PET基磁性膜材料的制备与性能表征

用共沉淀法制备出具有磁性的Fe3O4纳米粒子水溶液。红外光谱和XRD表明,纳米粒子是Fe3O4且其粒径在15 nm左右。通过磁滞回线得到纳米粒子比饱和磁化强度σr=56.58 emu/g。对PET薄膜进行预处理和阴离子化后,在PET表面交替吸附聚电解质聚二甲基二烯丙基氯化铵(PDDA)和纳米粒子水溶液,由于PDDA的存在,Fe3O4纳米粒子能均匀地被吸附在PET表面,形成PET基磁性膜材料,且吸附的强度较强。该材料的矫顽力为41.11 Oe,剩余磁化强度为0.66 emu,与Fe3O4纳米粒子一样,具有超顺磁性。     

强磁性Fe_3O_4纳米粒子的制备及其性能表征

采用共沉淀法在无N2气保护下制备了比饱和磁化强度达到75 9emu g的强磁性Fe3O4纳米粒子。在用NaOH溶液沉淀Fe3+和Fe2+混合溶液的过程中,考察了n(Fe2+)∶n(Fe3+)、晶化时间、晶化温度、总铁浓度和NaOH溶液浓度等条件对Fe3O4纳米粒子的粒径分布及磁性的影响。当n(Fe2+)∶n(Fe3+)=5 5∶1 0,晶化时间为2h,晶化温度为50℃时,Fe3O4纳米粒子磁性最佳。所制得的Fe3O4粒子为结晶完整、具有较高纯度和粒径分布均匀的立方体形纳米颗粒;其相变温度随着Fe3O4纳米粒子粒径的减小而降低。Fe3O4纳米粒子的等电点约为pH=7 2。     

微波水热法制备超顺磁性Fe3O4纳米粒子

采用微波水热法制备超顺磁性Fe3O4纳米粒子,讨论了[Fe3 ]/[Fe2 ]、晶化温度、晶化时间、pH值4因素对平均粒度大小的影响,探索Fe3O4纳米粒子的最佳制备条件,在该基础上采用油酸对其进行表面改性。利用XRD、FT-IR、TEM和VSM对Fe3O4纳米粒子的结构、形貌、磁性能进行表征。结果表明,改性后的纳米Fe3O4粒子为粒度均匀的球形,具有良好的分散性,平均粒径约8 nm;该产物具有超顺磁性,饱和磁化强度为61.8 emu/g。     

Au/Fe3O4纳米复合材料的制备及其催化性能

通过将金纳米粒子铆接到Fe3O4载体表面,制得了Au/Fe3O4纳米复合粒子。首先以对苯二酚为还原剂还原HAuCl4制得球形金纳米粒子;然后采用溶剂热法制备Fe3O4磁性纳米颗粒,并用巯基丙酸(MPA)对其修饰;最后通过MPA与金纳米粒子之间的相互作用,将金纳米颗粒固定到Fe3O4表面。采用透射电子显微镜(TEM)、扫描电子显微镜(SEM)、X射线衍射仪(XRD)、傅里叶变换红外光谱仪(FTIR)和振动样品磁强计(VSM)和紫外-可见分光光度计(UV-vis)对所制备材料进行形貌、晶型、磁性和催化性能的表征。结果表明,金纳米颗粒成功包覆在Fe3O4表面,所得到的Au/Fe3O4复合纳米材料具有单分散性和超顺磁性,并且对NaBH4还原对硝基苯酚(4-NP)制备对氨基苯酚(4-AP)的反应显示出优良的催化性能。     

表面引发AGET ATRP原位聚合法制备Fe_3O_4/PGMA复合纳米粒子

以多元醇还原法制备亲水性超顺磁四氧化三铁(Fe3O4)纳米粒子,并利用表面引发电子活化再生原子转移自由基聚合(SI-AGET ATRP)法,制备了Fe3O4/聚甲基丙烯酸缩水甘油酯(Fe3O4/PGMA)磁性复合纳米粒子。研究了原位聚合过程中还原剂异辛酸亚锡(Sn(EH)2)用量对PGMA接枝量和复合纳米粒子磁性能的影响。结果表明:Sn(EH)2在0.005~0.03 mmol时,聚合物接枝量随着Sn(EH)2用量的增大而增加;当Sn(EH)2用量大于0.15 mmol时,PGMA接枝量先增大后减少。磁性能研究表明,复合纳米粒子在室温下具有超顺磁特性,其饱和磁化强度从改性前的Ms=73 emu?g?1降低到Ms=1 emu?g?1。     

