Optically healable metallosupramolecular polymers

A novel class of optically healable supramolecular polymers based on ligand-terminated telechelic building blocks and metal salts has been developed.

Polymers which can be repaired after sustaining damages are appealing because this feature can improve the reliability, functionality, and lifetime of many products. One attractive approach to create healable polymers exploits non-covalent, dynamic supramolecular motifs. These allow one to temporarily reduce the polymer’s molecular weight by shifting the equilibrium to the monomer side when needed. The resulting increase in chain mobility and decrease in viscosity promote healing capability, before the equilibrium is shifted back and the polymer is reformed. In collaboration with Prof. Stuart Rowan (Case Western Reserve University) a novel class of optically healable supramolecular polymers based on ligand-terminated telechelic building blocks and appropriate metal salts has been developed. Upon exposure to ultraviolet light, the metal-ligand motifs are excited and convert the absorbed energy into heat. This facilitates the temporary dissocia­tion of the metal-ligand motifs and transforms the poly­mer into a low-viscosity liquid, which can easily fill small defects. When the light is switched off, the polymer re-assembles and the original properties are restored. Since light can be applied locally, objects can be healed under load. The general design is currently being applied to a range of supra­molecular materials that use different chemistries.

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