Dynamic color-tunable ultra-long room temperature phosphorescence polymers with photo-chromism and water-stimuli response for multilevel anti-counterfeiting

Abstract

Developing dynamic color-tunable ultra-long room temperature phosphorescence (URTP) polymers with afterglow of over 1 s, photo-chromism, and multi-stimuli response for practical anti-counterfeiting and information security applications is attractive but very challenging. Herein, by doping multicolor phosphorescence pyridinium bromide L block or viologen-based photo-chromic V block into polyvinyl alcohol matrixes, the water-stimuli-responsive color-tunable URTP polymer films with afterglow of up to 8 s and the reversible viologen-based photochromic polymer films have been developed. More significantly, a series of dynamic color-tunable URTP polymer films with ultra-long afterglow of over 6 s, photo-chromism, and water-stimuli response have been successfully exploited by integrating L and V blocks into one polymer system. Mechanistic investigations have revealed that their photo-chromism mainly comes from the photo-generated viologen free radicals. Furthermore, their dynamic multilevel anti-counterfeiting applications have been demonstrated. These results pave the way to develop smarter multifunctional URTP materials for anti-counterfeiting and optical sensing.