Template synthesis and magnetic response of polyaniline/Fe3O4 composite microtubes

Template synthesis technique was employed to prepare magnetic polyaniline (PANI)/Fe₃O₄ composite microtubes using anodic aluminum oxide (AAO) membrane as template. Magnetic microtubes were obtained through in situ polymerization of aniline in the presence of Fe₃O₄ nanoparticles in the microchannels of template. A tubular structure was formed once when aniline was preferentially adsorbed and polymerized on the surface of channels wall. Electron microscope images demonstrated that the shape and size of guest (PANI/Fe₃O₄ composite microtubes) were strictly depended on those of the host (template channels). Magnetic force microscopy images showed that the PANI/Fe₃O₄ composite microtubes possessed reasonable magnetism and the magnetism distribution of microtubes was regular as distribution of template channels. Moreover, the magnetic response and oriented arrangement of PANI/Fe₃O₄ microtubes were fulfilled in the magnetic field. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Fabrication of PMMA/PANI/Fe3O4 as a Novel Conducting Hybrid Coating

In this paper, an excellent new hybrid coating including poly(methyl methacrylate) (PMMA), polyaniline (PANI), and magnetite nanoparticles (Fe₃O₄) was obtained. Fe₃O₄ nanoparticles were synthesized using coprecipitation method, and then magnetite nanoparticles have been dispersed into the PANI to increase compatibility with PMMA. Also, PANI/Fe₃O₄ nanocomposites were synthesized through in situ emulsion polymerization, and then PMMA/PANI/Fe₃O₄ hybrid coating was successfully synthesized using batch emulsion polymerization method. Structure, morphology and thermal stability of the samples were characterized using Fourier transform infrared, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and thermal gravimetric analysis (TGA). The synthesized samples were well distributed with an average diameter smaller than 20?nm. Microscopy and X-ray photoelectron spectroscopy results illustrated a great dispersion of magnetite nanoparticles in hybrid matrix. Moreover, the TGA results demonstrated that the PMMA/PANI/Fe₃O₄ hybrid coating nanoparticle is an excellent hybrid coating with high thermal resistance.     

Polyaniline/FE3O4 magnetic nanocomposite prepared by ultrasonic irradiation

Ultrasonic irradiation is employed to assist the chemical oxidative polymerization of aniline in the presence of Fe₃O₄ nanoparticles in order to prepare a polyaniline (PANI)/Fe₃O₄ magnetic nanocomposite. In the chemical oxidative polymerization of aniline in the initially neutral medium, the optimum molar ratio of the oxidant ammonium persulfate to the monomer aniline is 2 : 1. The prepared PANI is in the emeraldine form and is doped by sulfate anions. Fe₃O₄ particles are encapsulated by PANI and dispersed well in PANI. Fe₃O₄ increases the doping level and decreases the crystallinity of PANI. The PANI/Fe₃O₄ nanocomposite possesses conductivity and magnetic properties. Increasing the Fe₃O₄ content increases the magnetization of the PANI/Fe₃O₄ composite but decreases its conductivity. © 2006 Wiley Periodicals Inc. J Appl Polym Sci 102: 2107–2111, 2006     

Synthesis and characterization of novel conducting composites of Fe3O4 nanoparticles and sulfonated polyanilines

Surface charged iron oxide (Fe₃O₄) nanoparticles were used for the synthesis of sulfonated polyaniline (SPAN)‐Fe₃O₄ nanocomposites (SPAN/Fe₃O₄‐NCs). 2,5‐diaminobenzenesulfonic acid (DABSA) and 2‐aminobenzenesulfonic acid (ABSA) were independently polymerized with aniline to form SPAN. The structure of the composites was characterized by means of transmission electron microscopy (TEM), X‐ray diffraction (XRD), thermogravimetric analysis (TGA), Fourier transform infrared (FTIR) spectra, conductivity and magnetic properties. TEM reveals that Fe₃O₄ nanoparticles are “glued” with SPAN in the composite. TGA indicates that SPAN/Fe₃O₄‐NCs are having better thermal stability. The room temperature conductivity of SPAN/Fe₃O₄‐NCs is higher than that of pristine PANI and SPAN. SPAN/Fe₃O₄‐NCs exhibits magnetic behavior. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 4127–4134, 2007     

