Fabrication and characterization of the orientated MMT/PI composite films via relatively low magnetic field

Anisotropic cetylpyridinium modified magnetic montmorillonite/polyimide (CPC‐Fe₃O₄‐MMT/PI) composite films were prepared based on CPC‐Fe₃O₄‐MMT capable of exfoliation and magnetic‐field response via in situ polymerization and relatively low magnetic field adjustment (0.6 T) in the film casting followed by imidization. The stability of CPC‐Fe₃O₄‐MMT during the in situ polymerization over flow shearing of the polymers and longtime stirring was evaluated by comparison the composition of CPC‐Fe₃O₄‐MMT before and after polymerization via TG analysis and element analysis. Besides, the structural anisotropy of the produced CPC‐Fe₃O₄‐MMT/PI composite films deriving from orientation of plate‐like CPC‐Fe₃O₄‐MMT was confirmed by 1‐D and 2‐D XRD and SEM. The CPC‐Fe₃O₄‐MMT/PI composite films with structural anisotropy exhibit gas permeation, optical and magnetic anisotropic properties which would widen the application fields of the composite films. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41224.     

Crystallinity,conductivity, and magnetic properties of PVDF‐Fe3O4 composite films

The formation of Fe₃O₄ nanoparticles by hydrothermal process has been studied. X‐ray Diffraction measurements were carried out to distinguish between the phases formed during the synthesis. Using the synthesized Fe₃O₄ nanoparticles, poly(vinyledene fluoride)‐Fe₃O₄ composite films were prepared by spin coating method. Scanning electron microscopy of the composite films showed the presence of Fe₃O₄ nanoparticles in the form of aggregates on the surface and inside of the porous polymer matrix. Differential Scanning calorimetry revealed that the crystallinity of PVDF decreased with the addition of Fe₃O₄. The conductitivity of the composite films was strongly influenced by the Fe₃O₄ content; conductivity increased with increase in Fe₃O₄ content. Vibration sample magnetometry results revealed the ferromagnetic behavior of the synthesized iron oxide nanoparticles with a Ms value of 74.50 emu/g. Also the presence of Fe₃O₄ nanoparticles rendered the composite films magnetic. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Crystallization behavior of polylactide matrix under the influence of nano‐magnetite

Iron oxide nanoparticle (Fe₃O₄) has gained remarkable research interest for various applications, from environmental to biological, because of its superparamagnetic properties and good biocompatibility. In this work, the nucleation effect of Fe₃O₄ in a polylactide (PLA) matrix under an influence of an alternating magnetic field was studied. The nanocomposite films that is, containing different concentrations of Fe₃O₄ (~8 nm) which were uniformly dispersed in the PLA matrix, were prepared via a solution casting method. The amplitude and frequency of the magnetic field impose great effects on the morphology and nucleation rate of PLA crystallization. Thermogravimetric analysis was used to study the thermal stability of Fe₃O₄/PLA and it showed that the thermal stability of Fe₃O₄/PLA was affected by the Fe₃O₄ content. Fourier transform infrared spectroscopy and X‐ray diffractometry indicated that Fe₃O₄ shows impeding effect to the crystallization of PLA. Based on the differential scanning calorimetry results, composite with 1% of Fe₃O₄ content could promote the crystallization of PLA but it would become an obstacle when 3% of Fe₃O₄ was added. The result of polarized optical microscopy also showed a good agreement that the incorporation of Fe₃O₄ could act as an effective nucleation regent to the composite film. POLYM. ENG. SCI., 59:608–615, 2019. © 2018 Society of Plastics Engineers     

Examining the use of Fe<Subscript>3</Subscript>O<Subscript>4</Subscript> nanoparticles to enhance the NH<Subscript>3</Subscript> sensitivity of polypyrrole films

Summary Polypyrrole (PPy) composite films with different contents of Fe₃O₄ were prepared by in-situ polymerization of pyrrole in aqueous solutions. The dependence of dc current changes on the response of the samples exposure to NH₃ vapor has been investigated. The results shows the composite films are more stable than the pristine ones after being exposed to NH₃ vapor. Meanwhile, the response time was reduced with increasing the Fe₃O₄ content in the films. The results might be originated from the structural changes in the PPy films caused by the addition of Fe₃O₄.     

