- Silver nanoparticles capped by long-chain unsaturated carboxylates
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We study the preparation and capping of silver nanoparticles by several unsaturated long-chain carboxylates. UV-visible and FTIR spectroscopy and high-resolution electron microscopy are used to characterize the effect of the chain length, its configuration, and the degree of unsaturation on the size distribution of the nanoparticles. Langmuir layers and Langmuir-Blodgett films are used to study the adsorption of these carboxylates on the particles. We find that unsaturated carboxylates in the cis configuration are useful stabilizers for the control of particle size and its surface properties. ? 1999 American Chemical Society.
- Wang, Wei,Chen, Xiao,Efrima, Shlomo
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- Phase behavior of organic-inorganic crystal: Temperature-dependent diffuse reflectance infrared spectroscopy of silver stearate
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We have investigated the structure and phase behavior of nonmolecularly layered silver stearate by means of temperature-dependent diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy. Upon heating the sample, remarkable spectral changes took place. The first phase transition took place that might be associated with a premelting event characterized by the formation of gauche conformers at 390-420 K. A second phase transition took place in which silver nanoparticles with a size of ~4 nm were formed by thermal decomposition of silver stearate at 520-550 K. These silver nanoparticles, derivatized by stearate, were readily spread as a monolayer at air/water interface, and could be packed in 3-D assemblies by the Langmuir-Blodgett method.
- Lee,Han,Choi,Kim
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- Morphologic characteristics of bismuth and silver particles formed upon the reduction of metal stearates with benzyl alcohol
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The products of the reduction of individual and mixed bismuth oxohydroxostearate and silver stearate with benzyl alcohol are studied by electron microscopy and X-ray powder diffraction. The reduction of mixed bismuth and silver carboxylates with benzyl alcohol is a promising route to both individual submicronzised bismuth and silver metal powders and to their alloys. Nauka/Interperiodica 2007.
- Bokhonov,Yukhin
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- Structural, odd-even chain alternation and thermal investigation of a homologous series of anhydrous silver(i) n-alkanoates
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Molecular and lattice structures of a homologous series (nc = 8-20, inclusive) of silver (i) n-alkanoates are determined from X-ray Powder Diffraction, Solid State spin decoupled 13C-NMR and variable temperature Fourier Transform Infrared Spectroscopies. The compounds crystallize in a monoclinic crystal system with hydrocarbon chains in the fully extended all-trans conformation. Moreover, the chains are tilted ca. 75° with respect to the metal basal plane and are arranged as methyl(tail)-to-methyl(tail) bilayers within a lamellar. The methyl chain ends, from different layers in the bilayer, do not overlap but are in such close proximity to cause methyl-methyl interactions. In a molecule, two carboxylate groups bind in a syn-syn type bridging bidentate mode to two silver atoms to form an eight-membered structure. Intramolecular silver-silver and intermolecular Ag-O-Ag interactions stabilize the head group and promote the formation of layer type polymeric sheets. Though the compounds are nearly isostructural, odd-even chain alternation is observed in density, anti-symmetric stretching vibrations of methyl and unusually, carboxylate (head) groups, as a result of packing differences of hydrocarbon chains within the crystal lattice. These arise from the relative vertical distances between polymeric sheets, which are not in the same plane. Thus, for odd chain length compounds, where those distances are less than for even chains, more ordered packing and hence higher densities are observed for these adducts. Also, the numbers and natures of the thermotropic phase transitions are chain length dependent and irreversible. The Royal Society of Chemistry 2012.
- Nelson, Peter Nattaniel,Ellis, Henry Anthony
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p. 2632 - 2638
(2012/04/10)
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- FATTY ACID METAL SALT FOR FORMING ULTRAFINE METAL PARTICLE
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A fatty acid metal salt used for forming ultrafine metal particles satisfying at least one of that: (i) the water content is 200 ppm or less; (ii) the volume-cumulative particle diameter D90 is 80 μm or smaller as measured by the particle size distribution measuring method of the laser diffraction/scattering type; or (iii) a metal of an atomic weight of 50 to 200 is contained, and the amount of the unreacted substance or the by-product is 4.0 mol% or less when the fatty acid metal salt is formed. The fatty acid metal salt can be favorably used for forming ultrafine metal particles in a resin, or for forming a resin composition, a coating, a dispersion solution or a molded article containing the ultrafine metal particles.
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Page/Page column 11
(2010/11/19)
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- Microwave-assisted preparation of silver nanoparticles
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We succeeded in preparing silver (Ag) nanoparticles by alcohol reduction of fatty acid silver salts under microwave irradiation (2.45 GHz) for 1-5 min at 413-430 K. The average sizes of Ag nanoparticles were controlled in the range from 4.9 to 7.4 nm only
- Yamamoto, Tetsushi,Wada, Yuji,Sakata, Takao,Mori, Hirotaro,Goto, Masaki,Hibino, Shingo,Yanagida, Shozo
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p. 158 - 159
(2007/10/03)
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- Liquid Phase Oxidation of s-Butyltoluene
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Oxidation of s-butyltoluene (SBT) to its hydroperoxide (ROOH) by oxygen has been studied in the presence and absence of catalysts in aqueous suspension at 80 deg to 116 deg C and 1 to 8.5 kg/cm2 O2 pressure.The oxidation rate is higher at higher pressures and the selectivity to ROOH formation is the highest when no catalyst is used.Effects of various reaction parameters have been studied in the absence of catalyst.A reaction temperature of 100 deg, SBT-water ratio of 1:2 and oxygen pressure of more than 3 kg/cm2 are found to be the most suitable for ROOH formation.Oxidation above 11.5percent ROOH level leads mainly to byproducts including s-butylbenzoic acid.
- Kulsrestha, Girendra N.,Pathania, Bikram S.,Sharma, Krishna G.,Sharma, Jaipal S.,Negi, Janaki,Bhattacharyya, Kshitindra K.
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p. 636 - 638
(2007/10/02)
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