磁性Fe_3O_4微粒表面有机改性

在分散聚合法制备复合磁性微球过程中 ,采用硅烷偶联剂 KH- 570对磁性 Fe_3O_4微粒进行表面改性 .红外光谱 (FTIR)、光电子能谱 (XPS)分析结果表明 ,偶联剂与磁性微粒表面以化学键形式结合 .改性后 ,Fe_3O_4微粒与单体及其聚合物之间具有良好的亲和性 ,采用改性后的磁性微粒可以显著改善磁性微球的性能指标 .     

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%.     

原子转移自由基聚合法制备表面聚合物接枝四氧化三铁纳米粒子

为制备表面具有柔性高分子链的磁性微球,采用化学共沉淀法制备了具有超顺磁性的Fe3O4纳米微球,用KH550对Fe3O4纳米微球进行化学改性得到表面氨基化的Fe3O4纳米微球,与2-溴代异丁酰溴反应后制得含有引发官能团的Fe3O4纳米微球,随后将含溴的Fe3O4纳米微球与小分子单体与之通过原子转移自由基聚合(ATRP)法共聚。测试结果表明聚合物链成功地接枝到了Fe3O4纳米微球表面。     

表面含羧基的交联磁性高分子复合微球的合成

首先用化学共沉淀法制备了Fe3O4纳米微粒,并对其表面进行改性。然后在分散介质水中,以二乙烯基苯(DVB)为交联剂,采用改进的乳液聚合法,制备了磁性Fe3O4为核、苯乙烯和丙烯酸的共聚物为壳的交联复合微球,并利用FT-IR、TEM、XRD和XPS等对其进行表征。结果表明:该复合微球的粒度分布均匀、表面含有一定羧基,为单分散性、表面功能化的交联磁性高分子纳米复合微球。     

基于Fe3O4@SiO2/Ni-NTA磁性微球的His-tag融合蛋白纯化体系的建立

合成了表面共价结合Ni-氨基三乙酸(Ni-NTA)基团的Fe3O4@ SiO2微球,这种磁性微球可用于分离含有His-tag标签的融合蛋白.微球中心由尺寸约402 nm的Fe3O4微粒组成,赋予了微球极好的磁性分离和离心分离的特性.应用Fe3O4@ SiO2/Ni-NTA磁性微球对含有6×His-tag(6聚组氨酸)标签的蛋白进行了分离纯化,结果表明,10 mg Fe3O4@ SiO2/Ni-NTA微球能够从10mL重组蛋白裂解液中纯化出约1 mg带有6×His-tag标签的融合蛋白.微球的高效分离效果使其能够用于含量较低的带有6×His-tag标签蛋白的分离纯化.     

控制自由基聚合制备Fe_3O_4/SiO_2/P(AA-MMA-St)磁性复合微球

用原硅酸乙酯对Fe3O4纳米粒子进行表面改性得到Fe3O4/SiO2磁流体.在Fe3O4/SiO2磁流体存在下,以1,1-二苯基乙烯(DPE)为自由基聚合控制剂,利用乳液聚合法制备了Fe3O4/SiO2/P(AA-MMA-St)核-壳磁性复合微球.用红外光谱(FTIR)、振动样品磁强计(VSM)、透射电镜(TEM)、X光电子能谱(XPS)、热重分析(TGA)、示差扫描量热仪(DSC)对所制备的磁流体、磁性高分子复合微球的结构、形态、性能进行了表征.研究发现,原硅酸乙酯水解后能在Fe3O4表面形成硅膜保护层从而避免Fe3O4的酸蚀,使Fe3O4/SiO2/P(AA-MMA-St)复合微球的比饱和磁化强度比同样条件下制备的Fe3O4/P(AA-MMA-St)微球提高了28%;DPE能有效控制自由基在Fe3O4/SiO2磁流体表面均匀地引发单体聚合,得到平均粒径为422 nm,无机粒子含量为40%,比饱和磁化强度为34.850 emu/g,表面羧基含量为0.176 mmol/g的磁性复合微球.     

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.     

