Solvent-free and anticounterfeiting fluorescent inks based on epoxy-functionalized polyacrylic nanoparticles modified with Rhodamine B for cellulosic substrates

Abstract

Nowadays, anticounterfeiting technology and information security by solvent-free photoluminescent polymeric latex nanoparticles are of considerable interest in variety of hi-tech systems. Herein and for the first time, Rhodamine B ethylenediamine acrylate (N-RhBAc) was synthesized and copolymerized with methyl methacrylate and glycidyl methacrylate to obtain epoxy-functionalized fluorescent latex nanoparticles (RhAcL-series) through emulsion polymerization. Inclusion of N-RhBAc into the spherical polyacrylic nanoparticles with average particle size of 40−70 nm enhanced its absorption intensity (λmax of 571 nm) and emission intensity (λem of 588 nm) up to 8 and 3.5-fold with respect to N-RhBAc in the solution state (λmax of 524 nm and λem of 582 nm), respectively. The nanometric size of particles and decorated epoxy functional groups on their outer layer provided well-wetting and fine-diffusion into the cellulosic nanofiber. To obtain anticounterfeiting inks with high-resolution marking on cellulosic paper without spreading and tracing, fluorescent RhAcL-1 was formulated with required thickening agent and defoamer. The painted pattern by the above ink could immediately be developed and illuminated with brilliant red-pink fluorescence emission upon UV irradiation.