Magnetoresistive polyaniline-magnetite nanocomposites with negative dielectrical properties

Magnetic polyaniline (PANI) polymer nanocomposites (PNCs) reinforced with magnetite (Fe₃O₄) nanoparticles (NPs) have been successfully synthesized using a facile surface initiated polymerization (SIP) method. The chemical structures of the PANI/Fe₃O₄ PNCs are characterized by Fourier transform infrared (FT-IR) spectroscopy. The thermal stability of the PANI/Fe₃O₄ PNCs is performed by thermogravimetric analysis (TGA). Both transmission electron microscopy (TEM) and scanning electron microscopy (SEM) are used to characterize the morphologies of the PANI, Fe₃O₄ nanoparticles (NPs) and the PNCs. X-ray diffraction (XRD) shows a significant effect of the Fe₃O₄ NPs on the crystallization structure of the formed PANI. The dielectrical properties of these PNCs are strongly related to the Fe₃O₄ nanoparticle loadings and unique negative permittivity is observed in all the samples. Temperature dependent resistivity analysis from 50 to 290 K reveals a quasi 3-dimension variable range hopping (VRH) electron conduction mechanism for the nanocomposite samples. The PNCs do not show hysteresis loop with zero coercivity, indicating the superparamagnetic behavior at room temperature. The PNCs with 30 wt% Fe₃O₄ NP loading exhibit a larger positive magnetoresistance (MR = 95%) than 53% of the pure PANI.     

Polyaniline grafted chitosan/GO-CNT/Fe3O4 nanocomposite as a superior electrode material for supercapacitor application

Developing appropriate stable electroactive electrode materials for supercapacitor application is the challenging issue, which attracts enormous attention in recent decades. In this regard, Fe₃O₄ nanoparticles are firstly synthesized on chitosan/graphene oxide-multiwall carbon nanotubes (CS/GM/Fe₃O₄). Then, polyaniline (PANI) is grafted on it via in situ chemical polymerization and named as CS/GM/Fe₃O₄/PANI. The as-prepared nanocomposites are characterized by Field emission scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and energy dispersive X-ray spectroscopy. The capacitive properties of the electrodes are investigated in a three electrode configuration in 0.5 M Na₂SO₄ electrolyte by various electrochemical techniques. The specific capacitance of CS/GM/Fe₃O₄/PANI electrode is 1513.4 Fg⁻¹ at 4 Ag⁻¹ which is 1.9 times higher than that of CS/GM/Fe₃O₄ (800 Fg⁻¹). Meanwhile, the electrodes exhibit appropriate cycle life along with 99.8% and 93.95% specific capacitance at 100 Ag⁻¹ for chitosan/GO-CNT/Fe₃O₄ and polyaniline grafted chitosan/GO-CNT/Fe₃O₄, respectively.     

Magnetite/graphene/polyaniline composite for removal of aqueous hexavalent chromium

Here, we report the synthesis of Fe₃O₄/G/PANI composite containing magnetite nanoparticles (Fe₃O₄), graphene sheets (G), and polyaniline (PANI) via chemical route for removal of toxic Cr (VI) from water. TEM image shows the formation of uniformly distributed magnetite nanoparticles on graphene/PANI composite. HRTEM images shows the formation of crystalline magnetite nanoparticles showing lattice fringes with inter‐planner distance 0.21 nm. The magnetic measurement shows magnetization 22 emu/g and ferromagnetic property of the adsorbent. The equilibrium adsorptions were well‐described by the Langmuir isotherm model and shows maximum adsorption capacity 153.54 mg/g at pH 6.5 and temperature 30 °C. The kinetics data well fitted by pseudo‐second‐order model and around 86% Cr (VI) removal completed within 20 min. The Cr (VI) removal capacitive decreases with increase in pH and ionic strength. The adsorbent shows leaching of iron nanoparticles at pH 1 whereas stable in solution having pH 2 and more. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44002.     

