1.
Wettability of Interface Boundaries as an Indicator of Their Properties and State A. M. Emelyanenko Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Leninskii pr. 31, Moscow, 119991 Russia E-mail:
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Received July 25, 2007 Abstract — The method of studying wettability is analyzed in application to the fundamental problems of the physical chemistry of surfaces, such as the structure and properties of interfaces and the characteristics of processes on them, and to the technological aspects related to the development of novel materials. The digital processing of a sessile drop image recently developed provides a qualitatively new accuracy of measuring the contact angle. Besides that, a high speed of mathematical processing of the data in these methods enables one not only to follow the changes in the system parameters, but also create a feedback for the directed control over the parameters. Experimental devices that allow one to study various geometries of interfaces, including a pendant drop, a sessile drop, and a drop on a filament, are described. Factors that affect the contact angle on heterogeneous surfaces are analyzed. The accumulated fundamental knowledge about the relation between the measured contact angle and the properties of the surface studied, in one cases, enables one to get quickly a reliable and detailed information about the roughness, chemical composition, and topology of the surface without using expensive equipment, while in some other cases, provides an additional information that makes it possible to clarify the mechanisms of the interfacial phenomena studied. As examples, some most interesting experimental results concerning the properties of interfaces and the processes proceeding on them are considered. PACS numbers: 68.08.Bc DOI: 10.1134/S0033173208050019
12/09/2008 | 1194 Hits | Print
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2.
Scanning Tunneling Microscopic and Scanning Tunneling Spectroscopic Studies of Nanostructure and Surface Energy Properties of Stainless Steel Kh18N10T. 1. Measurements at Interfaces with Air and 0.01 N HCl solution Yu. M. Stryuchkova and E. V. Kasatkin Karpov Institute of Physical Chemistry, ul. Vorontsovo pole 10, Moscow, 105054 Russia Received November 7, 2007 Abstract — Stainless steel Kh18N10T is studied by electrochemical scanning tunneling microscopy (ESTM) and electrochemical scanning tunneling spectroscopy (ESCS) methods at the interface with air and for the fixedsample and probe potentials in 0.1 N HCl. Local spectral dependences of tunneling current on the tunneling voltage (It,Ut) are studied in either air or solution in the vicinity of potentials corresponding to stable properties. The local tunneling conductivity (G), the coefficient of the probability of tunneling transfer of an electron to the tip (), and the logarithmic-dependence slope ( = Ut/ln(It) are calculated. As for Fe–Cr alloys, it is shown that at the atomic level, the local energy properties of a steel Kh18N10T are determined by the mutual effect of neighboring atoms (the matrix effect). PACS numbers: 68.37.Ef, 81.07.-b DOI: 10.1134/S0033173208050020
12/09/2008 | 1219 Hits | Print
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3.
The Effect of Sulfate and Nitrate Ions on the Passivation and Activation of Silver in Alkaline Solutions N. N. Lesnykh, N. M. Tutukina, and I. K. Marshakov Voronezh State University, Universitetskaya pl. 1, Voronezh, 394006 Russia E-mail:
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Received December 10, 2007 Abstract — Based on the concept of a competitive adsorption of hydroxide ions with S and N activating anions, some peculiarities of the anodic behavior of silver in alkaline solutions containing sulfates or nitrates are explained. At the ascending branches of the anodic peaks, a co-adsorption of OH and S or N results in the formation of mixed adsorption complexes, which are soluble better than hydroxide ones. An increase in the part of the soluble oxidation products of silver is observed if a rotating disc electrode with a ring is used. Passivation of silver is explained by a change in the electronic structure of the adsorption complexes when certain potential values are reached, while a local activation, by the destruction of these complexes at the passive state potentials between the anodic peaks. At the depassivation, pH value of the solution in pits decreases, which results in the formation of Ag2SO4 or AgNO3 salts. The presence of the salts in a deposit on the electrode is confirmed by the appearance of a C3 cathodic peak. PACS numbers: 82.45.Bb DOI: 10.1134/S0033173208050032
12/09/2008 | 1295 Hits | Print
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4.
