Fabrication of Anti-Counterfeiting Films by Dyeing Cellulose Nanofiber with Berberine

Abstract

Incorporation of planchettes and use of films which are capable to take part in color-forming reactions are the common methods in fabricating security paper documents. In this paper, a novel cellulose nanofiber-based (CNF) films with high performance in optical properties were developed for use in anti-counterfeiting applications. In order to enhance dyeability of CNFs with eco-friendly cationic berberine, functional modification was carried out by in-situ polymerization along with grafting approach with acrylic acid (AA-g-CNF). Grafting achievement was demonstrated with determination of grafting percentage and further characterized by FTIR spectroscopy. Tensile strength impairment of AA-g-CNF films which was accompanied with alteration of crystallinity and partially changing the structure of cellulose I to cellulose II was demonstrated by X-ray diffraction (XRD) analysis. The variations of dyeing reaction time and temperature caused to alter color strength of CNFs due to different adsorption rate of berberine. It can be concluded that exhibition of appropriate appearance characteristics such as color, transparency and color strength make the berberine-dyed CNF films as a novel anti-counterfeiting element for application like security paper documents.