In Germany, researchers at the Leibniz Institute for New Materials developed a new “active nanocomposite” that is teeming with motion: small particles connect or separate, thus changing the color of the entire material. The transparent material can “answer” temperature changes or, in the future, the presence of chemical substances and toxins with a color change. The researchers want to create packaging films that change their color when food spoils, for example.
The research team used a trick: like raisins in a pudding, they distributed small liquid droplets in a polymer. “The particles are now free to either agglomerate or freely move in the entire droplet. The nanocomposite’s color depends on how far the nanoparticles are from each other, it changes from ruby red to grey-violet in our example. The particles can separate again, and the color change is fully reversible,” said Professor Kraus. “The result is relevant for applications that require transparent materials. We envision coating it onto clear films, for example.”