Surface organic modification of Fe<Subscript>3</Subscript>O<Subscript>4</Subscript> magnetic nanoparticles

The surface organic modification of Fe3O4 nanoparticles with silane coupling reagent KH570 was studied. The modified and unmodified nanoparticles were characterized by FT-IR, XPS and TEM. The spectra of FT-IR and XPS revealed that KH570 was coated onto the surface of Fe3O4 nanoparticles to get Fe-O- Si bond and an organic coating layer also was formed. Fe3O4 nanoparticles were spheres partly with mean size of 18,8 nm studied by TEM, which was consistent with the result 17.9 nm calculated by Scherrer＇s equation. KH570 was adsorbed on surface and formed chemistry bond to be steric hindrance repulsion which prevented nanoparticles from reuniting. Then glycol-based Fe3O4 magnetic liquids dispersed stably was gained.     

纳米CaCO_3表面有机化处理

采用水性体系对纳米CaCO3进行表面处理。XPS、FT-IR、TGA分析表明,硅烷偶联剂KH-570能与纳米CaCO3生成Si O Ca键,从而化学健接到CaCO3粒子表面。TEM分析表明,改性后的纳米CaCO3能有效地以初始粒子结构进行分散。     

Surface Modfication of Fe3O4 Nanoparticles

Nanometer particles are important portion of magnetic fluid. Fe3O4 magnetic nanoparticles were studied in this paper and the surface modification of Fe3O4 nanoparticles was investigated by a series of experiments. Fe3O4 magnetic nanoparticles were synthesized with pH value, temperature, and the dosage of surfactant. The phase, structure, size and magnetism of nanoparticles were tested by X-ray diffration （XRD）, transmission electron microscopy （TEM） and magnetic balance. On the basis of the surface modification coating mechanism, the experimental phenomena and the effects on the variation of size, magnetism and stability of Fe3O4 nanoparticles were theoretically analyzed. X-Ray diffraction spectrum and TEM photograph show that 1） the nanoparticles structure is perfect, 2） the diameter of narnoparticles is small and have good deliquescence, and 3） Sodium oleate is the anion surfactant. Therefore 1） the good condition of surface modification is in an acidic solution, 2） the best temperature of surface modification is at 80 ℃, and 3） the dosage of surfactant should be about 0.6 times of that of Fe^2＋.     

PREPARATION AND MAGNETORHEOLOGICAL PROPERTIES OF AQUEOUS SUSPENSION BASED ON EMULSION DROPLETS CONTAINING Fe_3O_4 NANOPARTICLES

The Fe3O4 nanoparticles with mean size of 10 nm were prepared by chemical common precipitation . The factors influencing the size and shape of Fe3O4 nanoparticles such as the adding rate of NaOII to the mixed solution and the final pH of the solution were studied . The Fe3O4 based magnetorheological(MR) fluid was formed by adding surfactant . The rheological properties of this MR fluid were studied when the magnetic fields with different direction are applied. It has been found that the MR fluid has the magnetic anisotropy.     

Sol-gel preparation and characterization of Co_3O_4 nanocrystals

A new citrate acid-hydrazine sol-gel route for preparation of Co3O4 nanoparticles has been developed. Co3O4 nanoparticles with different particle-sizes and morphology were prepared at different heat-treatment temperatures and the pure cubic nanocrystals of Co3O4 were obtained at 600℃. The synthesis process was monitored by infrared spectroscopy (IR), thermal gravimetric and differential thermal analysis (TG-DTA). The structure and morphology of Co3O4 nanocrystals were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM) and X-ray-photoelectron spectroscopy (XPS). The infrared absorption bands blue-shifted with particle size decreasing, which could be attributed to increasing surface effect. XPS results showed that predominant species at surface layers of Co3O4 nanocrystals are octahedral Co (Ⅲ).     

纳米CaCO3表面有机化处理

采用水性体系对纳米CaCO3进行表面处理.XPS、FT-IR、TGA分析表明,硅烷偶联剂KH-570能与纳米CaCO3生成SiOCa键,从而化学健接到CaCO3粒子表面.TEM分析表明,改性后的纳米CaCO3能有效地以初始粒子结构进行分散.     

