Mechanochemistry: Polymers react to stress.

The article discusses research reporting on polymers that exhibit preprogrammed chemical reactions when an external force is applied. This interest pertains to polymer materials whose properties change when influenced by stimuli such as chemicals, heat, or light. Such materials could be used in applications including camouflage systems, artificial muscles, and drug delivery. The researchers incorporated a spiropyran dye into the polymers as a mechanophore, or mechanically reactive unit. These dyes change colors when exposed to various types of mechanical stress. Through a combination of experimental and theoretical models, the study shows that these stress-induced reactions are the impetus for color change.