Gao Yanfeng, Masuda Yoshitake, Koumoto Kunihito
Department of Applied Chemistry, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan.
Langmuir. 2004 Apr 13;20(8):3188-94.
We report on the photoinduced superhydrophilicity of the surface of amorphous TiO2. Amorphous TiO2 thin films were prepared on self-assembled monolayers by the peroxotitanate-complex deposition (PCD) and liquid-phase deposition (LPD) methods. The surface morphology and topography were characterized in detail. The contact angles were 34 degrees and 66 degrees for the as-deposited thin films through the PCD and LPD methods, respectively, which slowly increased to about 70 degrees and 73 degrees after being stored in air. After irradiation by UV light, the contact angle vanished and the surface exhibited superhydrophilicity. The superhydrophilicity and hydrophobicity could be switched by alternatively exposing the surface to UV light and drying in an atmosphere filled with organic gases. Although the oxidation of the contamination on the surface has effects on the increase in hydrophilicity, the X-ray photoelectron spectroscopy results suggested that the superhydrophilicity was also related to the transformation of the Ti-OH groups to groups that have dangling bonds. This paper indicates that an amorphous TiO2 thin film does not need to be heated to obtain superhydrophilicity; such a self-cleaning surface can be achieved at room temperature by our newly developed environmentally friendly method.
我们报道了非晶态TiO₂表面的光致超亲水性。通过过氧钛酸盐络合物沉积（PCD）和液相沉积（LPD）方法在自组装单分子层上制备了非晶态TiO₂薄膜。详细表征了其表面形态和形貌。通过PCD和LPD方法制备的沉积态薄膜的接触角分别为34°和66°，在空气中储存后缓慢增加到约70°和73°。紫外光照射后，接触角消失，表面呈现超亲水性。通过将表面交替暴露于紫外光并在充满有机气体的气氛中干燥，可以实现超亲水性和疏水性的切换。尽管表面污染物的氧化对亲水性的增加有影响，但X射线光电子能谱结果表明，超亲水性还与Ti-OH基团向具有悬空键的基团的转变有关。本文表明，非晶态TiO₂薄膜无需加热即可获得超亲水性；通过我们新开发的环保方法，在室温下即可实现这样的自清洁表面。
