News Release

A chameleon-inspired material that stiffens and changes color

Peer-Reviewed Publication

American Association for the Advancement of Science (AAAS)

A Chameleon-inspired Material that Stiffens and Changes Color

video: A video demonstrating how the color and mechanical properties of this new material depend on plastomer morphology. This material relates to a paper that appeared in the 30 March 2018 issue of <i>Science</i>, published by AAAS. The paper, by M. Vatankhah-Varnosfaderani at University of North Carolina at Chapel Hill in Chapel Hill, N.C., and colleagues was titled, "Chameleon-like elastomers with molecularly encoded strain-adaptive stiffening and coloration." view more 

Credit: M. Vatankhah-Varnosfaderani <i>et al., Science</i> (2018)

Researchers have developed a new material that mimics the dynamic properties of skin as it tenses - and that changes colors in the process. Skin protects the body in a number of ways, including by rapidly stiffening in order to prevent injury. In some organisms, such as chameleons, skin can even change color when the animal goes from a relaxed to an excited state. However, combining these two abilities -- stiffening and color change -- into a single manmade material has remained challenging. Here, Mohammad Vatankhah-Varnosfaderani and colleagues sought to build a polymer-based material that mimics the proteins in skin that are responsible for stiffness: collagen and elastin. In skin, a scaffold of stiff collagen fibers resists deformation, while an interwoven network of elastin ensures the skin can recoil to its original form. To create a synthetic version of this, the researchers developed a type of "bottlebrush" polymer that exhibits a linear backbone with side chains. While the backbone of the polymer forms a soft matrix, the flexible linear chains become rigid when pushed together. This combination results in a rigid-while-flexible and soft-while-stiff material, the authors report. Furthermore, the changes in the distance between polymer sidechains affect how light is reflected off the material, meaning the material shifts towards a blue color when elongated and shifts towards a red color when more condense.

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