Immobilization of metalloporphyrins on CeO_2@SiO_2 with a core-shell structure prepared via microemulsion method for catalytic oxidation of ethylbenzene

Ce O2@Si O2 core-shell nanoparticles were prepared by microemulsion method, and metalloporphyrins were immobilized on the Ce O2@Si O2 core-shell nanoparticles surface via amide bond. The supported metalloporphyrin catalysts were characterized by N2 adsorption-desorption isotherm(BET), scanning electron microscopy(SEM), transmission electron microscopy(TEM), X-ray diffraction(XRD), ultraviolet and visible spectroscopy(UV-Vis), and Fourier transform infrared spectroscopy(FT-IR). The results show that the morphology of Ce O2@Si O2 nanoparticles is core-shell microspheres with about 30 nm in diameter, and metalloporphyrins are immobilized on the Ce O2@Si O2 core-shell nanoparticles via amide bond. Especially, the core-shell structure contains multi Ce O2 core and thin Si O2 shell, which may benefit the synergistic effect between the Ce O2 core and the porphyrin anchored on the very thin Si O2 shell. As a result, this supported metalloporphyrin catalysts present comparably high catalytic activity and stability for oxidation of ethylbenzene with molecular oxygen, namely, ethylbenzene conversion remains around 12% with identical selectivity of about 80% for acetophenone even after six-times reuse of the catalyst.     

双功能Fe3O4/Au、Fe3O4/Au@SiO2复合微球的构筑和磁学性质研究

给出一种温和条件下构筑Fe3O4/Au,Fe3O4/Au@SiO2复合纳米结构材料的方法,并研究所得产物的光学、磁学性质。首先,用3-氨丙基三甲氧基硅烷(APS)对平均粒径300 nm的Fe3O4微球进行表面修饰使得其拥有大量的氨基官能团(-NH2),利用这些官能团末端的孤对电子可以共价吸附Au纳米粒子的特性,在一定条件下制备出Fe3O4/Au复合纳米结构材料,不经过任何表面处理利用St?ber方法在室温条件下对其进行SiO2包覆,得到Fe3O4/Au@SiO2复合材料。借助场发射扫描电子显微镜(FESEM)、透射电子显微镜(TEM)对产物的形貌和结构进行表征,并利用紫外-可见(Uv-Vis)分光光度计和超导量子干涉仪(SQUID)对产物的光学和磁学性质进行分析。结果表明,由于所含金浓度太低,Fe3O4/Au复合材料并没有显示金纳米粒子的特征表面等离子体共振吸收峰;Fe3O4/Au,Fe3O4/Au@SiO2复合纳米结构均显示出超顺磁性和高的饱和磁化率。     

Modification of Fe3O4 Magnetic Nanoparticles by L-dopa or Dopamine as an Enzyme Support

Fe3O4 magnetic nanoparticles were prepared by co-precipitation of Fe2+ and Fe3+ in an ammonia solution,and its size was about 36 am measured by an atomic force microscope.Fe3O4 magnetic nanopanicles were modified by L-dopa or dopamine using sonication method.The analysis of FTIR clearly indicated the formation of Fe-O-C bond.Direct immobilization of trypsin(EC:3.4.21.4)on Fe3O4 magnetic nanoparticles with L-dopa and dopamine spacer was investigated using glutaraldehyde as a coupling agent.No significant changes in the size and magnetic property of the three kinds of magnetic nanoparticles linked with or without trypsin were observed.The existence of the spacer molecule on magnetic nanoparticles could greatly improve the activity and the storage stability of bound trypsin through increasing the flexibility of enzyme and changing the microenvironment on nanoparticles surface compared to the naked magnetic nanoparticles.     

Preparation of titanium nitride nanoparticles from a novel refluxing derived precursor

Titanium nitride (TiN) nanoparticles were prepared from a novel refluxing-derived precursor.The organic/inorganic hybrid precursor was prepared by a two-stage refluxing method using hydrous TiO2 as titania source and n-dodecane as carbon source.The precursor was heat-treated to 1 200 °C in flowing ammonia (NH3) to get TiN nanoparticles.The phase and chemical compositions were investigated by means of XRD,Raman spectroscopy and XPS.Samples microstructure was studied by means of SEM,TEM and SEAD.XRD pattern indicated that the product was face-centered cubic TiN with a lattice constant a = 4.236 · and average crystallite sizes of 35.2 nm.Raman spectra indicated that long time refluxing results in Alkane dehydrogenation and the formation of coke on TiO2 nanoparticles.Oxygen presence in TiN lattice was confirmed by XPS investigation.The particle size that was showed by Electron microscopy photographs ranged from 20 to 60 nm.     

