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Preparation and Characterization of Composite Microspheres with High Magnetic Susceptibility

Author: Xia
Tutor: WangChangChun
School: Fudan University
Course: Polymer Chemistry and Physics
Keywords: Magnetic nanoparticles Magnetic Polymer Microspheres Magnetic silica microspheres Polystyrene Poly ( methyl methacrylate ) Poly - N- isopropyl acrylamide The magnetic temperature sensitive microspheres High magnetic -responsive microspheres Magnetic micelles Core-shell structure Janus structure Self-assembly Chemical co-precipitation method Solvothermal Precipitation polymerization Miniemulsion Double emulsion emulsion Stober method Soft template
CLC: TB383.4
Type: PhD thesis
Year: 2009
Downloads: 1075
Quote: 3
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Abstract


In recent years due to the rapid development of biomedical research and the improvement of the relevant material requirements, multifunctional magnetic composite microspheres with environmental response more and more people's attention. Order to meet the demand for high magnetic response microspheres of the biomedical field, it is not only necessary to study how to prepare high magnetic magnetic particles, also need to study how the preparation of the obtained magnetic particles are used as the magnetic function unit with the polymer, silica, etc. the type of matrix material combination for preparing multifunctional composite microspheres with high magnetic responsiveness. Based on the above demand background, this paper studies mainly focus on the preparation and characterization of high-magnetic-responsive polymer and silica composite microspheres expand. And studied the magnetic particles in the tri-iron tetroxide as the the magnetic functional unit of the polymer, silica matrix composite process, the interaction between the four iron oxide magnetic particles and the matrix material, thereby controlling the composite microspheres four the amount of iron oxide magnetic particles loaded and distribution in the composite microspheres prepared with different weaving group hierarchy magnetic polymer matrix, silica-based composite microspheres. Paper the main results of the work in the following areas: 1, were prepared with different particle size, morphology and surface properties of iron oxide magnetic particles for further preparation of high magnetic responsive composite microspheres of different types of magnetic functional unit. In the group on the basis of previous work and existing literature summary, choose a different route to prepare a variety of different particle size, morphology and surface properties at the nanoscale or submicron tri-iron tetroxide magnetic particles, the initial exploration and The reaction conditions in the different preparation routes generate tetroxide ferromagnetic particles, particle size, particle size distribution, morphology and magnetic properties. First, by chemical coprecipitation an average particle size of about 15 nm single-layer four of oleic acid-modified oil-soluble iron oxide magnetic nanoparticles. Secondly, the use of organic metal complexes of the pyrolysis method and seed growth method, was prepared by a particle diameter of 4 nm, 6 nm, 9 nm, 12 nm and 14 nm monodisperse oil-soluble tri-iron tetroxide magnetic nanoparticles, . Once again, the legal system by the oxidation of ferrous hydroxide gel prepared micron and sub-micron particle size and morphology of iron oxide magnetic particles. Further introduction of the relative concentration gradient method, changes in the concentrations of the reactants tetroxide ferromagnetic particles was investigated in the preparation process protection of nitrogen tetroxide prepared final three ferromagnetic particles, particle size and morphology affected. The Solvothermal nearly monodisperse submicron iron oxide magnetic particles. 2 monolayer oleic acid modified iron oxide (Fe 3 O 4 ), magnetic nanoparticles magnetic microspheres functional unit preparation of high magnetic content polymer-based microspheres. The use of polymer matrix selection effect of the magnetic nanoparticles, combined with the emulsion polymerization method, prepared magnetic polymer microspheres have different organizational hierarchy. First, the chemical co-precipitation prepared monolayer oleic acid modified Fe 3 O 4 magnetic nanoparticles as a the composite microspheres magnetic function unit preparation of high magnetic content Fe 3 O 4 / PMMA polymer microspheres. By changing the course of the reaction adding emulsifier monomer and a monolayer of oleic