| Due to the unique characteristic of superparamagnetism,high Coercivity,low curier temperature as well as broad absorbtion, nanosized magnetite particles have a wide application prospect in aviation,electron,communication,Environmental Industry,chemical engineering,such as Radar absorbing materials,shielding material,magneto-optical devices,high-density magnetic recording media and so on. Recently with the research to the depth and interdisciplinary cross-infiltration,the research on multi-functional magnetic composite microspheres applied to fields of biomedicine and biological Engineering such as drug delivery,separation of biological macromolecules,biosensors and immobilized enzyme becomes hot.The dissertation focuses on the preparation,surface modification of nano magnetic particles and synthesis of functional magnetic composite microspheres.It refers to preparation of nano-ferroferric oxide by microemulsion and coprecipitation methods,improving the dispersity of nano magnetic particles modified with small molecular, synthesis of magnetic polymer microspheres as well as preparation of magnetic and fluorescent dual-response microspheres.Detailed contents include:1. Preparation and characteriztion of magnetic nanoparticlesMagnetic nanoparticles (Fe3O4) synthesized by microemulsion and coprecipitation methods were studied. Transmission electron microscopy results showed that: Fe3O4 nanoparticles prepared by microemulsion method were spherical shaped in narrow size distribution,and magnetic nanopariticles synthesized by coprecipitation demonstrated morepolydispersed size distribution in comparison with that prepared by microemulsion method. X-ray diffraction indicated a low crystallinity of the nanoparticles obtained by microemulsion and a high crystallinity of the nanoparticles obtained by coprecipitation. The characterization of vibrating sample magnetometer showed that: the specific saturation magnetization Ms=13.5 emu·g-1 of nanoparticles prepared by microemulsion,which was lower than Ms=57.9 emu·g-1 of nanoparticles obtained by coprecipitation.The influences of some factors on magnetic nanopariticles prepared by titration hydrolyzation method were studied, the following conclusions were drawn:when the ratio of FeCl3·6H2O and FeCl2·4H2O to 2,the product was pure and good crystallinity; the nanoparticles were cubic shaped with Sodium Hydroxide Solution as alkali liquor and that were spherical shaped with ammonia titrated;the magnetic property was enhanced after 60℃ripening process.2. Study on surface modification and dispersion performance of magnetic nanopariticlesCharge stabilization and sterically stabilized Fe3O4 nanoparticles modified with Salts (sodium citrate), multiple base salts (tetramethylammonium hydroxide), small molecule organic acids (oleic acid) and the coupling agent (KH-570) are gotten,after the surface modification, Fe3O4 nanoparticles contains -COO-, OH-,-CH = CH- functional groups and can form hydrophilic / hydrophobic magnetic fluid.The achievements and conclusions are listed as follows:(1) Elucidate the principle of the stability of magnetic particles modified with sodium citrate and study the impact of the modifier's concentration on modified effect.It has been found experimentally that in a certain area to increase the amount of sodium citrate, can make Fe3O4 nanoparticles smaller size, scattered performance enhancement;(2)Show the way tetramethylammonium hydroxide to improve the dispersive property of magnetic particles, and the dispersion effect was characterized by the transmission electron microscope and ultraviolet - visible spectrophotometry, the results showed that: the suspension stability of the system was very well;(3)Explain the process of magnetic particles modified with oleic acid, and product as well as the dispersion of the system were characterized;(4)Indicate the mechanism of coupling modified magnetic particles, and the product was characterized through transmission electron microscopy as well as dynamic light scattering , at the same time get the best amount of the coupling. 3. Study on preparation and performance of core-shell magnetic polymer microspheresMagnetic composite microspheres were obtained by emusion polymerization selecting K2S2O8 as initiation,St and MMA as comonomer.Before the process of the polymerization,nanoparticles was modified with siliane coupling to endow the particles with double bond and affinity between magnetic particles and monomer.Then the magnetic composite microspheres was synthsized by the emulsion polymerization based on nanoparticles grafted with double bond ,the effects of the addition of the coupling agent as well as the contents of magnetic particles were studied and the properties of composite microspheres were characterized by the FTIR, SEM, DSC and so on.4. Study on preparation and performance of Luminous and Magnetic Microsphere with Tb-MMA-Phen ComplexLuminescent and magnetic microspheres with rare earth were obtained. In the composite microsphere, Tb(MAA)3phen and Fe3O4 were introduced by deposition and embedding with SiO2.The composition and morphology were characterized by IR AND TEM .The fluorescence as well as magnetic properties were tested by Solid Fluorophotometry and Vibrating Sample Magnetometer.Then,the factors of effect fluorescence were discussed.
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