共沉淀法磁性纳米Fe_3O_4粒子的制备及性能研究

采用共沉淀法,用Na OH沉淀Fe3+/和Fe2+混合溶液合成磁性纳米Fe3O4粒子,考察了n(Fe2+)/n(Fe3+)的比例、反应温度对Fe3O4纳米粒子磁性能的影响。采用红外光谱分析、X射线衍射、扫描电镜及振动磁强计对样品进行表征。研究结果表明,n(Fe2+)/n(Fe3+)为1:2,反应温度为60℃条件下得到磁性能最佳的Fe3O4纳米粒子。所制得的磁性Fe3O4纳米粒子纯度较高,形貌为规则球形,平均粒径为57 nm,其饱和磁强度为65.86emu/g。     

基于叶酸受体介导的磁性荧光靶向纳米探针的制备及其性能研究

拟采用一步溶剂热法先制备出带有无定型碳层包覆的磁性Fe3O4纳米粒子;然后通过静电结合法,将巯基丙酸修饰的水溶性Cd Te量子点组装到其表面;为了使所制备的磁性探针具有较好的稳定性和生物相容性,通过Stober法在纳米粒子最外层包裹上生物相容性和结构稳定的带有胺基修饰的二氧化硅壳层;最后与叶酸(FA)进行耦合,制得具有磁性和荧光的双功能靶向纳米探针。分别利用荧光光谱,傅里叶变换红外光谱(FTIR),X射线衍射(XRD),扫描电镜(SEM),透射电子显微镜(TEM)和振动样品磁强计(VSM)等对所制备的磁性荧光复合纳米粒子的形态、大小、化学成分及磁性能进行表征。实验结果表明:所得产物粒径大小约200 nm,磁化强度约21.9 emu·g-1,仍然保持有较强的荧光性能,在生物成像方面具有潜在的应用价值。     

单分散超顺磁性Fe_3O_4纳米粒子的合成及表征

利用高温裂解法制备了油酸修饰的Fe3O4磁性纳米粒子,采用TEM、VSM、XRD以及FT-IR对粒子的结构和性能进行了表征和分析。结果表明:Fe3O4纳米粒子粒径为2nm,呈单分散性,结晶性能良好,室温下为超顺磁性,饱和磁化强度为11.73emu/g,可应用于磁流体、磁性分离等领域。     

沉积法制备Fe_3O_4/P(AA-DVB)磁性复合微球

通过静电吸附与机械力共同作用的沉积法制备得到了Fe3O4/P(AA-DVB)磁性复合微球。分别采用无皂乳液聚合和共沉淀法制备得到单分散的P(AA-DVB)胶体粒子及Fe3O4纳米粒子,在静电吸附和机械力作用下,将Fe3O4纳米粒子附着并嵌入P(AA-DVB)胶体粒子表面及内部,制备得到Fe3O4/P(AA-DVB)磁性复合微球。该方法的优势在于最终磁性复合微球的粒径及粒径分布可以由前驱体P(AA-DVB)胶体粒子调控。磁性复合微球表面和内部Fe3O4纳米粒子的分布及磁含量可以由机械力作用时间进行调节。所制备的Fe3O4/P(AA-DVB)磁性复合微球平均粒径为542 nm,磁含量范围在11%~33%内可调。     

Fe_3O_4/P(St/ACPA)磁性高分子纳米球的制备与磁性能研究

采用化学共沉淀方法制备Fe_3O_4磁性粒子,并使用油酸和十一烯酸对其进行表面改性,然后采用一步细乳液聚合法制备含有羧基官能团的Fe_3O_4/P(St/ACPA)磁性高分子纳米球,对磁流体和磁性高分子纳米球进行性能表征。结果表明,改性的Fe_3O_4磁流体分散性好,粒径均一,在室温下呈超顺磁性,磁含量为68.5%(w),饱和磁化强度为51.3emu/g;Fe_3O_4/P(St/ACPA)磁性高分子纳米球成球性好,粒径为70 nm,磁含量为39%(w),饱和磁化强度为27.9 emu/g。     

Magnetic properties and magnetoresistance effect of SnFe2O4 spinel nanoparticles: Experimental,ab initio and Monte Carlo simulation

In this contribution, SnFe₂O₄ nanoparticles were prepared by the solvothermal method, the structural properties were performed using X-Ray Diffraction (DRX) to prove the success of tin ferrite formation and to determine de crystals parameters. The size and morphological study were build using Scanning Electron Microscopy (SEM) and Transmission Electron microscopy (TEM), the results showed that the size of particles is uniform with a range of particles (5–7 nm). The magnetic properties were carried out using the SQUID device, the SnFe2O4 nanoparticles have a magnetic transition at 750 K. In addition, the hysteresis loops at low temperature displayed Ms and Mr equals to 23 emu/g and 6 emu/g, respectively. The magnetoresistance properties were investigated, the SnFe₂O₄ nanoparticles present a large magnetoresistance effect (80%). The experimental results are supplemented by model calculations utilizing density functional theory and Monte-Carlo simulations.     

