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1.
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 (Fe 3O 4) 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 相似文献
2.
This study describes the preparation of a nanocomposites fabricated from monodispersed 4‐nm iron oxide (Fe 3O 4) coated on the surface of carboxylic acid containing multi‐walled carbon nanotube (c‐MWCNT) and polypyrrole (PPy) by in situ chemical oxidative polymerization. High‐resolution transmission electron microscopy images and X‐ray diffraction (XRD) data indicate that the resulting Fe 3O 4 nanoparticles synthesized using the thermal decomposition are close to spherical dots with a particle size about 4 ± 0.2 nm. The resulting nanoparticles were further mixed with c‐MWCNT in an aqueous solution containing with anionic surfactant sodium bis(2‐ethylhexyl) sulfosuccinate to form one‐dimensional Fe 3O 4 coated c‐MWCNT template for further preparation of nanocomposite. Structural and morphological analysis using field‐emission scanning electron microscopy, high‐resolution transmission electron microscopy, and XRD showed that the fabricated Fe 3O 4 coated c‐MWCNT/PPy nanocomposites are one‐dimensional core (Fe 3O 4 coated c‐MWCNT)‐shell (PPy) structures. The conductivities of these Fe 3O 4 coated c‐MWCNT/PPy nanocomposites are about four times higher than those of pure PPy matrix. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 727–733, 2008 相似文献
3.
Iron oxides are considered as the promising pseudocapacitive materials for high-performance supercapacitors due to their high theoretical specific capacitance, low cost, environmental benignity, and natural abundance. In this work, we study capacitive behavior of different magnetite (Fe 3O 4) nanoparticles/carbon black (CB) composites ratios. These composites are synthesized by the coprecipitation method in the presence of ultrasonic waves. The structural and morphological characteristics of the magnetite/CB composites are investigated by X-ray diffraction and scanning electron microscopy, respectively. The electrochemical performance of magnetite/CB composite electrodes is tested by cyclic voltammetry and galvanostatic charge/discharge in a Na 2SO 4 electrolyte. The results indicate that the magnetite/CB electrodes show typical pseudo-capacitive behavior in Na 2SO 4 solution. Moreover, in comparison to the pure Fe 3O 4 (37 F g ?1) and carbon black (23 F g ?1), the as-prepared 45 % magnetite/CB nanocomposite electrode shows a higher specific capacitance (300 F g ?1). Additionally, the supercapacitor device of the magnetite/CB nanocomposite exhibits excellent long cycle life along with 98.5 % specific capacitance retained after 10,000 cycle tests. 相似文献
4.
This work provides an insight into the effect of incorporating of magnetite nanoparticles on the rheology of fluids. In this respect, polymer-stabilized magnetite nanoparticles were obtained using sodium salt of poly (2-acrylamido-2-methylpropanesulfonate (PAMPS-Na). Monodisperse polymer coated magnetite nanoparticles Fe 3O 4/poly(styrene-AMPS) copolymer nanoparticles with diameters of 50–300 nm were prepared by radical polymerization in the presence of a ferrofluid coated with PAMPS-Na. The magnetic nanoparticles were easily separated in a magnetic field. The structure of the obtained magnetic nanoparticles was characterized by Fourier transform infrared spectroscopy (FTIR). The morphology and size of the magnetic nanoparticles were determined by transmission electron microscopy (TEM). FTIR and TEM revealed that the Fe 3O 4 nanoparticles were incorporated into the shells of poly(styrene-AMPS). Aqueous dispersed solutions of a charged hydrophobically modified Fe 3O 4/poly(styrene-AMPS) copolymer nanoparticles exhibit high viscosities even at low polymer concentrations (0.1 wt %), which is an interesting feature in connection with enhanced oil recovery. Effects of temperature and addition of sodium chloride on the viscosity properties of a semidilute dispersed solution of Fe 3O 4/poly(styrene-AMPS) copolymer nanoparticles are examined. The results indicated that Fe 3O 4/poly(styrene-AMPS) copolymer nanoparticles disclose strong interactions between magnetite and coated polymers of both PAMPS-Na and styrene-AMPS copolymers. 相似文献
5.
Composite microspheres of core-shell type were prepared by a seeded polymerization using monodispersed polystyrene seed latex (Ps) combined with an in situ dispersion of magnetite (Fe 3O 4) fine particles. The heterogeneous polymerization was carried out in aqueous dispersions of the Fe 3O 4 particles modified with sodium oleate. All the synthetic processes were carried out in a wet state to avoid serious agglomeration. The morphology of the composite particle and the size distribution were examined to discuss the effects on the polymerization parameters, such as monomer concentration, type and concentration of an initiator, magnetite particle concentration and the method of surface modification of Fe 3O 4. 相似文献
6.
