共查询到20条相似文献,搜索用时 15 毫秒
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T. N. Rostovshchikova M. S. Korobov D. A. Pankratov G. Yu. Yurkov S. P. Gubin 《Russian Chemical Bulletin》2005,54(6):1425-1432
Nanosized iron oxides stabilized on the surface of ultradispersed poly(tetrafluoroethylene) (UPTFE) granules were synthesized
by the thermal destruction of iron formate in boiling bed of UPTFE on the surface of heated mineral oil. The particle size
of nanoparticles (∼6 nm) containing 5, 10, and 16 wt.% Fe depends weakly on the temperature of synthesis and iron to polymer
ratio. The metal state is determined by the synthesis conditions. The nanoparticles synthesized at 280 °C consist mainly of
the Fe3O4 and Fe2O3 phases. The samples obtained at 320 °C also contain iron(II) oxide. The catalytic properties of the obtained samples were tested in dichlorobutene isomerization. Unlike isomerization
on the iron oxide nanoparticles supported on silica gel, reaction over the UPTFE supports proceeds without an induction period.
The sample with 10 wt.% Fe containing magnetically ordered γ-Fe2O3 nanoparticles possesses the highest catalytic activity. Fast electron exchange between the iron ions in different oxidation
states and high defectiveness of the nanoparticles contribute, most likely, to the catalytic activity.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1383–1390, June, 2005. 相似文献
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Ping‐Chieh Wang Wen‐Yen Chiu Chia‐Fen Lee Tai‐Horng Young 《Journal of polymer science. Part A, Polymer chemistry》2004,42(22):5695-5705
A magnetic poly(methyl methacrylate) (PMMA) composite latex was prepared by soapless emulsion polymerization in the presence of ferrofluid, and the ferrofluid was prepared by means of a coprecipitation method. The effects of various polymerization parameters, such as the monomer concentration, ferrofluid content, and initiator concentration, on the conversion curve and particle size of the magnetic composite latex particles were examined in detail. The results showed that two nucleation mechanisms were involved according to the polymerization conditions. In the monomer‐rich and less ferrofluid system, self‐nucleation of PMMA was dominant over the entire course of emulsion polymerization. In the ferrofluid‐rich system, seeded emulsion polymerization was the main course to form the magnetic composite latex particles. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5695–5705, 2004 相似文献
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H. Kaczmarek J. Kowalonek Z. Klusek S. Pierzgalski S. Datta 《Journal of Polymer Science.Polymer Physics》2004,42(4):585-602
The photooxidative degradation of blends (in a full range of compositions) of amorphous poly(vinyl chloride) (PVC) with semicrystalline poly(ethylene oxide) (PEO) in the form of thin films is investigated using absorption spectroscopy (UV–visible and Fourier transform infrared) and atomic force microscopy (AFM). The amount of insoluble gel formed as a result of photocrosslinking is estimated gravimetrically. It is found that the PVC/PEO blendsí susceptibility to photooxidative degradation differs from that pure of the components and depends on the blend composition and morphology. Photoreactions such as degradation and oxidation are accelerated whereas dehydrochlorination is retarded in blends. The photocrosslinking efficiency in PVC/PEO blends is higher than in PVC; moreover, PEO is also involved in this process. AFM images showing the lamellar structure of semicrystalline PEO in the blend lead to the conclusion that the presence of PVC does not disturb the crystallization process of PEO. The changes induced by UV irradiation allow the observation of more of the distinct PEO crystallites. This is probably caused by recrystallization of short, more mobile chains in degraded PEO or by partial removal of the less stable amorphous phase from the film surface. These results confirm previous information on the miscibility of PVC with PEO. The mechanism of the interactions between the components and the blend photodegradation are discussed. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 585–602, 2004 相似文献
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Thermal stability of poly(vinyl chloride)/poly(ethylene oxide) (PVC/PEO) blends has been investigated by thermogravimetric analysis (TGA) in dynamic and isothermal heating regime. PVC/PEO blends were prepared by hot-melt extrusion (HME). According to TG analysis, PEO decomposes in one stage, while PVC and PVC/PEO blends in two degradation stages. In order to evaluate the effect of PEO content on the thermal stability of PVC/PEO blends, different criteria were used. It was found that thermal stability of PVC/PEO blends depends on the blend composition. The interactions of blends components with their degradation products were confirmed. By using multiple heating rate kinetics the activation energies of the PVC/PEO blends thermal degradation were calculated by isoconversional integral Flynn–Wall–Ozawa and differential Friedman method. According to dependence of activation energy on degree of conversion the complexity of degradation processes was determined. 相似文献
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Allan J. Easteal Rakesh Malhotra William E. Price Lawrence A. Woolf 《Journal of solution chemistry》1991,20(3):319-334
Intradiffusion of species in acidified (using eithe hydrochloric or perchloric acid) iron(III) chloride solutions has been
studied using labeled iron(III), chloride and water. Comparison with data for iron(III) perchlorate has enabled the influence
of complexed species upon the diffusion to be ascertained. The chloro-iron species formed have larger diffusion coefficients
than the free iron(III) ion as would be expected from their lower net charge. Simple diffusion models have been employed to
enable estimates of the diffusion of the complexed species and of the free chloride diffusion coefficients to be obtained.