Magnetically aligning multilayer graphene to enhance thermal conductivity of silicone rubber composites

The increasing demand for packaging materials calls for new technologies to achieve excellent thermal conductivity of polymer composites with low content of thermal conductive filler. This article prepared a kind of magnetically functionalized multilayer graphene (Fe₃O₄@MG) via electrostatic interactions, which efficiently enhanced the thermal conductivity of silicone rubber (SR) composites by the alignment of Fe₃O₄@MG in an external magnetic field. The morphology and structure of the Fe₃O₄@MG together with the thermal conductivity of corresponding Fe₃O₄@MG/SR composites were systematically investigated by SEM, TEM, XRD, elemental mapping, and thermal conductivity tester. The obtained results showed that Fe₃O₄@MG was induced to form chain-like bundles in silicone rubber matrix under the applied magnetic field, which enhanced the MG–MG interaction, and formed effective thermal pathways in the alignment direction. Furthermore, as coating mass ratio of Fe₃O₄@MG increased, the thermal conductivity of randomly oriented Fe₃O₄@MG/silicone rubber composites (R-Fe₃O₄@MG/SR) decreased gradually, whereas the through-plane thermal conductivity of vertically aligned Fe₃O₄@MG/silicone rubber composites (V-Fe₃O₄@MG/SR) increased even filled with same contents of thermal conductive filler. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47951.     

Effect of surface modification of Fe<Subscript>3</Subscript>O<Subscript>4</Subscript> nanoparticles on the preparation of Fe<Subscript>3</Subscript>O<Subscript>4</Subscript>/polystyrene composite particles via miniemulsion polymerization

Fe₃O₄ nanoparticles were modified by n-octadecyltrimethoxysilane (C18TMS) and 3-trimethoxysilylpropylmethacrylate (MPS). The modified Fe₃O₄ nanoparticles were used to prepare Fe₃O₄/polystyrene composite particles by miniemulsion polymerization. The effect of surface modification of Fe₃O₄ on the preparation of Fe₃O₄/polystyrene composite particles was investigated by transmission electron microscopy, Fourier transform infrared spectrophotometer (FT-IR), contact angle, and vibrating sample magnetometer (VSM). It was found that C18TMS modified Fe₃O₄ nanoparticles with high hydrophobic property lead to the negative effect on the preparation of the Fe₃O₄/polystyrene composite particles. The obtained composite particles exhibited asymmetric phase-separated structure and wide size distribution. Furthermore, un-encapsulated Fe₃O₄ were found in composite particles solution. MPS modified Fe₃O₄ nanoparticles showed poor hydrophobic properties and resulted in the obtained Fe₃O₄/polystyrene composite particles with regular morphology and narrow size distribution because the ended C=C of MPS on the surface of Fe₃O₄ nanoparticles could copolymerize with styrene which weakened the phase separation distinctly.     

Dielectric properties of graphene–iron oxide/polyimide films with oriented graphene

