Anticounterfeiting and photoluminescent cellulosic papers based on fluorescent acrylic copolymer nanoparticles containing coumarin.

Fluorescent nanoparticles are widely exploited as probes in cell tracking, drug delivery systems and high-performance security devices nowadays. Herein, we report the synthesis of novel 7-acryloxycoumarin (7-AC) through modification reaction of 7-hydroxycoumarin with acryloyl chloride and its copolymerization with methyl methacrylate and glycidyl methacrylate to produce epoxy-functionalized fluorescent polymer nanoparticles through emulsion polymerization. Chemical modification of cellulose pulp papers with the as-prepared fluorescent latex nanoparticles was also assessed. Spherical nanoparticles with average particle size of 40-93 nm and their diffusion into cellulosic fibers with excellent wetting and coating were monitored. Fluorimetery analysis demonstrated that immobilization of 7-AC into the hydrophobic acrylic copolymer substrate enhanced its emission intensity significantly with respect to its molecularly solution due to the elimination of unwanted environmental effects and non-radiative processes such as probable internal conversions. The obtained products exhibited intensified fluorescence emission with potentiality of being used in anticounterfeiting inks and security documents.