Molecular Nanocrystals in Polyaniline-based Light-Emitting Diode Structures E. I. Mal’tsev, D. A. Lypenko, O. M. Perelygina, V. F. Ivanov, O. L. Gribkova, M. A. Brusentseva, and A. V. Vannikov Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Leninskii pr. 31, Moscow, 119991 Russia E-mail:
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Received February 29, 2008 Abstract - It is found that one of the types of molecular organic nanocrystals, the so-called J-aggregates, is able to modify optoelectronic properties of electroactive polymers. It is intrinsic that the polyaniline interpolymeric complex, known as p-type semiconductor, turns into electroluminescent material in the presence of Jaggregates of 3,3-di(gamma-sulfopropyl)-5,5-dichlorotiamonomethincyanine triethylammonium salt. During the studying of new organic light-emitting diode structures, in which the polyaniline/J-aggregates polymeric composite forms both recombination and emitting layers, a polyaniline intrinsic electroluminescence spectrum is obtained. The electroluminescence band completely coincides with the polyaniline photoluminescence spectrum; it has maximum at 400 nm. The electroluminescence mechanism in the studied nanocomposites is discussed. PACS numbers: 78.67.Bf DOI: 10.1134/S0033173208050044
12/09/2008 | 1324 Hits | Print
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5.
AFM Study of the Structuration of an Ionic Surfactant and Phenylalanine with -Carrageenan D. V. Kolesov*,**, T. E. Grigor’ev**, D. Yu. Gavrilko*, E. E. Makhaeva**, I. V. Yaminskii**, and A. R. Khokhlov** * Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Leninskii pr. 31, Moscow, 119991 Russia ** Department of Physics, Moscow State University, Vorob’evy gory, Moscow, 119992 Russia E-mail:
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Received March 6, 2008 Abstract — Local networks of -carrageenan adsorbed in the presence of an ionic surfactant and phenylalanine were examined by atomic force microscopy (AFM). Polymer chains of adsorbed carrageenan are aligned with crystallographic axes. The helical and globular conformations of carrageenan effectively bind the surfactant. Phenylalanine is not involved in the structuration of the carrageenan gel. PACS numbers: 87.64.Dz DOI: 10.1134/S0033173208050056
12/09/2008 | 1245 Hits | Print
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6.
Conversion of the Surface Layers of Poly(Vinyl Chloride) into Aminoethyl Podand Nanofilms as a Matrix at the Surface of Borane-Selective Sorbents A. Yu. Tsivadze, A. Ya. Fridman, N. P. Sokolova, E. M. Morozova, I. A. Gagina, A. M. Gorbunov, A. V. Dorokhov, and A. Yu. Masanov Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Leninskii pr. 31, Moscow, 119991 Russia Received June 28, 2007 Abstract — Nondetachable nanofilms of aminoethyl podands were obtained at the developed surface of PVC materials. Interactions of these films with gaseous boranes were studied for use as a hydrogen source. The steps of surface development were checked and the nature of diborane absorption was studied by FTIR spectroscopy. PACS numbers: 68.47.Pe, 82.35.Gh DOI: 10.1134/S0033173208050068
12/09/2008 | 1252 Hits | Print
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7.
Phase Nanotomography in the Superficial Layers V. A. Kotenev, D. N. Tyrin, and A. Yu. Tsivadze Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Leninskii pr. 31, Moscow, 119991 Russia E-mail:
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Received June 27, 2007 Abstract — A method of phase nanotomography and spectral multiplexing for a nondestructive monitoring of the nanoscale disturbance of refractive index distribution across the nonuniform near-electrode layer at a metal/solution interface is analyzed. It is shown that the amplitude Fourier-spectroscopy of reflection from the nonuniform near-electrode layer with a weak (nanoscale) disturbance of the complex refractive index profile, and weak optical parameters dispersion makes one realize the multiplex principle of measuring and reconstructing the refractive index (and hence, the concentration) distribution across the near-electrode solution layer by using either interference pattern or additional Fourier-transform. Combining the multiplex reconstruction of a three-dimensional profile of the dissolved-products layer and the standard Fourier-spectroscopy allows in situ controlling both the metal dissolution intensity at any point of its surface and the metal dissolution product composition over each section of the near-electrode layer. PACS numbers: 81.70.Tx; 78.67.-n DOI: 10.1134/S003317320805007X
12/09/2008 | 1374 Hits | Print
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8.
