Preparation Of Light-emitting Polymer Composite Films And Their Sensing Performance

With the intensification of the industrialization process, it has increased of toxic and hazardous substances released into the environment every year, followed by other problems, such as air pollution, water pollution and soil pollution. These problems not only cause negative impact on the ecological environment and threaten the survival of humanity. Therefore, the study of sensing material for sensing toxic and hazardous substances is particularly important.Photoluminescent composite film, due to its introduction of the luminescent species(inorganic fluorescent material or organic fluorescent material) in the interior or surface of the film material, it has a certain optical properties. Moreover, the film is processing easily, has high transparency, good luminescence stability and high luminous efficiency. This kind of composite film has become a promising class of functional materials currently.The thesis chose strontium aluminate and cholesterol which modified by 7-nitrobenzofuran(NBD-chol) as fluorescent species respectively, easy film-forming polymer as matrix material, designed and synthesized a series of fluorescent polymer composite film, and investigated these films for gas and liquid hazardous substances sensing performance systematically.Firstly, for the preparation of SrAl2O4/PMMA composite film, we took poly(methyl methacrylate)(PMMA) as film-forming polymer matrix, which was synthesized by bulk polymerization, luminescent strontium aluminate(SrAl2O4) was introduced during the synthesis process of PMMA. SEM, fluorescence microscopy and other means were used to characterize the film, static fluorescence spectroscopy, fluorescence lifetime and fluorescence quenching were used to characterize the photophysical properties of film. Finally, the effect of drying and preparation methods to sensing performance of film was investigated. The research showed that the film is selective and sensitive to the alcohol compounds in gas phase. Furthermore, the fluorescence signal obtained is reversible, fluorescence lifetime test result showed that the quenching process is static.Secondly, in order to detect harmful substances in aqueous solution, considering the rapid diffusion of analytes in the composite film, we chose more hydrophilic poly-hydroxyethyl methacrylate(PHEMA) as film-forming matrix, introduced a fluorescent species NBD-chol with the ability of self-assembling, and prepared a series of fluorescence composite sensing film. SEM, fluorescence microscopy and other means were used to characterize the film, sensing performance test showed that the amine compounds had a significant quenching effect to the fluorescence emission of the film in aqueous solution. The film is high sensitivity, and sensing process is reversible. Fluorescence lifetime confirmed that it was a static quenching process of the film to the amine compounds in liquid phase, and quenching mechanism was also studied.The third part of this thesis is based on the outcome of the above-mentioned, NBD-chol/PMMA fluorescent film was prepared firstly, considering the detection of harmful substances in the liquid phase, the NBD-chol/PMMA film was hydrolyzed by concentrated sulfuric acid, then NBD-chol/PMAA composite film was accomplished. Film components was characterized by infrared spectroscopy. The sensing properties results indicated that ether in the liquid phase had obvious quenching effect to the fluorescent emission of the film, and sensing process is reversible. The fluorescence lifetime results shown that the quenching process is static.