Preparation Of Ferroferric Oxide Particles By Solvent-thermal Method And Preparation Of Magnetite-composite Particles

Ferroferric oxide can widely be applied in paints, sensors, microwave, absorbing, biological medicine field,because of its physical and chemical stability and good biocompatibility and mag-netic properties.Our work is mainly focused on study of the structural, morphological and magnetic properti-es of Fe3O4magnetite nanoparticles prepared by solvent-thermal method, Fe3O4@SiO2@PMMA composite particles prepared by Precipitation Polymerization and Fe3O4@SiO2@PMAA compo-site particles prepared by Solution Polymerization by XRD, SEM,TEM and Mossbauer spectrum respectively. The effects of reaction system, reaction time and surfactant on the structural, morpho logical and magnetic properties of magnetite nanoparticles are studied.The main results and conclusions are:(1) Submicrometer particles of ferroferric oxide with about400nm were synthetized by solvent-thermal method in ethylene glycol/sodium acetate/poly (ethylene glycol) system. With increasing reaction time, the morphology of the as-synthetized particles approached the spherical, The cryallization of the as-synthetized particles gradually increases. The obtained particles show room temperture ferromagnetism.(2) Hollow ferroferric oxide particles were synthetized by solvent-thermal method in ethylene glycol/carbamide/poly (ethylene glycol) system. The sturcture of compounds mainly depend on the reacting time.The hollow parcticals with the size of400nm can be obatined under20h racting time.The morphology of particles was affected by the molecular wight of the surfactant. The best morphology was obtained with PEG-400.(3) Ferroferric oxide particles about150nm were synthetized by solvent-thermal method in ethylene glycol/sodium acetate/sodium citrate system. The SEM results indicate that each Fe3O4particle is composed of many nanoparticles of about15nm in diameter. XRD and Mossbauer spectrum verified that the synthesized particles were Fe3O4instead of γ-Fe2O3The saturated magnetization was58.4emu/g for Fe3O4.The coercive force was10Oe for Fe3O4. Compared with bulk Fe3O4, the as-synthetized particles are superparamagnetic at room temperature. (4) Ferroferric oxide particles with about50nm were synthetized by solvent-thermal method in ethylene glycol/carbamide/sodium citrate system. The results exhibit each Fe3O4particle is composed of many nanoparticles of about15nm diameter. But the dispersity of as-synthetized particles is rahter poor.(5) The magnetite-composite particles of Fe3O4@SiO2were prepared by modified stober method. The results reveal that the surface modification of Fe3O4particles was very necessary before coating with silica, magnetic particles without modified could not be coated by silica. The Fe3O4@SiO2microspheres show outstanding monodispersity.(6) Finally, the Fe3O4@SiO2@PMMA and Fe3O4@SiO2@PMAA composite particles were successfully obtained by Precipitation Polymerization and Solution Polymerization respectively.