(654b) A Dimeric Anthracene Mechanophore for Early Damage Detection in Epoxy Matrices

Catastrophic damage in materials, whether it be in an aerospace, mechanical, or consumer application, often occurs suddenly and without warning, resulting in loss of mechanical properties, complete functionality, or even loss of life. Thus, the ability to observe and quantify the amount of damage sustained by a material before ultimate failure is quite desirable in these applications. We have completed the synthesis, characterization, and validation of multiple mechanophores, which are compounds possessing mechanically sensitive chemical moieties that act as sensors for applied stress or strain. In particular, we have employed cyclooctane-based mechanophores, created by the dimerization of anthracene moieties with UV light, to detect damage in epoxy matrix composites. For the dimeric anthracene mechanophore studied, when damage is applied and cracks are formed, there is spontaneous bond cleavage in the cyclooctane rings, resulting in an observable fluorescent signal via the recovery of the monomeric structure. The utilization of the anthracene chemistry features a number of advantages compared to other fluorescent mechanophores, including an increase in quantum fluorescence yield, damage detection deep within the matrix, and, most notably, early damage precursor detection before the yield point in compression tests. Overall, the application of this self-sensing mechanophore into epoxy polymer matrix composites has been successful.