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1.
《Polymer Composites》2017,38(5):974-980
Polyvinyl alcohol (PVA) films containing magnetite Fe3O4 nanoparticles have been prepared by co‐precipitation method for use in gamma ray shielding and protection. Characterizations of the magnetite/PVA nanocomposite films were investigated by X‐ray diffraction (XRD), transmission electron microscopy (TEM), UV–vis spectroscopy, and magnetization measurements. TEM images showed that the synthesized magnetite particles had about 6–11 nm dimensions. Optical study's results revealed that the optical energy band gaps of thin films range between 1.82 and 2.81 eV at room temperature using UV–visible absorption spectroscopy. The saturation magnetization (MS) value measured by vibrating sample magnetometer VSM was found to be 8.1 emu/g with superparamagnetic nature. The radiation shielding properties such as linear attenuation coefficients (μ ) and half‐value thickness (HVT) for the magnetite nanocomposite films have been obtained experimentally for different photon energies. The results imply that these nanocomposites films are promising radiation shielding materials. POLYM. COMPOS., 38:974–980, 2017. © 2015 Society of Plastics Engineers 相似文献
2.
We have prepared carbon‐supported nanoparticles with the heterogeneous structure of a PdPt shell on a PdCo core which are effective for the oxygen reduction reaction (ORR) in the presence of methanol. The preparation was based on the galvanic replacement reaction between PdCo/C nanoparticles and PtCl42–, a method of general utility which can be extended to the preparation of other core‐shell electrocatalysts. The heterogeneous PdCo‐core and PtPd‐shell architecture was confirmed by multiple techniques including high resolution transmission electron microscopy, energy dispersive X‐ray spectroscopy, powder X‐ray diffraction and X‐ray photoelectron spectroscopy. The activity of the PdCo@PdPt/C catalyst in ORR was evaluated in acidic solutions both with and without methanol (0.1 M). The results showed four to sixfold increases in activity over a standard Pt/C catalyst with no apparent loss of catalyst stability. It is inferred that the strain effect from the lattice mismatch between the shell and core components is the major contributor for the enhancement of ORR activity and selectivity. 相似文献
3.
A magnetic core‐mesoporous shell KOH/Fe3O4@γ‐Al2O3 nanocatalyst was synthesized using the Fe3O4@γ‐Al2O3 core‐shell structure as support and KOH as active component. The prepared samples were characterized by X‐ray diffraction (XRD), field‐emission scanning electron microscopy (FE‐SEM), energy‐dispersive X‐ray spectroscopy (EDS), Fourier transform infrared (FTIR), Brunauer‐Emmett‐Teller (BET), and vibrating sample magnetometry (VSM) techniques. Transesterification of canola oil to methyl esters (biodiesel) in the presence of the magnetic core‐mesoporous shell KOH/Fe3O4@γ‐Al2O3 nanocatalyst was investigated. Response surface methodology (RSM) based on the Box‐Behnken design (BBD) was employed to optimize the influence of important operating variables on the yield of biodiesel. A biodiesel yield of 97.4 % was achieved under optimum reaction conditions. There was an excellent agreement between experimental and predicted results. 相似文献
4.
Monika Saini S. K. Singh Rajni Shukla Ashok Kumar 《Journal of Inorganic and Organometallic Polymers and Materials》2018,28(6):2306-2315
Electromagnetic interference shielding materials based on polyaniline/Mg0.6Cu0.4Fe2O4 ternary nanocomposites were prepared using in situ chemical oxidation polymerization method. The crystalline, structural and morphology analyses of the synthesized material were studied by X-ray diffractometer (XRD), Fourier transform infrared spectroscopy (FTIR) and high resolution transmission electron microscopy (HR-TEM). The nanocomposites were examined by UV–Vis spectroscopy (UV–Vis), four probe resistivity, vibrating sample magnetometer (VSM), thermal gravimetric analysis (TGA) and vector network analyzer (VNA) for the optical, electrical, thermal, magnetic and shielding properties. XRD, FTIR and UV–Vis spectra analyses confirmed the formation of ferrites and polyaniline phases in the composites. The particle sizes of Mg0.6Cu0.4Fe2O4 are lying in the range of 15–40 nm verified by the HR-TEM. VSM study proved the presence of magnetic nanoparticles in the polyaniline matrix. TGA results revealed that the mixing of ferrites particles in polyaniline has improved its thermal stability. The nanocomposites are showing the significant shielding effectiveness value up to 32.8 dB in the X-band frequency range which makes them potential shielding material for electromagnetic interference shielding applications due to lightweight, good processability and low cost. 相似文献
5.
