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131.
The aqueous polymerization of methyl methacrylate initiated by the bromate-thiourea redox system in dilute HC1 has been investigated under nitrogen atmosphere. The rate of polymerization increases with increasing concentration of thiourea in the range 5 × 10?3?10 × 10?3 M. The percentage of conversion increases with increasing concentration of the catalyst, but beyond 1.5 × 10?2 M, there is a decreasing trend in the rate of polymerization. The rate of polymerization increases with increasing monomer concentration, but beyond 0.184 M the polymerization rate decreases due to gel effect. The rate of polymerization increases with temperature up to 35°C and beyond 40°C a decreasing trend is noticed. The effect of water miscible organic solvents, certain neutral salts on the rate of polymerization has also been investigated. 相似文献
132.
A series of new diamagnetic ruthenium(II) complexes of the type [RuCl(CO)(B)(L)] (where B = PPh3, AsPh3 or Py; L = monobasic tridentate Schiff base ligands derived from o‐aminophenol or o‐aminothiophenol with ethylacetoacetate or ethylbenzoylacetate) have been synthesized and these complexes were characterized by physico‐chemical and spectroscopic methods. Cyclic voltammograms of all the complexes show quasi‐reversible oxidation in the range 0.24–1.05 V and the quasi‐reversible reduction in the range ? 0.14 to ? 0.51 V. The observed redox potentials show little variation with respect to the replacement of triphenyl phosphine/arsine by pyridine. The complexes were tested as catalysts in the oxidation of primary and secondary alcohols using molecular oxygen at room temperature and also in C? C coupling reactions. Further, the antibacterial properties of the free ligands and their metal complexes were evaluated against certain bacteria such as Escherichia coli and Staphylococcus aureus. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
133.
D. K. Padma R. S. Veena 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-4):17-25
Abstract Poly(sulphur oxide) has been prepared by the low temperature thermal decomposition of the lower oxides of sulphur. This yellow, elastic solid resists water hydrolysis. It is unstable at room temperature when stored under vacuum and decomposes slowly to a powdery yellow white cyclic(sulphur oxide) and sulphur dioxide. In the presence of silicon tetrachloride, the thermal decomposition gives rise to an adduct of the lower oxide of sulphur along with the poly(sulphur oxide). The adduct hydrolyses to silica, hydrogen chloride, hydrogen sulphide and hydrogen sulphite. Based on the analysis of the hydrolysed products and the IR data, the adduct is assigned a formula of SiCl4·2(SO), in which the silicon is hexacoordinated. 相似文献
134.
Julien Warnan Yann Pellegrin Errol Blart Fabrice Odobel Wei Zhang Bin Liu Veluru Jagadeesh Babu Seeram Ramakrishna 《Macromolecular rapid communications》2011,32(15):1190-1194
A series of three poly(3‐hexylthiophene) functionalized either with a cyanoacetic acid (CA) or a rhodanine‐3‐acetic acid anchoring groups were synthesized and characterized. The TiO2 based dye‐sensitized solar cells have been fabricated and performances were tested. We show that shorter chain length (15 thiophene units) linked to CA binding group gives good performances as Jsc, Voc, FF and η(%) were 6.93(mA · cm−2), 0.65(V), 0.67 and 3.02%, respectively. A maximum IPCE of ≈50% at 500 nm was recorded with a liquid electrolyte, under AM 1.5 simulated solar irradiance.
135.
V. Siddaiah G. Mahaboob Basha G. Padma Rao U. Viplava Prasad R. Suryachendra Rao 《合成通讯》2013,43(5):627-634
Hantzsch 1,4-dihydropyridines and polyhydroquinoline derivatives were synthesized in good yields by PEG-mediated, catalyst–free synthesis under solvent-free conditions. The products were directly recrystallized from hot methanol. The reaction gave excellent yields with low- as well as high-molecular-weight polyethylene glycols. 相似文献
136.
