Study On Preparation And Luminescence Properties Of Fluorescent Microgel Containing Rare Earth

Fluorescent polymer microsgel/microspheres containing rare earth organic complexes has become an important field of functional microsphere materials along with the preparation technology and testing method are increasingly mature, because they not only contain organic complexes which possess high luminescence efficiency, but also possess the advantages of polymer such as good mechanical stability and post-processing ability. Poly(N-isopropylacrylamide) is temperature-sensitive, and has the volume transition temperatue(VPTT)where heating an aqueous solution of PNIPAM above 32℃ induce conformat-ion transition. Because of its themosensitive property, microgels are widely used in the fields of drug controlled release, catalyst carrier, etc. Polystyrene(PS) has become a common carrier material to prepare these functional microsphere due to its excellent mechanical property and high thermal stability. In our dissertation,water soluble europium complexes with electronegativity Eu(TTA)4, hydration europium complexes Eu(TTA)3(H2O)2 and three kind of europium complexes contain new β-diketone ligand were prepared. Poly[N-isopropyl acrylamide-co-1-vinyl imidazole(VI)] microsgel and poly[styrene-co-acrylic acid diphenyl phosphoryl methyl ester(ADPME)] micropheres with different copolymer proportion were prepared by dispersion polymerization. The fluorescence microgel and microsphere were prepared by chemical or physical methods, then its fluorescent properties were tested and the influence of copolymerization proportion on its fluorescence properties were studied. The results of this study provide theoretical and experimental basis on the application of microgel and microsphere. The detailed outlines are elaborated as follows:(1) PNIPAM-co-PVI with different copolymer proportion was successfully synthesized and the optimum conditions for the copolymerization were settled via large number of experiments as follows: dispersion polymerization with the following conditions: distilled water was used as a solvent,monomer concentration of 12%, crosslinker amount of 4%, disperser amount of 10%, initiator amount of 3%, reaction took place under stirring speed of 120r/min for 6h under 60℃. Then, the microgel was combined with benzyl bromide to obtain [P(NIPAM-co-VI)]Br, followed by reaction with europium complexes Eu(TTA)4 with a negative charge to obtain fluorescent microgel. The experiment result indicates that:with the increase of proportion of VI in the microgel, the microspheres become coarser and adherent, but the fluorescence intensity was enhanced and the excitation spectrum also widens.(2) Microgel containing hydrated Eu(TTA)3(H2O)2 complexes was synthesized through the physical adsorption method. The result shows that: with the increase of proportion of VI in the microgel, the VPTT become higher and inconspicuous and the microgel become non-thermosensitive, on the contrary, the fluorescence intensity and the fluorescence lifetime of the microgel enhanced.(3) PS-co-PADPME copolymer microsphere was synthesized by dispersion polymerization, and the optimum conditions were determined via large number of experiments as follows: ethanol:distilled = 42.5:7.5 was used as a solvent, crosslinker amount of 10%, disperser amount of 7%, initiator amount of 1%, reaction took place by delay crosslinking technology under stirring speed of 120r/min for 24 h under 70℃. The microsphere was obtained by solvent evaporation method, and the fluorescence property was studied. It turns out that:with increase of the amount of ADMPE in microsphere, the fluorescence intensity was enhanced.(4) Three type of new β-diketone with different substituent groups were prepared through the Claisen condensation method, they are methyl replaced β-diketone ligand,trifluoroacetic replaced β-diketone ligand and benzene replaced β-diketone ligand,respectively. The corresponding rare earth complexes were synthesized and the fluorescence property was studied. The experiment result indicates that:the fluorescence intensity of trifluoroacetic replaced β-diketone ligand is strongest and the range of excitation wavelength of excitation spectrum is the widest.