External-Field Hot-Water Treatments of Sol-Gel Derived SiO2-TiO2 Coatings for Surface Nanostructure Control —A Review—
External-Field Hot-Water Treatments of Sol-Gel Derived SiO2-TiO2 Coatings for Surface Nanostructure Control —A Review—
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DOI：
10.2109/jcersj.114.26
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发表时间：
2006
影响因子：
1.1
通讯作者：
A. Matsuda;M. Sakai;T. Kogure;K. Tadanaga;M. Tatsumisago
中科院分区：
文献类型：
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作者：
A. Matsuda;M. Sakai;T. Kogure;K. Tadanaga;M. Tatsumisago
这篇综述论文的重点是该地区的二氧化钛纳米涂层制备溶胶-凝胶衍生膜的热水处理下的外部反应场，设计其功能，通过控制其表面形貌和结晶度在低加工温度。首先，简要回顾了低温湿化学法制备二氧化钛纳米晶涂层的研究进展。其次，基于溶胶-凝胶衍生膜的外场热水处理的材料设计的概念和外场对从溶胶-凝胶衍生膜形成二氧化钛纳米晶体的影响进行了讨论。最后，所得到的具有独特形貌的二氧化钛纳米粒子分散涂层的有前途的特性进行了描述。在热水处理过程中，外加振动场和电压场对SiO2-TiO 2凝胶涂层上形成的TiO 2微晶的纳米结构有影响。在没有外部场的情况下，在热水处理期间在涂层上形成尺寸为30-50 nm的颗粒状纳米晶体，而通过在热水处理期间向基底施加振动，沉淀物的形状变成片状。也观察到涂层上沉淀物形状的类似变化，并且通过在衬底之间施加电场在负电极处形成枝状（树枝状）微晶。片状和枝状微晶主要由水合二氧化钛m（TiO 2）·nH 2 O组成，具有片状层状结构，d间距为0.6- 0.8nm。二氧化钛纳米片的特征在于大的表面积与体积比，这产生了优异的水润湿性和防雾性能。用于制备涂层的加工温度在大气压下低于100°C，使得该涂层具有应用于包括耐热性差的有机聚合物在内的各种基材的巨大潜力。
This review paper is focused on the area of titania nanocoatings prepared from sol-gel derived films by hot-water treatment under external reaction fields to design their functionality through the control of their surface morphology and crystallinity at low processing temperatures. First, the formation of titania nanocrystalline coatings at low temperatures by wet chemical procedures is briefly reviewed. Second, a concept of material design based on an external-field hot-water treatment for sol-gel derived films and the effects of the external fields on the formation of titania nanocrystals from the sol-gel derived films are discussed. Finally, promising characteristics of the resultant titania nanocrystal-dispersed coatings with unique morphology are described. External fileds of vibrations and electric voltages affect the nanostructure of titania crystallites formed on SiO 2 -TiO 2 gel coatings during hot-water treatment. Without the external fields granular anatase nanocrystals of 30-50 nm in size are formed on the coatings during the hot-water treatment, whereas the shape of the precipitates becomes sheetlike by applying a vibration to the substrate during hot-water treatment. Similar changes in shape of the precipitates on the coatings are also observed, and ramiform (branchlike) crystallites are formed at the negative electrode by applying an electric field between the substrates. The sheetlike and ramiform crystallites are mainly composed of a hydrated titania, m(TiO 2 ) .nH 2 O, with the lepidocrocite-like layered structure with a d-spacing of 0.6-0.8 nm. Titania nanosheets are characterized by a large surface-to-volume ratio, which gives rise to the excellent wettability for water and antifogging properties. Processing temperatures for the preparation of the coatings are lower than 100°C under atmospheric pressure, so that the coatings have a great potential for applications to various substrates including organic polymers with poor heat resistance.