The preparation of high‐dielectric‐constant (k) materials is important in the field of electronics. However, how to effectively use the function of fillers to enhance k is still a challenge. In this study, anisotropic graphene (GNS)–iron oxide (Fe₃O₄)/polyimide (PI) nanocomposite films with oriented GNSs were prepared by the in situ polymerization of 4,4′‐oxydianiline and pyromellitic anhydride in the presence of GNS–Fe₃O₄. Films of the precursors were fabricated, and this was followed by stepwise imidization under a magnetic field at a higher temperature to orient the magnetic sheets. The orientation of GNS–Fe₃O₄ and the relationships of the GNS–Fe₃O₄ content and measurement frequency with the dielectric properties of the GNS–Fe₃O₄/PI films were studied in detail. The dielectric property differences of the GNS–Fe₃O₄/PIs with GNS–Fe₃O₄ parallel or perpendicular to the film surface were not obvious, when the content of GNS–Fe₃O₄ was lower than 5 wt %. However, at the percolation threshold, the k values of GNS–Fe₃O₄/PI films with horizontal GNS–Fe₃O₄ were much higher than those of the other two kinds of films at 10³ Hz; this was derived from the contribution of more effective microcapcitors parallel to the film surface. So, making the GNS–Fe₃O₄ parallel to the film surface greatly enhanced k of GNS–Fe₃O₄. However, switching the charges on the large lateral surface of the parallel GNSs with the electric field also caused a higher dielectric loss and the frequency dependence of k and the dielectric loss at low frequency. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43041.     

Electromagnetic properties of electrospun Fe3O4/carbon composite nanofibers

In order to develop multifunctional nanofibers, the electrical conductivity and magnetic properties of Fe₃O₄/carbon composite nanofibers have been examined. Polyacrylonitrile (PAN) is used as a matrix to produce magnetic composite nanofibers containing different amounts of magnetite (Fe₃O₄) nanoparticles. Electrospun composite nanofibers were thermally treated to produce electrically conductive and magnetically permeable composite carbon nanofibers. The composite nanofibers were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffractometry (XRD), Raman spectroscopy, four-point probe and Superconducting Quantum Interference Device (SQUID). Uniform nanofibers were obtained with successful transferring of magnetic properties of Fe₃O₄ into the as-spun composite nanofibers. The electromagnetic properties were tuned by adjusting the amount of Fe₃O₄ in the matrix and carbonization process. The electrical conductivity, magnetic moment and also magnetic hysteresis rise up by adding Fe₃O₄ and increasing carbonization temperature. The high surface area provided by the ultrafine fibrous structures, the flexibility and tuneable electromagnetic properties are expected to enable the expansion of the design options for a wide rage of electronic devices.     

Effect of copper sulfate pentahydrate on the structure and properties of poly(vinyl alcohol)/graphene oxide composite films

Poly(vinyl alcohol) (PVA)/graphene oxide (GO)/copper sulfate pentahydrate (CuSO₄·5H₂O) composite films were prepared by the solution casting method, and the effect of CuSO₄·5H₂O on the structure and properties of the PVA/GO composites was investigated. Fourier transform infrared (FTIR) analysis proved the crosslinking interaction between CuSO₄·5H₂O and the ? OH group of PVA. The crystallinity of the composite films increased first and then decreased. For the composite films, the tensile strength, Young's modulus, and yield stress values improved with increasing CuSO₄·5H₂O, whereas the elongation at break decreased compared with that of the neat PVA/GO composite film. The thermogravimetric analysis (TGA) and derivative thermogravimetry (DTG) patterns of the PVA/GO/CuSO₄·5H₂O composite films showed that the thermal stability decreased; this was consistent with the TGA–FTIR analysis. A remarkable improvement in the oxygen‐barrier properties was achieved. The oxygen permeability coefficient was reduced by 60% compared to that of the neat PVA/GO composite film. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44135.     

Fabrication and characterization of polymer composites surface coated Fe3O4/MWCNTs hybrid buckypaper as a novel microwave‐absorbing structure

