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Processing of hard super-hydrophobic film with TiO_2 photocatalyst, and mechanisms responsible for self-cleaning performance

TiO_2光催化剂制备硬质超疏水薄膜及其自清洁性能机制

基本信息

批准号：
12555241
负责人：
HASHIMOTO Kazuhito
金额：
$ 8.19万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2001
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-12555241/
关键词：
Titanium Dioxide Super-hydrophobic carbon black contact angle ゾルゲル分相コロイダルシリカ

项目摘要

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.

超疏水表面需要适当的表面粗糙度，表面具有低表面能。然而，具有高粗糙度的表面通常显示出比平坦表面低的硬度，这是超疏水表面应用的关键问题。我们通过结合两种不同的粗糙度尺寸制备了具有可见光透射的硬超疏水二氧化硅薄膜。我们结合了由溶胶-凝胶法的相分离制备的火山口状粗糙度（约800 nm）和由胶体二氧化硅提供的精细粗糙度（约20 nm）。利用TiO_2溶胶可以将光催化剂复合到薄膜上。利用硅溶胶的凝聚作用，将加工温度降低到250℃。粗糙度组合的概念对于设计高耐久性的超疏水膜是非常重要的，TiO_2光催化剂可以有效地为超疏水膜提供自清洁性能，并在长时间的户外暴露中保持高的接触角。我们已经研究了可能负责整体自清洁性能的机制。根据实验结果，证实了至少有以下两种机制：1）自由基物种在氟涂层表面上的长扩散距离; 2）TiO_2的光诱导亲水性降低静电。