Poly[(oligoethylene oxide) ethoxysilane)] ( I ) and poly[(oligoethylene oxide) ethoxysilane)]/(EuCl3)0.67 ( II ) were synthesized by reacting tetraethoxysilane with oligo(ethylene glycol) of molecular weight 400 and oligo(ethylene glycol)400/(EuCl3)0.317, respectively. The products so obtained are very transparent and rubbery. By Fourier transform infrared and Raman spectroscopy studies and by using analytical results it was concluded that these products are crosslinked macromolecular materials where the Si atom is bonded to one OEt group and to three poly(ethylene oxide) 400 chains. Scanning electronic microscopy studies showed that the presence of EuCl3 in polymer host significantly affects the morphology of the material. Laser luminescence investigations on (II) showed that Eu3+ ion in the polymer host is accommodated in two different types of sites having a distorted C2v symmetry. Moreover, the ionic conductivity of these systems was investigated and the data were satisfactorily fitted by the empirical Vogel Tamman Fulcher equation. At 70°C the conductivities of ( I ) and ( II ) were 9 × 10−6 and 14.3 × 10−6 Ω−1 cm−1 respectively. 相似文献
A novel and quick method has been developed for the preparation of tin sulfide (SnS and SnS2) nanoflakes in high yield (≈93%) by a microwave irradiation technique for 10–40 min. The sulfides were synthesized in a simple domestic microwave oven (DMO) using stannic chloride and stanous chloride as the precursors of tin and thiourea as the precursor of sulfur in ethylene glycol under argon atmosphere. Elemental sulfur and sodium thiosulfate were also tried as precursors of sulfur. The structures, morphologies, compositions, and physical properties of the products were characterized by powder X-ray diffraction (XRD), differential scanning calorimetry, energy dispersive X-ray analysis, transmission electron microscopy, selected area electron diffraction, Raman spectroscopy, and standard electrochemical techniques. The XRD patterns indicate that the as-synthesized product, obtained after microwave irradiation, is crystalline orthorhombic in the case of the SnS phase and amorphous in the case of SnS2. Heat treatment of this SnS2 produced a crystalline hexagonal phase. A possible mechanism for the formation of the tin sulfide nanoflakes is proposed herein. The electrochemical performance of these materials as Li-insertion materials was investigated in a number of electrolyte solutions and was found to be highly sensitive to the solution composition. A stable reversible capacity higher than 600 mAh/g could be obtained with SnS electrodes. 相似文献
Summary: Poly(alkylene hydrogen phosphonate)s with a number‐average molecular weight of about 3 000 Da were obtained by a transesterification of dimethyl hydrogen phosphonate with poly(ethylene glycol) (PEG 400) under microwave irradiation with a very short reaction time (55 min) relative to that of classical thermal heating (9 h). The structure of the resulting polymer was confirmed by 1H, 31P, and 13C NMR spectroscopy. The molecular weight was determined by 1H, 31P{H} NMR spectroscopy, MALDI‐TOF, and GPC.
The transesterification of dimethyl hydrogen phosphonate with poly(ethylene glycol). 相似文献
Organic-inorganic hybrid materials were prepared by reacting 3-isocyanatopropyltriethoxysilane (IPTS) with hydroxyl terminated
poly(ethylene glycol) (PEG), poly(propylene glycol) (PPG) and poly(propylene glycol)-block-poly(ethylene glycol)-block-poly(propylene
glycol) (PEPG), followed by hydrolysis and condensation with acid catalysis. Composite membranes have been obtained by casting
hybrid sol on the microporous polysulfone substrate. The membranes were characterized by Fourier transform infrared (FT-IR),
13C NMR and 29Si NMR. The permeability coefficients of N2, O2, CH4 and CO2 were measured by variable volume method. The gas permeability coefficients increase with increasing molecular weight of the
polyethers. For the membranes containing PEG and PEPG, the higher values of CO2 permeability coefficients and CO2/N2 separation factors are due to the presence of ethylene oxide segments. In case of PEPG membranes, molecular weight has more
influence on CO2 permeability than the effect of facilitation by ethylene oxide. The addition of TEOS into hybrid sol results in the decrease
of all the gas permeability and does not affect the gas selectivity. PEG2000 membrane display the most performance among the
hybrid membranes investigated here. The best values observed are CO2 permeability of 94.2 Barrer with selectivity of 38.3 for CO2/N2 and 15.6 for CO2/CH4. 相似文献
Microwave activation of electrochemical processes has recently been introduced as a new technique for the enhancement and
control of processes at electrode|solution (electrolyte) interfaces. This methodology is extended to processes at glassy carbon
and boron-doped diamond electrodes. Deposition of both Pb metal and PbO2 from an aqueous solution of Pb2+ (0.1 M HNO3) are affected by microwave radiation. The formation of PbO2 on anodically pre-treated boron-doped diamond is demonstrated to change from kinetically sluggish and poorly defined at room
temperature to nearly diffusion controlled and well defined in the presence of microwave activation. Calibration of the temperature
at the electrode|solution (electrolyte) interface with the Fe3+/2+ (0.1 M HNO3) redox system allows the experimentally observed effects to be identified as predominantly thermal in nature and therefore
consistent with a localized heating effect at the electrode|solution interface. The microwave-activated deposition of PbO2 on boron-doped diamond remains facile in the presence of excess oxidizable organic compounds such as ethylene glycol. An
increase of the current for the electrocatalytic oxidation of ethylene glycol at PbO2/boron-doped diamond electrodes in the presence of microwave radiation is observed. Preliminary results suggest that the electrodissolution
of solid microparticles of PbO2 abrasively attached to the surface of a glassy carbon electrode is also enhanced in the presence of microwave radiation.