Ni/NiO-carbon composite fibers prepared by solution blow spinning: Structure and magnetic properties

Nickel/nickel oxide-carbon magnetic fibers were prepared by Solution Blow Spinning (SBS) of polyvinyl alcohol (PVA) and Ni-nitrate. As-spun fibers with relative Ni nitrate/PVA concentrations of 30 wt% and 60 wt% were calcined at 550 °C in argon flux. The samples characterization was carried out by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier-transform infrared (FTIR) spectroscopy, and DC magnetic measurements. TEM images show a carbon matrix containing sphere-like nanoparticles with diameters in the range of 4–45 nm. The magnetic assessment shows the presence of superparamagnetic small particles with blocking temperatures between 14 and 22 K, and large particles that are thermally blocked at 300 K. The low magnetization signal, with saturation magnetization in the range of 7–10 emu/g, is due to dead magnetic layers at the surface of nanoparticles.     

Preparation of monodisperse magnetic polystyrene microspheres and its surface chemical modification

Monodisperse magnetic polystyrene (PS) microspheres were prepared in the presence of PS seed particles and styrene‐based magnetic colloid by the method of magnetic colloid swelling polymerization. The PS seed particles were prepared in advance by soap‐free emulsion polymerization. Styrene‐based magnetic colloid was used for swelling the PS seed particles in the magnetic colloid swelling polymerization process. After polymerization, functional amino groups were introduced onto the surface of the magnetic PS microspheres by surface Friedel‐Crafts acylation reaction. The morphology, size distribution, and magnetic properties of magnetic PS microspheres were characterized with scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM), respectively. SEM showed that the magnetic PS microspheres had an average size of 1078 nm with a narrow size distribution. VSM showed that the magnetic PS microspheres were superparamagnetic, and saturation magnetization was found to be 5.714 emu/g. The concentration of functional amino groups on the surface of magnetic PS microspheres was measured by atomic absorption spectroscopy and UV−Vis spectroscopy, and the concentration of amino groups was found to be 0.168 mmol/g. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Anisotropy investigation of cobalt ferrite nanoparticles embedded in polyvinyl alcohol matrix: A Monte Carlo study

The magnetic properties of the cobalt ferrite/polyvinyl alcohol nanocomposites have been studied experimentally and theoretically. For investigation the impact of polymeric matrix on magnetic properties of magnetic nanoparticles, four different processes have been considered for synthesizing the polymer based nanocomposites by co-precipitation method. The effective magnetic anisotropy obtained by Monte Carlo simulation and law of approach to the saturation magnetization showed a significant decrease relative to the bulk and bare cobalt ferrite nanoparticles. The polymeric matrix interacted with the surface of particles by different strength and made them approximately non-interacting. The as synthesized samples characterized by X-Ray diffractions (XRD) and Fourier transform infrared spectroscopy (FT-IR). Magnetic measurements were carried out at room temperature using a vibrating sample magnetometer (VSM).     

Halloysite nanotubes coated with magnetic nanoparticles

Co nanoparticles were assembled on the surface of halloysite nanotubes (HNTs) to prepare one-dimensional magnetic Co-HNTs via electroless deposition. The samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), energy-dispersive X-ray spectrometry (EDXS) and vibrating sample magnetometer (VSM). The cobalt nanoparticles of 3–7 nm in size were uniformly deposited on the surface of the nanotubes. The remanent magnetization (M_r), saturation magnetization (M_s) and coercivity (H_c) values of the Co-HNTs were 13.9 emu/g, 27.05 emu/g and 1659 O_e, respectively, larger than that of the pure Co nanoparticles (580.72 O_e). A mechanism of the deposition of the magnetic nanoparticles on the surface of the halloysite nanotubes is suggested. Co-HNTs showed an interesting potential in the field of magnetic devices.     

