Cellulose-based nanocomposites for anti-counterfeiting applications

Counterfeit products have become more accurate with technology development, and deterrent anti-counterfeiting solutions are in constant demand. Structural-color-generating films from cellulose nanocrystals (CNC) nanocomposites present good properties to be used as anti-counterfeiting systems. Derived from liquid crystalline suspensions, these photonic materials present selective left-handed circular reflection that acts as a covert anti-counterfeiting feature, while the structural coloration that can act as an overt feature, flexibility, and response to multiple stimuli (can act as additional covert features). [1-4] Tunning optical properties and flexibility of solid films of CNC with other cellulosic derivatives was explored by the addition of hydroxypropylcellulose (HPC) [3] and hydroxypropylmethylcellulose (HPMC) [5] in home-made and commercial cellulose nanocrystals in liquid crystalline colloidal suspension, within the biphasic regime. HPC and HPMC content allows modulation of the reflected pitch value within all composite systems and induces flexibility. These new photonic cellulose-based nanomaterials are excellent candidates as anti-counterfeiting optical variable devices.