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211.
Influence of different alkyl‐methylimidazolium tetrafluoroborate ionic liquids on the structure of pebax® films. Consequences on thermal,mechanical, and water sorption and diffusion properties
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Sylvain Magana Olivier Gain Fabrice Gouanvé Eliane Espuche 《Journal of Polymer Science.Polymer Physics》2016,54(8):811-824
In this work, three ionic liquids (ILs) differing by the length of the alkyl chain linked to their cation were incorporated in a Pebax® copolymer matrix through a solvent cast process for composition from 0 to 70 wt % IL. The copolymer/IL miscibility was investigated via IR Spectroscopy, Differential Scanning Calorimetry and Scanning Electron Microscopy. The three ILs dissolved in the copolymer soft phase for ILs content below 30 wt % whereas they formed segregated dispersed domains at higher loadings. The plasticizing effect of the ILs was examined through DSC and thermomechanical analyses. In the range of IL amount from 0 to 30 wt %, no significant differences were observed in the thermomechanical properties as a function of the IL structure. At higher IL content, the films based on 1‐ethyl‐methylimidazolium tetrafluoroborate sustained better properties. All films exhibited a good thermal stability up to 300 °C. The water sorption isotherms were modeled with GAB equation and both the kinetic and thermodynamic parameters of the sorption mechanism were investigated. A non‐monotonic evolution of the GAB parameters and diffusion coefficient as a function of the IL content was evidenced. Moreover, different behaviors were observed as a function of the IL nature and structuration within the copolymer matrix. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 811–824 相似文献
212.
A Kinetic Investigation of Regioselective Solvation of a Solvatochromic Dye in Aqueous Alcohols
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Moisés Domínguez Vanderlei Gageiro Machado Leandro Guarezi Nandi Marcos Caroli Rezende Patricia Silva 《国际化学动力学杂志》2015,47(12):803-810
The kinetics of methylation of the solvatochromic dye 4‐[(2,4‐dinitrobenzyli‐dene)imino]‐2,6‐diphenylphenolate by dimethyl sulfate was investigated in three aqueous alcohols (1‐propanol, ethanol, and methanol), in the search of a sharp change in its reactivity in water‐rich media. The observed kinetic results paralleled previous observations of a sharp change in the solvatochromic behavior of the dye in the same media and was supported by a QM/MM simulation of the dye in two methanol–water mixtures, which rationalized the observed sharp change in the phenolate reactivity. 相似文献
213.
The synthesis of annofolin (1), an alkaloid isolated from Annona hayesii in small amounts, by a phase-transfer catalytic reduction-methylation of cleistopholin (2) is reported, together with the preparation of its derivatives (3) and (4) by the same method. 相似文献
214.
Fe‐DPA as Catalyst for Oxidation of Organic Contaminants: Evidence of Homogeneous Fenton Process
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Paulize H. Ramos Felipe A. La Porta Eliane C. de Resende Juliana O. S. Giacoppo Mario C. Guerreiro Teodorico C. Ramalho 《无机化学与普通化学杂志》2015,641(5):780-785
Fenton‐type reactions using transition metal complexes in the decomposition of hydrogen peroxide to hydroxyl radical generation have received special attention due to their advantages over classical homogeneous processes involving soluble iron salts. Thus, the goal of this study was to investigate the use of an iron complex with the ligand pyridine‐2,6‐dicarboxylic acid (dipicolinic acid or DPA) as a homogeneous catalyst for the oxidation of the quinoline. The synthesized iron complex showed a molar ratio of 1:2 metal/ligand and was efficient in the quinoline oxidation at pH values near neutrality. The tests were monitored by mass spectrometry that allows identification of the different intermediates and showed complete oxidation of the quinolone compound. Moreover, in order to shed some light on the formation of hydroxyl radicals and the overall reaction mechanism, some theoretical calculations at the DFT level were performed. The results of this study demonstrated that the iron‐DPA complex is a good catalyst for the oxidation of quinoline by a Fenton‐like mechanism. All theoretical data show good agreement with experimental results. 相似文献
215.
Bram Verbelen Lucas Cunha Dias Rezende Stijn Boodts Jeroen Jacobs Prof. Luc Van Meervelt Prof. Johan Hofkens Prof. Wim Dehaen 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(36):12667-12675
A one‐step synthetic procedure for the radical C?H alkylation of BODIPY dyes has been developed. This new reaction generates alkyl radicals through the oxidation of boronic acids or potassium trifluoroborates and allows the synthesis of mono‐, di‐, tri‐, and tetraalkylated fluorophores in a good to excellent yield for a broad range of organoboron compounds. Using this protocol, multiple bulky alkyl groups can be introduced onto the BODIPY core thus creating solid‐state emissive BODIPY dyes. 相似文献
216.