New magnetic and heat resistant poly(amide–imide) nanocomposite (PAIN) was prepared from Fe3O4 nanoparticles and poly(amide‐imide) (PAI) in a solution of N‐methyl‐2‐pyrrolidone. New PAI derived from bisphenol A containing aryl sulfone and ether moiety was synthesized from 2,2′‐(4,4′‐(4,4′‐(propane‐2,2‐diyl)bis(4,1‐phenylene))bis(oxy)bis(4,1‐phenylene))bis(1,3‐dioxoisoindoline‐5‐carboxylic acid) 5 as a new diacid and 4,4′‐diaminodiphenyl sulfone by direct polycondensation reaction. Fe3O4 nanoparticles were prepared by coprecipitation method and characterized using Fourier transform infrared, X‐ray diffraction, scanning electron microscopy (SEM), and vibrating samples magnetometer (VSM). The new poly(amide‐imide)/Fe3O4 nanocomposite was characterized using SEM, FTIR, and VSM. The effect of Fe3O4 nanoparticles on the thermal properties of PAI was studied using thermogravimetric analysis and differential scanning calorimeter. POLYM. COMPOS., 34:1682–1689, 2013. © 2013 Society of Plastics Engineers 相似文献
6.
Thermally and magnetically dual‐responsive mesoporous silica nanospheres: preparation,characterization, and properties for the controlled release of sophoridine
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Liling Dong Hailong Peng Shenqi Wang Zhong Zhang Jinhua Li Fanrong Ai Qiang Zhao Mei Luo Hua Xiong Lingxin Chen 《应用聚合物科学杂志》2014,131(13)
Novel thermally and magnetically dual‐responsive mesoporous silica nanoparticles [magnetic mesoporous silica nanospheres (M‐MSNs)–poly(N‐isopropyl acrylamide) (PNIPAAm)] were developed with magnetic iron oxide (Fe3O4) nanoparticles as the core, mesoporous silica nanoparticles as the sandwiched layer, and thermally responsive polymers (PNIPAAm) as the outer shell. M‐MSN–PNIPAAm was initially used to control the release of sophoridine. The characteristics of M‐MSN–PNIPAAm were investigated by transmission electron microscopy, Fourier transform infrared spectroscopy, X‐ray diffraction, thermogravimetry, N2 adsorption–desorption isotherms, and vibrating specimen magnetometry analyses. The results indicate that the Fe3O4 nanoparticles were incorporated into the M‐MSNs, and PNIPAAm was grafted onto the surface of the M‐MSNs via precipitation polymerization. The obtained M‐MSN–PNIPAAm possessed superparamagnetic characteristics with a high surface area (292.44 m2/g), large pore volume (0.246 mL/g), and large mesoporous pore size (2.18 nm). Sophoridine was used as a drug model to investigate the loading and release properties at different temperatures. The results demonstrate that the PNIPAAm layers on the surface of M‐MSN–PNIPAAm effectively regulated the uptake and release of sophoridine. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40477. 相似文献
7.
Jianguo Deng Yuxing Peng Chuanlan He Xingping Long Pei Li Albert S C Chan 《Polymer International》2003,52(7):1182-1187
Magnetic and conducting Fe3O4–polypyrrole nanoparticles with core‐shell structure were prepared in the presence of Fe3O4 magnetic fluid in aqueous solution containing sodium dodecylbenzenesulfonate (NaDS) as a surfactant and dopant. Both the conductivity and magnetization of the composites depend strongly on the Fe3O4 content and the doping degree. With increase of Fe3O4 content in the composite, the conductivity at room temperature decreases, but the saturated magnetization and coercive force increase. Transmission electron microscopy (TEM) images of Fe3O4 and Fe3O4–polypyrrole particles show almost spherical particles with diameters ranging from 20 to 30 and 30 to 40 nm, respectively. The thermal stability of Fe3O4–polypyrrole composites is higher than that of pure polypyrrole. Studies of IR, UV–visible and X‐ray photoelectron spectroscopy (XPS) spectra suggest that the increased thermal stability may be due to interactions between Fe3O4 particles and polypyrrole backbone. Copyright © 2003 Society of Chemical Industry 相似文献
8.
