investigation the effect of polymer chain flexibility on kinetics of spiropyran photochromism in copolymer nanoparticles

Glass transition temperature (tg) is a significant parameter for the physical and chemical properties of the copolymer nanoparticles prepared by emulsion polymerization. here, the copolymer nanoparticles with different tg or chain flexibility were synthesized by emulsion copolymerization of methyl methacrylate (mma) and butylacrylate (ba) in different copolymer compositions. afterward, the prepared copolymer nanoparticles were modified physically with spiropyran to develop of the photochromic and photoluminescent nanoparticles. the effect of chain flexibility on photochromic and photoluminescence properties of nanoparticles was studied by uv-vis spectroscopy, which the absorbance intensity and λmax are changed depending on chain flexibility. in addition, the effect of chain flexibility on kinetics of sp to mc and mc to sp isomerization was investigated by uv-vis spectroscopy under uv and visible light irradiation, respectively. the results indicated that kinetics of photochromism and fluorescence emission can be influenced significantly by tg of the polymer nanoparticles.