Chameleon Skin Inspired Color Changing Films
Researchers inspired by the Chameleon develop a flexible color-changing film. Chameleons are famous for their ability to camouflage themselves to their environment, to communicate, and to regulate their body temperature. For different present-day technologies like electronic displays, anti-counterfeiting measures, and stealth technologies, scientists have tried to replicate these color-changing properties of Chameleons but were limited by materials.
Researchers now developed a color-changing flexible film that displays changes in response to pressure, stretching or humidity. The results are reported in ACS Applied Materials & Interfaces.
Chameleons use guanine crystals under their skin to change the way light is reflected, simply by tensing or relaxing their skin. This phenomenon is known as structural coloration. These colors are not like the pigments that are responsible for the hues in many other creatures.Scientists have tried to reproduce the crystalline nanostructures present in the chameleon skin in materials with the ability to change color, but it is difficult to achieve that, or when produced, they rely on non-renewable petroleum resources. In contrast to the previous materials, cellulose nanocrystals are renewable, and the material can assemble by itself into an iridescent structural color film. However, unlike the chameleon skins
that stretch with breaking, the films are fragile, cannot be stretched without causing breaks. Fei Song, Yu-Zhong Wang, and colleagues wanted to come up with a highly flexible cellulose nanocrystal film that would change color on being stretched.The researchers added a polymer called PEGDA so as to make cellulose nanocrystals more flexible. With the help of UV light, the team crosslinked the polymer to the rod-shaped nanocrystals. This resulted in a film that was both flexible and has more tensile strength, which can be stretched up to 39% of its original length before it breaks. On being stretched, the red color of the film changed to green and then back, on releasing the stretch.
The stretching-and-relaxing-induced change of brilliant colors that is also visible to the naked eye have been realized for the first time on cellular nanocrystal material, according to research. Humidity and pressure can induce a change of color in the film, this allowed the team to hide or show writings made with an inkless pen. This new bio-based smart skin can be useful in strain sensing, encryption, and anti-counterfeiting measures said the researchers.
Chameleon Skin Inspired Color Changing Films.
