A review of mechanochromic polymers and composites: From material design strategy to advanced electronics application

The design and fabrication of functional polymers with fascinating mechanochromic properties are of profound significance to their prospective applications, such as wearable electronic skin, smart screen, artificial muscle, encryption, and anti-counterfeiting devices. Drawn inspiration from color-changing properties of biological skins, numerous approaches, from molecular synthesis to special biomimicry engineering, have been employed to construct flexible stimuli-responsive materials with superior mechano-stimulated optical change performance. In this review, we highlight and discuss recent important progress in material structure design strategy for mechanochromic polymers and composites. These optical variations primarily originate from the force-induced molecular structure change, disruption of intermolecular interaction, evolution of physical photonic and morphological structure. Moreover, according to their respective structure-property relationships, their multifunctional applications in advanced electronics field are also demonstrated with representative examples. Furthermore, a summary and perspective regarding the existing challenges in this field will be discussed, aiming to provide valuable insight into their future developments. We believe this feature review will bring helpful guidance to readers for choosing effective chromogenic material design method to satisfy different application requirements.