Smart Anti-Counterfeiting Inks: Controlled Luminescence Polarization and Its Fixation by Photoisomerization and Subsequent Photopolymerization of Cyanostilbene-Based Liquid Crystal Monomers

摘要

To identify and protect authentics from counterfeits, anti-counterfeitingmaterials are developed. In spite of many advances in luminescentanti-counterfeiting materials, there is still a need for easily processible,multilevel anti-counterfeiting materials. Here, the study reports a novelstrategy for the production of smart anti-counterfeiting inks and films using acyanostilbene-based liquid crystal (LC) monomer (CSRM). This smart ink isprepared by mixing CSRM and conventional nematic LC monomers. Theoptimized ink with a nematic mesophase is uniaxially oriented by simpleshear coating for high transmittance and linearly polarized light emission.Upon subsequent irradiation with 365 nm UV light using a photomask, aphase transition to an isotropic state occurs by photoisomerization of CSRMin selected areas, resulting in unpolarized photoluminescence in those areas.Two optically different regions (UV treated and untreated) can be permanentlyfixed by photopolymerization under 460 nm blue light. Multilevelanti-counterfeiting labels programmed by simple shear coating, molecularself-assembly, selective photoisomerization, and photopolymerization fixationcan provide a new insight in developing smart anti-counterfeiting inks andfilms.