Functional Holocellulose Nanofibrils Fabricated by Multicomponent Reactions Pretreatment for Anti-Counterfeiting

Abstract To address the issues of high cost, non-biodegradability, and complex preparation processes of conventional fluorescent anti-counterfeiting materials, this study developed a series of biodegradable fluorescent films with aggregation-induced emission (AIE) characteristics using pine holocellulose and pure cellulose as substrates. Through acetoacetylation followed by the Hantzsch multicomponent reaction, formaldehyde, vanillin, and cinnamaldehyde were respectively grafted onto fiber surfaces to construct 1,4-dihydropyridine (DHP) fluorescent structures. Structural characterizations confirmed the successful construction of DHP moieties, and the nitrogen content was consistently higher for holocellulose-based materials than for cellulose-based counterparts, indicating that hemicellulose enhances fiber accessibility and grafting efficiency. UV–vis absorption and fluorescence measurements revealed that the cinnamaldehyde-modified film exhibited the strongest UV absorption yet the weakest fluorescence, while the formaldehyde-modified film showed moderate UV absorption but the strongest fluorescence; holocellulose-based films outperformed cellulose-based films in both UV absorption and fluorescence intensity. The prepared waterborne inks exhibited shear-thinning rheology, thixotropy, and favorable yield stress, satisfying screen-printing requirements. Printed patterns were invisible under daylight but emitted bright blue fluorescence under 365 nm UV light, with excellent solvent and thermal stability. This work provides a pathway for developing high-performance, biodegradable bio-based anti-counterfeiting inks.