Dual responsive cellulose-based fluorescent material fabricated in a CO2 switchable solvent for multifunctional applications

Fabrication of multi-responsive fluorescent sensors for real-time and visual monitoring or detection is practical and challenging. Herein, a novel cellulose-based fluorescent functional material with dual-responsive properties arising from two different functional sites was successfully designed and prepared in a CO2 switchable solvent. Cellulose was effectively dissolved in this solvent and easily functionalized by successively grafting poly (lactic acid) and 7-hydroxy-4-trifluoromethyl coumarin (HFC) onto the cellulose backbone, resulting in C-g-PLLA/HFC with good processibility and fluorescence quenching response (turn off) towards Fe3+ due to the coordination of Fe3+ with the carbonate linkage. Acetylation of HFC under microwave-assisted conditions gave rise to C-g-PLLA/ HFC-Ac which showed fluorescence enhancement response (turn on) to various organic amines because of the removal of the acetyl group by aminolysis reaction. Therefore, they could be respectively used for selective identification and detection of Fe3+, and real-time, accurate and visual monitoring of aquatic product freshness. Furthermore, an interesting application for irreversible information encryption was demonstrated by combining the dual-responsive property. This study suggests a new strategy for constructing cellulose-based functional material with multiple responsiveness and applications.