Cellulose-based fluorescent films with anti-counterfeiting and UV shielding capabilities enabled by enamine bonds

Abstract

Natural cellulose-based materials with multifunctionality are highly pursued and yet a scientific challenge. To this end, fluorescent polymer films with UV shielding and anti-counterfeiting abilities were designed by grafting microcrystalline celluloses with acetoacetyl groups followed by a cross-linking treatment with polyetherimide. After the cross-linking process, the mechanical properties of the polymer films were improved, and they produced enamine linkages, which can effectively prevent the transmittance of ultraviolet light and emit fluorescence. The crosslinked films completely shielded all wavelengths of UV. On account of the dynamic nature of the enamine bonds, the polymer films can be de-cross-linked and recycled. The fluorescence of the polymer film can be quenched by Cr(VI) solution, through which the film can be applied in the anti-counterfeiting area. Considering the wide accessibility of the cellulose, and the multifunctionality of our designed cellulose-based polymers, we believe that they have the potential for application on a large scale.