These are discussed in relation to literature data for similar systems. In addition esitmates of the effective hydration of
the iron(III) species in solutions have been obtained from the diffusion data. These are discussed in relation to two other
trivalent metal salt systems, chromium chloride and lanthanum chloride; the overall hydration of the three cations is virtually
identical. 相似文献
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Dao Fam Kim Gaidadin A. N. Gorkovenko D. A. Navrotsky V. A. 《Russian Journal of Applied Chemistry》2019,92(6):759-766
Russian Journal of Applied Chemistry - The modification of natural rubber with poly(diallyldimethylammonium chloride) and polyvinyl chloride by mixing latexes was studied. It was established that... 相似文献
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Q He T Yuan S Wei N Haldolaarachchige Z Luo DP Young A Khasanov Z Guo 《Angewandte Chemie (International ed. in English)》2012,51(35):8842-8845
About phase: Ferromagnetic γ-Fe(2) O(3) nanowires (left in the figure) with a saturation magnetization (M(s) ) of 54.0?emu?g(-1) and coercivity of 518?Oe at room temperature, and superparamagnetic hollow α-Fe(2) O(3) nanoparticles (right) with a room-temperature M(s) of 2.9?emu?g(-1) were synthesized by the thermal decomposition of [Fe(CO)(5) ] but with the stabilizing action of maleic anhydride grafted polypropylene. 相似文献
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Haemin-functionalised magnetic iron(II, III) oxide (Fe3O4) nanoparticles (Fe3O4/haemin) were synthesised by changing the acidity of a solution of the two compounds. The nanoparticles were characterised by transmission electron microscopy, UV–vis absorption spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy, measurement of magnetisation, and electrochemical techniques. The properties of both haemin and Fe3O4 were retained. Thus, Fe3O4/haemin nanoparticles exhibited pronounced electrocatalytic activity towards trichloroacetic acid (TCA) like haemin itself. Interestingly, electrocatalytic activity towards TCA was affected by detection temperature, which was controlled via electrically heated carbon paste electrodes. The maximal catalytic current was 5.8 times higher at 60 °C than at room temperature (25 °C). This proposed electrochemical sensor for TCA possessed a linear detection range of 5–80 μM and a detection limit of 0.3 μM at 60 °C. 相似文献
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Determination of serum albumin in the presence of poly(diallyldimethylammonium chloride) by resonance light scattering technique 总被引:1,自引:0,他引:1
Chen Y Tian Y Gao D Bai Y Yu A Zhang H 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2007,66(4-5):1011-1015
By means of the resonance light scattering (RLS) technique, a new method was developed to determine the bovine serum albumin (BSA) and human serum albumin (HSA) by the interaction of serum albumin with poly(diallyldimethylammonium chloride) (PDDA). At Tris-NaOH buffer solution, the RLS intensity of serum albumin at the wavelength 320, 550 and 590 nm was obviously enhanced in the presence of PDDA. The influences of some experimental factors, including incubation time, addition sequence of reagents, pH value, concentration of PDDA and foreign substances, on the enhancement of the RLS intensity were examined. The optimum conditions of the experiment were selected. Under the selected experimental condition, the enhanced RLS intensities were directly proportional to the concentrations in the range of (0.0250-2.75)x10(-6) mol/L for BSA and (0.0235-1.17)x10(-6) mol/L for HSA. The detection limits (S/N=3) were 8.40x10(-9) mol/L for BSA and 7.39x10(-9) mol/L for HSA. The synthetic samples were analysed and the results obtained were satisfactory. 相似文献
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Gopalakrishnapanicker Rajesh Krishnan Modiyuzhathil K. Sreeraj Krishnapillai Sreekumar 《Comptes Rendus Chimie》2013,16(8):736-741
