Various pigments that are the basis of color are used in inks and cosmetics that emit beautiful colors.Poster posted outdoors will fade over a long period of time.This is because the pigment contained in the ink undergoes a chemical change due to ultraviolet rays and the like.In addition, many pigments use harmful substances.When used in cosmetics, strict regulations must be cleared, and there are moves to tighten regulations, especially in Europe.From the viewpoint of durability and safety, we are looking for a color element that can replace pigments.

　Bird feathers are attracting attention there.The bright blue bird feathers are regularly lined with small holes on a scale of a few micrometers (1 micrometer = 0.000001 meters) or less.The light that passes through this hole is scattered and interferes with each other to develop a vivid color.The color will not change unless the structure is destroyed.Due to the characteristics of light interference, it is possible to emit different colors as the hole spacing changes.The group has succeeded in developing a material that changes to various colors by applying a hole structure to the gel that expands and contracts due to changes in temperature.Also, because the holes are arranged regularly in all directions, the color does not change when you change the viewing angle like a jewel beetle shell.Materials that change color due to changes in the fine structure and environment have been developed so far, but most of them change color depending on the viewing angle.

　It is being considered whether this material can be used for paper-type displays.If the same idea is applied not only to gels but also to resins, the applications may be further expanded, such as inks that do not burn even outdoors.

Source:[Nagoya University] Developed Soft Mattel Al, which changes color in response to stimuli, with reference to bird feathers that show a blue structural color that is independent of angle.