悬浮聚合法制备磁性分子印迹聚合物微球

以苯胺和二甲基苯胺为模板分子、甲基丙烯酸(MAA)为功能单体、三羟甲基丙烷三丙烯酸酯(TRIM)为交联单体、Fe3O4为磁性组分,采用悬浮聚合法制备了磁性分子印迹聚合物微球(MMIPMs)。结果表明,改性Fe3O4微粒在MMIPMs中分散较好,MMIPMs在水性介质中对模板分子的选择吸附性较差,但在有机介质中有较好的选择吸附性。     

磁场-温度双重响应性复合微球的制备与表征

采用部分还原共沉淀法制备了尺寸约为10nm的Fe3O4磁性纳米粒子,并用油酸对其进行表面改性,通过无皂乳液聚合的方法将Fe3O4与温敏性N-异丙基丙烯酰胺-丙烯酰胺共聚物(PNIPAAm-co-Am)复合,获得了具有磁场和温度双重响应的复合微球.采用TEM,FTIR和XRD等方法研究了复合微球的结构与形貌,分别采用动态激光光散射(DLS)和振动样品磁强计(VSM)表征了复合微球的温度响应性和磁场响应性.结果表明,所制备的Fe3O4/(PNIPAAm-co-Am)复合微球具有核壳结构,尺寸约为100nm,该微球具有良好的磁响应性和温度响应性,其最低临界溶解温度(LCST)约为40℃.     

免疫磁性纳米微球的制备与表征

成功制备了Fe3O4磁性纳米颗粒及二甲基丙烯酸乙二醇酯-甲基丙烯酸(EGDMA-MAA)共聚物包覆的Fe3O4磁性复合微球。将吲哚美辛抗体固定在复合微球表面,形成了Fe3O4(核)/聚合物-抗体(壳)的复合免疫磁性颗粒。XRD结果表明,制备的Fe3O4的晶型为反立方尖晶石型且纯度较高;TEM表征表明Fe3O4粒径较为均匀,平均粒径为12nm;磁性复合微球的平均直径为460nm。制备的Fe3O4磁性纳米颗粒和磁性复合微球有较强的磁响应强度,其饱和磁化率分别为49.16和8.38emu/g,能够满足磁性分离的要求。FT IR验证了磁性复合微球中羧基特征峰的存在,表明羧基成功连接在磁性微球上面。通过碳二亚胺/N-羟基琥珀酰亚胺(EDC/NHS)活化法将微球表面羧基活化并成功与抗吲哚美辛抗体交联。     

β-Cyclodextrin assisted one-pot synthesis of mesoporous magnetic Fe3O4@C and their excellent performance for the removal of Cr Ⅵ from aqueous solutions

Mesoporous magnetic Fe3O4@C nanoparticles have been synthesized by a one-pot approach and used as adsorbents for removal of Cr (Ⅳ) from aqueous solution. Magnetic iron oxide nanostructured materials encapsulated by carbon were characterized by scanning electron microscope (SEM), nitrogen adsorption and desorption, X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. The adsorption performance of the nanomaterial adsorbents is tested with the removal of Cr (Ⅳ) from aqueous solution. The results reveal that the mesoporous magnetic Fe3O4@C nanospheres exhibit excellent adsorption efficiency and be easily isolated by an external magnetic field. In comparison with magnetic Fe3O4 nanospheres, the mesoporous magnetic Fe3O4@C exhibited 1.8 times higher removal rate of Cr Ⅵ. Themesoporous structure and an abundance of hydroxy groups on the carbon surfacemay be responsible for high absorbent capability.     

Preparation of surface plasmon resonance biosensor based on magnetic core/shell Fe3O4/SiO2 and Fe3O4/Ag/SiO2 nanoparticles

In this paper, surface plasmon resonance biosensors based on magnetic core/shell Fe(3)O(4)/SiO(2) and Fe(3)O(4)/Ag/SiO(2) nanoparticles were developed for immunoassay. With Fe(3)O(4) and Fe(3)O(4)/Ag nanoparticles being used as seeding materials, Fe(3)O(4)/SiO(2) and Fe(3)O(4)/Ag/SiO(2) nanoparticles were formed by hydrolysis of tetraethyl orthosilicate. The aldehyde group functionalized magnetic nanoparticles provide organic functionality for bioconjugation. The products were characterized by scanning electronic microscopy (SEM), transmission electronic microscopy (TEM), FTIR and UV-vis absorption spectrometry. The magnetic nanoparticles possess the unique superparamagnetism property, exceptional optical properties and good compatibilities, and could be used as immobilization matrix for goat anti-rabbit IgG. The magnetic nanoparticles can be easily immobilized on the surface of SPR biosensor chip by a magnetic pillar. The effects of Fe(3)O(4)/SiO(2) and Fe(3)O(4)/Ag/SiO(2) nanoparticles on the sensitivity of SPR biosensors were also investigated. As a result, the SPR biosensors based on Fe(3)O(4)/SiO(2) nanoparticles and Fe(3)O(4)/Ag/SiO(2) nanoparticles exhibit a response for rabbit IgG in the concentration range of 1.25-20.00 μg ml(-1) and 0.30-20.00 μg ml(-1), respectively.     

