Versatile Fluorescent Cellulose-Based Materials via Hydroxyl–Yne Click Chemistry

Cellulose-based fluorescent materials are attractive for sustainable applications owing to their biocompatibility and biodegradability; however, their practical utility is often limited by aggregation-caused quenching (ACQ) and insufficient functional diversity. Here, we report a versatile strategy to construct aggregation-induced emission (AIE)-active cellulose materials via an organobase-catalyzed hydroxyl–yne click reaction, enabling the efficient incorporation of tetraphenylethene (TPE) units into the cellulose backbone. The resulting EC-TPEs exhibit high optical transparency (>95%), full UV-shielding capability, and intense fluorescence, allowing simultaneous UV protection and real-time optical indication. Notably, the fluorescence properties can be precisely tuned by controlling the grafting ratio, enabling multicolor emission and the fabrication of high-resolution fluorescent quick response (QR) codes. Furthermore, secondary grafting of AIE-active MTPAP unit affords an acid-responsive system of EC–TPE–MTPAP with dynamic fluorescence color switching, facilitating advanced multicolor encryption and high-density information storage. Importantly, the dynamic enol ether linkages formed via the hydroxyl-yne click reaction enable an efficient amine-exchange defunctionalization process, restoring cellulose hydroxyl groups without loss of reactivity. This work establishes a reversible and modular platform for engineering multifunctional fluorescent cellulose materials, offering new opportunities for sustainable optical materials and information technologies.