A naval hybrid buckypaper was fabricated by vacuum filtration method with monodispersion solution of Fe₃O₄ decorated Multiwalled carbon nanotubes (MWCNTs). The morphology, element composition and phase structure of hybrid buckypaper were characterized by field‐emission scanning electron microscope, energy dispersive spectrometer, and X‐ray diffraction. The microwave absorption and complex electromagnetic properties of the composites surface coated MWCNTs buckypaper (or Fe₃O₄/MWCNTs hybrid buckypaper) have been investigated in the frequency range of 8–18 GHz. The results indicate that the microwave absorption properties of composite structure have been evidently improved due to the Fe₃O₄/MWCNTs hybrid buckypaper' high magnetic loss and suitable dielectric loss properties. The reflection loss of composite surface coated Fe₃O₄/MWCNTs hybrid buckypaper (with a matching thickness d = 0.1 mm) is below ?10 dB in the frequency range of 13–18 GHz, and the minimum value is ?15.3 dB at 15.7 GHz. Thus, Fe₃O₄/MWCNTs hybrid buckypaper can become a promising candidate for electromagnetic‐wave‐absorption materials with strong‐absorption, thin‐thickness and light‐weight characteristics. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41974.     

Synthesis and characterization of (Fe3O4/MWCNTs)/ epoxy nanocomposites

A sonochemical technique is used for in situ coating of iron oxide (Fe₃O₄) nanoparticles on outer surface of MWCNTs. These Fe₃O₄/MWCNTs were characterized using a high‐resolution transmission electron microscope (HRTEM), X‐ray diffraction, and thermogravimetric analysis. The as‐prepared Fe₃O₄/MWCNTs composite nanoparticles were further used as reinforcing fillers in epoxy‐based resin (Epon‐828). The nanocomposites of epoxy were prepared by infusion of (0.5 and 1.0 wt %) pristine MWCNTs and Fe₃O₄/MWCNTs composite nanoparticles. For comparison purposes, the neat epoxy resin was also prepared in the same procedure as the nanocomposites, only without nanoparticles. The thermal, mechanical, and morphological tests were carried out for neat and nanocomposites. The compression test results show that the highest improvements in compressive modulus (38%) and strength (8%) were observed for 0.5 wt % loading of Fe₃O₄/MWCNTs. HRTEM results show the uniform dispersion of Fe₃O₄/MWCNTs nanoparticles in epoxy when compared with the dispersion of MWCNTs. These Fe₃O₄/MWCNTs nanoparticles‐infused epoxy nanocomposite shows an increase in glass transition (T_g) temperature. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Carboxyl‐containing polyarylene ether nitrile/Fe3O4 hybrids and their effects on the PEN composites

In this study, the novel polyarylene ether nitrile containing carboxyl groups (CPEN)/Fe₃O₄ hybrids were synthesized via the solvent‐thermal route. The SEM and TEM images showed that the surface of functionalized Fe₃O₄ hybrids (CPEN‐f‐Fe₃O₄) became rough and coated with a thin polymer layer successfully. Chemical bonds were formed between the carboxyl groups and Fe₃O₄ spheres, which were characterized by FTIR and XRD. Series of PEN composite films were prepared through solution‐casting method with different contents of CPEN‐f‐Fe₃O₄ hybrids and raw Fe₃O₄ spheres. The SEM images showed that the CPEN‐f‐Fe₃O₄ hybrids became much more dispersible and compatible in PEN matrix than that of raw Fe₃O₄ spheres, which was further confirmed by rheological study. The magnetic analysis showed that the saturation magnetization of composites films increased with the increase of CPEN‐f‐Fe₃O₄ hybrids loading content. The results of thermogravimetric and mechanical study exhibited that the composite films had good thermal stability and mechanical property. POLYM. COMPOS., 36:1325–1334, 2015. © 2014 Society of Plastics Engineers     

A sonochemical method for synthesis of Fe3O4 nanoparticles and thermal stable PVA-based magnetic nanocomposite

Fe₃O₄ nanoparticles were synthesized via a simple surfactant-free sonochemical reaction. Room temperature synthesis without using inert atmosphere is the novelty of this work. The effect of different parameters on the morphology of the products was investigated. The magnetic properties of the samples were also investigated using an alternating gradient force magnetometer. Fe₃O₄ nanoparticles exhibit a ferromagnetic behavior with a saturation magnetization of 66 emu/g and a coercivity of 39 Oe at room temperature. For preparation magnetic nanocomposite, Fe₃O₄ nanoparticles were added to the polyvinyl alcohol (PVA). Nanoparticles can enhance the thermal stability and flame retardant property of the PVA matrix.     

