聚(苯乙烯-马来酸酐)/Fe3O4纳米杂化材料的制备与表征

采用2,2,6,6-四甲基-1-哌啶氧化物(TEMPO)的溴盐对化学共沉淀法制备的Fe3O4纳米粒子进行表面修饰,以该粒子为过氧引发剂,苯乙烯(St)、马来酸酐(MA)为单体,采用"活性"/可控自由基聚合技术在粒子表面原位引发聚合,制备了聚(苯乙烯-马来酸酐)/Fe3O4纳米杂化材料,并对纳米Fe3O4及杂化材料进行了FT-IR、XRD、TGA、TEM和GPC表征。结果表明,所制备的纳米杂化材料的平均粒径约为70 nm,磁性粒子表面的聚合物分子链随着聚合时间的增长而增长。振动样品磁强计测试结果显示,在室温、外加磁场下,该纳米杂化材料呈现超顺磁性,饱和磁化强度随着包覆聚合物量的增加而降低。     

聚丙烯酰胺修饰Fe_3O_4磁性纳米粒子的制备与表征

首先通过化学处理在Fe3O4磁性纳米粒子表面引入Si—H键,然后通过选择性的硅氢加成反应制备了一个端基带溴的磁性引发剂,并利用原子转移自由基聚合(ATRP)技术,在该磁性引发剂表面接枝了聚丙烯酰胺高分子,该聚丙烯酰胺高分子展现出分子量高度可控性和窄的分子量分布.经聚丙烯酰胺修饰后Fe3O4磁性纳米粒子的比饱和磁化强度为58.5 emu.g-1,与未修饰纳米Fe3O4相比下降约20%.     

纳米Fe3O4/聚苯乙烯均匀分散体系的制备及结构

用化学共沉淀法制备了Fe3O4纳米颗粒,以油酸为表面活性剂,苯乙烯为载液,制备了稳定的纳米Fe3O4可聚合磁流体,将可聚合磁流体经自由基引发聚合制成纳米Fe3O4/聚苯乙烯均匀分散体系,用WAXRD研究了Fe3O4纳米粒子的结晶情况;用FTIR研究了油酸表面改性前后Fe3O4粒子表面官能团的变化;用TEM研究了Fe3O4颗粒的粒径大小及其在苯乙烯单体和聚苯乙烯中的分散情况;用DSC和TGA研究了纳米Fe3O4/聚苯乙烯均匀分散体系的玻璃化转变温度(Tg)和热稳定性,结果表明,合成的纳米Fe3O4为立方晶型,平均粒径在10nm左右,油酸分子在Fe3O4表面是化学吸附,经表面处理的Fe3O4超细颗粒在苯乙烯和聚苯乙烯基体中分散较均匀.界面粘结较好,含1.8％Fe3O4纳米颗粒的聚苯乙烯的最大热失重温度比聚苯乙烯提高了13K,Fe3O4/聚苯乙烯复合体系的饱和磁化强度σs为17.43emu/g.     

表面引发原子转移自由基聚合方法合成Fe3O4/PMMA复合纳米微粒

采用表面引发原子转移自由基聚合方法合成了核壳结构的磁性高分子纳米微粒. 作为聚合反应引发剂的3-氯丙酸, 首先与油酸修饰的Fe3O4纳米微粒表面的部分油酸置换, 然后在Fe3O4纳米微粒表面引发甲基丙烯酸甲酯聚合, 合成的纳米复合材料用TEM, FTIR, XRD和DSC表征. 磁性测试结果表明, 所制备的磁性高分子纳米微粒仍具有超顺磁性, 但由于聚合物的存在, 其饱和磁化强度降低.     

1,1-二苯基乙烯存在下无皂乳液聚合制备磁性复合微球

报道了一种制备磁性复合微球的方法——DPE法.在自由基控制剂1,1-二苯基乙烯(DPE)存在条件下,甲基丙烯酸甲酯(MMA)与丙烯酸(AA)发生无皂乳液聚合,制备能与Fe3O4粒子相螯合的活性短链共聚物,加入Fe3O4粒子把短链共聚物引到其表面,引发其它单体继续在Fe3O4粒子表面聚合,制备磁性复合微球.研究了AA、DPE、引发剂及Fe3O4粒子加入量等对制备磁性复合微球的影响.并在此基础上,对优化后工艺制备的磁性复合微球进行了TEM、TGA及磁响应性表征.结果表明,利用该新的方法制备出了磁含量为20%、比饱和磁化强度为32.2emu/g、平均粒径为265nm且表面不含任何杂质的磁性复合微球.     

