Magnetic Polymer Nanocomposites Research Articles

Synthesis and Structural Characterization of Polymer-Based Cobalt Ferrite Nanocomposite with Core–Shell Structure

Polymer hybrids have become a major area of research and development owing to the remarkable properties and multifunctional behaviour deriving from their nanocomposite/nanohybrid structure. In this class, magnetic polymer nanocomposite are of special interest because of the combination of excellent magnetic properties, high specific area, surface active sites, high chemical stability and good biocompatibility. The present communication primarily concentrates on the investigation of structural characterization of alginate–cobalt ferrite nanocomposite (CoFe2O4–ANa NC) prepared by ex situ polymerization method. The structural and morphological properties of CoFe2O4–ANa NC were analysed using X-ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and dynamic light scattering. The specific surface area of the nanocomposite was analysed using BET surface area analysis. The functional group and the thermal stability were examined using FTIR and TGA/DTA respectively. The characterization results have pointed out the successful role of sodium alginate in stabilizing cobalt ferrite nanoparticles (CoFe2O4 NP). The SEM and TEM images revealed the well interspersed state of cobalt ferrite with sodium alginate. It is obvious to note the increased size and the specific surface area for CoFe2O4 nanocomposite.

Role of synthesis process variables on magnetic functionality, thermal stability, and tetracycline adsorption by magnetic starch nanocomposite

Poor understanding and possible control of influence of synthesis variables on intrinsic properties/characteristics, has negatively impacted full utilization of magnetic polymer nanocomposite in potential applications. This study was therefore designed to investigate the synthesis variables that control the magnetic functionality, thermal stability, yield and tetracycline adsorption by magnetic starch nanocomposite. Subsequent upon this, the study is set to further develop a goal oriented multiple response optimization (GOMRO) approach for simultaneous control of these intrinsic properties and their potential applications. Magnetic starch nanocomposite was synthesized by in-situ co-precipitation of Fe2+ and Fe3+ in the presence of soluble starch, and characterized with FTIR, TEM, XRF, and TGA/DTA. The characterization tests confirmed that magnetic starch nanocomposite was successfully synthesized. Model evaluation parameters showed that quadratic model adequately (r2 > 0.98) described the experimental data for all the studied properties and tetracycline adsorption. Variance analysis of influence of quantity of starch gave F-values of 695.95, 22.43, and 134.89 for magnetic functionality, thermal stability, and tetracycline adsorption, respectively, while Prob > F gave value of <0.0001, in each case. These data indicated that quantity of starch and ammonia volume were the dominant factors controlling the studied properties and tetracycline adsorption. For the first time, response surface methodology (RSM) was successfully applied in elucidating the adsorption interaction mechanism, as both experimental and RSM trend confirmed that π-cation interaction was the dominant interaction mechanism for tetracycline adsorption by magnetic starch nanocomposite. Besides controlling the process cost from the yield, the GOMRO approach opened additional degree of freedom on cost control by creating opportunity for manipulating the quantities of reactants for achieving a set goal.

Magnetic dendritic polymer nanocomposites as supports for palladium: a highly efficient and reusable catalyst for Mizoroki–Heck and Suzuki–Miyaura coupling reactions

A novel catalyst Fe3O4@SiO2-Dendrimer-Pd based on palladium immobilized on magnetic dendritic polymer nanocomposites was successfully synthesized and characterized by FT-IR, EA, XRD, TEM, EDX, VSM and XPS.

