Ultralong phosphorescence cellulose with excellent anti-bacterial, water-resistant and ease-to-process performance

Abstract

Herein, we present a phosphorescent cationized cellulose derivative by simply introducing ionic structures, including cyanomethylimidazolium cations and chloride anions, into cellulose chains. The imidazolium cations with the cyano group and nitrogen element promote intersystem crossing. The cyano-containing cations, chloride anions and hydroxyl groups of cellulose form multiple hydrogen bonding interactions and electrostatic attraction interactions, effectively inhibiting the non-radiative transitions. The resultant cellulose-based RTP material is easily processed into phosphorescent films, fibers, coatings and patterns by using eco-friendly aqueous solution processing strategies. Furthermore, after we construct a cross-linking structure by adding a small amount of glutaraldehyde as the cross-linking agent, the as-fabricated phosphorescent patterns exhibit excellent antibacterial properties and water resistance. Therefore, considering the outstanding biodegradability and sustainability of cellulose materials, cellulose-based easy-to-process RTP materials can act as antibacterial, water-resistant, and eco-friendly phosphorescent patterns, coatings and bulk materials, which have enormous potential in advanced anti-counterfeiting, information encryption, disposable smart labels, etc.

Fig. 1. Phosphorescent Cell-ImCNCl.

Chemical structure, processability, and performance of the cationic cellulose derivative Cell-ImCNCl with RTP property.

Fig. 2. Synthesis, RTP mechanism, and performance of Cell-ImCNCl.

a Synthesis route and photograph of Cell-ImCNCl; b Schematic illustration of the RTP mechanism of Cell-ImCNCl; c Jablonski diagram energy level diagram of RTP materials; d Photographs of Cell-ImCNCl powder taken under 365 nm lamp and with the lamp off.

Fig. 3. Influence of the chemical structure of Cell-ImCNCl on its RTP performance.

a Schematic diagram of Cell-ImCNCl with different DS_CN; b RTP spectra of Cell-ImCNCl with different DS_CN (Ex = 320 nm); c Photoluminescence quantum yield of Cell-ImCNCl with different DS_CN (Ex = 320 nm); d RTP lifetime spectra of Cell-ImCNCl with different DS_CN; e Schematic diagram of Cell-ImCNCl with different DS_t; f RTP spectra of Cell-ImCNCl with different DS_t (Ex = 320 nm); g Photoluminescence quantum yield of Cell-ImCNCl with different DS_t (Ex = 320 nm); h RTP lifetime spectra of Cell-ImCNCl with different DS_t; i Schematic diagram of Cell-ImCNX with different anions; j RTP spectra of Cell-ImCNX (Ex = 320 nm); k Photoluminescence quantum yield of Cell-ImCNX with different anions; l RTP lifetime spectra of Cell-ImCNX with different anions.

Fig. 4. Processability and formability of Cell-ImCNCl.

a Processing methods of Cell-ImCNCl; b Phosphorescent Cell-ImCNCl film made by the doctor blade coating method; c Phosphorescent “Chinese knot” from PVA fibers produced by the dip coating method; d–i Phosphorescent patterns on various substrates. The ultraviolet light used is 365 nm.

Fig. 5. Water-resistant phosphorescent materials based on Cell-ImCNCl.

a Schematic diagram of the preparation process of water-resistant phosphorescent materials; b Optical images of the water-resistant phosphorescent pattern; c Water-resistant test of the phosphorescent patterns; d Antibacterial properties of water-resistant phosphorescent patterns by the inhibition ring experiment (Staphylococcus aureus (S. auresus) and Escherichia coli (E. coli)); e Anticounterfeiting patterns made by phosphorescent Cell-ImCNCl and fluorescent Cell-BimCl. The ultraviolet light used is 365 nm.