Mechanochromic polymers based on supramolecular mechanophores

Mechanochromic polymers respond to mechanical forces with a change in color or luminescence and are potentially useful for applications that range from soft robotics to damage-sensing. Mechanochromic responses also permit the investigation of defect origination and propagation and other mechanical phenomena. In the last two decades, the incorporation of so-called mechanophores—molecules that undergo a specific chemical or physical change in response to mechanical force—has emerged as a widely employed design approach to render polymers mechanochromic. While the activation of most mechanophores is based on the cleavage of covalent bonds, supramolecular mechanophores leverage non-covalent interactions and change their molecular conformation or the interactions between multiple optically active moieties. This mini-review provides a historical perspective on my group’s 25-year-long journey in developing such motifs and integrating them into polymers.