Luminescent and magnetic properties of cerium-doped yttrium aluminum garnet and yttrium iron garnet composites

Functional materials exhibiting magnetic and luminescent properties have been recognized as an emerging class of materials with great potential in advanced applications. Herein, properties of multifunctional ceramic composites consisting of two garnets, luminescent cerium-doped Y₃Al₅O₁₂ (Ce:YAG) and magnetic Y₃Fe₅O₁₂ (YIG), are reported. On increasing the sintering temperature, both the photoluminescence and saturation magnetization of the Ce:YAG-YIG composites decreased gradually because of the interdiffusion of trivalent ions such as Al³⁺ and Fe³⁺. At a constant sintering temperature of 1100?°C, the YIG contents in the composites increased, thereby causing their luminescent properties to degrade and the saturation magnetizations to increase. For application to electronics, Ce:YAG-YIG composite thin films were integrated on quartz substrates by sputtering the ceramic target. The composite thin films exhibited both magnetic and luminescent properties after annealing. These techniques facilitate the incorporation of multifunctional nanocomposites into various devices.     

Lead-free BLTO/NMFO magnetoelectric composite films prepared by the sol-gel method

The lead-free ferroelectric films of Bi_4?xLa_xTi₃O₁₂(BLTO) and ferromagnetic films of Ni_1?xMn_xFe₂O₄(NMFO) were prepared on Pt/Ti/SiO₂/Si substrate by means of the sol-gel and spin-coating method. The lead-free magnetoelectric composite films with the structure of Bi_3.4La_0.6Ti₃O₁₂/Ni_0.7Mn_0.3Fe₂O₄/substrate (BN) and Ni_0.7Mn_0.3Fe₂O₄/Bi_3.4La_0.6Ti₃O₁₂/ substrate (NB) were also deposited on Pt/Ti/SiO₂/Si substrate. The X-ray diffraction results show that two composite films possess BLTO and NMFO phases without any intermediate phase. The SEM images show that two composite films exhibit layered structure, clear interface and no transition layer between BLTO and NMFO films. Two composite films exhibit both good ferromagnetic and ferroelectric properties, as well as magnetoelectric coupling effect. The deposition sequence of ferroelectric and ferromagnetic films in the composite films has significant influence on the ferroelectric, ferromagnetic and magnetoelectric coupling properties of the composite films. The values of magnetoelectric voltage coefficient of the BN composite films are higher than those of the NB composite films at any fixed H_bias.     

Preparation and characterization of carbon films prepared from poly(vinyl alcohol) containing metal oxide and nano fibers with iodine pretreatment

This research focused on the combination of catalyst effect of metal oxide, thermal conductive effect of carbon nano fibers and iodine pretreatment during carbonization of polymer precursor in order to prepare tough carbon films. Poly(vinyl alcohol) (PVA) composites containing metal oxide (Fe₃O₄) and vapor-grown carbon fibers (VGCFs) were prepared by gelation/crystallization method with the freezing/thawing technique. The dry gel films as precursor were pretreated in the atmosphere of vapor iodine, and then heat-treated at 600-1200 °C. The combined effect of iodine, Fe₃O₄ and VGCF on the carbonization of PVA was analyzed with thermo-gravimetric analysis, X-ray diffraction, and scanning electron microscope in details. Iodine pretreatment for 24 h significantly promoted the dehydration of PVA, and resulted the carbon film with a high crystallinity. Fe₃O₄ as catalyst facilitated the carbonization of PVA at a low temperature of 800-900 °C. The addition of VGCFs was found to play an important role to prepare tough films by mild carbonization due to its high thermal conductivity. The degree of graphitization in the carbon film depended on the filler contents, pretreatment conditions and carbonization conditions. The graphitization degrees for G- and T-components in the film were investigated on the basis of X-ray diffraction intensity distribution from the (0 0 2) plane.     

