The Synthesis Of Magnetic Polymer Microspheres

Magnetic Polymer Microspheres (MPM) are a kind of novel functional materials, which exhibit properties of magnetic materials and polymer materials. MPM are quite fit for application in biological system because of their small particle size, large specific surface area, great capacity of coupling biology molecules, and good suspension in disperse system. Heretofore, MPM have exhibited extensive application prospect. In this paper, micro- and nano- magnetic polystyrene was prepared with monodispersity and strong magnetic responsivity on the base of others' research. The main content of this paper is such as following:1 the preparation and modification of iron oxide magnetic nanoparticles and thesynthesis of magnetic fluidIn this paper we prepared iron oxide magnetic nanoparticles with the chemical coprecipitation method, which take the size and saturation magnetization of iron oxide nanoparticals as criterion. Some properties such as the crystal structure , particle size and magnetism of iron oxide nanoparticles are characterized by XRD TEM and AGM, which exhibit perfect crystal structure, about 12 nm particle size and saturation magnetization being 70.8 emu/g. On the base of that, we choose oleic acid as modified surfactant. Modified iron oxide nanopartical with monolayer and bilayer oleic acid(OA) is synthesized and the properties are also investigated respectively. On one hand, we find the bilayer OA capped nanoparticles behaved hydrophilic-hydrophobic transformation through changing the pH value. And the nanoparticles with monolayer oleic acid covered are so good dispersion in the oil phase that we prepare stable toluene and octane oil-based magnetic fluids. On the other hand, the water-based magnetic fluids are prepared by adding the second surfactant undecylenic acid or sodium dodecyl sulfate to the monolayer modified nanoparticles via hydrophobic association. In the preparation process, we choose chloroform as dispersion medium not only simplify the process but also synthesize the stable and high solid content water-based magnetic fluids.2. Synthesis and characterization of polystyrene magnetic microspheres Polystyrene magnetic microspheres are prepared by dispersion polymerization method. According to the hydrophilic- hydrophobic property of the bilayer modified OA nanoparticles, we solve the difficulty of the low output in the dispersion polymerization. Besides, product structure, particle size and magnetic properties are characterized. The particle size is about 2-4 um with smooth surface and the iron oxide content is 9.65%. The product exhibits superparamagnetism, the saturation magnetization being 4.02 emu/g and remanence and coercivity are both zero. In addition, the reaction mechanism is analyzed and the influence factors of the pH value and medium proportion were discussed.3, Preparation of polystyrene magnetic microspheres with the ultrasonic methodMaking use of the ultrasonic homogeneous method in the dispersionpolymerization effectively improve the homogenization of the polystyrene magnetic microsphere. According to the research of the polymerization reaction dynamics, we prove that the ultrasonic enhance the reaction rate remarkably. The product structure, particle size and magnetic properties are characterized and the different influence factors are discussed.4, Synthesis and characterization of polystyrene magnetic nanospheresPolystyrene magnetic nanospheres are prepared by low energy emulsificationmethod using the UA-stable water-based magnetic fluids. We characterize the properties of the magnetic nanospheres, which exhibit monodispersion and particle size being about 90 nm. The magnetic content is up to 27.21% by the TGA measure. The product exhibits superparamagnetism, the saturation magnetization being 19.5 emu/g and remanence and coercivity are both zero.