Ultrathin SiO(x) Film Coating Effect on the Wettability Change of TiO(2) Surfaces in the Presence and Absence of UV Light Illumination.
Wettability of sol-gel TiO(2) film surfaces has been studied by following the H(2)O contact angle (straight theta) as functions of illumination time and subsequent dark storage time. Upon illumination of the TiO(2) surface (lambda(ex)>300 nm), the value of straight theta rapidly decreased to reach approximately zero (photoprocess). When the resultant superhydrophilic sample was stored in the dark, the straight theta value increased slowly with increasing storage time (dark process). Ultrathin SiO(x) films were formed on the surface of TiO(2) by repeating chemisorption of 1,3,5,7-tetramethylcyclotetrasiloxane and its photooxidation. With increasing thickness of the SiO(x) monolayer coating, the rate for the dark process significantly decreased, while that for the photoprocess also decreased. Both X-ray photoelectron spectroscopic studies and product analyses during the photoprocess clarified that photocatalytic oxidation of organic adsorbates in air causes the superhydrophilicity of the TiO(2) surfaces. Copyright 2000 Academic Press.
Hattori
A
Technical Research Laboratory, Kansai Research Center Nippon Sheet Glass Co., Ltd., 1, Kaidoshita, Konoike Itami, Hyogo, 664-8520, Japan
Kawahara
T
Uemoto
T
Suzuki
F
Tada
H
Ito
S