热解-还原法制备单分散Fe3O4亚微空心球

在用模板法水解FeCl3制备单分散聚(苯乙烯-共-丙烯酸)/Fe2O3[P(St-co-AA)/Fe2O3]核壳粒子的基础上, 于N2环境下热解内核直接得到了单分散的磁性Fe3O4亚微空心球. 用透射电镜(TEM)、场发射扫描电镜(FESEM)、X射线衍射(XRD)、振动样品磁强计(VSM)表征并测试了空心微球的结构形貌、成分以及静磁性能. 结果表明, P(St-co-AA)/Fe2O3核壳粒子在热处理过程中, 由于内核热解生成的有机小分子将Fe2O3 壳层同时还原为Fe3O4, 从而生成了粒径和壁厚均匀的单分散Fe3O4亚微空心球. 该空心微球在室温下的饱和磁化强度、剩余磁化强度和矫顽力分别为50.91 A·m2·kg-1、3.97 A·m2·kg-1和2.33 kA·m-1.     

Nanocomposite particles with core-shell morphology II. An investigation into the affecting parameters on preparation of Fe3O4-poly (butyl acrylate-styrene) particles via miniemulsion polymerization

The encapsulation of inorganic particles with polymers is desirable for many applications in order to improve the stability of the encapsulated products and disperse ability in different media. Colloidal particles with magnetic properties have become increasingly important both technologically and for fundamental studies. This is due to their tunable anisotropic. In the absence of an applied magnetic field, the particles have isotropic sphere dispersion, whereas in an external magnetic field the particles form anisotropic structures. Here, latexes containing nanocomposite particles of styrene-butyl acrylate/Fe₃O₄ with core-shell structure were prepared through miniemulsion polymerization technique. Magnetic composite nanospheres with high magnetic content were synthesized through miniemulsion polymerization using a new process based on a three-steps preparation route including two miniemulsion processes: (1) preparing a dispersion of oleic acid coated magnetite particles in water; (2) mixing of modified magnetite particles with styrene/butyl acrylate in the presence of sodium dodecyl sulfate (SDS), sorbitane mono oleate (Span 80), hexadecane (HD) and (3) miniemulsification of the modified Fe₃O₄ into the monomer droplets to reach to complete encapsulation. Subsequent polymerization generated magnetic nanocomposite spheres. Hence, the copolymerization reaction was performed on the surface of such particles in order to obtain core-shell morphology for these nanoparticles, which were characterized by several techniques such as TEM, SEM, DLS, TGA, VSM and FT-IR. The magnetic copolymer particles with diameter of 120-170 nm were obtained. The effect of several parameters such as magnetite, surfactants and hydrophobe amounts on the stability, particle size and magnetization were investigated and also optimized.     

Preparation and colloidal stability of monodisperse magnetic polymer particles

A previously proposed method was examined for producing monodisperse, submicrometer-sized magnetic polymer particles. The method applies soap-free emulsion polymerization during which Fe3O4 magnetic nanoparticles are heterocoagulated onto precipitated polymer nuclei. To chemically fix the magnetic particles to the polymer nuclei, vinyl groups were introduced on the Fe3O4 particles in a preliminary surface modification reaction with methacryloxypropyltrimethoxysilane, and methacryloxypropyldimethoxysilane (MPDMS) was added to reaction systems of the soap-free emulsion polymerization. The colloidal dispersion stability of magnetic polymer particles was improved by the addition of an ionic monomer, sodium p-styrenesulfonate (NaSS), during the polymerization. The polymerizations were carried out with styrene monomer and potassium persulfate initiator in ranges of NaSS concentrations (0-2.4 x 10(-3) M), NaSS addition times (60-80 min), and monomer concentrations (0.3-0.6 M) at fixed concentrations of 1.6 x 10(-2) M initiator and 1.3 x 10(-2) M MPDMS for pH 4.5 adjusted with a buffer system of [CH3COOH]/[NaOH]. The addition of NaSS during the polymerization could maintain the dispersion stability of magnetic polymer particles during the polymerization. Selection of the reaction conditions enabled the preparation of colloidally stable, submicrometer-sized magnetic polymer particles that had coefficients of variation of distribution smaller than the standard criterion for monodispersity, 10%.     