A Novel Strategy for Synthesis of Polystyrene/Fe3O4 Nanocomposite: RAFT Polymerization,Functionalization, and Coordination Techniques

A facile strategy for the synthesis of polystyrene/Fe₃O₄ nanocomposite is suggested. For this purpose, styrene and 4-chloromethyl styrene monomers was copolymerized through reversible addition of fragmentation chain transfer technique [P(St-co-CMSt)] and then the chlorine groups of CMSt units were converted to diethyl malonate groups through a nucleophilic substitution reaction. Afterward, esteric groups of diethyl malonate were hydrolyzed to afford carboxylic acid-functionalized polystyrene. This polymer with carboxylic acid groups can adsorbed onto the surface of Fe₃O₄ nanoparticles through the interaction with hydroxyl groups onto the surface of the nanoparticles. We envision that the synthesized PSt/Fe₃O₄ nanocomposite may be find applications in electromagnetic interference shielding and environment sciences.     

Electrorheological Response of Novel polyaniline-Fe2O3 Nanocomposite Particles

A novel polyaniline-Fe₂O₃ (PANI-Fe₂O₃) nanocomposite has been successfully prepared by oxidative in situ polymerization of aniline in the presence of iron nanoparticles. The characterization suggested the interactions between Fe₂O₃ and PANI. The PANI-Fe₂O₃ nanoparticles were used as a novel dispersed phase of electrorheological (ER) fluid and the evaluation results revealed that the yield stress of the new ER fluid can reach up to 10 kPa at 4.3 kV/mm, much higher than those of the ER fluids using PANI, Fe₂O₃ or their mixture as dispersed phase, confirming that the interactions between Fe₂O₃ and PANI are responsible for the high performance.     

One-pot method fabrication of superparamagnetic sulfonated polystyrene/Fe<Subscript>3</Subscript>O<Subscript>4</Subscript>/graphene oxide micro-nano composites

In this work, using monodispersed sulfonated polystyrene (SPS) microspheres as carriers, FeCl₃·6H₂O and FeSO₄·7H₂O as precursors, NaOH as precipitant in the presence of graphene oxide (GO), SPS/Fe₃O₄/GO micro-nano composites were fabricated by a simple one-pot method employing an inverse coprecipitation in-situ compound technology. The SPS/Fe₃O₄/GO micro-nano composites were characterized by scanning electron microscopy, transmission electron microscopy, X-ray powder diffractometer, Fourier transform infrared spectroscopy, nitrogen adsorption/desorption isotherms and vibrating sample magnetometer. The results show that the SPS/Fe₃O₄/GO micro-nano composites were fabricated with SPS as core, GO and Fe₃O₄ nanoparticles as shell. The SPS/Fe₃O₄/GO micro-nano composites had larger BET specific surface area, average pore width and micropore volume than the pure SPS microspheres. Meanwhile, the SPS/Fe₃O₄/GO micro-nano composites had superparamagnetism and hydrophilic property. The saturation magnetization (M_s) of the SPS/Fe₃O₄/GO micro-nano composites was 10.86 emu/g, which was enough to ensure the convenient magnetic separation of solid and liquid phase.     

Iron Oxide and Titanium Dioxide Nanoparticle Effects on Plant Performance and Root Associated Microbes

In this study, we investigated the effect of positively and negatively charged Fe₃O₄ and TiO₂ nanoparticles (NPs) on the growth of soybean plants (Glycine max.) and their root associated soil microbes. Soybean plants were grown in a greenhouse for six weeks after application of different amounts of NPs, and plant growth and nutrient content were examined. Roots were analyzed for colonization by arbuscular mycorrhizal (AM) fungi and nodule-forming nitrogen fixing bacteria using DNA-based techniques. We found that plant growth was significantly lower with the application of TiO₂ as compared to Fe₃O₄ NPs. The leaf carbon was also marginally significant lower in plants treated with TiO₂ NPs; however, leaf phosphorus was reduced in plants treated with Fe₃O₄. We found no effects of NP type, concentration, or charge on the community structure of either rhizobia or AM fungi colonizing plant roots. However, the charge of the Fe₃O₄ NPs affected both colonization of the root system by rhizobia as well as leaf phosphorus content. Our results indicate that the type of NP can affect plant growth and nutrient content in an agriculturally important crop species, and that the charge of these particles influences the colonization of the root system by nitrogen-fixing bacteria.     