This study describes the preparation of nanocomposites fabricated from monodispersed iron oxide (Fe 3O 4) and polypyrrole (PPy) by in situ chemical oxidative polymerization. The monodispersed 4 nm Fe 3O 4 nanoparticles which served as cores were synthesized using the thermal decomposition of a mixture of Iron (III) acetylacetonate and oleic acid in the presence of high boiling point solvents. The resulting nanoparticles were further dispersed in an aqueous solution with anionic surfactant sodium bis(2‐ethylhexyl) sulfosuccinate to form micelle/Fe 3O 4 spherical templates that avoid the aggregation of Fe 3O 4 nanoparticles during the further preparation of the nanocomposites. The Fe 3O 4/PPy nanocomposites were then synthesized via in situ chemical oxidative polymerization on the surface of the spherical templates. Both field‐emission scanning electron microscopy (FESEM) and high‐resolution transmission electron microscopy (HRTEM) images indicate that the resulting Fe 3O 4 nanoparticles are close to spherical dots with a particle size of about 4 nm and a standard deviation of less than 5% (4 ± 0.2 nm). Structural and morphological analysis using FESEM and HRTEM showed that the fabricated Fe 3O 4/PPy nanocomposites are core (Fe 3O 4)‐shell (PPy) structures. Morphology of the nanocomposites shows a remarkable change from spherical to tube‐like structures as the content of monodispersed Fe 3O 4 nanoparticles increases from 9% up to 24 wt %. The conductivities of these Fe 3O 4/PPy nanocomposites are about six times higher than those of PPy without Fe 3O 4. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4647–4655, 2007 相似文献
7.
The superparamagnetic magnetite (Fe 3O 4) nanoparticles with an average size of 7 nm were synthesized using a rapid and facile microwave hydrothermal technique. The structure of the magnetite nanoparticles was characterized by X-ray diffraction (X-ray), field effect scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDS), and transmission electron microscopy (TEM). The prepared Fe 3O 4 was shown to have a cubic phase of pure magnetite. Magnetization hysteresis loop shows that the synthesized magnetite exhibits no hysteretic features with a superparamagnetic behavior. The ethanol gas sensing properties of the synthesized magnetite were investigated, and it was found that the responsibility time is less than 10 s with good reproducibility for ethanol sensor. Accordingly, it is evaluated that the magnetite nanoparticles can be effectively used as a solid state ethanol sensor in industrial commercial product applications. 相似文献
8.
A synthetic method developed for preparation of sulfate- and carboxyl-functionalized magnetite/polystyrene (Fe 3O 4/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 Fe 3O 4/PS spheres used as the seeds, PMAA-coated magnetic Fe 3O 4-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
Fe 3O 4 nanoparticles, Fe 3O 4/PS spheres, PMAA-coated Fe 3O 4/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. 相似文献
9.
Triclosan is broadly utilized as preservative or antiseptic in various cosmetic and personal care products. It becomes hazardous for environmental safety and human health more than a certain concentration. In this research, graphene oxide (GO) nanosheets were prepared by composing Fe 3O 4@Au nanostructure decorated GO together with polypyrrole (PPy) (Fe 3O 4@Au‐PPy/GO nanocomposite) in a facile way. The composite excellent increased the electrochemical response, presenting a high sensitive electrochemical method for triclosan detection. The synthesized Fe 3O 4@Au‐PPy/GO nanocomposite was characterized for its morphological, magnetically and structural properties by FESEM‐mapping, TEM, and XRD. The Fe 3O 4@Au‐PPy/GO nanocomposites modified glassy carbon electrodes (GCE), Fe 3O 4@Au‐PPy/GO GCE, showed a higher sensitivity good stability, reproducibility, lower LOD (2.5×10 ?9 M) and potential practical application in electrochemical detection of triclosan under optimized experimental conditions. 相似文献
10.
Magnetite (Fe 3O 4) nanoparticles were synthesized by chemical precipitation. To reduce the aggregation of Fe 3O 4 nanoparticles, an effective surface modification method was proposed by grafting polystyrene onto the Fe 3O 4 particles. The results of Fourier transform infrared spectra and elemental analysis showed that the polymer chains have been successfully grafted from the surface of the Fe 3O 4 nanoparticles and that the percentage of grafting can reach 73%. Transmission electron microscope showed that grafted polymer chains on nanoparticles could prevent the aggregation of Fe 3O 4 nanoparticles markedly in toluene and improve their compatibility with organic phase. Another finding was the grafting reaction did not alter the crystalline structure of the Fe 3O 4 nanoparticles according to the X-ray diffraction patterns, and the saturation magnetization of PS-Fe 3O 4 nanoparticles was found to be lower than bulk magnetite. 相似文献
11.
