Self‐Reporting Diels–Alder Networks: Fluorescent Tracking of Reaction Conversion and Thermal History

ABSTRACT

Dissociative networks comprising reversible Diels‐Alder bonds have received increasing attention due to their potential for end‐of‐life recyclability. Here, we demonstrate that a tetraphenylethylene‐based probe can act as a universal self‐reporting additive for scalable Diels–Alder networks, enabling reversible optical monitoring of network conversion and thermal history at loadings below 0.8 wt%. Upon Diels–Alder reaction, suppression of photoinduced electron transfer activates a clear light‐blue fluorescence, enabling direct optical tracking of network formation. The luminogen is homogeneously distributed within the polymer matrix and exhibits fully reversible fluorescence upon repeated heating–cooling cycles, reflecting the reversible nature of the crosslinks. Importantly, the fluorescence intensity evolves with Diels–Alder conversion, providing a direct indicator of the network state and its thermal history. This work establishes a general approach for reaction conversion tracking in dynamic covalent polymer networks and offers new opportunities for monitoring processing, self‐healing, and recycling of sustainable thermosets.