Microwave assisted hydrothermal synthesis of (Fe,Co)3O4 nanoparticles in the presence of surfactants and effects of Co/Fe ratio on microstructure and magnetism

Microstructure and magnetic properties of nanoparticles can be tailored by optimising the synthesis procedure and changing chemical composition. In this study, a two-step procedure, i.e., coprecipitation in the presence of PEG 300 followed by microwave assisted (MW) hydrothermal synthesis, was introduced to obtain Co_xFe_3-xO₄ (x?=?0, 0.1 and 0.2) nanoparticles. It was found that with the increase of Co content, particle/crystallite size increased, with significant change of coercivity (H_c). The mixed samples of Co_xFe_3-xO₄ (x?=?0.1 and 0.2) were magnetically harder in comparison with Fe₃O₄. Тhe H_c of Fe₃O₄ was 91?Oe, while for Co_0.10Fe_2.90O₄ and Co_0.20Fe_2.80O₄, H_c was 256?Oe and 1070?Oe, respectively. Saturation magnetisation (M_s) of mixed samples also increased up to 6% compared to Fe₃O₄. A special effort was devoted to study the effects of introducing different surfactants (PEG 300, PEG 4000 or SDS) during the synthesis procedure in order to improve morphological and microstructural properties of CoFe₂O₄ nanoparticles. The influence of surfactants on physical/chemical properties of nanoparticles is discussed.     

Synthesis of new electromagnetic nanocomposite based on modified Fe3O4 nanoparticles with enhanced magnetic,conductive, and catalytic properties

A new method for the fabrication of an electromagnetic nanocomposite based on Fe₃O₄ and polyaniline (PANI) is offered. The authors focused on improvement of the physical and electromagnetic properties of the nanocomposite using a new synthetic method. Supermagnetic Fe₃O₄ nanoparticles were synthesized through coprecipitation method. As a chemical modification, the third generation of poly (amidoamine) dendrimer was grafted on the surface of the nanoparticles. PANI was grafted from –NH₂ functional groups of dendrimer via in situ polymerization of aniline. Finally, Au nanoparticles were loaded on the nanocomposite and its catalytic activity for reduction reactions was studied.     

Preparation and characterization of thermosensitive organic-inorganic hybrid microgels with functional Fe3O4 nanoparticles as crosslinker

A methodology is described for the preparation of thermosensitive organic-inorganic hybrid microgels with functional Fe₃O₄ nanoparticles as the crosslinker and N-isopropylacrylamide (NIPAm) as the monomer. Magnetic Fe₃O₄ nanoparticles were first prepared via a redox reaction in aqueous solution and then modified with 3-(trimethoxysilyl)propylmethacrylate (TMSPMA) via the silanization. The bonding of multiple TMSPMA monomers on the surface of Fe₃O₄ nanoparticles renders them as crosslinker. Surfactant-free emulsion polymerization (SFEP) of NIPAm was then carried out with the presence of TMSPMA-modified Fe₃O₄ nanoparticles at 70 °C in aqueous solution, leading to the formation of thermosensitive PNIPAm-Fe₃O₄ hybrid microgels crosslinked with Fe₃O₄ nanoparticles. Transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), thermogravimetric analysis (TGA), dynamic light scattering (DLS) and physical properties measurement system (PPMS) were then used to characterize the resultant hybrid microgels. The experimental results show that the PNIPAm-Fe₃O₄ hybrid microgels were spherical in shape with a large size distribution and the Fe₃O₄ nanoparticles were randomly distributed inside the microgels. The PNIPAm-Fe₃O₄ hybrid microgels were thermosensitive, exhibiting a reversible swelling and deswelling behavior as a function of temperature. The PNIPAm-Fe₃O₄ hybrid microgels also show superparamagnetic behavior at room temperature (300 K).     