Panayiotis Bilalis Eleni K. Efthimiadou Alexandros Chatzipavlidis Nikos Boukos George C. Kordas 《Polymer International》2012,61(6):888-894
Temperature and pH responsive poly(N‐isopropylacrylamide‐co‐methacrylic acid) (P(NIPAAm‐co‐MAA)) microcontainers with encapsulated magnetic nanoparticles in the shell were prepared by a two‐stage distillation precipitation polymerization. PMAA@Fe3O4/P(NIPAAm‐co‐MAA) core–shell nanoparticles were synthesized by the second‐stage polymerization of NIPAAm, MAA and N, N′‐methylenebisacrylamide as crosslinker in the presence of magnetic nanoparticles and PMAA as core. These novel triple‐functional microcontainers were prepared by selective removal of the PMAA core in water. Daunorubicin hydrochloride (DNR) was loaded into the microcontainers and the release profile was studied by UV–visible spectroscopy. The synthesized nanostructures were characterized with transmission and scanning electron microscopy, X‐ray diffraction and Fourier transform infrared spectroscopy. The magnetic properties were evaluated by vibrating sample magnetometry. The shrink and swelling behavior was studied by dynamic light scattering. Copyright © 2012 Society of Chemical Industry 相似文献
9.
Fe3O4 magnetic nanoparticles were prepared by coprecipitation using NH3 · H2O as the precipitating agent, and were characterized by Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and X‐ray powder diffraction (XRD). The compatibility between the Fe3O4 nanoparticles and water were enhanced by grafting acrylic acid onto the nanoparticle surface. FTIR, XRD, thermogravimetry (TG), and differential scanning calorimetry (DSC) were used to characterize the resultant sample. The effects of initiator dosage, monomer concentration, and reaction temperature on the characteristics of surface‐modified Fe3O4 nanoparticles were investigated. Moreover, magnetic fluids (MF), prepared by dispersing the PAA grafted Fe3O4 nanoparticles in water, were characterized using UV–vis spectrophotometer, Gouy magnetic balance, and laser particle‐size analyzer. The rheological characteristics of magnetic fluid were investigated using capillary and rotating rheometers. The MF was added to prepare PVA thin film to improve mechanical properties. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007 相似文献
10.
In this study, polystyrene and poly(vinyl chloride) particles were coated successfully with polythiophene in aqueous media. These nanocomposites were prepared in situ by polymerization of thiophene in the presence of FeCl3 as an oxidant and poly(vinyl pyrrolidone) as a surfactant. The effect of Fe2O3 nanoparticles on the characteristics of products such as thermal stability and morphology was investigated. The chemical structure, morphology, and thermal stability of these core‐shell nanocomposites were studied by Fourier‐transform infrared spectroscopy, scanning electron microscopy, X‐ray diffraction, and thermogravimetric analysis. Thermal stability of the nanocomposites was compared and indicated that the thermal stability of polythiophene/polystyrene was better than the polythiophene/poly(vinyl chloride) nanocomposite. Also, the presence of Fe2O3 nanoparticles can drastically increase the thermal stability of polythiophene nanocomposites. J. VINYL ADDIT. TECHNOL. 20:212–217, 2014. © 2014 Society of Plastics Engineers 相似文献
11.
Immobilization of Pd(II) ions on magnetite nanoparticle (MNP) has been simply achieved through a surface modification of Fe3O4 nanoparticle with a biguanide. This surface-modified nanoparticle was characterized by various techniques such as TEM, XRD, VSM, TGA, elemental analyzer, atomic absorption spectroscopy, N2 adsorption–desorption (BET and BJH), and FT-IR. This nanosolid exhibits excellent catalytic activity for heterogeneous Suzuki reaction in aqueous media, and could be easily separated by an external magnet and reused for several times. TEM study of the recovered catalyst showed the preservation of the support core–shell structure and the good dispersion of the produced palladium nanoparticles. 相似文献
12.
Xiaoqian Chen Ronghui Lu Duo Meng Yao Rong Bolong Yao Caihua Ni 《Polymer Composites》2012,33(12):2134-2139
Magnetic star‐shaped amphiphilic copolymers (S‐Fe3O4‐PLA‐b‐MPEG) consisting of Fe3O4 as the core, poly(L ,D ‐lactide) (PLA) as the inner layer, and monomethyl polyethylene glycol (MPEG) as the out shell were synthesized. The syntheses included ring‐opening polymerization of L ,D ‐lactide initiated by hydroxyl modified Fe3O4 (Fe3O4‐(OH) n), followed by the esterification of the PLA with MPEG. The structure of the star block copolymers were characterized by Fourier Transform infrared spectroscopy, thermogravimetric analysis, X‐ray diffraction, transmission electron microscopy, nanoparticle size analyzer, and vibrating sample magnetometer. The nanoparticles in aqueous solution were made from the amphiphilic star copolymer. The average size of the nanoparticles was adjustable and increased with the increase of the PLA segments in the copolymer. The cytotoxicity grade of the nanoparticles was zero determined by the analysis of cytotoxicity. The nanoparticles could potentially be used as the drug vehicles for magnetic‐response controlled release. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers 相似文献
13.