The Detection of the Effect of Viscosity Growth in Nanodisperse Systems during Their Shearing with Ultralow Rates N. B. Ur’ev, Yu. S. Svistunov, A. N. Potapov, and V. A. Starikov Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Leninskii pr. 31, Moscow, 119991 Russia E-mail:
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Received March 12, 2008 Abstract — With a precision Haake RS1 rheometer, it is first found that at extremely low rates of shear ( 103 to 10–4 s–1 or lower), in nanodisperse systems based on highly dispersed aerosil or aerosil–bentonite compositions, with an increase in the shear rate, a non-Newtonian flow is observed. It is accompanied with a continuous growth of the effective viscosity of the dispersions eff, till the yield point P Pk is reached. At P Pk, the effective viscosity decreases abruptly; the structure decomposes via an aggregate mechanism. Earlier it was believed, that each viscosity level there corresponds to a combination of the full destruction of structural bonds and their partial restoring up to the equilibrium level determined by eff. In addition, the structured dispersed system flow remains Newtonian unless the static yield point has been overcome; it corresponds to the largest viscosity of a virtually undestructed system. Using a special procedure, SEM-imaging of the structure of the bentonite-suspension, as well as the bentonite added with minor amounts of aerosil, was carried out in waterethanol medium. Photomicrographs of structure of the studied nanodisperse systems subject to shearing were obtained. The active filler (aerosil) particles distribution in the model system structure is studied. A procedure of studying the thixotropic properties of the structured nanodisperse systems in dynamic conditions is developed. The complex modeling of the structured nanodisperse system spreading over the scaled physical model, as well as special conditions of rheological tests in the Haake RS1 rotational rheometer cell, made us detecting a correlation between the spreading macroscopic factors and microscopic factors of the rheological behavior of the nanodisperse systems structure in dynamic conditions. PACS numbers: 47.57.qk; 81.07.-b DOI: 10.1134/S0033173208050081
12/09/2008 | 1278 Hits | Print
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9.
Chemical Synthesis of Stable Nano-Sized Water-Organic Copper Dispersions I. N. Terskaya, D. S. Sal’nikov, S. V. Makarov, O. V. Yarovaya*, and S. A. Lilin** Ivanovo State University of Chemistry and Technology, pr. F. Engel’sa 7, Ivanovo, 153000 Russia; * D.I. Mendeleev University of Chemical Technology of Russia, Miusskaya pl. 9, Moscow, 125047 Russia; ** Institute of Solution Chemistry, Russian Academy of Sciences, ul. Akademicheskaya 1, Ivanovo, 153045 Russia E-mail:
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Received January 25, 2008 Abstract — The formation of aggregatively stable copper dispersions by the reduction of copper salts with thiourea dioxide or sodium hydroxymethane sulfinate in a water–organic solvent is studied. X-ray electron spectroscopy and photon correlation spectroscopy showed that the chemically formed copper exists as nano-sized particles. PACS numbers: 81.07.-b DOI: 10.1134/S0033173208050093
12/09/2008 | 1296 Hits | Print
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10.
Films Containing Nickel and Iron Compounds on Aluminum and Titanium V. S. Rudnev and V. P. Morozova Institute of Chemistry, Russian Academy of Science, Far-East Division, pr. 100-Letiya Vladivostoka 159, Vladivostok, 690022 Russia E-mail:
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Received March 19, 2007 Abstract — The composition of films formed by plasma electrochemical oxidation–deposition on aluminum and titanium in aqueous solutions containing both Ni(II) and Fe(III) polyphosphate complexes is studied. Elementary compositions of the outer part of the layers on aluminum and titanium differ insubstantially. Concentrations of nickel and iron (up to 30 wt %) in the films vary in proportion to their molar ratio in the electrolyte. Upon annealing in air, simple and multiple metal (M) oxides and phosphates crystallize in the layers, particularly, AlPO4, NiAl2O4, and Fe2O3 on aluminum, while Ni2P2O7, Ni0.5TiOPO4; NaTi2(PO4)3, M(II)M(III)Ti(PO4)3, FePO4, and Fe2Fe(P2O7) on titanium. PACS numbers: 82.45.Cc; 81.15.Pq DOI: 10.1134/S003317320805010X
12/09/2008 | 1274 Hits | Print
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