Surface modification of Fe_3O_4 nanoparticles and their magnetic properties

Fe3O4 magnetic nanoparticles were synthesized by the hydrothermal method,and the influences of the surfactant sodium bis(2-ethylhexyl) sulfosuccinate (AOT) on the particles were investigated. The structure,morphology,and magnetic properties of the products were characterized by X-ray powder diffraction (XRD),transmission electron microscopy (TEM),Fourier transform infra-red spectroscopy (FT-IR),and vibrating sample magnetometer (VSM). It is confirmed that the as-prepared nanoparticles have been modified by ...     

Synthesis of Polyaniline-Fe_3O_4 Nanocomposites and Their Conductivity and Magnetic Properties

By using inorganic Fe3O4 nanoparticles of different content as nucleation sites, PAn-Fe3O4 nanorods were successfully synthesized through a simple, conventional, and inexpensive one-step in-situ polymerization method. The TEM images revealed the size and morphology of the resultant nanocomposite. The EDS pattern confirmed the existence of Fe3O4 in the composite. The FT-IR spectral analysis confirmed the formation of PAn encapsulated Fe3O4 nanocomposite. With the content of Fe3O4 increasing, the conductivity of the nanocomposites gradually decreases, meanwhile, the saturation magnetization increases and reveals a super paramagnetic behavior. With controllable electrical, magnetic, and electromagnetic properties, the well-prepared nanocomposites may have the potential applications in chemical sensors, catalysis, microwave absorbing, and electro-magneto-rheological fluids, etc.     

纳米Fe_3O_4粒子的制备及表面包覆

采用化学共沉淀法和氧化沉淀法制备磁性纳米Fe3O4粒子,并用柠檬酸三钠为表面活性剂包覆制备纳米Fe3O4粒子,同时利用包覆磁性粒子制备水基纳米磁性液体。对两种方法制备的纳米Fe3O4粒子的晶体结构、微观形貌及化学共沉淀法制备的Fe3O4在包覆前后等电点的变化进行了表征。结果表明,化学共沉淀法制备的纳米Fe3O4粒子平均粒径约为20 nm且分布比较均匀,表面活性剂包覆后,等电点由原来的pH=6.70移向pH=2.35,证实了Fe3O4粒子表面被柠檬酸离子所包覆,且制得的磁性液体的稳定性比较高;而氧化沉淀法制备Fe3O4纳米粒子粒径分布是从几十纳米到上百纳米,制得的磁性液体出现很明显的团聚。     

聚丙烯酸模板制备PAA/PbCrO_4复合纳米颗粒

以低分子量聚丙烯酸(PAA)为高分子模板构建自组装体系,合成核-壳结构的PAA/PbCrO4纳米颗粒.通过TEM、XRD、FT-IR、UV-vis、荧光光谱等表征手段对产物的结构、形貌与光学性能进行研究.结果表明:PAA通过羧基与Pb2+的配位作用包覆在PbCrO4纳米颗粒表面,形成核-壳结构,内核PbCrO4尺寸为50~100 nm,为单斜晶系;外壳PAA层厚20 nm.与普通PbCrO4体相材料相比,产物在829~854 cm-1红外吸收峰变宽,紫外与荧光光谱产生了"蓝移",表现出纳米粒子所具有的特殊光学现象.     