Studies on Properties of Rice Straw/Polymer Nanocomposites Based on Polycaprolactone and Fe3O4 Nanoparticles and Evaluation of Antibacterial Activity

Modified rice straw/Fe₃O₄/polycaprolactone nanocomposites (ORS/Fe₃O₄/PCL-NCs) have been prepared for the first time using a solution casting method. The RS/Fe₃O₄-NCs were modified with octadecylamine (ODA) as an organic modifier. The prepared NCs were characterized by using X-ray powder diffraction (XRD), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), Thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FT-IR). The XRD results showed that as the intensity of the peaks decreased with the increase of ORS/Fe₃O₄-NCs content in comparison with PCL peaks, the Fe₃O₄-NPs peaks increased from 1.0 to 60.0 wt. %. The TEM and SEM results showed a good dispersion of ORS/Fe₃O₄-NCs in the PCL matrix and the spherical shape of the NPs. The TGA analysis indicated thermal stability of ORS/Fe₃O₄-NCs increased after incorporation with PCL but the thermal stability of ORS/Fe₃O₄/PCL-NCs decreased with the increase of ORS/Fe₃O₄-NCs content. Tensile strength was improved with the addition of 5.0 wt. % of ORS/Fe₃O₄-NCs. The antibacterial activities of the ORS/Fe₃O₄/PCL-NC films were examined against Gram-negative bacteria (Escherichia coli) and Gram-positive bacteria (Staphylococcus aureus) by diffusion method using nutrient agar. The results indicated that ORS/Fe₃O₄/PCL-NC films possessed a strong antibacterial activity with the increase in the percentage of ORS/Fe₃O₄-NCs in the PCL.     

Synthesis,characterization, and corrosion inhibition study of polyaniline‐α‐Fe2O3 nanocomposite

Polyaniline (PANI)‐α‐Fe₂O₃ nanocomposites (NCs) have been synthesized by chemical oxidative in situ polymerization of aniline in presence of α‐Fe₂O₃ nanoparticles at 5°C using (NH₄)₂S₂O₈ as an oxidant in an aqueous solution of sodium dodecylbenzene sulphonic acid (SDBS), as surfactant and dopant under N₂ atmosphere. The room temperature conductivity of NCs decreases and coercive force (H_c) increases with an increase addition of α‐Fe₂O₃ in PANI matrix. The result of FTIR and TGA shows that the interaction between α‐Fe₂O₃ particles and PANI matrix could improve the thermal stability of NCs. NCs demonstrate the superparamagnetic behavior. The performance of PANI and PANI‐α‐Fe₂O₃ NCs as protective coating, against corrosion of 316LN stainless steel in 3.5% NaCl was assessed by potentiodynamic polarization technique. The study shows a good corrosion inhibition effect of both the coatings. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

An efficient magnetically modified microbial cell biocomposite for carbazole biodegradation

Magnetic modification of microbial cells enables to prepare smart biocomposites in bioremediation. In this study, we constructed an efficient biocomposite by assembling Fe₃O₄ nanoparticles onto the surface of Sphingomonas sp. XLDN2-5 cells. The average particle size of Fe₃O₄ nanoparticles was about 20 nm with 45.5 emu g^-1 saturation magnetization. The morphology of Sphingomonas sp. XLDN2-5 cells before and after Fe₃O₄ nanoparticle loading was verified by scanning electron microscopy and transmission electronic microscopy. Compared with free cells, the microbial cell/Fe₃O₄ biocomposite had the same biodegradation activity but exhibited remarkable reusability. The degradation activity of the microbial cell/Fe₃O₄ biocomposite increased gradually during recycling processes. Additionally, the microbial cell/Fe₃O₄ biocomposite could be easily separated and recycled by an external magnetic field due to the super-paramagnetic properties of Fe₃O₄ nanoparticle coating. These results indicated that magnetically modified microbial cells provide a promising technique for improving biocatalysts used in the biodegradation of hazardous compounds.     