P(St-GMA)/Fe3O4磁性聚合物微球的制备及表征

采用沉淀法制备了Fe3O4纳米粒子, 以苯乙烯(St)、甲基丙烯酸缩水甘油酯(GMA)为聚合单体, 使用分散聚合法制备了P(St-GMA)/Fe3O4磁性聚合物微球. 分析了Fe3O4粒子的形貌和结构. 研究了制备条件对磁性聚合物微球磁含量的影响. 采用FTIR, XRD, TG及TEM等手段对磁性聚合物微球的微观结构及形貌、磁含量等进行了分析表征. 研究结果表明, 制备的磁性聚合物微球粒径均一, 磁含量高达74%.     

羧甲基壳聚糖磁性纳米粒子的合成及应用

通过合成油酸修饰的Fe3O4纳米粒子和羧甲基壳聚糖直接包埋油酸修饰的Fe3O4纳米粒子的两步合成法制备了羧甲基壳聚糖磁性纳米粒子。采用透射电子显微镜、傅里叶变换红外光谱、振动样品磁强计和同步热分析测试技术对制备的羧甲基壳聚糖磁性纳米粒子进行了表征。所得磁性纳米粒子呈规则球形,粒径约为10 nm;表面含羧基,且具有很好的顺磁性和稳定性。考察了羧甲基壳聚糖磁性纳米粒子对阿霉素的载药量和对阿霉素在磷酸盐缓冲溶液中的缓释性能。结果表明,磁性纳米粒子对阿霉素展示了较高的载药量(91.8 mg/g),结合了阿霉素的磁性复合物对阿霉素的缓释作用明显,说明制备的羧甲基壳聚糖磁性纳米粒子有望作为治疗肿瘤的纳米磁靶向药物输送载体。     

叶酸对磁性Fe_3O_4纳米粒子的表面修饰

以FeCl3·6H2O作为单一铁源,1,6-己二胺作为胺化试剂,利用无模板的溶剂热方法制备了胺基功能化的磁性Fe3O4纳米粒子,并利用其键合叶酸分子,制备出表面修饰了叶酸的磁性Fe3O4复合纳米粒子。利用傅里叶变换红外光谱仪、X-射线衍射仪、透射电镜、差热-热重分析仪和振动样品磁强计对所得纳米粒子的形貌、粒径、化学组成和磁性能进行了表征。结果表明,叶酸分子通过化学键牢固键合在磁性纳米Fe3O4粒子表面,叶酸修饰的复合纳米粒子仍然具有良好的磁性能。     

Fe_3O_4纳米材料的低温溶剂控制合成及其磁性质

报道了一种低温(60℃～100℃)溶剂控制合成立方相Fe3O4及正交相FeOOH等纳米材料的简易方法,即采用氯化亚铁为铁源,六亚甲基四胺为弱碱源,借助回流装置,通过改变反应温度、溶剂(分别以水、水与乙醇、水与乙二醇为溶剂)、时间等实验条件,合成出正交相的FeOOH、正交相FeOOH与立方相Fe3O4的混合物以及立方相Fe3O4磁性纳米粒子.利用X射线衍射仪(XRD)、透射电子显微镜(TEM)、物性磁测量系统以及穆斯堡尔光谱仪对产物进行了表征和分析.结果显示,所制备的混合相磁性纳米粒子为片状和棒状,而立方相的的Fe3O4磁性纳米粒子呈颗粒状.磁测量表明立方相的Fe3O4比混合相磁性纳米粒子有更大的磁饱和强度,对立方相的Fe3O4纳米粒子进行穆斯堡尔谱分析可以明确判断所合成的样品是Fe3O4,而不是γ-Fe2O3.此外,通过对实验过程、现象及表征结果等的分析;对不同条件下Fe3O4磁性纳米粒子的形成机理做了初步探讨.     