Orlando David Henrique dos Santos Maria Fernanda Pires de Camargo Fernanda Frota de Andrade Pedro Alves da Rocha Filho 《Journal of Dispersion Science and Technology》2013,34(7):997-1001
During evaporation, the rate between volatile and nonvolatile components in an emulsion changes. In this study, emulsions of marigold and canola oil were made according to a phase diagram, simulating the decreasing water amount that happens when the water evaporates from an emulsion. In addition, two basic emulsions were submitted to evaporation and then to microscopic analysis to compare the results of both tests. It was observed that when the water rate decreases, the liquid‐crystalline phase changes its organization, reaching a proportion that it is not hydrated anymore, having a solid aspect. Moreover, these emulsions submitted to evaporation remained to show lamellar phase even when there was no water in the formulation. This is interesting to understand the behavior of an emulsion after it is applied under the skin. 相似文献
217.
The preparation of several amides and hydrazides from the reaction of the title compounds with different nitrogen nucleophiles is shown to be a general high-yield conversion of synthetic utility. 相似文献
218.
Aluísio S. ReisJr Eliane S. C. Temba Geraldo F. Kastner Roberto P. G. Monteiro 《Journal of Radioanalytical and Nuclear Chemistry》2011,287(2):567-572
Radiochemical separation of Pu, Am and U was tested from synthetic solutions and evaporator concentrate samples from nuclear
power plants for isolation of each of them for alpha-spectrometry analysis. The separation was performed by anion-exchange
chromatography, extraction chromatography, using TRU resin, and precipitation techniques. The aim of the study was to develop
a sensitive analytical procedure for the sequential determination of 242Pu, 238Pu, 239+240Pu, 241Am and 235, 238U in radioactive wastes. 238Pu, 242Pu, 243Am and 232U were used as tracers. The measurements of α emitting radionuclides were performed by semiconductor detector that is used
especially when spectrometric information is needed. For synthetic solutions the chemical recovery was based on associated
iron concentration and was about 93%. 相似文献
219.
Géraldine Lafitte Eliane Espuche Jean-François Gérard 《European Polymer Journal》2011,47(10):1994-2002
A series of PA11/PHAE blends was prepared by melt mixing across the full composition range. Films were obtained for each composition by an extrusion-cast process keeping the same processing conditions. The blends exhibited a two phase morphology. PHAE-rich nodules surrounded by the PA11-rich matrix were observed for PA11 contents higher than 50 wt% in the blends. For lower PA11 weight amounts, PA11 became the dispersed phase and appeared as long fibrillar domains lying in the plane of the film. PA11/PHAE interactions were discussed from DSC and DMA analyses. The effects of the blend composition and morphology on mechanical properties in the linear range and on hydrogen barrier properties were investigated. Hydrogen permeability decreased with increasing amount of PHAE in the blends. A confrontation between the experimental permeability values and the theoretical ones calculated by taking account of the specific properties and morphology of the PA11- and PHAE-rich phases was carried out. In the films series under study, the improvement of hydrogen barrier properties was mainly related to the blend composition whereas a significant effect of the blend morphology was observed on mechanical properties in the rubbery state. 相似文献
220.
Quantification of nitrogen compounds in diesel fuel samples by comprehensive two‐dimensional gas chromatography coupled with quadrupole mass spectrometry
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Gabriela P. S. Maciel Maria E. Machado Michele E. da Cunha Eliane Lazzari Juliana M. da Silva Rosângela A. Jacques Laiza C. Krause Jamily A. S. Barros Elina B. Caramão 《Journal of separation science》2015,38(23):4071-4077
Although several methods for the analysis of nitrogen compounds in diesel fuel have been described in the literature, the demand for rapid, sensitive, and robust analyses has increased in recent years. In this study, a comprehensive two‐dimensional gas chromatographic method was developed for the identification and quantification of nitrogen compounds in diesel fuel samples. The quantification was performed using the standard addition method and the analysis was conducted using comprehensive two‐dimensional gas chromatography coupled with fast quadrupole mass spectrometry. This study is the first to report quantification of nitrogen compounds in diesel fuel samples using the standard addition method without fractionation. This type of analysis was previously performed using many laborious separation steps, which can lead to errors and losses. The proposed method shows good linearity for target nitrogen compounds evaluated (m‐toluidine, 4‐ethylaniline, indole, 7‐methylindole, 7‐ethylindole, carbazole, isoquinoline, 4‐methylquinoline, benzo[h]quinolone, and acridine) over a range from 0.05 to 2.0 mg/L, and limits of detection and quantification of <0.06 and 0.16 mg/L, respectively, for all nitrogen compounds studied. 相似文献