Feng-Yi Chou Chao-Ming Shih Meng-Chao Tsai Wen-Yen Chiu Shingjiang Jessie Lue 《Polymer》2012,53(14):2839-2846
This paper reports a novel method to synthesize magnetic, stimuli-sensitive latex nanoparticles made with magnetite/poly(N-isopropylacrylamide-co-acrylic acid) (Fe3O4/P(NIPAAm-co-AAc)). To form a stabilized suspended core, iron oxide (Fe3O4) was functionalized with AAc such that further polymerization with NIPAAm and AAc monomers could occur. The P(NIPAAm-co-AAc) shell layer exhibited thermosensitive properties. The inclusion of Fe3O4 into the latex nanoparticles was confirmed using transmission electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction spectroscopy, thermogravimetric analyzer (TGA), and superconducting quantum interference device magnetometer. The NIP–(AAc2.6–Fe) latex nanoparticles contained 2.25% Fe3O4 (by weight), as determined by TGA analysis. The particle diameters measured approximately 160–240 nm with a lower critical solution temperature of 35 °C. These novel magnetic stimuli-responsive latex nanoparticles have potential applications in numerous fields, such as catalyst supports, protein immobilization, cancer therapy, target drug delivery systems, and other biomedical applications. 相似文献
14.
Umran Kurtan Abdulhadi Baykal Hüseyin Sözeri 《Journal of Inorganic and Organometallic Polymers and Materials》2014,24(6):948-953
Grafting of chlorosulfuric acid on the amino-functionalized Fe3O4 nanoparticles produced sulfamic acid-functionalized magnetic Fe3O4 nanoparticles as a novel organic–inorganic hybrid material, which was characterized with X-ray diffractometry (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy, scanning electron spectroscopy, and magnetization measurements (VSM). The as-prepared nanocomposite with a narrow size distribution has the crystallite size from XRD (11 ± 4 nm) and particle size from TEM analysis (12.9 ± 0.4 nm) are consistent with each other. Magnetization measurements proved the superparamagnetic property of the product. 相似文献
15.
Yuhang Wang Chunmei Li Jiaojun Tan Wenbin Wang Qiuyu Zhang Hongxia Yan 《Journal of Porous Materials》2017,24(3):639-646
In this paper, the core–shell structured NiFe2O4@TiO2 nanoparticles and nanochains as photocatalysts were successfully prepared through hydrothermal and hydrolysis method. The as-prepared core–shell structure was composed of a magnetic NiFe2O4 core and photocatalytic titanium oxide coating shell. SEM and TEM images characterized the morphology of NiFe2O4@TiO2 nanoparticles. Moreover, the results of XRD patterns proved that the TiO2 coating shell consisted of anatase. The VSM measurements showed that the saturation magnetization values of NiFe2O4 and NiFe2O4@TiO2 nanoparticles was 65 and 53 emu/g, respectively. The photocatalyst of NiFe2O4@TiO2 nanoparticles exhibited the outstanding recyclable performance for RhB. And, the photo_degradation ration of maintained 69 % after the photocatalyst experienced ten photocatalysis experiments, which is better than that of Fe3O4@TiO2 photocatalysts. 相似文献
16.
Ch. Koti Reddy L. Yugandhar Raju P. V. S. S. Srinivas P. Shanthan Rao T. Shekharam D. Shailaja 《应用聚合物科学杂志》2011,122(3):1807-1814
Core shell latex particles with a glassy core and a low Tg polymeric shell are usually preferred. More so, the glassy core happens to be a fluoropolymer with a shell polymer that helps in processability. We describe here the preparation and characterization of core shell nanoparticles consisting of poly(chlorotrifluoroethylene‐co‐ethylvinylether) as core encapsulated in poly(styrene‐acrylate) copolymer shell using seeded emulsion polymerization method under kinetically controlled monomer starved conditions. Properties of the emulsion using surfactants (fluoro/conventional) and surfactant free conditions were investigated. Average size (100 nm), spherical shape and core–shell morphology of the latex particles was confirmed by dynamic light scattering and transmission electron microscopy. Absence of C? F and C? Cl peaks in X‐ray photoelectron spectroscopy proves that cores are completely covered. Polymerization in the presence of fluorocarbon surfactant was found to give optimum features like narrow size distribution, good shell deposition and no traces of agglomeration. Films of core shell latex particles exhibited improved transparency and enhanced water contact angles thus making them suitable for applications in various fields including coatings. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 相似文献
17.
