Self-cleaning Cotton Fabrics
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0920-S06-04
Self-cleaning Cotton Fabrics Kaihong Qi1, Walid A Daoud1, John Xin1, and C.L. Mak2 1 Institute of Textiles & Clothing, The Hong Kong Polytechnic University, Hung Hom,Kowloon, Hong Kong, Hong Kong, China, People's Republic of 2 Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom,Kowloon, Hong Kong, Hong Kong, China, People's Republic of ABSTRACT Nanocrystalline anatase titanium dioxide films were successfully produced on cotton fabrics from alkoxide solutions under ambient pressure using the low temperature sol-gel process. At a temperature as low as 40°C, only anatase phase formed from X-ray diffraction spectroscopy (XRD). Field scanning electron microscopy (FESEM) images show the formation of uniform continuous films of titanium dioxide on cotton fabrics. The self-cleaning properties of these fabrics were evaluated by measuring anti-bacterial activities and the decomposition of a colorant Neolan Blue 2G. The results indicated that anatase treated cotton fabrics exhibited good selfcleaning performance.
INTRODUCTION Nanocrystalline titanium dioxide films have received much attention as a photocatalyst [1-3] due to its high oxidizing ability, nontoxicity and long term stability. More recent applications of TiO2 in various fields have involved self-cleaning, [4, 5] deodorizing, [6] sterilization, [7] and antifouling [8] functions. Nanoscaled titania particles show high photocatalytic activities because of their large surface area per unit mass and volume and hence facilitate the diffusion of excited electrons and holes towards the surface before their recombination. [9] Among the crystalline phases of TiO2, anatase is reported to have the highest performance. [10] A variety of physical and chemical approaches have been used to prepare crystalline titanium dioxide. The sol-gel process has been widely employed to produce TiO2 thin films. However, the preparation of anatase thin films is usually achieved at relatively high temperature. The application of transparent anatase films is essentially infeasible to substrates with low thermal resistance such as plastics, wood, papers and textiles. Stability of the films is a particular requirement for textile because they are subject to frequent washing and hence good adhesion is essential for the practical application of sol-gel derived titania in textiles. In addition, porous coating on textiles may not have high level of durability due to peel-off effect. Recently, much work has been carried out the nucleation of anatase by various low temperature methods such as hot water treatment of silica-titania coatings, [11-13] water vapor. [14] It has been reported that anatase TiO2 sols can be synthesized by, hydrolysis of titanium-nbutoxide in nitric acid aqueous solution and subsequent reflux at a low temperature of 75°C. [15] However, their synthesis product was a mixture of anatase and brookite, rather than pure anatase. Nature has recently reported that Daoud and Xin in our group have successfully grown anatase nanocrystallites on cotton f
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