Scientists turn to the chameleon to develop color-changing filmsMarie Donlon | October 26, 2020
Scientists from China’s Sichuan University have developed a film that mimics the color-changing properties of the chameleon.
The new film, which is composed of renewable cellulose nanocrystals, reportedly changes color in response to stretching, pressure and humidity, much like the guanine crystals beneath the surface of the chameleon’s skin. These crystals, according to researchers, change how light is reflected off of them according to how the chameleon stretches and relaxes, producing what is called structural coloration.
To replicate this, the team improved the flexibility of the cellulose nanocrystals, which are generally inflexible, by adding the polymer PEGDA. The team applied ultraviolet (UV) light to crosslink the PEGDA with the rod-shaped nanocrystals and the result was film with iridescent colors ranging from blue to red based on the amounts of PEGDA present.
According to the Sichuan scientists, the new films can reportedly stretch to 39% of their original length. Additionally, the new films feature reversible structural colors — the film will change from red to green when stretched then back again to red when the film relaxes.
The Sichuan team believes the films could be used for encryption, strain sensing and anti-counterfeiting applications.
For more on the research, which appears in the journal ACS Applied Materials and Interfaces, watch the accompanying video that appears courtesy of the American Chemical Society.