Phototunable dual-emitting and water-resistant cellulose acetate-based fluorescent materials

A water-resistant cellulose acetate (CA)-based fluorescent film with optically tunable dual-emitting property was synthesized using CA as the matrix, with fluorescein isothiocyanate (FITC) and inorganic phosphor CaAl₂O₄:Eu²⁺, Dy³⁺ (NH₂-CAO) as luminescent particles. Structural characterization via Fourier-transform infrared spectroscopy (FTIR), ¹H nuclear magnetic resonance (¹H NMR), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) confirmed the successful grafting of FITC and NH₂-CAO onto CA molecular chains. The anchoring and dilution effects of the CA backbone effectively mitigated the aggregation-caused quenching of fluorophores, enabling CA-FITC and CA@NH₂-CAO systems to emit green (535 nm) and blue (485 nm) fluorescence in both solution and solid-film states, respectively. On the fluorescence spectrum of the CA-FITC@NH₂-CAO film, emission peaks corresponding to both FITC and NH₂-CAO were observed. A gradual increase in NH₂-CAO content induced chromatic transition and conferred a long afterglow effect. Moreover, the CA-based fluorescent films demonstrated water resistance and thermal stability. Compared with existing cellulose-based fluorescent films, this work achieved prolonged luminescence duration and superior water resistance performance, providing a novel strategy for developing biomass-derived smart textiles with water-resistant color-shifting coatings.