Fluorescence behavior of semicrystalline functionalized maleic acid copolymers containing 1,3,4-oxadiazole side chains

The fluorescence behavior in solution and in solid state of functionalized copolymers based on poly(styrene-co-maleic acid) and poly(N-vinylpyrrolidone-co-maleic acid) containing 1,3,4-oxadiazole side chains was studied showing the UV- and blue light-emitting ability of these polymers. For the first time, maleic acid copolymer derivatives were synthesized by using Yamazaki–Higashi reaction. The polymers have a substitution degree in the range of 21–43.3% and are fully characterized in terms of chemical structure by 1H NMR, FTIR and UV–Vis spectroscopy, and by molecular weight measurements. The thermal stability and glass transition temperatures of the modified polymers were measured and compared with those of the raw polymeric support. The solid polymers were studied by X-ray diffraction which revealed a semicrystalline state. Different morphologies, e.g. porous or spherulite-like were found in the very thin films prepared from these new copolymers when investigated by atomic force microscopy and polarized light microscopy. The influence of the morphology and crystallinity of the thin copolymer films on their fluorescence behavior was studied.