Mechanochemical Synthesis and Fluorescence Reporting of Conjugated Polymers through Flex-Activation.

-Diels-Alder reaction via a bond-bending mechanism. Upon ball milling, poly(BTCD) achieves efficient activation, simultaneously releasing the fluorescent reporter 1,4-bis(hexyloxy)naphthalene (BHN) for straightforward quantification and generating semiconducting polyacetylene. The reaction kinetics and activation efficiency show clear dependencies on the milling time and polymer molecular weight. The same flex-activation pathway can be triggered under uniaxial compression, enabling iterative activation in cross-linked networks without macroscopic fracture. By integration of built-in fluorescence reporting with mechanochromic response, this system establishes a multifunctional platform for mechanoresponsive materials. Our work provides a scalable and quantitative strategy to mechanochemically generate functional polyenes directly in bulk polymers, significantly expanding the scope of flex-activated mechanophores.