Novel fluorescent copolymers of styrene with benzazole chromophores

Novel green fluorescent copolymers of styrene and 2-[(5′-N-acryloyl)-2′-hydroxyphenyl]benzoxazole or 2-[(5′-N-acryloyl)-2′-hydroxyphenyl]benzothiazole were synthesized by radical polymerization. The copolymers were characterized by size exclusion chromatography, thermal analyses (DSC, TGA), UV-Vis and fluorescence spectrophotometry. The glass transition temperatures of the fluorescent copolymers were similar to that of the parent polystyrene and the average molecular weight was lower due to the chain transfer effect of the benzazole dyes. The maximum fluorescence emission wavelength of the copolymers in the solid state or in chloroform solution accessed by fluorescence spectrophotometry was also similar. The Stokes shift of the styrene-benzoxazole or -benzothiazole copolymers was similar to those presented by fluorochromes that exhibit an excited state intramolecular proton transfer mechanism.