Clément Cabanetos Wissam Bentoumi Errol Blart Yann Pellegrin Véronique Montembault Yann Bretonnière Chantal Andraud Loic Mager Laurent Fontaine Fabrice Odobel 《先进技术聚合物》2013,24(5):473-477
We report herein the peripheral functionalization of a high glass transition temperature hyperbranched polyimide with a new and highly performing electro‐optic chromophore for the elaboration of a second‐order nonlinear optical material. In this study, the CPO1 chromophore was selected for its very high quadratic hyperpolarizability coefficient (μβ = 31,000 ? 10?48 esu at 1990 nm) and its ease of synthesis in multigram scale. As a result, the new electro‐optic polymer was characterized by an r33 coefficient around 40 pm/V at 1.5 µm, although the poling conditions were not optimized. For sake of comparison, the electro‐optic r33 coefficient of our previously reported similar polymer functionalized with the well‐known Disperse Red One chromophore was also measured using the technique and gave a much lower r33 coefficient. This study underscores that hyperbranched polymers are particularly promising matrices to host highly efficient chromophore to achieve more efficient and more stable electro‐optic devices than classical linear polymers. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
137.
Abstract The graft copolymerization of methyl methacrylate (MMA) onto mulberry silk fibers was studied in aqueous solution using the acetylacetonate oxovanadium (IV) complex. The rate of grafting was investigated by varying the concentration of the monomer and the complex, the acidity of the medium, the solvent composition of the reaction medium, the surfactants, and the inhibitors. The graft yield increases with increasing concentration of the initiator up to 8.75 × 10?5 mol/L, of the monomer up to 0.5634 mol/L, and thereafter it decreases. Among the various vinyl monomers studied, MMA was found to be most suitable for grafting. Grafting increases with increasing concentration of HCIO4 and with increasing temperature. Inhibitors like picryl chloride and hydroquinone significantly decrease the extent of grafting. Alcoholic solvents at a solvents/water ration of 10:90 seem to constitute the most favorable medium for grafting. A suitable reaction scheme has been proposed, and the activation energy calculated from the Arrhenius plots. 相似文献
138.
Polymerization of methyl methacrylate in visible light was studied at 30°C using the α-picoline-chlorine charge-transfer complex as the photoinitiator. Analysis of kinetic and other data indicate that polymerization proceeds via a radical mechanism and that termination is initiator dependent. Chain termination via degradative chain (initiator) transfer appears to be significant. 相似文献
139.
The vinyl polymerization of acrylonitrile initiated by the redox system Mn3+-cyclohexanol was investigated in aqueous sulfuric acid in the temperature range of 30–45° C. The rate of polymerization Rp and the rate of Mn3+ ion disappearance were measured. The effects of certain water-miscible organic solvents and certain anionic, cationic, and nonionic surfactants on the rate of polymerization were investigated. Based on the results obtained, a suitable reaction mechanism involving the formation of a complex between Mn3+ and the alcohol, whose decomposition yields the initiating free radical with the polymer chain being terminated by the mutual combination of growing chains is suggested. 相似文献
140.
Victoria E. Campbell Peerasak Paoprasert Justin D. Mykietyn Insik In David J. McGee Padma Gopalan 《Journal of polymer science. Part A, Polymer chemistry》2007,45(15):3166-3177
A family of fluorinated azobenzene‐based push‐pull chromophores with one, two, and three trifluorovinyl ether (TFV) groups in linear and branched architecture was synthesized and utilized as active materials in the low optical loss electro‐optic (EO) composites. The fluorinated azobenzene chromophores exhibited increased solubility (30–50 wt %) in semifluorinated polymer host, such as perfluorocyclobutane (PFCB) aromatic ether resin after crosslinking, compared with the commercially available nonfluorinated azobenzene chromophore Disperse Red 1 (1–2 wt %). The impact of this approach on the optical properties on the polymer blends is assessed through optical propagation loss measurements and EO characterization. The resulting fluorinated EO composites showed excellent optical clarity, low birefringence, and low optical loss less than 0.5 dB/cm, while giving EO coefficients of about 3–7 pm/V at 1550 nm. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3166–3177, 2007 相似文献