【作者】 徐智中；

【导师】 汪长春； 府寿宽； 胡建华； 杨武利；

【作者基本信息】 复旦大学 ， 高分子化学与物理， 2005， 博士

【摘要】 磁性聚合物微球是指通过适当的方法使聚合物与无机磁性粒子结合形成具有一定磁性及特殊结构的复合微球。从目前文献看,可分成三类:①核为无机磁性材料,壳为聚合物;②核为聚合物,壳为无机磁性材料;③内外层为聚合物,中间层为磁性材料的夹心结构。与常规微球相比,具有超顺磁性磁性聚合物微球能够在外磁场的作用下迅速从混合物中分离出来。正因为磁性聚合物的种种优点,在过去几十年中,无数科学家使用多种实验手段制备了性能和结构不同的磁性聚合物微球。迄今为止,这些结构产物制备方法一般有三种:一种是通过天然或合成高分子包裹磁性无机粒子获得磁性聚合物复合微球,它是制备磁性聚合物微球较早的一类方法;另外一种是由Ugelstad发展起来的在多孔聚合物内沉淀铁盐,经处理和再包裹—层聚合物获得磁性聚合物微球;第三种是目前用的最多的一种方法,它是在无机磁性粒子存在下进行单体聚合制备磁性聚合物微球。本文运用细乳液聚合法和无皂乳液聚合法制备了不同结构的磁性聚合物微球,然后对微球性能进行X射线衍射（XRD）、透射电镜（TEM）、扫描电镜（SEM）、热重分析（TGA）、动态激光光散射（DLS）、傅立叶红外（FTIR）和振动样品磁强计（VSM）等表征,取得的结果主要有以下方面: 1.以FeCl₂.4H₂O和FeCl₃.6H₂O为铁源,NH₃.H₂O为碱,用化学沉淀法制备Fe₃O₄粒子。在制备过程中加入亲水性聚合物聚甲基丙烯酸和疏水性油酸改性Fe₃O₄粒子,改性Fe₃O₄粒子形状为椭圆和圆形,粒径尺寸约10纳米左右,呈超顺磁性,其水基和油基磁流体能稳定保存,具有磁流变现象。把所制备的磁流体用于油水分离和用作磁共振成像造影剂研究,获得较好的效果。 2.把油酸改性Fe₃O₄分散于苯乙烯单体中,以十二烷基硫酸钠为乳化剂,BPO为引发剂,用超声制备稳定的O/W型细乳液,然后把上述细乳液直接加入到80℃水溶液中聚合制备Fe₃O₄/PSt复合微球。所制备的磁性聚合物微球大小在亚微米范围,粒径大小较均匀,Fe₃O₄较好的被聚苯乙烯包裹,磁响应性强。用相似方法制备了粒径为120nm左右的磁性Fe₃O₄/PSt-DVB-tBMA微球。当tBMA用量为总单体用量的10%和20%时,磁性聚合物微球水解后,微球不能稳定地分散于水,当更多还原

【Abstract】 Magnetic polymer microsphere is a kind of hybrid microsphere with magnetic property, which is composed of polymer and inorganic magnetic particles. They can be classified into three kinds according to their structures. One is composed of polymeric core and magnetic shell; the other is composed of magnetic core and polymeric shell; the third is composed of polymeric core and shell, and the magnetic material located in the middle layer. The main advantage of magnetic polymeric microspheres over conventional polymeric microspheres is that, because of their superparamagnetic properties, they can be rapidly separated from solution under magnetic field. In the past decades, a great number of scientists have dedicated their efforts to preparation of different kinds of magnetic polymer microspheres and many strategies have been performed to producing magnetic polymer microspheres. Up to now, there are three ways to prepare magnetic polymer microspheres: (1) Encapsulation of magnetic particles with preformed natural or synthetic polymers is the simple and classical method to prepare magnetic polymer microspheres; (2) Another method is developed by Ugelstad through direct precipitation of iron salt inside the porous polystyrene particles; (3) The third method is to suspend magnetic particles in the dispersed phase and then polymerize the monomer in the presence of the magnetic particles to form magnetic polymer microspheres. In this article, miniemulsion polymerization and soap-free emulsion polymerization were adopted to prepare magnetic polymer microspheres with different structures. The magnetic polymer microspheres were characterized by X-ray diffraction (XRD), dynamic light scattering (DLS), transmission electron microscopy (TEM), scanning electron microscopy (SEM), vibrating sample magnetometer (VSM) and thermogravimetric analysis (TGA). Some results have been obtained as follows:1. The Fe3O4 magnetic particles were prepared by the coprecipitation of FeCl3.6H2O and NH3.H2O. Polymethacrylic acid or oleic acid was used to modify the iron oxide nanoparticles in synthetic process. The Fe3O4 particles are somewhat irregularly shaped from oval to sphere and the particle size was around 10 nm. The Fe3O4 particles are superparamagnetic. Stable water-based and oil-based magnetic fluid can be achieved. The magnetic fluid was used in collecting leaked oil and used as contrast agent in magnetic resonance imaging.2. The magnetic polystyrene microspheres were prepared by miniemulsion polymerization. The monomer is styrene and the initiator is benzoyl peroxide. The nanosized iron oxide particles can be well encapsulated in polystyrene microspheres and they are superparamagnetic. Fe3(VPSt-DVB-tBMA microspheres were also prepared and the size of these microspheres was about 120nm. Stable water-based magnetic fluid could be achieved when Fe3(VPSt-DVB-tBMA microspheres containing 30% tBMA in monomers were hydrolyzed.3. The magnetic polyacrylamide microspheres were prepared by one-step inverse miniemulsion polymerization using Span 80 as the emulsifier and isobutyronitrile as the initiator. The magnetic polymer microspheres are spherical and their size was about 80 nm. The nanosized iron oxide particles can be well encapsulated in polyacrylamide particles and the magnetic polymer microspheres are superparamagnetic. Crosslinked magnetic polyacrylamide microspheres can been transfered to aqueous solution .4. Fe3O4/SiO2 composite particles were prepared via sol-gel process based on inverse miniemulsion. The composite particles are superparamagnetic and each composite particle contains many magnetic nanoparticles. X-ray diffraction patterns show silica shell is amorphous, and the crystallinity of the magnetic nanoparticulate core is retained after the coating’s procedure. Fe3O4/SiO2 nanosized composite particles can be更多还原