R. Arundhathi D. Damodara M. Lakshmi Kantam P. Saravanan Travis Magdaleno Sun Hee Kwon 《Advanced Synthesis \u0026amp; Catalysis》2011,353(9):1591-1600
A high surface, magnetic Fe3O4@mesoporouspolyaniline core‐shell nanocomposite was synthesized from magnetic iron oxide (Fe3O4) nanoparticles and mesoporouspolyaniline (mPANI). The novel porous magnetic Fe3O4 was obtained by solvothermal method under sealed pressure reactor at high temperature to achieve high surface area. The mesoporouspolyaniline shell was synthesized by in situ surface polymerization onto porous magnetic Fe3O4 in the presence of polyvinylpyrrolidone (PVP) and sodium dodecylbenzenesulfonate (SDBS), as a linker and structure‐directing agent, through ‘blackberry nanostructures’ assembly. The material composition, stoichiometric ratio and reaction conditions play vital roles in the synthesis of these nanostructures as confirmed by variety of characterization techniques. The role of the mesoporouspolyaniline shell is to stabilize the porous magnetic Fe3O4 nanoparticles, and provide direct access to the core Fe3O4 nanoparticles. The catalytic activity of magnetic Fe3O4@mesoporousPANI nanocomposite was evaluated in the cross‐coupling of aryl chlorides and phenols. 相似文献
18.
Peijun Gong Jiahui Yu Hanwen Sun Jun Hong Sufang Zhao Dongmei Xu Side Yao 《应用聚合物科学杂志》2006,101(3):1283-1290
A novel preparation method of net magnetic polymer nanogels with swollen shell was developed. UV‐induced photopolymerization of 2‐hydroxyethyl methacrylate (HEMA) was performed in the magnetite aqueous suspension, free of any additive to obtain monodisperse magnetic nanogels with swollen shell. Owing to the step‐growth polymerization of the monomer, the particle size of magnetic nanogels can be conveniently manipulated by changing the irradiation time and the volume of the monomer dropped. The crystalline structure of Fe3O4 core and chemical composition of PHEMA magnetic nanogels were characterized by using X‐ray diffraction, Fourier transform infrared spectroscopy, and thermogravimetric analysis, respectively. Particle sizes, size distributions of magnetic nanogels in swollen state and dry state were measured by photo‐correlation spectroscopy (PCS) and transmission electron microscopy (TEM), respectively. The morphology of swollen magnetic nanogels and that of polymer capsules obtained from magnetic nanogels etched by hydrochloride acid were observed by TEM. The high magnetizations and superparamagnetic behaviors of naked Fe3O4 and magnetic nanogels at room temperature were confirmed by the measurement of hysteresis curves. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1283–1290, 2006 相似文献
19.
Mixed rutile–anatase TiO2 nanoparticles were synthesized by hydrothermal treatment under acidic conditions and incorporated into poly(vinyl alcohol) (PVA). These nanocomposites were electrospun to produce nanofibers of PVA/TiO2, which were characterized by scanning electron microscopy, transmission electron microscopy, X‐ray diffraction (XRD), UV–vis diffuse reflectance spectroscopy, thermogravimetric analysis, and differential scanning calorimetry. The photocatalytic degradation of Rhodamine B and degradation of the polymer by UV‐C lamps were also investigated. The results showed that TiO2 nanoparticles did not change the morphology and thermal behavior of the nanofiber polymer, but were effective in modifying the UV absorption of PVA without reducing its stability. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 相似文献
20.
Poly(vinylidene difluoride) (PVDF)/Fe3O4 magnetic nanocomposite was prepared by a simple coprecipitation method, and was characterized by scanning electron microscope (SEM), X‐ray diffraction (XRD), vibrating sample magnetometer (VSM), and ultraviolet visible spectroscopy (UV‐Vis). The SEM images showed that Fe3O4 nanoparticles were dispersed in the PVDF matrix as some aggregates with the sizes of 50 nm–2 μm, and the XRD curves showed the incorporation of the Fe3O4 nanoparticles in PVDF matrices and the decrease of the crystallinity of the PVDF. VSM results showed that the saturation magnetization (Ms) and remnant magnetization (Mr) of the PVDF/Fe3O4 nanocomposite increased with the increase of the Fe3O4 content, and that Ms and Mr along the parallel direction were higher than those along the perpendicular direction at the same Fe3O4 content. The coercive force (Hc) of the nanocomposite was independent of the Fe3O4 content and approximately equal along the parallel and perpendicular direction at the same Fe3O4 content. The optical band gap (Eg) of the PVDF/Fe3O4 nanocomposite was influenced by the Fe3O4 content, and decreased by 0.75 eV compared with that of pure PVDF when the Fe3O4 content was 3 wt %. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 相似文献