PREPARATION,COMPLEX MECHANISM AND STRUCTURE MODEL OF METALLOPHTHALOC- YANINE-Fe3O4 NANOPARTICLES COMPOSITE

MPc-Fe_3O_4-nanoparticles com posite (M=Co, Cu, Ni, Mn) have been prepared and the factors that influence their mean size have been studied. The mean size of the nanoparticles composite increase with the increase of complex temperature. The interaction of MPc with Fe_3O_4 nanoparticles has been studied. There are M-O covalent bonding and ionic bonding between MPc and Fe_3O_4 nanoparticles. The intensities of M-O bonding and ionic bonding are in vestigated. The complex mechanism of MPc with Fe_3O_4 nanoparticles have been studied. First, there are complex between MPc and all Fe_3O_4 nanoparticles. Then, Fe_3O_4 nanoparticles accumulate together to form the accumulators, MPc have the function of cohering Fe_3O_4 nanoparticles. A considerable number of MPc combine with Fe_3O_4 nanoparticles on the surface of the accumulators to form MPc-Fe_3O_4 nanoparticles composite. All the above proesses take place spontaneously. The structure model of MPc-Fe_3O_4 nanoparticles composite has also been investigated. Insi     

CHARACTERIZATION OF MANGANESE PHTHALOCYANINE-Fe_3O_4 NANOPARTICLE COMPOSITE AND ITS ELECTROMAGNETORHEOLOGICAL FLUID

Manganese phthalocyanine (MnPc)-Fe3O4 nanoparticles composite was prepared and characterized. The results show that MnPc are completed on the surface of Fe3O4 nanoparticles in the state of single molecule. There is effective composite between MnPc and Fe3O4 nanoparticles which can improve the antioxidization ability of Fe3O4 nanoparticles greatly. The composite was dispersed into chlorinated paraffin oil to form electromag-netorheological (EMR) fluid with high activity, and the EMR properties of this EMR fluid are studied.     

ZnFe_2O_4纳米粒子的制备及其磁性能

以乙酰丙酮铁和乙酰丙酮锌为原料、三甘醇为溶剂,采用一步法制备ZnFe2O4纳米粒子。通过透射电子显微镜(TEM)、X-射线粉末衍射仪(XRD)和磁性能测量系统(MPMS)等表征手段对ZnFe2O4纳米粒子进行了表征。结果表明,所制备的ZnFe2O4纳米粒子平均粒径约为6 nm,尺寸均匀,水溶性良好,在室温条件下呈现超顺磁性。     

The coupling agents’ effects on the BSA intercalated into montmorillonite

The effects of surface modification on montmorillonite （MMT） were illustrated in order to produce the composite material with premium properties. MMT was treated with two coupling agents： glutaraldehyde （GA） and 7-methacryloxy-propyl-trimethoxy silane （KH570）. The effects of different coupling agents on MMT and protein interaction were investigated by XRD, FT-IR, TGA, UV-Vis, etc. The results of structure characterization indicated that KH570 modification could change the surface crystal structure of MMT. However, GA reacted with amino groups of Bovine serum albumin （BSA） and the ordered layer structures of MMT were not completely destroyed. Coupling agents could greatly increase the amounts of BSA intercalated and the effect of KH570 is better than that of GA. And, the optimum concentrations of KH570 and GA were 2% and 6%, respectively. The rate of weight loss increased by about 12% after MMT was pretreated with coupling agents. The possible reason is that coupling agent treatment makes the structure of MMT more accessible to protein absorption and helps to stabilize the protein structure. Moreover,the presence of coupling agents can reduce the direct chemical interaction between BSA and MMT, which results in increasing protein desorption.     

复合Fe3O4磁性纳米粒子的制备及在环境领域的应用研究进展

介绍了Fe3O4磁性纳米粒子主要的液相合成制备方法,并对比了各方法的优缺点.概述了将无机、有机或生物大分子等材料包覆到纳米粒子表面的多种表面修饰方法.重点介绍了复合Fe3O4磁性纳米粒子作为固相萃取吸附剂在富集环境中的有机物方面的应用.     

复合磁性纳米粒子的合成和特性研究

通过在磁性纳米粒子表面修饰柠檬酸得到了分散性良好的水基磁流体,为了研究磁性纳米粒子在生物医药上的应用,通过Stober法合成了Fe3O4/SiO2复合粒子。透射电镜(TEM)和红外光谱仪(IR)研究表明,SiO2成功地包裹在Fe3O4粒子表面,且复合粒子的分散性好,粒径均匀。振动样品磁强计测试表明磁性复合粒子仍然具有较强磁性。