Journal ArticleMechanochemical Reactivity of a 1,2,4‐Triazoline‐3,5‐dione‐Anthracene Diels‐Alder AdductChang, Hao‐Chun; Liang, Min‐Chieh; Luc, Van‐Sieu; Davis, Chelsea; Chang, Chia‐Chih<title>Abstract</title> <p>Force‐responsive molecules that produce fluorescent moieties under stress provide a means for stress‐sensing and material damage assessment. In this work, we report a mechanophore based on Diels‐Alder adduct<bold>TAD‐An</bold>of 4,4′‐(4,4′‐diphenylmethylene)‐bis‐(1,2,4‐triazoline‐3,5‐dione) and initiator‐substituted anthracene that can undergo retro‐Diels‐Alder (rDA) reaction by pulsed ultrasonication and compressive activation in bulk materials. The influence of having C−N versus C−C bonds at the sites of bond scission is elucidated by comparing the relative mechanical strength of<bold>TAD‐An</bold>to another Diels‐Alder adduct<bold>MAL‐An</bold>obtained from maleimide and anthracene. The susceptibility to undergo rDa reaction correlates well with bond energy, such that C−N bond containing<bold>TAD‐An</bold>degrades faster C−C bond containing<bold>MAL‐An</bold>because C−N bond is weaker than C−C bond. Specifically, the results from polymer degradation kinetics under pulsed ultrasonication shows that polymer containing<bold>TAD‐An</bold>has a rate constant of 1.59×10⁻⁵ min⁻¹, while<bold>MAL‐An</bold>(C−C bond) has a rate constant of 1.40×10⁻⁵ min⁻¹. Incorporation of<bold>TAD‐An</bold>in a crosslinked polymer network demonstrates the feasibility to utilize<bold>TAD‐An</bold>as an alternative force‐responsive probe to visualize mechanical damage where fluorescence can be “turned‐on” due to force‐accelerated retro‐Diels‐Alder reaction.</p>Wiley2023-11-2410483321Chemistry – An Asian Journal1861-4728https://doi.org/10.1002/asia.2023008502045908National Science Foundation