New Magnetic Polymer Nanocomposites on the Basis of Isotactic Polypropylene and Magnetite Nanoparticles for Adsorption of Ultrahigh Frequency Electromagnetic Waves

ABSTRACTIn this study, we report about the preparation of magnetic polymer nanocomposites on the basis of isotactic polypropylene and magnetite Fe3O4 nanoparticles. The structure and composition of polymer nanocomposite materials have been studied by scanning electron microscopy, atomic force microscopy, and X-ray dispersive analysis. The magnetic properties of polymer nanocomposites based on PP+Fe3O4have been investigated. It is found that not significant adhesion and agglomeration of nanoparticles occur, by increasing the nanoparticle content in polymer matrix up to 40%, and therefore they act as single-domain nanoparticles. The samples of nanocomposites based on PP+Fe3O4, with up to 40% content of Fe3O4, exhibit superparamagnetic properties. It was also found out that the magnetic polymer nanocomposite material based on PP+Fe3O4 is able to absorb ultrahigh frequency electromagnetic waves in the frequencies range from 0.1 to 30 GHz. The increase in Fe3O4 concentration from 5 to 40% at the 400 µm thicknesses of the films leads to an increase in absorption of electromagnetic waves of high frequency from 15 to 22.7%.

Superparamagnetic Fe3O4@ wood flour/polypropylene nanocomposites: Physical and mechanical properties

Given the high potential applications of magnetic green polymer nanocomposites in the construction, automotive and military industries, fabrication and characterization of superparamagnetic Fe3O4@ wood flour/polypropylene nanocomposites were investigated for the first time in this study. Magnetite (Fe3O4) nanoparticles were in situ synthesized on poplar wood flours. The filler loading used was 40wt.% and the virgin wood flours (VWFs) and magnetic wood flours (MWFs) were used as filler at three levels of mixing ratios (VWFs: MWFs=100:0, 50:50, and 0:100wt.%). Maleic anhydride-grafted PP (MAPP) was used as the MAPP at two levels of 1 and 3wt.%. Characterization of the MWFs confirmed the successful “in situ synthesis” of spherical superparamagnetic Fe3O4 nanoparticles on the wood flours with an average crystal size of about 8nm at approximately 30wt.%. The physical properties examinations indicated that the increase of MWFs up to 100wt.% of filler phase increased the long-term water absorption and thickness swelling of specimens up to 2.6 and 2.4-fold, respectively. The ultimate tensile and flexural strengths increased when MWFs increased by up to 50wt.% and then decreased at higher weight ratios of MWFs. Increasing the MAPP from 1 to 3wt.% improved both physical and mechanical properties, but this effect was more perceptible in improving mechanical strengths compared to the elastic modulus. The magnetization characterization showed about 10% reduction in saturation magnetization (Ms) of the final MWFs/polypropylene nanocomposites in comparison with the Ms values of the starting MWFs (≈1emu/g). This observation was attributed to the formation of a nonmagnetic layer on the Fe3O4 nanoparticles during the melt-blending process.

Preparation and Characterization of Polyvinylpyrrolidone/ Magnetite Decorated Carboxylic Acid Functionalized Multi-walled Carbon Nanotube (PVP/MWCNT-Fe3O4) Nanocomposite

Magnetite decorated carboxylic acid functionalized multi-walled carbon nanotube (MWCNT-Fe3O4) was successfully inserted in polyvinylpyrrolidone (PVP) matrix in the aqueous media, as a result of which magnetic polymer nanocomposite (PVP/MWCNT-Fe3O4) was formed. With application of SEM, the surface morphology of the produced PVP/MWCNT-Fe3O4 nanocomposite was compared with that of pure PVP. The diameter distribution of Fe3O4 decorated carboxylic acid functionalized multi-walled carbon nanotube was determined by image analysis of the SEM micrographs. In addition, the structural and thermal characterizations of PVP/MWCNT-Fe3O4 nanocomposite were performed by FT-IR, XRD, TGA, and DSC techniques. Moreover, magnetic characterization of the prepared nanocomposite was determined by VSM. The obtained results indicated that addition of MWCNT-Fe3O4 (5% w/w) to PVP improved the thermal properties of pure polyvinylpyrrolidone. According to the results of DSC analysis, the glass transition temperature of 160 °C was observed for the PVP/MWCNT-Fe3O4 (5% w/w) nanocomposite. The FT-IR spectra showed that an interaction was taking place between MWCNT-Fe3O4 and PVP. The strong interaction with ~31 cm−1 red shift along with good complexation of carbonyl functional group of PVP with MWCNT-Fe3O4 was observed for PVP/MWCNT-Fe3O4 (5% w/w) nanocomposite as a result of a better distribution of carbon nanotubes in the PVP matrix.

