Mechanochromism

Under pressure – Piezochromic polymers

Mechanochromic effects respond to mechanical forces by changing their optical properties. Typical influences are compression, stretching or shearing. Changes in color caused by pressure changes form the subgroup of the piezochromic effects.

Some materials respond to the application of forces by changing their fluorescence properties. Mostly, this change occurs only at very high pressures above 100 bar. The focus of the work at the Fraunhofer IAP is on polymeric materials with a visible color change at a pressure change of a few bar.

Color variety of piezochromic layers

Blue, green or red colored piezochromic materials that change color by pressure.
© Fraunhofer IAP

Blue, green or red colored piezochromic materials that change color by pressure.

By varying the starting materials and the polymerization conditions, the colors of the piezochromic layers can be adjusted along the spectrum.