Poly(vinyl chloride) was modified to develop an alternative support for the preparation of polymer-supported catalysts. Commercially available poly(vinyl chloride) was synthetically modified to a polymer containing pendant primary amino groups. The Schiff-base of salicylaldehyde and the amino polymer were prepared and were used as the ligands in the synthesis of a polymer-supported copper complex. The polymer-supported ligand and catalysts were characterized by various physical methods. The polymer with the pendant copper complex was able to catalyze the one-pot three-component Mannich reaction between aldehydes, ketones and anilines under mild and environmentally friendly conditions. The catalyst can be recovered by simple filtration and is reusable. 相似文献
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Shadpour Mallakpour Mashal Javadpour 《International Journal of Polymer Analysis and Characterization》2018,23(5):415-429
We reported a general facile approach for modifying NPs and incorporating them into PVC polymer via ultrasonic irradiation. ZnO nanoparticles (NP)s modified with ascorbic acid (AS) and citric acid (CA) were employed to investigate the agglomeration behavior under poly(vinyl chloride) PVC matrix. To compare and determine the suitable construction, the prepared PVC/ZnO-CA-AS NCs (4, 8, 12?wt%) were characterized. UV-visible measurements indicate, increasing absorption value results in an increase of ZnO content. According to the obtained information from the TGA of the NCs, further increases in modified ZnO results in an increase in flame-retardancy. The mechanical properties investigation revealed improvement of the elongation at maximum stress. 相似文献
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Yuqing Ge Yu Zhang Jingguang Xia Ming Ma Shiying He Fang Nie Ning Gu 《Colloids and surfaces. B, Biointerfaces》2009,73(2):294-301
We synthesized three types of magnetic iron oxide nanoparticles (MNPs), which were meso-2,3-dimercaptosuccinic acid (DMSA) coated MNPs (DMSA@MNPs, 17.3 ± 4.8 nm, negative charge), chitosan (CS) coated MNPs (CS@MNPs, 16.5 ± 6.1 nm, positive charge) and magnetic nanoparticles agglomerates, formed by electronic aggregation between DMSA@MNPs and CS (CS-DMSA@MNPs, 85.7 ± 72.9 nm, positive charge) respectively. The interactions of these MNPs with Oral Squamous Carcinoma Cell KB were investigated. The results showed that cellular uptakes of MNPs were on the dependence of incubation time, nanoparticles concentration and nanoparticles properties such as surface charge, size, etc. The cellular uptake was enhanced with the increase of incubation time and nanoparticles concentration. Although all MNPs could enter to cells, we observed apparent differences in the magnitude of nanoparticles uptaken. The cellular uptake of CS-DMSA@MNPs by KB cells was the highest and that of DMSA@MNPs was the lowest among the three types of MNPs. The same conclusions were drawn via the reduction of water proton relaxation times , resulting from the different iron load of labeled cells using a 1.5 T clinical MR imager. The finding of this study will have implications in the chemical design of nanomaterials for biomedical applications. 相似文献
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Seon Jeong Kim Seoung Gil Yoon Sun I. Kim 《Journal of Polymer Science.Polymer Physics》2004,42(5):914-921
Semi‐interpenetrating polymer network (SIPN) hydrogels, composed of chitosan (CS) and poly(diallyldimethylammonium chloride) (PDADMAC), were prepared, and they exhibited electrically sensitive behavior. The swelling behavior of the CS/PDADMAC SIPN hydrogels was studied through the immersion of the gels in various concentrations of aqueous NaCl solutions, and their responses to stimuli in electric fields were also investigated. When the swollen SIPN hydrogels were placed between a pair of electrodes, they exhibited bending behavior upon the application of an electric field, which was stepwise and dependent on the magnitude of the field. To clarify the relationship between the equilibrium‐swelling ratio and the bending behavior of the SIPN hydrogels, the state of water in the SIPN hydrogels was also investigated with differential scanning calorimetry. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 914–921, 2004 相似文献
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