In-situ core-shell polymerization of magnetic polymer nanocomposite (PAAc/Fe3O4) particles via gamma radiation

Gamma radiation as a novel approach to synthesize core-shell magnetic polymer nanocomposite (PAAc/Fe3O4) particles was investigated. The Fe3O4 nanoparticles were primarily prepared by in situ precipitation–oxidation and radiation polymerization of polyacrylic acid PAAc. The polymerization process was carried out by dissolving two salts of Fe2+/3+ sulfates into a 20% solution of PAAc followed by exposing them to gamma radiation at a dose of 30 kGy. Subsequently, an appropriate amount of ammonium (NH4OH) solution was added to the PAAc/Fe2+/3+ polymer solution, yielding a black precipitate of PAAc/Fe3O4. Transmission electron microscopy revealed that the in situ polymerization of core-shell magnetic polymer nanocomposites resulted in sphere-like particles of PAAc/Fe3O4 with diameters of 30 nm. Hysteresis loops indicated that these particles are ferromagnetic in nature.

Studies on the effect of magnetite nanoparticles on magnetic, mechanical, thermal, temperature dependent electrical resistivity and DC conductivity modeling of poly (vinyl alcohol-co-acrylic acid)/Fe3O4 nanocomposites

Magnetic polymer nanocomposites containing different concentration of magnetite (Fe3O4) with poly (vinyl alcohol-co-acrylic acid) (PVA-co-PAA) were prepared by in situ chemical oxidative polymerization method. The effect of nanoparticles on the structural, magnetic and glass transition temperature of the composite was carried out by XRD, FE-SEM, VSM and DSC. Mechanical properties, temperature dependent AC conductivity and room temperature DC conductivity were evaluated. FE-SEM and XRD patterns revealed the uniform dispersion and structural regularity of nanoparticles in the copolymer. The magnetic property of copolymer nanocomposite shows ferromagnetic and super-paramagnetic behavior. Tensile strength, hardness and glass transition temperature of composites increased with the increase in content of nanoparticles whereas the elongation at break decreases. The AC conductivity increased rapidly with temperatures and it obeys power law. Values of activation energy for the AC conduction process of the composite and the Cole-Cole plot of impedance was also determined. DC conductivity of nanocomposite was higher than copolymer and the maximum conductivity was obtained for 15 wt% of composite. Variation in DC conductivity with the addition of nanoparticles in PVA-co-PAA was correlated with theoretical conductivity based on Bueche, Scarisbrick and McCullough model. A new model for conductivity has been proposed which showed better agreement with the experimentally observed conductivity over a wide range of concentration of nanoparticles.

Palladium Supported on Metformin‐Functionalized Magnetic Polymer Nanocomposites: A Highly Efficient and Reusable Catalyst for the Suzuki–Miyaura Coupling Reaction

AbstractIn this paper, a novel magnetically responsive nanocatalyst, Pd/Fe3O4@PMAA‐Met (PMAA=poly(methacrylic acid), Met=metformin), has been successfully prepared by immobilizing palladium on the surface of metformin‐functionalized magnetic polymer nanocomposites. This novel nanocatalyst was characterized by FTIR, XRD, TEM, X‐ray photoelectron spectroscopy (XPS), and vibrating sample magnetometry (VSM). The prepared nanocatalyst showed excellent catalytic activity for Suzuki–Miyaura coupling reactions of aryl halides (I, Br, Cl) with arylboronic acids even at palladium loadings of 0.01–0.0007 mol % and the turnover frequency (TOF) reached up to 125 714 h−1. The excellent activity of this Pd/Fe3O4@PMAA‐Met catalyst could be attributed to a “release and catch” catalytic mechanism as well as its nanometer size. This nanocatalyst could be simply separated with an external magnet and reused at least twelve times with excellent yields achieved.

