Processing of hard super-hydrophobic film with TiO_2 photocatalyst, and mechanisms responsible for self-cleaning performance
| Project/Area Number |
12555241
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 展開研究 |
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| Research Field |
工業物理化学
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| Research Institution | The University of Tokyo |
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Principal Investigator |
HASHIMOTO Kazuhito Research Center for Advanced Science and Technology, Professor, 先端科学技術研究センター, 教授 (00172859)
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| Co-Investigator(Kenkyū-buntansha) |
NAKAJIMA Akira Advanced Systems of Technology Incubation LTD., Research Manager, 取締役研究所長(研究職) (00302795)
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| Project Period (FY) |
2000 – 2001
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| Project Status |
Completed (Fiscal Year 2001)
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| Budget Amount *help |
¥12,800,000 (Direct Cost: ¥12,800,000)
Fiscal Year 2001: ¥4,200,000 (Direct Cost: ¥4,200,000)
Fiscal Year 2000: ¥8,600,000 (Direct Cost: ¥8,600,000)
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| Keywords | Titanium Dioxide / Super-hydrophobic / carbon black / contact angle / ゾルゲル / 分相 / コロイダルシリカ |
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| Research Abstract |
Super-hydrophobic surfaces require appropriate surface roughness with surfaces having low surface energy. However, surfaces with a high roughness commonly show lower hardness than flat surfaces, and this is a crucial problem for the application of super-hydrophobic surfaces. We have prepared a hard super-hydrphobic silica film with visible light transmission by combining two different roughness dimensions. We combined a crater-like roughness (〜800nm) prepared by a phase separation of sol-gel method, and a fine roughness (〜20nm) provided by colloidal silica. Photocatalyst can be combined to this film by utilizing TiO_2 sol. Processing temperature has been lowered to 250℃ by utilizing the coagulation of colloidal silica. The concept of roughness combination is important for the design of super-hydrophobic films with high durability.
It has been known that TiO_2 photocatalyst effectively provides a self-cleaning property to super-hydrophobic films and maintains high contact angles during long periods of outdoor exposure. We have investigated the mechanism that might be responsible for the overall self-cleaning performance. Based on the experimental results, it was confirmed that at least following two mechanisms are responsible : 1) a long diffusion distance of the radical species on the fluorine-coated surface ; and 2) reduction of static electricity by the photo-induced hydrophilicity of TiO_2.
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Report
(3 results)
Research Products
(14 results)
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[Publications] A. Nakajima, Z. Yoshimitsu, C. Saiki, K. Hashimoto, and T. Watanabe , edited by S. Hirano, G. L. Messing, and N. Claussen: "Processing of a Super-Hydrophobic Silica Film by Combining Two Different Roughness Dimensions , Ceramic Processing Science IV, Ceramic Transactions"American Ceramic Society, Westerville. 112 (2001)
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