Mechanoresponsive Healable Metallosupramolecular Polymers

The development of polymers that possess superb mechanical properties and at the same time are capable of sensing damage and self-healing is presented. Copper-catalyzed azide–alkyne cycloaddition (CuAAC) based tridentate ligand 2,6-bis(1,2,3-triazol-4-yl)pyridine (BTP) and covalent mechanophore spiropyran (SP) units are incorporated into the polymer backbone to prepare ligand macromolecule. Upon coordinating with transition or lanthanide metal salts, metallosupramolecular films with phased-separated soft/hard morphology are spontaneously formed. The resulting materials show a rare combination of strong, tough, and elastic mechanical properties and are able to sense damage by changing optical properties. The Zn 2+ -containing material can self-heal in the presence of solvent and fully restore its mechanical properties. The underlying structure–property relationship is unveiled. In particular, the interplay between the covalent SP mechanophore and the noncovalent metal–ligand interactions and their hard phase is demonstrated.