Magnetic Responsive Polymer Nanocomposites with In–situ Tunable Anisotropy by Magnetic Self‐Organization

AbstractThe tunable magnetic response has rarely been achieved in conventional magnetic responsive polymer nanocomposites (MRPNCs). Here we show a new approach to offer effective rules for designing novel MRPNCs with in‐situ tunable magnetic anisotropy which are self‐organized in a low magnetic field via controlling the self‐organization temperature between the melting points of isotactic polypropylene (iPP) and poly(ϵ‐caprolactone) (PCL), and magnetic ferroferric oxide (Fe3O4) nanoparticles selectively dispersing in PCL with low melting temperature. The iPP/PCL/Fe3O4 nanoparticles with magnetic anisotropy not only exhibit tunable rotation behavior, but also show tunable mechanical enhancement. The deflection force, tensile strength and Young modulus of the iPP/PCL/Fe3O4 nanocomposites with 10 wt% Fe3O4 particles with magnetic anisotropy show nearly 3.2, 3.2 and 2.7 times higher than that of the samples with random dispersion of magnetic nanoparticles, respectively.

Reactive Extrusion Strategies to Fabricate Magnetite–Polyethylene Nanocomposites with Enhanced Mechanical and Magnetic Hyperthermia Properties

Biofouling is a major problem in water filtration units, which leads to premature system failure. Conventional treatment methods involving the use of chemicals or high‐pressure hydraulics exert mechanical strain on filter materials, leading to shortened service lifetimes. In this study, a novel magnetic polymer nanocomposite is fabricated using a blend of high density/ultrahigh molecular weight polyethylene with magnetite nanoparticle (MNP) fillers. The resulting magnetite–polyethylene nanocomposite (MPE‐NC) is mechanically robust and can be externally actuated with an alternating magnetic field to generate localized heating that is effective in eradicating bacterial biofilms. The MNPs are functionalized with silane‐based coupling agents and crosslinked onto the polyethylene backbone via a reactive extrusion approach, which results in a twofold enhancement in mechanical properties of the polymer matrix. Furthermore, the magnetic hyperthermia performance of the MPE‐NC is improved eightfold by replacing undoped magnetite nanospheres with zinc‐doped magnetite nanocube fillers, and the magnetic hyperthermia treatment approach is shown to be 12 times more effective in destroying bacterial biofilms compared to a direct heat‐treatment method. During hyperthermia treatment, the mechanical integrity of the MPE‐NC is preserved, thereby validating the potential of the MPE‐NC as a new filter material with high efficiency in biofilm removal and extended durability.image

Green synthesized Fe3O4 nanoparticles as a magnetic core to prepare poly 1, 4 phenylenediamine nanocomposite: employment for fast adsorption of lead ions and azo dye

Different approaches such as precipitation, combustion, and hydrothermal method are available to prepare Fe3O4 nanoparticles. Respect to other methods, precipitation, especially with one iron source and natural reducing agents is a more green, economic, fast, and simple route for Fe3O4 synthesis. Based on these viewpoints, we have prepared Fe3O4 magnetic nanoparticles via a sonochemistry precipitation method using only one iron source and sugar, which was employed as a reducing agent. The combination of these prepared magnetic nanoparticles with polyphenylenediamine via an emulsion polymerization resulted in a magnetic polymer nanocomposite. The prepared magnetic material was characterized by Fourier transform infrared (FT-IR), scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray powder diffraction (XRD), and vibration sample magnetometer techniques. The magnetic nanocomposite was then successfully employed as an adsorbent in the removal of Pb2+ ions and Direct red 81 (DR-81) from single and binary solution. The results demonstrated that the maximum adsorption was obtained within 5 min at pH 4.0 and also the adsorption processes of Pb2+ and DR-81 both were well fitted by pseudo-second-order kinetic model. The experimental data were analyzed by the Langmuir and Freundlich adsorption models. Freundlich model provided the best correlation of the experimental data for dye but lead adsorption well fitted with Langmuir model. Moreover, the maximum capacity of polymer nanocomposite was found to be 144.92 and 370.37 mg g−1 for DR-81 and Pb2+, respectively.