Bimagnetic Pt 3Co/Fe 3O 4 nanocomposite is synthesized in aqueous solution. The nanoparticles are characterized with TEM, FTIR, and magnetic measurements. The as‐synthesized nanocomposite exhibits ferromagnetic properties at room temperature due to the exchange coupling between Pt 3Co and Fe 3O 4. Magnetic properties of Pt 3Co/Fe 3O 4 nanoparticle can be tuned by varying of the molar ratio of iron to platinum. Pt 3Co/Fe 3O 4 nanoparticles exhibit higher saturation magnetization when the molar ratio of iron to platinum is 1. 相似文献
12.
Polypyrrole/iron oxide (PPy/γ-Fe 2O 3) nanocomposites were synthesized by in situ oxidative polymerization of pyrrole in the presence of surface modified γ-Fe 2O 3 in supercritical carbon dioxide (scCO 2). The structural properties of nanocomposite particles thus obtained were characterized by FT-IR, thermal analysis (TGA), X-ray diffraction (XRD), and transmission electron microscopy (TEM). It was found that ca. 50 nm γ-Fe 2O 3 nanoparticles were well dispersed in PPy powder in TEM pictures. X-ray photoelectron spectroscopy (XPS) analysis also support that all γ-Fe 2O 3 nanoparticles are encapsulated by PPy. Magnetic property of the nanocomposites was measured by SQUID, which indicated that the nanocomposites are superparamagnetic. The effects of different loadings of γ-Fe2O3 on the polymerization were also investigated. 相似文献
13.
An extracting medium based on chitosan–polypyrrole (CS–PPy) magnetic nanocomposite was synthesized by chemical polymerization of pyrrole at the presence of chitosan magnetic nanoparticles (CS-MNPs) for micro-solid phase extraction. In this work, magnetic nanoparticles, the modified CS-MNPs and different types of CS–PPy magnetic nanocomposites were synthesized. Extraction efficiency of the CS–PPy magnetic nanocomposite was compared with the CS-MNPs and Fe 3O 4 nanoparticles for the determination of naproxen in aqueous samples, via quantification by spectrofluorimetry. The scanning electron microscopy images obtained from all the prepared nanocomposites revealed that the CS–PPy magnetic nanocomposite possess more porous structure. Among different synthesized magnetic nanocomposites, CS–PPy magnetic nanocomposite showed a prominent efficiency. Influencing parameters on the morphology of CS–PPy magnetic nanocomposite such as weight ratio of components was also assayed. In addition, effects of different parameters influencing the extraction efficiency of naproxen including desorption solvent, desorption time, amount of sorbent, ionic strength, sample pH and extraction time were investigated and optimized. Under the optimum condition, a linear calibration curve in the range of 0.04–10 μg mL −1 ( R2 = 0.9996) was obtained. The limits of detection (3S b) and limits of quantification (10S b) of the method were 0.015 and 0.04 μg mL −1 ( n = 3), respectively. The relative standard deviation for water sample spiked with 0.1 μg mL −1 of naproxen was 3% ( n = 5) and the absolute recovery was 92%. The applicability of method was extended to the determination of naproxen in tap water, human urine and plasma samples. The relative recovery percentages for these samples were in the range of 56–99%. 相似文献
14.
Aqueous chemical oxidative dispersion polymerizations of pyrrole using PdCl 2 oxidant were conducted using water-soluble polymeric colloidal stabilizers in order to synthesize polypyrrole–palladium (PPy–Pd) nanocomposite particles in one step. PPy–Pd nanocomposite particles with number average diameters of approximately 30 nm were successfully obtained as colloidally stable aqueous dispersions, which were stable at least for 7 months, using poly(4-lithium styrene sulfonic acid) colloidal stabilizer. The resulting nanocomposite particles were extensively characterized with respect to particle size, size distribution, colloidal stability, nanomorphology, surface/bulk chemical compositions, and conductivity. X-ray photoelectron spectroscopy indicated the existence of poly(styrene sulfonic acid) colloidal stabilizer on the surface of the nanocomposite particles. Transmission electron microscopy studies confirmed that nanometer-sized Pd nanoparticles were distributed in the PPy matrix. 相似文献
15.
The design of complex heterostructured electrode materials that deliver superior electrochemical performances to their individual counterparts has stimulated intensive research on configuring supercapacitors with high energy and power densities. Herein we fabricate hierarchical tectorum‐like α‐Fe 2O 3/polypyrrole (PPy) nanoarrays (T‐Fe 2O 3/PPy NAs). The 3D, and interconnected T‐Fe 2O 3/PPy NAs are successfully grown on conductive carbon cloth through an easy self‐sacrificing template and in situ vapor‐phase polymerization route under mild conditions. The electrode made of the T‐Fe 2O 3/PPy NAs exhibits a high areal capacitance of 382.4 mF cm −2 at a current density of 0.5 mA cm −2 and excellent reversibility. The solid‐state asymmetric supercapacitor consisting of T‐Fe 2O 3/PPy NAs and MnO 2 electrodes achieves a high energy density of 0.22 mWh cm −3 at a power density of 165.6 mW cm −3. 相似文献
16.
