Vol 80, No 5 (2018)

The relaxation kinetics of polydisperse cylindrical micelles has been numerically studied under different initial conditions corresponding to fast concentration and dilution of a surfactant solution. The kinetic description has been based on a set of difference Smoluchowski equations, which takes into account the capture and release of surfactant monomers by micelles, as well as the fusion and fission of micelles. The dependences of fusion coefficients of cylindrical aggregates on aggregation numbers have been plotted on the basis of the Burgers−Oseen equations for translational motion of spherocylindrical particles in a viscous liquid. The solution of the generalized Smoluchowski kinetic equations obtained for a nonequilibrium distribution of cylindrical micelles over aggregation numbers has been compared with the numerical solution of the Becker−Döring kinetic equations for cylindrical micelles under the same initial conditions given the mechanism of molecular aggregation via the attachment and detachment of surfactant monomers.

It has been shown that silica container particles can be loaded with large amounts of an anionic corrosion inhibitor, sodium N-oleyl sarcosinate, at the stage of the sol−gel synthesis of the particles by using its micelles as a template. When incorporated into paint and varnish coatings, such containers efficiently protect low-carbon steel and D16 aluminum alloy from corrosion under severe conditions of neutral salt spray.

The structural (structural resistance coefficient, volume porosity, average pore radius, and specific surface area) and transport (specific electrical conductivity and counterion transport numbers) characteristics of high-silica micro- and macroporous glasses with different compositions (magnetite-free and magnetite- containing glasses) have been compared in solutions of an indifferent electrolyte (sodium chloride). It has been shown that the incorporation of iron(III) oxide into basic sodium-borosilicate glass changes the structure of the pore space of both microporous glasses produced by acidic leaching and macroporous glasses obtained from the microporous samples by additional alkaline treatment. Moreover, it has been found that the transport characteristics of microporous glasses with different compositions are similar, while, for magnetite- phase-containing macroporous glasses, the specific conductivity of a pore solution and counterion transport numbers are increased.

It has been shown that the presence of small amounts of di-(2-ethylhexyl)phosphoric acid (below 6 mol % in the mixture of surfactants) in a sodium di-(2-ethylhexyl)phosphate–di-(2-ethylhexyl)phosphoric acid–decane–water system widens the region of microemulsion existence with respect water and decreases the slope of the dependence of hydrodynamic droplet diameter of on water-to-sodium di-(2-ethylhexyl) phosphate molar ratio. At di-(2-ethylhexyl)phosphoric acid concentrations in its mixture with sodium di-(2-ethylhexyl)phosphate higher than 6 mol %, the fraction of water bound with ions in microemulsion droplets decreases, the region of microemulsion existence narrows, specific conductance decreases, and the slope of the dependence of the hydrodynamic droplet diameter of on the water-to-sodium di-(2-ethylhexyl) phosphate molar ration increases.

A classical all-atom molecular dynamics simulation has been used to study the adsorption of mesotetra( 3-pyridyl)porphyrin dye on colloidal quantum dots of cadmium selenide. The competition between dye molecules and ligands covering the quantum dots has been investigated by the examples of trioctylphosphine, trioctylphosphine oxide, octadecylphosphonic acid, and hexadecylamine. It has been shown that the dye is strongly retained by the surface and is not washed out with a solvent either from a free surface or in the presence of trioctylphosphine in the shell. The strength of the adsorption of the dye is equal to that of trioctylphosphine. At the same time, it gives up its place on the surface to stronger ligands, octadecylphosphonic acid and hexadecylamine.

Seedless synthesis of gold nanorods with the use of sodium borohydride and hydroquinone as reductants of metal ions has been systematically studied. The effect of reaction system composition on the morphology and optical characteristics of the formed particles has been determined. It has been found that the position of the band of the longitudinal surface plasmon resonance of the nanorods varies nonmonotonically with variations in the concentration of hydroquinone or silver nitrate. The seedless synthesis has been shown to yield high-quality gold nanorods, with the tunable position of their longitudinal surface plasmon resonance in a wide spectral range (from 700 to ~1050 nm). Therewith, the conversion of metal ions is no lower than 78 wt %.

The method of capillary electrokinetics has for the first time been used to measure streaming current at high electrolyte concentrations. It has been shown that the streaming current is proportional to the applied pressure. At an electrolyte concentration of 1 M, the thickness of the diffuse layer is comparable with the size of a water molecule (0.3 nm); i.e., there is almost no diffuse layer. The existence of the streaming current in this case indicates that there are no hydrodynamically immobile layers near a smooth solid surface.

The interaction between asymmetric dimethylhydrazine and thiocontaining mineral schungite-III has been studied. Chromatography–mass spectrometry has been used to identify alkyl polysulfides as the products of desorption of asymmetric dimethylhydrazine from schungite surface. The interaction of asymmetric dimethylhydrazine with crystalline sulfur has been investigated in a model system. Dimethyl polysulfides, CH₃S_nCH₃; (dimethylamino)methyl polysulfides, (CH₃)₂NS_nCH₃; and bis(dimethylamino) polysulfides, (CH₃)₂NS_nN(CH₃)₂, with 2 ≤ n ≤ 4 have been detected. Gas-chromatographic retention indices have been determined for the products of the interaction of asymmetric dimethylhydrazine with sulfur and the schungite material.

The self-consistent theory of nanoaerosol filtration has been considered at small Peclet numbers. It has been shown that, at Pe < 1, it is necessary to consider the deposition of particles simultaneously on thePe < entire ensemble of fibers. Only at can the filtration efficiency be found from the collection efficiencies calculated separately for each fiber. The self-consistent theory has been used to estimate the efficiencies of filtration with polydisperse fibrous filters. The penetrations of particles through filters with different variances of the functions of fiber length distribution over fiber radii have been compared at a constant packing density or a constant total length of all fibers. It has been shown that, at a constant packing density, a rise in the variance leads to a decrease in the filtration efficiency, while, at a constant total fiber length, the efficiency is almost independent of the width of the distribution function.