Study Of Preparation And Properties On Fe₃O₄ Magnetic Nanoparticles And Core/shell Polymer Magnetic Microspheres

The research of macromolecule biomaterials having biological activity is an important area which produced between macromolecule science and life science and is also an important characteristic of the improvement in macromolecule science. In one hand, the magnetic polymer microspheres have special functional group which can react with biological active matter and are used as supporter on biological active matter. In other hand, it has paramagnetism and can separate rapidly in external magnetic field. So the research about it enlarges increasingly in bioengineering, biomedicine, separation and sign of cells. In the preparation of Fe₃O₄ magnetic polymer microspheres, it is important to prepare magnetic nanoparticles and ensure magnetic nanoparticles is embedded by monomer and form core-shell composite microspheres during the monomer's polymerization. In view of this study, the objectives of the current work were to develop a convenient method to prepare magnetic nanoparticles and core-shell composite microspheres and discuss the influence factors on average particle size of microspheres. The thesis major explored in the following aspects: a. Through the analysis of preparation mechanism of nanoparticles, we adopted the chemical co-precipitation method to prepare magnetic Fe3O4 nanoparticles. Under a certain kind of condition, we got the magnetic Fe3O4 nanoparticles coated by sodium oleate, polysorbate 80(tween-80) and PEG4000 as surfactants respectively. The size distribution of magnetic nanoparticles is uniformity and the saturation magnetization is high. b. after the completion of the preparation of magnetic nanoparticles, we change it into magnetic fluid. Then Using BPO as the initiator, the styrene and acrylic acid as polymerization monomer, the core-shell composite magnetic polymer microspheres with carboxyl groups were synthesized by dispersion copolymerization. c. The production were characterized by X-ray diffraction ,transmission electron microscope,scan electron microscope,FIIR spectroscopy etc. The results indicate that the only product prepared by co-operation method was Fe3O4 single-phase and its diameter was about 10 nm. The microspheres with carboxyl groups was spherical and its diameter was about 1-5 μm. The results of VSM tests show the sample's magnetism is the strongest when using PEG4000 as the surface active reagent.