Ultrafine magnetite particles are prepared through an electrochemical process, at room temperature, from an iron-based electrode immersed in an alkaline aqueous medium containing complexing compounds. XRD and chemical analysis indicate that the product is pure magnetite, Fe 3O 4. The size and morphology of the particles are studied by SEM. The magnetite nanoparticles present a magnetoresistance of almost 3%, at 300 K, under a magnetic field of 1 T. A reactive mechanism for the electrochemical process is proposed. 相似文献
17.
One step solvothermal route has been developed to prepare a well dispersed magnetically separable palladium–graphene nanocomposite, which can act as a unique catalyst against hydrogenation due to the uniform decoration of palladium nanoparticles throughout the surface of the magnetite–graphene nanocomposite and hence can be reused for several times. In addition to catalytic activity, palladium nanoparticles also facilitate the formation and homogeneous distribution of magnetite (Fe 3O 4) nanoparticles onto the graphene surfaces or else an agglomerated product has been obtained after the solvothermal reduction of graphene oxide in presence of Fe 3+ alone. 相似文献
18.
The magnetic nanocomposite materials represent an important class of nanomaterials extensively studied nowadays due to their varied applications from medical diagnostic to storage information. The iron oxides in silica matrix systems are highly investigated. The sol-gel method is a suitable way of preparation of Fe 3O 4-SiO 2 nanocomposite materials, since this method allowed the preparation of nanocomposite materials with narrow size distribution of magnetite in silica matrix. In the present work, nanocomposite materials in the Fe 3O 4-SiO 2 system were prepared by sol-gel method via alkoxide and aqueous route. As SiO 2 sources, tetraethoxysilan (TEOS) for the alkoxide route, as well as silica sol Ludox (30%) for the aqueous route, were used. This study shows the influence of the type of silica matrix on the structure, size, and distribution of the Fe 3O 4 nanoparticles in the Fe 3O 4-SiO 2 systems. The gels were annealed at 550°C in order to consolidate the matrices. The structural characterization of the obtained materials via the two preparation routes was performed by DTA/TGA analysis, X-ray diffraction, IR and Mössbauer spectroscopy, Transmission Electron Microscopy (TEM) and Selected Area Electron Diffraction (SAED). 相似文献
19.
Magnetic hydrogels (ferrogels) based on poly(vinyl alcohol) (PVA) and poly(hydroxyethyl methacrylate) (PHEMA) with magnetite (Fe 3O 4) nanoparticles were prepared. PVA ferrogels were synthesised by submitting the aqueous solution of polymer and Fe 3O 4 to freezing-thawing (F-T) cycles yielding a physical gel. Different samples were prepared by varying (i) the concentration of PVA, (ii) the concentration of magnetite and (iii) the number of F-T cycles applied. PHEMA ferrogels were prepared by a crosslinking polymerization reaction in the presence of magnetite yielding chemical gels. Different samples were prepared by varying (i) the concentration of HEMA, (ii) the concentration of EGDMA and (iii) the concentration of magnetite nanoparticles. All ferrogel samples were first dried before been analysed in a thermogravimetric analyzer. The resulting thermograms showed that the concentration of magnetite nanoparticles does affect the thermal stability of either ferrogels system, a general improvement in comparison with PVA and PHEMA hydrogels, respectively, being observed. The apparent activation energy ( Ea) of the thermal degradation for PVA ferrogels was evaluated and calculated applying the Flynn-Wall and the Kissinger methods. Values of apparent Ea increased with the content of Fe 3O 4 in the ferrogel sample. 相似文献
20.
N,N,N′,N′-tetraoctyl diglycolamide (TODGA) and bis(2-ethylhexy)phosphoric acid (HDEHP) were coated on Fe3O4 nanoparticles under different chemical conditions. The TODGA-coated magnetite nanoparticles (Fe3O4@TODGA) captured representative actinides Am(III) and Pu(IV) at 3–4 M HNO3 with high efficiency. However, the HNO3 induced pre-organization of TODGA, before coating on the magnetite nanoparticles, was found to be important for the sorption of Am(III) and Pu(IV) ions. The Fe3O4@HDEHP particles exhibited selectivity toward Pu(IV), and Am(III) did not sorb from 3 to 4 M HNO3. The quantification of Pu(IV) preconcentrated on coated particles was carried out by removing the extractant coating in dioxane based scintillator, followed by liquid scintillation counting. 相似文献
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