Sensing stresses and damage in adhesive bonds using mechanophores

The detection of stresses in adhesive bonds as well as interfacial failure are ongoing challenges. Current approaches and strategies for sensing stresses in the bulk adhesive and at the interface are limited and often destructive. Recently, organic molecules that undergo bond scission or isomerization upon the application of force have been developed. These mechanoresponsive molecules (called mechanophores (MPs)) exhibit unique optical properties such as fluorescence when exposed to force. The utilization of MPs in thermoplastics and networked polymers is a field of active study. By applying this emerging technology to structural adhesive systems, stresses can be sensed in real time as they develop within a loaded structural adhesive joint. Further, installation of these single molecule force sensors at the interface of an adhesive and adherend will enable interfacial damage to be directly observed.