低浓度甲烷甲醇深度氧化Ag/La0.6Sr0.4MnO3催化剂

Ag-modified La0.6Sr0.4MnO3 catalysts were prepared and their catalytic performance for deep oxidation of CH4 and CH3OH at low concentrations were investigated. The results showed that the La0.6Sr0.4MnO3 host catalyst with the perovskite-type nano-crystallite structure displayed considerably high catalytic activity for deep oxidation of CH4 and CH3OH at low concentrations. Ag modification to the La0.6Sr0.4MnO3 host catalyst resulted in significant enhancement of the catalyst activity, making the T95 (the reaction temperature needed for conversion of 95%of CH4 or CH3OH) lowered down to 735K (for CH4) and 421K (for CH3OH) from 813 and 465 K over the Ag-free system under the reaction conditions:0.1MPa,CH4/O2/N2=2/12/86(molar ratio),GHSV=45000 h-1 and CH3OH/O2/N2= 0.2/1.0/98.8 (molar ratio),GHSV=58000 h-1,respectively.The carbon containing product was almost CO2 and the contents of HCHO and CO in the reaction exit gas were both under GC detectable limit in both cases.
The results of spectroscopic characterization indicated that modification by proper amount of Ag-dopant did not change the perovskite structure of the La0.6Sr0.4MnO3 host catalyst as a whole. Interaction of Ag-dopant with the surface of the host catalyst,La0.6Sr0.4MnO3,was in favor of high dispersion of the Ag component at the catalyst surface and led to the oxidation of part of the Mn3+species to Mn4+,resulting in an increase of amounts of the reducible Mnn+ species and a decrease of their reduction temperature. On the other hand, this interaction led also to enhancement of adsorption ability of the catalyst toward O2 at relatively low temperature. High activity of the Ag modified La0.6Sr0.4MnO3 catalyst for CH4 and CH3OH complete oxidation was closely related to high redox-activity of the catalyst and its prominent adsorption-activation ability to O2 at relatively low temperatures.     

Preparation and characterization of cross-linked β-cyclodextrin polymer/Fe_3O_4 composite nanoparticles with core-shell structures

Cross-linkedβ-cyclodextrin polymer/Fe₃O₄ composite nanoparticles with core-shell structures were prepared via cross linking reaction on the surface of carboxymethylβ-cyclodextrin（CM-β-CD） modified Fe₃O₄ nanoparticles inβ-cyclodextrin alkaline solution by using epichlorohydrin as crosslinking agent.The morphology,structure and magnetic properties of the prepared composite nanoparticles were investigated by transmission electron microscopy（TEM）,Fourier transform infrared（FTIR） spectrometry,X-ray diffraction（XRD） measurement,thermogravimetric analysis（TGA） and Vibrating sample magnetometry （VSM）,respectively.     

无机-高分子-无机多组分核壳纳米复合材料的制备和表征

Fe₃O₄ nanoparticles were prepared by chemical co-precipitation using palmitic acid as surfactant， then a uniformly dispersed system of Fe₃O₄@Polymethylmethacrylates(PMMA) core-shell structure was obtained. Furtherm-ore， polymethylmethacrylates(PNIPAM) was encapsulated on the surface of the Fe₃O₄@PMMA core-shell nano-structure to get Fe₃O₄@PMMA@PNIPAM double shell-core composite structure. After that， the Ag nano-particles were assembled on the surface of Fe₃O₄@PMMA@PNIPAM taking advantage of coordination reaction between Ag⁺ and nitrogen atom on the amide group of PNIPAM. The magnetism of composites is convenient for the catalyst separation from the solution.     

Synthesis and characterization of magnetic and luminescent Fe_3O_4/CdTe nanocomposites using aspartic acid as linker

In this study,the preparation of a new kind of magnetic and luminescent Fe₃O₄/CdTe nanocomposites was demonstrated. Superparamagnetic Fe₃O₄ nanoparticles were first synthesized by hydrothermal coprecipitation of ferric and ferrous ions,followed by the modification of their surfaces with tetramethylammonium hydroxide（TMAOH） and the chemical activation with aspartic acid.The surface-modified Fe₃O₄ nanoparticles were then covalently coated with CdTe quantum dots（QDs）,which were modified with mercaptoacetic acid（MPA）,to form the Fe₃O₄/CdTe magnetic and luminescent nanocomposites through the coordination of the amino groups on the surfaces of Fe₃O₄ and the carboxyl groups on CdTe QDs.The structure and properties of as-synthesized nanocomposites were characterized.It was indicated that the nanocomposites possessed structure with an average diameter of 40- 50 nm,yellow-green emission feature and room temperature ferro-magnetism.Both the fluorescence and UV-vis absorption spectra of the nanocomposites showed a blue shift comparing with those of CdTe QDs.The mechanism of the blue shift was presented.The nanocomposites retained the ferromagnetic property with a saturation magnetization of 8.9 emu/g.