胺基磁性纳米凝胶的光化学制备及形成机理

以Fe3O4纳米粒子为磁核,借助紫外光辐照含有烯丙基胺和N,N′-亚甲基双丙烯酰胺的水溶液,制备了胺基功能化的聚(烯丙基胺-共-N,N′-亚甲基双丙烯酰胺)磁性纳米凝胶(PAAm-Fe3O4),对其化学组成、表面电位、形貌、粒径分布及磁学性质进行了分析表征,并研究了光照时间和单体的滴加量对产物的粒径和粒径分布的影响.为探索聚合反应的引发方式,以烯丙基胺的类似物——苯胺为探针,借助激光光解-瞬态吸收装置研究了纳米Fe3O4粒子与有机电子供体的相互作用.结果表明,光化学方法实现了高分子凝胶层对单个Fe3O4粒子的有效包覆,通过控制光照时间和单体的滴加量可以获得在一定范围内尺寸可调且分布较窄的PAAm-Fe3O4.核壳结构的PAAm-Fe3O4近似球形,表面带正电性,磁含量接近88%,在室温下呈现准超顺磁性且饱和磁化强度达50emug?1.激光光解实验结果表明在光化学反应条件下Fe3O4与有机电子供体发生了电子转移反应,这可能是在Fe3O4表面引发有机胺单体的聚合并形成高分子壳的关键.最后,对PAAm-Fe3O4的形成机理进行了探讨.     

Characterization and Non-isothermal Decomposition Kinetic Analysis of PS/FeNi3 Nanocomposites

Polystyrene/iron-nickel (PS/FeNi3) nanocomposites were synthesized via an in-situ polymerization route and characterized by XRD,SEM and FTIR. FeNi3 nanoparticles were characterized by TEM and XRD. The pure FeNi3 nanoparticles (100～125 nm) were highly clustered and percolated through the PS matrix. When the content of FeNi3 nanoparticles reached 5 wt%,an interaction between FeNi3 nanoparticles and PS matrix was observed. The thermal decomposition behavior of PS/FeNi3 nanocomposites was investigated by thermal analysis. The activation energies (E) and pre-exponential factors (lnA) were calculated by using Archar method. The results show that the thermal decomposition of pure PS is a one-dimensional diffusion mechanism. A three-dimensional diffusion mechanism appears when FeNi3 nanoparticles incorporate. The E of PS/FeNi3 nanocomposites with different FeNi3 contents is 217.5,225.3,180.6 and 73.0 kJ·mol-1,and the corresponding lnA is 35.6,34.9,27.5 and 10.4 S-1,respectively.     

Preparation and characterization of polypyrrole/magnetite nanocomposites synthesized by in situ chemical oxidative polymerization

This work describes the preparation and characterization of polypyrrole (PPy)/iron oxide nanocomposites fabricated from monodispersed iron oxide nanoparticles in the crystalline form of magnetite (Fe₃O₄) and PPy by in situ chemical oxidative polymerization. Two spherical nanoparticles of magnetite, such as 4 and 8 nm, served as cores were first dispersed in an aqueous solution with anionic surfactant sodium bis(2‐ethylhexyl) sulfosuccinate to form micelle/magnetite spherical templates that avoid the aggregation of magnetite nanoparticles during the further preparation of nanocomposites. The PPy/magnetite nanocomposites were then synthesized on the surface of the spherical templates. Structural and morphological analysis showed that the fabricated PPy/magnetite nanocomposites are core (magnetite)‐shell (PPy) structures. Morphology of the PPy/magnetite nanocomposites containing monodispersed 4‐nm magnetite nanoparticles shows a remarkable change from spherical to tube‐like structures as the content of nanoparticles increases from 12 to 24 wt %. Conductivities of these PPy/magnetite nanocomposites show significant enhancements when compared with those of PPy without magnetite nanoparticles, in particular the conductivities of 36 wt % PPy/magnetite nanocomposites with 4‐nm magnetite nanoparticles are about six times in magnitude higher than those of PPy without magnetite nanocomposites. These results suggest that the tube‐like structures of 36 wt % PPy/magnetite nanocomposites may be served as conducting network to enhance the conductivity of nanocomposites. The magnetic properties of 24 and 36 wt % PPy/magnetitenanocomposites show ferromagnetic behavior and supermagnetism, respectively. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 1291–1300, 2008     