Electronic Publication 相似文献
Summary: This study reported the preparation and characterization of PCL-b-mPEG (poly(ε-caprolactone)-block-poly(ethylene glycol)) and PLL-b-mPEG (poly(L-lactide)-block-poly(ethylene glycol)) diblock copolymers by microwave heating and comparison of resulted products the ones with prepared by conventional heating. Diblock copolymers were synthesized successfully by the microwave-assisted ROP in the presence of stannous octoate (SnOct2) as catalyst under nitrogen atmosphere in different monomer ratios. Structural and functional characterization of copolymers were performed by FTIR, 1H-NMR and DSC. Molecular weight values were determined by GPC and also calculated from 1H-NMR. According to the results, microwave irradiation allowed to obtain polymers with very narrow size distribution in very short reaction time. Similar polymers prepared by conventional heating were also synthesized for comparison. Molecular weight and conversion of polymers were increased by irradiation time. This change was continued until a certain time point after which no more increase was observed. It was concluded that microwave irradiation is a succesful method to obtain these diblock copolymers in very short reaction time and with a similar conversion obtained by conventional method. 相似文献
The ionic title complex, bis(μ‐ethylene glycol)‐κ3O,O′:O′;κ3O:O,O′‐bis[(ethylene glycol‐κ2O,O′)(ethylene glycol‐κO)sodium] bis(ethylene glycolato‐κ2O,O′)copper(II), [Na2(C2H6O2)6][Cu(C2H4O2)2], was obtained from a basic solution of CuCl2 in ethylene glycol and consists of discrete ions interconnected by O—H...O hydrogen bonds. This is the first example of a disodium–ethylene glycol complex cation cluster. The cation lies about an inversion center and the CuII atom of the anion lies on another independent inversion center. 相似文献
A meostructured WO3/C composite with crystalline framework and high electric conductivity has been synthesized by a new in situ carbonization–replication route using the block copolymer (poly(ethylene glycol)‐block‐poly(propylene glycol)‐block‐poly(ethylene glycol)) present in situ in the pore channels of mesoporous silica template as carbon source. X‐ray diffraction, X‐ray photoelectron spectroscopy, transmission electron microscopy, thermogravimetry differential thermal analysis, and N2 adsorption techniques were adopted for the structural characterization. Cyclic voltammetry, chronoamperometry, and single‐cell test for hydrogen electrochemical oxidation were adopted to characterize the electrochemical activities of the mesoporous WO3/C composite. The carbon content and consequent electric conductivity of these high‐surface‐area (108–130 m2 g?1) mesostructured WO3/C composite materials can be tuned by variation of the duration of heat treatment, and the composites exhibited high and stable electrochemical catalytic activity. The single‐cell test results indicated that the mesostructured WO3/C composites showed clear electrochemical catalytic activity toward hydrogen oxidation at 25 °C, which makes them potential non‐precious‐metal anode catalysts in proton exchange membrane fuel cell. 相似文献
L-Lactide was polymerized in toluene with various alkoxide initiators. These initiators were prepared in situ from potassium t.-butoxide and primary or secondary alcohols such as tetradecanol, diethylene glycol butyl ether, menthol or testosteron. All these alcohols were incorporated as ester endgroups into the polylactide chain. However 1H-NMR spectroscopy proves the existence of more OH-endgroup than ester endgroups. This finding and 10–20% racemization observed for all anionic polymerizations suggest that chain-transfer reactions with the monomer via deprotonation take place. When poly(ethylene glycol) monomethyl ether in combination with KOtBu was used as initiator, twoblock copolymers were obtained. With poly(ethylene glycol) A-B-A-triblock copolymers could be synthesized. The quantitative reaction of the poly(ethylene glycol)s with L-lactide could be proven by both 1H NMR spectroscopy and gelpermeation chromatography. DSC-measurements show that depending on their lengths either the polylactide or the poly(ethylene oxide)blocks can crystallize. Due to partial racemization the melting temperatures (Tm) of the poly(L-lactide) blocks did not exceed 155°C. 相似文献
Various morphologies of ZnO nanostructures, such as nanoparticles, nanorods and nanoflowers have been achieved controllably by polymeric sol–gel method. In this approach, zinc nitrate Zn(NO3)2·6H2O, citric acid and ethylene glycol were used as the source of Zn2+, the chelating agent and the solvent agent, respectively. The microstructure of the ZnO nanostructures was characterized by X-ray diffractometry, scanning electron microscopy with the energy dispersive X-ray spectroscopy, transmission electron microscopy, thermogravimetric analysis and Fourier transform infrared spectroscopy. The effect of ethylene glycol to citric acid mole ratio on the morphology and structure of the products was discussed. The ZnO nanoparticles with diameter between 24 ± 2 nm was obtained with EG:CA mole ratio equal to 2:1. The optical properties of as-obtained power were investigated by ultraviolet–visible spectroscopy. 相似文献