Immobilization of lipase on surface modified magnetic nanoparticles using alkyl benzenesulfonate

The surface of nano-sized magnetite (NSM) particles synthesized by coprecipitation method was modified by alkyl benzenesulfonate (ABS) as a coating material. ABS on the NSM was expected to form a spacer between the surface of the NSM particles and the enzyme adsorbed and to play a role of strong enzyme adsorption onto a hydrophobic surface. Transmission electron microscopy showed that the NSM particles had an average size of 10 nm. Magnetic measurement revealed that the nanoparticles were superparamagnetic and the saturation magnetization was about 68 emu/g. Porcine pancreas lipase (PPL) was immobilized onto the ABS-NSM, which was to catalyze hydrolysis of olive oil and showed enhanced durability in the reuse after being recovered by magnetic separations.     

Aqueous chemical synthesis of iron oxides magnetic nanoparticles of different morphology and mesostructure

Magnetic nanoparticles of magnetite structure were obtained by the aqueous chemical synthesis, namely: using the chemical co-precipitation from the 1:2 M ratio mix of the iron chlorides (II, III) water solution with the ammonia used as precipitation agent as well as with oleic acid. Obtained nanopowders were studied using the X-Ray diffraction, infrared spectroscopy, scanning and transmission electron microscopy, low-temperature nitrogen absorption, and small-angle X-Ray scattering methods in order to determine the influence of synthesis techniques (homogenization procedure, separation methods – decantation, vacuum filtration, rotary evaporation, or magnetic separation), on the phase composition, size, morphology and magnetic parameters of the nanoparticles. It was demonstrated that the value of the specific surface area of nanoparticles with the average size of 10–20 nm is relatively high (75–132 m²/g) and their shape is lamellar or rod-shaped as well as cylindrical (round). The technique of separating nanoparticles from the mother liquor had a dominant effect on the morphology of nanoparticles. Dynamic and Electrophoretic Light Scattering methods showed that homogenization procedure, separation methods and especially surface modification with oleic acid affect the size and surface charge of the nanopowders.     

Synthesis of high magnetization hydrophilic magnetite (Fe3O4) nanoparticles in single reaction—Surfactantless polyol process

High magnetization hydrophilic magnetite nanoparticles have been synthesized in two different batches with mean particle sizes of 32.3 and 9.2 nm by inexpensive and surfactant-free facile one-pot modified polyol method. In the synthesis, polyethylene glycol was used as a solvent media and it has been found to play a key role to act as a reducing agent as well as a stabilizer simultaneously. It was shown that the size of the nanoparticles can be effectively controlled by modifying the reaction parameters such as reaction temperature, time and polyol/metal precursor ratio. X-ray diffraction and energy dispersive spectroscopy studies confirm the formation of a pure magnetite phase without the presence of any other phases. Transmission electron microscopy and the Fourier transform infrared spectroscopy results reveal that the particle size and surface adsorption properties are very much dependent on reaction parameters. The magnetic properties of the samples measured by physical property measurement system have shown that the as-synthesized magnetite nanoparticles possess a high magnetization of 85.87 emu/g at 300 K and 91.7 emu/g at 5 K with negligible coercivities. The structural and magnetic characterizations of these polyol coated, hydrophilic, monodisperse, superparamagnetic nanoparticles clearly indicate that they are suitable for biomedical applications.     

Synthesis and Characterization of Magnetite/Polyvinyl Alcohol Core–Shell Composite Nanoparticles

Magnetite (Fe₃O₄)/polyvinyl alcohol (PVA) core–shell composite nanoparticles were successfully synthesized using a coprecipitation of ferrous and ferric chloride followed by coating with PVA. The resulting nanoparticles were characterized using X‐ray diffraction, Fourier Transform Infrared Spectroscopy, Transmission Electron Microscopy, X‐ray photo electron spectroscopy, Zeta potential measurements, UV–Vis spectroscopy, Thermogravimetric Analysis, and Vibrating Sample Magnetometry (VSM). The average particle size was 13 nm. The presence of characteristic functional groups of PVA around the core of magnetite nanoparticles was confirmed by FTIR spectroscopy while the amount of PVA (%) bound to it was estimated by TGA analysis. Zeta potential measurements made by dispersing dilute sonicated samples in a Phosphate Buffer Saline (PBS pH 7.4) confirmed that the particles were negatively charged. The stability and retention of the coating material PVA in PBS (pH7.4) over a period of time were substantiated by UV–Vis spectroscopy. Room‐temperature magnetic measurements were made with a VSM which demonstrated the superparamagnetic nature of the particles with higher saturation magnetization of 56.41 emu/g. Furthermore, in vitro cytocompatibility testing of Fe₃O₄/PVA core–shell composite nanoparticles was carried out on human cervix cancer cells. This confirmed a 97% cell viability with no significant cytotoxicity and thereby substantiated their biocompatibility.