Abstract
The conspicuous blue of Morpho butterfly is a single color in too wide angular range (< ± 40° from the normal), which contradicts the optical interference effect originating its high reflectivity. After proven the principle of the mystery by emulating the specific nanostructures of their scales, we found the reproduced Morpho-color to serve wide applications, because it can produce a brilliant single color in wide angular range with high reflectivity without chemical pigment, which is resistant to fading caused by chemical change for long time. We have then developed various technologies for practical applications of the specific color, such as mass-production processes, control and simulation of their optical properties. One of the remaining key issues is to produce the substrate-free color materials, because all processes have long been accompanied with the thick substrate designed with a specific nanostructure, which has limited the variety of applications. We have recently developed a simple process to mass-fabricate the color powders that are substrate-free color material. The method was quite simple, because the colored thin-film part was peeled-off by immersion of the imprinted mass-productive color-material into hot water. However, this process was limited to produce powders, because the detached thin-film part was broken into small pieces during process. Thus, we developed a new process to produce a continuous colored thin-film without break, which can be realized only by immersion into hot water. The fabricated colored thin-film was flexible, having endurance against stress and strain, and found to maintain the original optical properties of Morpho-color under the bent condition. This process will extend effectively the applications of the Morpho-color, which enables the coloring without limit of solid substrate.