Nanoparticles composed of iron oxides and iron salts were obtained from polymeric resins produced by polymerizing Fe2+-citrate and Fe3+-citrate complexes with ethylene glycol. The citric acid:Fe molar ratio was varied to obtain different synthesis conditions. The materials were treated at 450 °C for 2 h to obtain nanoparticles, which were characterized by XRD, Mössbauer spectroscopy, FEG, CHNS, atomic absorption and surface area through N2 physisorption. Rhodamine B photo degradation in the presence of these nanoparticles and hydrogen peroxide was carried out to analyze the possible behavior of nanoparticles as heterogeneous Fenton reactants. UV–visible spectroscopy revealed that the catalytic activity in the presence of nanoparticles obtained with a citric acid:Fe molar ratio of 12:1 was the condition that provided the best results in this work. 相似文献
The synthesis and thermal and spectroscopic studies of a new CoII–FeIII heteropolynuclear coordination compound are presented. The in situ oxidation product of ethylene glycol plays the role of ligand. Under specific working conditions, the reaction of ethylene glycol with FeIII and CoII nitrates in dilute acid solutions occurs with the oxidation of the former to glyoxylic acid, coordinated to the CoII and FeIII cations as glyoxylate anion (C2H2O42?), with simultaneous isolation of the heteropolynuclear coordination compound. In order to separate and identify the ligand, the synthesized coordination compound, having the composition formula Co4Fe10(L)9(OH)20(H2O)32·14H2O, where L is the glyoxylate anion, has been treated with R–H cationite (Purolite C-100). After the retention of the metal cations, the resulting glyoxylic acid was confirmed by measuring its physical constants, by specific reactions and through spectroscopic methods. The synthesized coordination compound was characterized by physical–chemical analysis, electronic spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray diffractometry (XRD) and thermal analysis. Cobalt ferrite impurified with ferric oxide was obtained following the thermal decomposition of CoII–FeIII polyhydroxoglyoxylate. The oxides obtained through thermolysis were studied by FTIR, XRD, scanning electron microscopy (SEM) and elemental analysis. 相似文献
Monodispersed nanostructured TiO2 spheres were obtained by the Sol–Gel method modified with ethylene glycol. The sample morphology and surface textural properties
were characterized by X-ray diffraction (XRD), N2-physisorption, scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA) and diffuse reflectance spectroscopy (DRS). The SEM image showed spheres with sizes ranging
from 600 to 700 nm. In addition, HRTEM micrographs reveal hexagonal grains slightly elongated (20 nm). The powders present
a BET surface area of 116 m2 g−1. Samples without thermal treatment and those treated at 400 °C both showed characteristic reflections of the anatase phase.
The photocatalytic activity of the prepared TiO2 spheres was determined by degradation of 2,4-dichlorophenoxyacetic acid (2,4-D) in aqueous solution. Kinetics parameters
have displayed than the nanostructured material present a reaction half-life time of 30 min and it was two times faster than
commercial TiO2 (P25). 相似文献
The kinetics of the copper electroreduction in acid sulfate solutions containing ethylene glycol derivatives (EG) with the common formula HO-(CH2-CH2-O)m-H is studied by means of voltammetry and impedance spectroscopy. All the EG (m≤6) display weak surface activity and barely effect the cathodic kinetics in the absence of halides. Halides can initiate inhibiting adsorption of EG only when the number of ether oxygen atoms in them is 3 (m ≤ 4), by inhibiting the first-electron transfer onto ions Cu2+. These effects are discussed invoking notions on the formation of pseudocrown structures in the adsorption layer. 相似文献
KGd(WO4)2 (KGW) particles were synthesized at 3.5, 5.5 and 7.5 pH values by Pechini polymeric complex sol–gel method using potassium
nitrate, gadolinium nitrate, ammonium paratungstate, citric acid and ethylene glycol as starting materials. Deionized water
was used as solvent. Polymeric precursor gel was formed with citric acid as complexing agent and ethylene glycol as binder.
Synthesized gel was analyzed by FT-IR spectroscopy. Prepared precursor gels were further annealed using resistive and microwave
processes at 550 and 700 °C, respectively. The properties of heat treated samples were characterized by powder XRD, FT-IR,
Raman and SEM analysis to understand the crystallinity, organic liberation, tungstate ribbon formation and surface morphology,
respectively. The phase formation and different phases of intermediate oxides in pre-fired samples were investigated by powder
XRD. Organic liberation in the samples in relation to temperature, and the carbon content in the pre-fired powder was analyzed
using FT-IR spectrum. Raman spectrum reveals the formation of tungsten ribbons as well as the quality of the samples. The
morphological changes at different synthesis conditions were observed with SEM micrographs. 相似文献