Anisotropic magnetic polymer nanocomposite with self-assembled chains of titania-coated magnetite nanoparticles

An anisotropic magnetic nanocomposite has been prepared by incorporating magnetite nanoparticles (average size: 19nm) in titania (TiO2) particles with a typical size of about 100nm, which are subsequently dispersed in a liquid epoxy monomer cured under an inhomogeneous magnetic field. The magnetic force triggers the formation of elongated, self-assembled chains made of aggregated titania particles containing the magnetic cores. The chains have an average length of 7×10-5m and are almost homogeneously distributed throughout the sample; their length and degree of directional order decrease with distance from the magnet producing the magnetic field. FC/ZFC curves and isothermal hysteresis loops of the anisotropic nanocomposite have been studied under a magnetic field applied either parallel or perpendicular to the chains. The anisotropy of the magnetic response is explained by modeling the chains as individual magnetic entities at the mesoscopic level owing to the magnetic dipolar interaction among the embedded magnetite nanoparticles.

Magnetic polymer nanocomposite-supported Pd: an efficient and reusable catalyst for the Heck and Suzuki reactions in water

Pd supported on magnetic polymer nanocomposites serves as an efficient and recyclable catalyst for the water-phase Heck and Suzuki reactions.

Electromagnetic Field Absorbing Polypropylene Nanocomposites with Tuned Permittivity and Permeability by Nanoiron and Carbon Nanotubes

Highly efficient electromagnetic field absorption at gigahertz (GHz) was reported in the novel magnetic polymer nanocomposites (MPNCs) with in-situ synthesized Fe@Fe2O3 core@shell nanoparticles (NPs) or their decorated multiwall carbon nanotubes (MWNTs) dispersed in the polypropylene (PP) matrix through a one-pot bottom-up method. PP grafted maleic anhydride (PP-g-MA) with different molecular weights served as surfactant to stabilize the in-situ-formed NPs and simultaneously as compatibilizer to enhance the bonding at the PP–filler interfaces. Because of the strong magnetization of the PP MPNCs filled with 20.0 wt % Fe@Fe2O3 NPs stabilized by PP-g-MA (Mn = 800), a minimum reflection loss (RL) of −31.5 dB was observed at 18.0 GHz, and the frequency bandwidth with RL lower than −10.0 dB was 3.1 GHz (from 16.9 to 20.0 GHz) in the MPNC sample with a thickness of 5.5 mm. However, due to the lack of magnetic loss, only a weak RL of 4.3 dB was found at frequency of 16.8 GHz for the PP/PP-g-MA (Mn = 800)/1.0 wt % MWNTs nanocomposites sample with a thickness of 5.5 mm. When the PP MPNCs filled with Fe@Fe2O3 NPs decorated MWNTs (sample thickness of 5.0 mm) in the presence of low molecular weight PP-g-MA (Mn = 800), the RL of −24.5 dB at 20.0 GHz was observed. Through simply changing Mn of PP-g-MA from 800 to 8000, more oxidized iron resulted in a decreased permeability and smaller RL in the high frequency range. The in-situ-formed nanofillers significantly reduced the flammability of PP for potential wide applications.

Magnetic polymer nanocomposites for environmental and biomedical applications

Hybrid nanomaterials have received voluminous interest due to the combination of unique properties of organic and inorganic component in one material. In this class, magnetic polymer nanocomposites are of particular interest because of the combination of excellent magnetic properties, stability, and good biocompatibility. Organic–inorganic magnetic nanocomposites can be prepared by in situ, ex situ, microwave reflux, co-precipitation, melt blending, and ceramic–glass processing and plasma polymerization techniques. These nanocomposites have been exploited for in vivo imaging, as superparamagnetic or negative contrast agents, drug carriers, heavy metal adsorbents, and magnetically recoverable photocatalysts for degradation of organic pollutants. This review article is mainly focused on fabrication of magnetic polymer nanocomposites and their applications. Different types of magnetic nanoparticles, methods of their synthesis, properties, and applications have also been reviewed briefly. The review also provides detailed insight into various types of magnetic nanocomposites and their synthesis. Diverse applications of magnetic nanocomposites including environmental and biomedical uses have been discussed.