acid-modified Fe 3 O 4 of the quantity of the magnetic nanoparticles prepared with different magnetic content the Fe 3 O 4 / PMMA polymer microspheres and the the composite microsphere Fe 3 O 4 magnetic nano- maximum particle Now amount close to 60%, compared with the currently commercially available magnetic microspheres Now amount of 30% of the magnetic particles has been greatly improved. Secondly, the study of the reaction process, the monomers polymerized to form a polymer matrix of a monolayer of oleic acid-modified Fe 3 O 4 magnetic nano-particle selection effect, by The different types of monomers used in the preparation process and a change in monomer polymerization to control the sequence of the resulting magnetic composite microspheres structure, prepared PMMA / Fe is 3 O 4 PSt @ Fe 3 O 4 , PMMA / Fe 3 O 4 @ PSt, PSt @ PMMA / Fe < sub> 3 O 4 different magnetic polymer microspheres. And apply the principles of thermodynamics monomer to form the polymer matrix during the reaction of the Fe 3 the O 4 magnetic nanoparticles selection effects the preliminary theoretical derivation and interpretation . Finally, in front of the preparation of a variety of structural magnetic composite microspheres analyzed and summarized on the basis of the application of the polymer matrix on Fe 3 O 4 magnetic nanoparticles matrix choice the principle of effects, further preparation has the the Janus structure of magnetic composite microspheres. The Janus structure obtained Magnetic Polymer Microspheres one-dimensional self-assembly, use the Magnetic Composite Microspheres Fe 3 O 4 magnetic nanoparticles magnetic properties of magnetic composite microspheres one-dimensional self-assembly to explain the principles. 3, the use of silica as the Fe 3 O 4 magnetic particles coated materials, by selecting the route of different silica composite microspheres with different particle size and The surface properties of Fe 3 O 4 magnetic particles as magnetic composite microspheres functional unit prepared high magnetic response of silica microspheres. Silica spheres during the reaction and the formation mechanism of the particles prepared with different structure and morphology of the Fe 3 O 4 / the SiO 2 < / sub> composite microspheres and particles. First of all, the use of single-oleic acid modified iron oxide magnetic particles as a the magnetic functional unit of the composite microspheres, Stober method and emulsion preparation method combined by controlling the amount of aqueous ammonia were added during the reaction of different regulation tetroxide iron magnetic nanoparticles in the composite microspheres distribution of magnetic silica microspheres prepared by a variety of morphologies. Secondly, the use of the double emulsion method, a solution of tetraethyl orthosilicate (TEOS) of the monolayer of oleic acid-modified tri-iron tetroxide particles as multiple emulsion of the oil phase to adjust the conditions of the preparation process of the emulsified control emulsion Instead, the speed of water was added to the transfer process to prepare a complex emulsion droplets of the W / O / W structure, prepared by adding aqueous ammonia obtained having the Fe 3 the O 4 / SiO 2 magnetic shell micron hollow magnetic microspheres. Again, the monolayer oleic acid modified iron oxide magnetic particles as a the magnetic functional unit of the composite microspheres, sodium silicate as silica precursor, ethyl acetate or butyl acetate reaction control agent, CTAB as emulsifier, was prepared by changing the concentration of the starting reactants, the eggplant-shaped magnetic particles, the lines of magnetic silica and hollow silica magnetic microspheres. Ethyl acetate or butyl acetate as a reaction control agent, of CTAB join and concentration of magnetic silica microspheres and particle morphology evolution. Finally, using the solvothermal the unit of nearly monodisperse submicron iron oxide magnetic particles as a function of the magnetic properties of the magnetic silica microspheres prepared by a high magnetic response of Fe 3 O < sub> 4 @ SiO 2 composite microspheres. 3 O 4 @ of SiO 2 microspheres surface by high magnetic response of mononuclear Fe MPS modified introducing a double bond in aqueous solution thrown NIPAM precipitation polymerization. And studied the amount of initiator in the reaction process, the surface of the microspheres MPS modified polymerization prepared with high magnetic response and temperature-sensitive dual environment responsive Fe 3 the O 4 @ SiO 2 @ PNIPAM composite microspheres.

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