Synthesis and characterization of poly(styrene-co-fluorescein O-methacrylate)/poly(N-isopropylacrylamide)-Fe3O4 core/shell composite particles

We demonstrate the synthesis and characteristics of multifunctional poly(styrene-co-fluorescein O-methacrylate)/poly(N-isopropylacrylamide)-Fe₃O₄ [P(St/FMA)/PNIPAAm-Fe₃O₄] core/shell composite particles, in which the core consists of fluorescent materials and the shell consists of magnetic and thermo-responsive components. First, core/shell particles consisting of a fluorescent P(St/FMA) core and thermo-responsive PNIPAAm-rich shell were prepared by two-stage shot-growth emulsion polymerization. Next, Fe₃O₄ nanoparticles were immobilized via electrostatic interactions and then covalently linked to the shell via surface coordinated Aphen by a coupling reaction in order to obtain magnetic properties. The morphology of P(St/FMA)/PNIPAAm-Fe₃O₄ composite particles, confirmed by transmission electron microscopy (TEM), reveals that Fe₃O₄ nanoparticles are located in the PNIPAAm shell. The thermo-sensitivity of composite particles to hydrodynamic diameter was confirmed by using dynamic light scattering (DLS). Photoluminescence (PL) spectra indicate that the fluorescence emission intensity of core/shell particles is highly sensitive to the pH of an aqueous medium. The core/shell composite particles exhibited a combination of fluorescent, magnetic, pH and thermo-responsive behavior.     

Enhanced photocatalytic degradation of tri-chlorophenol by Fe3O4@TiO2@Au photocatalyst under visible-light

Heterogeneous Fe₃O₄@TiO₂@Au core-shell microspheres, a facile and highly efficient catalyst have been fabricated by a simple surface modification. The fabrication process involved the coating of TiO₂ nanoshell onto the magnetic core using by sol-gel process, and then the anchoring of Au nanoparticles onto the surface of the Fe₃O₄@TiO₂ microspheres through the wet chemical reaction of 3-aminopropyltriethoxysilane (APTES). The as-synthesized Fe₃O₄@TiO₂ microspheres exhibited a narrow size distribution, with a typical size of 350 nm and shell thickness of 25 nm. The Fe₃O₄@TiO₂@Au microspheres can be easily collected by applying external magnetic field due to the magnetic property of core Fe₃O₄ particles. Compared to unmodified Fe₃O₄@TiO₂ microspheres, the Fe₃O₄@TiO₂@Au microspheres showed higher photocatalytic activity for 2, 4, 6-trichlorophenol (TCP). The photocatalytic efficiency of the Fe₃O₄@TiO₂ microspheres was 28% after 40 min irradiation while, the efficiency of Fe₃O₄@TiO₂@Au microspheres was 98% at the same condition.     

Hydrothermal synthesis of magnetite nanoparticles as MRI contrast agents

Magnetite (Fe₃O₄) nanoparticles prepared using hydrothermal approach were employed to study their potential application as magnetic resonance imaging (MRI) contrast agent. The hydrothermal process involves precursors FeCl₂·4H₂O and FeCl₃ with NaOH as reducing agent to initiate the precipitation of Fe₃O₄, followed by hydrothermal treatment to produce nano-sized Fe₃O₄. Chitosan (CTS) was coated onto the surface of the as-prepared Fe₃O₄ nanoparticles to enhance its stability and biocompatible properties. The size distribution of the obtained Fe₃O₄ nanoparticles was examined using transmission electron microscopy (TEM). The cubic inverse spinel structure of Fe₃O₄ nanoparticles was confirmed by X-ray diffraction technique (XRD). Fourier transform infrared (FTIR) spectrum indicated the presence of the chitosan on the surface of the Fe₃O₄ nanoparticles. The superparamagnetic behaviour of the produced Fe₃O₄ nanoparticles at room temperature was elucidated using a vibrating sample magnetometer (VSM). From the result of custom made phantom study of magnetic resonance (MR) imaging, coated Fe₃O₄ nanoparticles have been proved to be a promising contrast enhanced agent in MR imaging.