Magnetic Polymer Nanocomposite for Medical Application

Magnetic Polymer Nanocomposite for Medical Application

Nanomaterials: Electrical, Magnetic, and Photonic Applications

The nanomaterials section of the April issue of JOM has a unique combination of short review papers and research papers. These papers present the recent progress on controlled synthesis of magnetic nanoparticles (MNPs), the discussion of a fundamental physics concept of quantum capacitance and its applications in nanoelectronics, and the exploration of novel Ti:Fe2O3-SnO2 nanostructured photoanodes for efficient photoelectrochemical (PEC) water splitting. MNPs have been extensively studied in the last few decades due to their potential applications in data storage, biomedical uses, and other possibilities. It is well known that the physicochemical properties of MNPs are size, shape, and crystallinity dependent. Therefore, for future mass applications, one key challenge is to explore reliable, scalable, and economical synthesis methods to produce MNPs with well-defined microstructures that allow for high permittivity and/or ferromagnetism at room temperature. The article ‘‘Unusual Function of Modified Polyolefins for Manipulating Magnetic Nanostructures’’ contributed by Qingliang He, Tingting Yuan, Suying Wei, and Zhanhu Guo reviews the usage of polypropylene-graftmaleic anhydride (PP-g-MA) as a polymeric surfactant for controlled synthesis of MNPs. PP-g-MA is widely used in industry as a well-known plastic additive to stabilize the inorganic materials in a polymer matrix because the PP-group and MA-group play complementary roles. Compared with other commonly used small-molecular-weight surfactants, PP-g-MA has certain advantages such as its unexpected controlling ability of the crystallinity of as-synthesized MNPs, and its compatibility with many polymers for future in situ preparation of magnetic polymer nanocomposites with desirable physicochemical properties.

Facile removal of oils from water surfaces through highly hydrophobic and magnetic polymer nanocomposites

In this study, magnetic polymer nanocomposites were investigated as highly selective absorbent materials for removing oils from water surfaces. The nanocomposites with highly hydrophobic and superoleophilic surface were synthesized through a low-cost emulsion polymerization, and exhibited some practical properties including unsinkability, thermal stability and corrosive-resistance for real applications. These as-prepared nanoparticles could effectively absorb three kinds of oils up to above 3.63 times of the particles’ weight while completely repelling water. It is very easy to collect the oil-absorbed nanoparticles by applying an external magnetic field. Besides, the oil could be readily removed from the surfaces of nanoparticles by a simple ultrasonic treatment, and the nanocomposites still kept highly hydrophobic and oleophilic characteristics after repeatedly removing oils from water surface for many cycles. The findings of this study might provide a convenient method for fast and selective removal of oils from the surface of water.

Electrospun Cellulose Acetate-Garnet Nanocomposite Magnetic Fibers for Bioseparations

Cellulose acetate fibers with magnetic properties have recently attracted much attention because of their potential novel applications in biomedicine such as for cell and protein separations, magnetic resonance imaging contrast agents, and magnetic filters. In this work, as synthesized yttrium iron garnet and gadolinium substituted yttrium iron garnet nanoparticles have been used to generate magnetic filter paper. Garnet nanoparticles dispersed in cellulose acetate polymer solutions were electrospun as free-standing nonwoven fiber mats as well as on cellulose filter paper substrates resulting in magnetic filter papers. The magnetic fibers were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), powder X-ray diffraction (PXRD), and superconducting quantum interference device (SQUID) magnetic property measurements. The resulting magnetic polymer nanocomposites can be easily picked up by an external magnet from a liquid medium. Fluorescein isothiocyanate (FITC) labeled bovine serum albumin (BSA) was separated from solution by using the magnetic filter paper.