Impact of initiators in preparing magnetic polymer particles by miniemulsion polymerization

Sub-micron sized polystyrene particles containing magnetite more than 30 wt.% were prepared by miniemulsion polymerization with commercially available ferricolloid. The effects of some water-soluble initiators and/or oil-soluble initiators on the particles characteristics, such as the size, morphology, magnetic properties and colloidal stability, were studied. The size of monomer droplets/polymer particles increased from 60 to 300 nm during polymerization, keeping magnetic in core when potassium persulfate (KPS) or ammonium persulfate (APS) was used as the sole initiator. These particles were easily separated from the medium within short time scale in external magnetic field, while such characteristics were controlled by the amount of persulfate used for the polymerization. In contrast, when 2,2′-azobis isobutyronitrile (AIBN) was used as the initiator, the size of droplets/particles was retained to be 90 nm at the most and magnetite nanoparticles located at the surface of polystyrene particles, which were so colloidally stable that they were not separated in external magnetic field. The above-mentioned effect of initiators on particle size in persulfate system was likely originated from the decrease of pH value and the increase of ionic strength, which induced the fusion of droplets/particles containing magnetite. Mixed-initiators system resulted in intermediate characteristics, compared with each initiator system. The location of magnetite in the particle seems to depend on where initiation/polymerization occurred in each initiator system.     

Magnetic polymer particles: Synthesis and properties

A possibility of preparation of monodisperse magnetic polymer particles containing carboxylic groups by the methid of emulsion (co)polymerization in the presence of a magnetic liquidis considered. Angulation of the magnetite nanoparticles by polymeric spheres of styrene-acroleine copolymer followed by incapsulation to the polystyrene coat is studied. Monodisperse particles with inclusion of the magnetite nanoparticles 30 nm to 1 μm size containing up to 5.6 μmol g^?1 surface carboxylic groups are obtained, their electrosurface and magnetic properties are studied.     

Preparation of Surface-Imprinted Polymer Magnetic Nanoparticles with Miniemulsion Polymerization for Recognition of Salicylic Acid

Molecular surface-imprinted polymers nanoparticles encapsulating magnetite modified with oleic acid, for recognition of salicylic acid was prepared by three-step miniemulsion polymerization. The important factors including polymerization process, solvents, miniemulsifying approaches, and co-stabilizer have been investigated to obtain magnetic molecular imprinting polymers (MMIPs) nanoparticles (NPs) with high saturation magnetization (Ms), regular morphology, and good monodispersion. The results showed that the amount of magnetite encapsulated in MMIPs NPs was 43.4 wt% and Ms was 33.584 emu/g. Thus, MMIPs NPs could be separated easily within 2 minutes by an external magnetic field. The transmission electron microscope (TEM) showed MMIPs NPs were of regular sphere with core-shell structure, where magnetite NPs were uniformly encapsulated in homogeneous polymer shells. The average diameter of MMIPs NPs was 98 nm with RSD of 6.6%. Good recognition and high loading of target molecule were achieved by MMIPs NPs in batch rebinding tests.     

细乳液聚合法制备磁性复合微球及其表征

在制备超细Fe3O4 磁性粒子的基础上 ,以 3种低分子量聚合物Disperbyk 1 0 6、Disperbyk 1 0 8和Disperbyk 1 1 1为Fe3O4 微粒在单体相中的分散稳定剂 ,采用细乳液聚合法制备了平均粒径为 3 40nm的PS Fe3O4 磁性复合微球 .详细研究了分散剂种类对细乳液聚合制备磁性复合微球的影响 ,并采用XRD、TGA和TEM等手段对磁性复合微球的形态、结构及磁响应性等进行了表征 .实验结果证明分散剂的选择对磁性复合微球的成功制备起着至关重要的作用 ,兼具酸性和碱性功能基的分散剂Disperbyk 1 0 6具有更好的分散和稳定效果 .TEM结果表明 ,所制备的复合微球具有一些缺陷 ,而缺陷处往往是Fe3O4 磁性粒子聚集的地方     

Physical and Chemical Properties of Magnetite and Magnetite-Polymer Nanoparticles and Their Colloidal Dispersions

