UChicago PME Materials Special Seminar-Professor Christoph Weder

Supramolecular Strategies for Real-Time Damage Sensing and Self-Healing in Polymers 

Stimuli-responsive polymers that dynamically adjust their properties in response to environmental cues offer a broad range of (emergent) functions such as mechanical morphing, actuation, the ability to heal, mechanochemical transduction, and many others. Leveraging the reversible nature of non covalent interactions, we engineered a variety of such responsive materials. This presentation will highlight our recent efforts to develop polymers that allow the detection and healing of defects using supramolecular design approaches. To render polymers mechanochromic and enable defect detection, we developed several families of supramolecular mechanophores, including rotaxanes, cyclophanes, and loop-forming motifs. These constructs all feature multiple optically active, electronically interacting moieties whose proximity is mechanically controlled. The operating principles exploited, including fluorescence quenching, excimer formation, energy transfer, and charge-transfer formation, offer instant, reversible visual cues such as fluorescence turn-on and emission color changes. To make polymers healable, we assemble them from monomeric units equipped with binding motifs that promote hydrogen bonding or metal-ligand coordination. The dynamic and reversible nature of these supramolecular interactions permits temporary disassembly and efficient healing. Through several design strategies, we have pushed the mechanical performance of these supramolecular polymers into the range of conventional thermoplastics, paving the way for advanced, multifunctional materials that can sense damage and allow efficient repair.