Sato Osamu, Kubo Shoichi, Gu Zhong-Ze
Institute for Materials Chemistry and Engineering, Kyushu University, 6-1 Kasuga-koen, Kasuga, Fukuoka, 816-8580, Japan.
Acc Chem Res. 2009 Jan 20;42(1):1-10. doi: 10.1021/ar700197v.
The structural blue color of a Morpho butterfly originates from the diffraction of light and interference effects due to the presence of the microstructures on the wing of the butterfly. Structural color on the surface of a damselfish reversibly changes between green and blue. Inspired by these creatures, we have been trying to prepare high-quality and functional structural color films. We describe our efforts in this Account. A useful technique to prepare such structural color films in colloidal solution is a "lifting" method, which allows us to quickly fabricate brilliant colloidal crystal films. The thicknesses of the films can be controlled by precisely adjusting the particle concentration and the lifting speed. Moreover, in order to prepare a complicated structure, we have used template methods. Indeed, we have successfully prepared the inverse structure of the wing of a Morpho butterfly with this technique. Initially, however, our structural color films had a whitish appearance due to the scattering of light by defects in the colloidal crystal film. Later, we were able to prepare a non-whitish structural color film by doping an appropriate dye in the colloidal particles to absorb the scattering light. In addition to the structural blue color, the wing of the Morpho butterfly has superhydrophobic properties. According to Wenzel's equation, the hydrophobic and hydrophilic properties are enhanced when the roughness of the hydrophobic and hydrophilic surface is increased, respectively. Based on this mechanism, we have successfully prepared structural color films with superhydrophobic properties, as well as with superhydrophilic properties. Another important property that can be seen in nature is tunable structural color, such as the color change that can be seen on the surface of a damselfish. In order to mimic such color change, we have developed several tunable structural color films. In particular, we have successfully prepared phototunable photonic crystals using photoresponsive azobenzene derivatives. In order to apply these structural color films, we developed a technique for patterning them by taking advantage of the wettability of the substrate surface. These materials can be used in the future for self-cleaning pigments and tunable photonic crystals.
大闪蝶的结构蓝色源于光的衍射以及蝴蝶翅膀上微观结构所产生的干涉效应。雀鲷体表的结构颜色可在绿色和蓝色之间可逆变化。受这些生物的启发，我们一直在尝试制备高质量的功能性结构色薄膜。我们在本综述中描述了我们的努力。在胶体溶液中制备此类结构色薄膜的一种有用技术是“提拉”法，它使我们能够快速制造出色彩鲜艳的胶体晶体薄膜。薄膜的厚度可以通过精确调整颗粒浓度和提拉速度来控制。此外，为了制备复杂结构，我们采用了模板法。事实上，我们已用此技术成功制备出大闪蝶翅膀的反结构。然而，最初我们的结构色薄膜由于胶体晶体薄膜中的缺陷导致光散射而呈现出白色外观。后来，我们通过在胶体颗粒中掺杂适当的染料以吸收散射光，从而制备出了无白色的结构色薄膜。除了结构蓝色，大闪蝶的翅膀还具有超疏水特性。根据文泽尔方程，当疏水和亲水表面的粗糙度分别增加时，疏水性和亲水性会增强。基于这一机制，我们成功制备出了具有超疏水以及超亲水特性的结构色薄膜。自然界中可见的另一个重要特性是可调节的结构颜色，比如在雀鲷体表能看到的颜色变化。为了模拟这种颜色变化，我们开发了几种可调节结构色薄膜。特别是，我们利用光响应性偶氮苯衍生物成功制备了光可调光子晶体。为了应用这些结构色薄膜，我们利用基底表面的润湿性开发了一种对其进行图案化的技术。这些材料未来可用于自清洁颜料和可调光子晶体。