Removal of Pb(ii) ions from aqueous solution using a novel composite adsorbent of Fe3o4/PVA/spent coffee grounds

ABSTRACT

A novel magnetic composite prepared from Fe₃O₄, poly(vinyl alcohol) and alkaline pretreated spent coffee grounds (Fe₃O₄/PVA/APSCGs) was utilized for the first time as an adsorbent for adsorption of Pb(II) ions after carefully characterizing it by various techniques (XRD, FTIR, SEM, EDX). The obtained results indicated that the adsorption was spontaneous, endothermic, fitting well with both Langmuir and Freundlich models, and more suitable to be described by the second-order kinetic model. The maximum adsorption capacity of Fe₃O₄/PVA/APSCGs for Pb(II) at optimum conditions (pH of 5, contact time of 24 h, APSCGs:Fe₃O₄ weight ratio of 4:1) was found to be 0.275 mmol.g^?1. Recycling study showed a good reusability of the composite with removal efficiency maintained at 78.12% after five continuous adsorption-desorption cycles.     

Quantitative analysis of diffraction and infra-red spectra of composite cement/BaSO4/Fe3O4 for determining correlation between attenuation coefficient,structural and optical properties

To better understand the structural and optical properties of composite cement/BaSO₄/Fe₃O₄ for various amount of BaSO₄/Fe₃O₄, the X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy have been used to investigate the correlation between their structural and optical properties. The structural properties including crystallite size, micro strain, stress and energy deformation were analyzed from the quantitative analysis of XRD spectra by using size-strain plot (SSP) methods. The refractive index (n), extinction coefficient (k), dielectric functions (ε), and energy loss function (Im (−1/ε)) were analyzed from the quantitative analysis of FTIR spectra by using kramers-kronig (K–K) relations. The corresponding structures for high amount of BaSO₄/Fe₃O₄ in composite cement/BaSO₄/Fe₃O₄ become less stable which consistent with the distance between the wavenumber of transversal and longitudinal optical phonon vibration mode become shorter. For all composites cement/BaSO₄/Fe₃O₄ in this study, we found that the distance wavenumber (Δ) between longitudinal optical (LO) and transversal optical (TO) phonon vibration decrease with increasing the crystallite size and linear attenuation coefficient. Our results indicated that the FTIR spectra could be useful for determining the optical phonon vibration, dielectric function, and energy loss function of composite cement/BaSO₄/Fe₃O₄.     

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.     

Single step modification of micrometer-sized polystyrene particles by electromagnetic polyaniline and sorption of chromium(VI) metal ions from water

This article describes a single-step reproducible approach for the surface modification of micrometer-sized polystyrene (PS) core particles to prepare electromagnetic PS/polyaniline–Fe₃O₄ (PS/PANi–Fe₃O₄) composite particles. The electromagnetic PANi–Fe₃O₄ shell was formed by simultaneous seeded chemical oxidative polymerization of aniline and precipitation of Fe₃O₄ nanoparticles. The weight ratio of PS to aniline was optimized to produce core–shell structure. PS/PANi–Fe₃O₄ composite particles were used as adsorbent for the removal of Cr(VI) via anion-exchange mechanism. The composite particles possessed enough magnetic property for magnetic separation. The adsorption was highly pH dependent. Adsorption efficiency reached 100% at pH 2 in 120 min when 0.05 g of composite particles was mixed with 30 mL 5 mg L⁻¹ Cr(VI) solution. The adsorption isotherm fitted best with Freundlich model and maximum adsorption capacity approached 20.289 mg g⁻¹ at 323 K. The prepared composite was found to be an useful adsorbent for the removal of soluble Cr(VI) ions. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47524.