO2 nanofilm was controlled by the thickness of PDA film, which was dependent on the polymerization time. The wettability of the as-prepared TiO2 nanofilm in different conditions was studied to reveal the mechanism of hydrophobic/hydrophilic conversion.