Reversible Multifunctional Fluorescent Cellulose Materials via Hydroxyl-Yne Click Reaction: Integrating UV-Shielding, Multicolor Fluorescence, and Acid-Responsive Properties

Cellulose-based fluorescent materials enjoy advantages such as excellent biocompatibility, biodegradability, and environmental friendliness, making them potentially useful for chemical sensing, bioimaging, and information encryption. However, traditional cellulose-based fluorescent materials face issues of single functionality and aggregation-caused quenching, making the development of multifunctional fluorescent cellulose materials applicable in aggregated states desirable but challenging. Herein, we innovatively endowed fluorescent cellulose materials with an aggregation-induced emission characteristic through hydroxyl-yne click reaction. The developed ECTPEs exhibit breakthrough performance with high transparency (>95%), full ultraviolet (UV)-shielding efficiency (>99.9%), accompanied by fluorescence characteristics, thereby achieving simultaneous UV blocking and indicating functions for UV-sensitive materials. Additionally, ECTPEs demonstrate grafting ratio-dependent multicolor fluorescence, enabling their application in high-resolution fluorescent QR codes. The further development of acid-responsive ECTPE-MTPAPs through secondary grafting realizes fluorescence color switching under acidic stimulation and enables the creation of dynamic multicolor coding devices with enhanced data storage density and sophisticated encryption capabilities. Significantly, an amine exchange strategy based on dynamic enol ether bonds effectively resolves the inherent conflict between material functionalization and degradability. This work provides an innovative methodology for developing reversible multifunctional fluorescent cellulose materials, offering crucial guidance for advancing the development of sustainable fluorescent materials.