The properties of polymer-coated magnetite nanoparticles, which have the potential to be used as effective magnetic resonance contrast agents, have been studied. The magnetite particles were synthesized by using continuous synthesis in an aqueous solution. The polymer-coated magnetite nanoparticles were synthesized by seed precipitation polymerization of methacrylic acid and hydroxyethyl methacrylate in the presence of the magnetite nanoparticles. The particle size was measured by laser light scattering. It was shown that the particle size, variance, magnetic properties, and stability of aqueous magnetite colloidal dispersion strictly depend on the nature of the stabilizing agent. The average hydrodynamic radius of the magnetite particles was found to be 5.7 nm in the stable aqueous colloidal dispersion. An inclusion of the magnetite particle into a hydrophilic polymeric shell increases the stability of the dispersion and decreases the influence of the stabilizing agent on the magnetic and structural properties of the magnetite particles as was shown by X-ray diffraction and M?ssbauer and IR spectroscopy, as well as by vibrating sample magnetometry. The variation in the polymeric shell size and the polymer net density can be useful tools for evaluation of the polymer-coated magnetite particles as effective contrast agents. Copyright 1999 Academic Press.     

Preparation of sulfate- and carboxyl-functionalized magnetite/polystyrene spheres for further deposition of gold nanoparticles

A synthetic method developed for preparation of sulfate- and carboxyl-functionalized magnetite/polystyrene (Fe₃O₄/PS) spheres that can be further decorated with gold (Au) nanoparticles is reported. By using emulsifier-free emulsion polymerization based on potassium persulfate (KPS)/methyl acrylic acid (MAA)/water system in the presence of Fe₃O₄/PS spheres used as the seeds, PMAA-coated magnetic Fe₃O₄-PS spheres were readily obtained. The sulfate group is inherent in KPS for initiating the polymerization of PMAA, and eventually it acts as the reducing agent for the deposition of Au nanoparticles. The carboxyl group, on the other hand, could seemingly contribute to immobilize Au nanoparticles precipitated. The morphologies, magnetic properties, and characteristics of oleate-stabilized Fe₃O₄ nanoparticles, Fe₃O₄/PS spheres, PMAA-coated Fe₃O₄/PS spheres, and Au-decorated resultant spheres were respectively studied using transmission electron microscopy, X-ray diffraction, Fourier transform infrared, and superconducting quantum interference device magnetometer.     

Porous Fe3O4 nanoparticles: synthesis and application in catalyzing epoxidation of styrene

A facile route was employed to synthesize porous magnetite via reaction of FeCl(3)·6H(2)O with N(2)H(4)·H(2)O in ethylene glycol without any structure-directing agent. The resultant Fe(3)O(4) particles were characterized by transmission electron microscopy, N(2) adsorption, X-ray photoelectron spectroscopy, and thermal gravimetric analysis. It was demonstrated that the particle size varied in the range of 40-220 nm, and the pore size of particles was centered around 2 nm. The gases produced in the formation process of the particles played key role in the formation of the porous structure. The obtained porous magnetite was used as support to immobilize Au nanoparticles with size less than 2 nm with the assistance of L-cysteine. The as-prepared Fe(3)O(4) particles can effectively catalyze epoxidation of styrene, and the immobilization of Au nanoparticles on the Fe(3)O(4) support significantly improved the activity of the catalyst.     

超顺磁性高分子微球的制备与表征

用化学共沉淀方法制备了Fe3O4纳米微粒,并用油酸(十八烯酸)和十二烷基苯磺酸钠为双层表面活性剂进行表面修饰,制备了稳定的水分散性纳米Fe3O4可聚合磁流体.在Fe3O4磁流体存在下,将苯乙烯与甲基丙烯酸通过乳液聚合方法制备了磁性高分子微球.透射电镜研究表明,Fe3O4微粒的平均粒径在10nm左右,乳液聚合形成的磁性高分子微球的粒径平均约为130nm;用超导量子干涉仪对微粒及高分子微球进行了磁性表征,结果表明,合成的Fe3O4纳米微粒以及磁性高分子微球均具有超顺磁性.同时,还用红外光谱及X射线衍射表征了磁性高分子微球的化学成分和晶体结构.用热失重方法测得磁性高分子微球中磁性物质的含量为23.6%.