Preparation And Properties Of Functionalized Magnetic Polymer Nanospheres

This dissertation is intended to prepare functionalized superparamagnetic nanospheres with small and uniform particle size,good dispersibility,high magnetite content and saturated magnetization by a modified one-step miniemulsion copolymerization.And histidine was covalently linked to the surface of magnetic nanospheres,and then the simulative labeling experiment of the resulting nanospheres with tri-carbonyl rhenium was primarily developed. Detailed experimental data and powerful theoretical evidence were obtained for realizing the successful radiolabeling of magnetic nanospheres with ¹⁸⁸Re.The details are described as below:Firstly,the inorganic magnetic particles are the key factors in influencing the properties of magnetic polymer nanospheres.In this paper,ferrite nanoparticles were prepared salt-assisted glycine combustion method,and Fe₃O₄ ferrofluids were prepared by modified coprecipitation. And their properties were characterized and analyzed.The resulted showed that compared with ferrite nanoparticles,Fe₃O₄ ferrofluids had better dispersibility,smaller and more uniform particle size,stronger magnetic responsiveness,better miscibility with oil phase,which were more fit for preparing magnetic polymer nanospheres.Secondly,the amide-functionalized and esterifiable Fe₃O₄/polymer core/shell magnetic nanospheres were prepared by a modified one-step miniemulsion copolymerization in presence of Fe₃O₄ ferrofluids,respectively.And styrene was polymerized monomer,and acrylamide and methyl methacrylate were chosen as functionalized monomer.The effects of various polymerization parameters,such as the functionalized monomer dosage,the surfactant dosage,the cross-linker dosage,the initiator dosage and the magnetic fluid concentration on the properties of magnetic nanospheres were discussed in detail.The resulted showed that by optimizing the technics parameters,superparamagnetic polymer nanopsheres with good dispersibility,small and uniform particle size,high magnetic content,large saturated magnetization(40-50 emu/g) and abundant functional groups were produced.Moreover,the miniemulsion copolymerization has the merits of simple process,tunable and abundant functional monomer and complete coverage,which can be introduced as a preferred method for preparing surface-functionalized magnetic nanospheres.On the basis of the synthesis technics of esterifiable nanospheres,the magnetic nanospheres with epoxy groups were prepared by introducing another functional monomer in the miniemulsion copolymerization.The resulted showed that epoxy nanopsheres had complete coverage,good dispersibility and small particle size.The average particle size was 60 nm, magnetic content was 19.8 wt.%and large saturated magnetization was 18.54 emu/g. Comparing with amide-functionalized and esterifiable magnetic nanospheres,epoxy magnetic nanospheres were transformed to amino-functionalized nanospheres more easily,and the amino-functionalized nanospheres remain well-dispersed and complete,which can be used in subsequent labeling experiment.Lastly,the compound[N(Et)₄][Re(CO)₃Br₃]was synthesized,and the labeling precursor fac-[Re(CO)₃(H₂O)₃]⁺ was obtained by dissolving[N(Et)₄][Re(CO)₃Br₃]in water.And the technology roadmap of labeling of magnetic nanopsheres with ordinary tri-carbonyl rhenium was designed.The histidine was covalently linked to the surface of amino-functionalized nanospheres using glutaraldehyde as cross-linker.The results showed that after immobilizing with histidine,magnetic nanospheres had complete structure,good dispersibility,high magnetic content(20 wt.%) and saturated magnetization(9.43 emu/g),which can be used in the next simulative labeling experiment.Using the magnetic nanospheres immobilized with histidine as magnetic targeted carrier, the simulative labeling experiment of them with tri-carbonyl rhenium was primarily developed.The resulted showed that the labeled products has complete structure,good dispersibility,high magnetic content(16 wt.%) and saturated magnetization(9.10 emu/g).The simulative labeling yield was tested by UV-spectrophotometer and calculated as 80.4%. These results exhibited that tri-carbonyl rhenium had good labeling ability for the magnetic nanospheres immobilized with histidine,which showed that it was hopeful in realizing the successful radiolableling with radionuclides ¹⁸⁸Re.