Mechanochemical Release of N‐Heterocyclic Carbenes from Flex‐Activated Mechanophores

We have discovered a new flex‐activated mechanophore that releases an N‐heterocyclic carbene (NHC) under mechanical load. The mechanophore design is based upon NHC‐carbodiimide (NHC‐CDI) adducts and demonstrates an important first step toward flex‐activated designs capable of further downstream reactivities. Since the flex‐activation is non‐destructive to the main polymer chains, the material can be subjected to multiple compression cycles to achieve iterative increases in the activation percentage of mechanophores. Two different NHC structures were demonstrated, signifying the potential modularity of the mechanophore design. A new kind of flex‐activated mechanophore, N‐heterocyclic carbene–carbodiimide adduct (NHC‐CDI), was developed as a platform to release different NHCs under mechanical load. The polymeric materials containing NHC‐CDI can be subjected to multiple compression cycles and successively release NHCs, which have potential to be utilized as self‐healing, self‐strengthening and self‐reporting materials.