Manufacture of Magnesium Oxide Nanoparticles Coated with Silica Shells

MgO@SiO₂ core–shell nanoparticles were manufactured, and a synthetic protocol was developed to prepare MgO nanoparticles where the SiO₂ shell thickness was less than 10 nm. The influence of synthesis parameters on the formation of MgO@SiO₂ nanoparticles was studied. The fact of a SiO₂ shell being formed on the MgO surface was established and the sizes of the thus-prepared MgO@SiO₂ nanoparticles were determined by TEM and Fourier-transform IR spectroscopy.     

Hydroxyapatite nanoparticle prepared by controlled precipitation from aqueous phase

Hydroxyapatite nanoparticles (NPs) were prepared by controlled precipitation in the presence of stabilizers that confined growth and inhibited the aggregation of nanoparticles. Electrostatically stabilized NPs were prepared in the presence of sodium citrate; Tween 80 was used for steric stabilization. At low stabilizer concentrations, nanorods were formed of grown together, spheroidal hydroxyapatite NPs of ~20 nm in diameter. The rod length decreased as ether sodium citrate or Tween 80 concentration increased. When Cit^3–/Ca²⁺ = 3mol/mol, platelike NPs were formed 20–45 nm long and ~10 nm wide; for Cit^3–/Ca²⁺ = 4 mol/mol, NPs had sizes of 10–15 nm. At relatively high Tween 80 concentrations (>0.05 mol/L), foamlike structures were obtained.     

Synthesis of copper nanoparticles stabilized by polyoxyethylenesorbitan monooleate

We studied the influence of synthesis parameters and the composition of the reaction mixture on the size and morphology of copper nanoparticles (NPs). Use of a surfactant (polyoxyethylenesorbitan monooleate) is promising for confining NP growth and stabilizing NPs. Concentration ranges of existence were determined for copper NP dispersions stable to aggregation and sedimentation. Scanning electron microscopy and dynamic light scattering were used to show that: the NP size varied from 10 to 65 nm, the average diameter was 25–35 nm, and the shape was spherical. The sizes of copper NP aggregates were determined.     

Highly porous polymeric sponges for oil sorption

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Lecithin Organogels in a Hydrocarbon Oil

We demonstrated the existence of lecithin organogel at 20°C in a system containing the following components: phospholipid mixture with 40 wt % of phosphatidylcholine, hydrocarbon (vaseline) oil, and water, at phosphatidylcholine concentrations above 1.2 wt % and in the range of W = [H₂O]/[lec] values varying from 3.25 to 7.0. The dependences of the viscosity of lecithin organogels in a hydrocarbon oil on water and lecithin concentrations, as well as on temperature were established.     

Phase Equilibria and Nonequilibrium Structures in the Sodium Di-2-Ethylhexyl Phosphate–Decane–Water System

Phase equilibria and nonequilibrium structures in the sodium di-2-ethylhexyl phosphate (NaSDEHP)–decane–water system were studied. It was found that, at a certain component ratio, a microemulsion and a liquid crystal phase are present in the system. The phase diagram was plotted, describing two- and three-phase equilibria: NaSDEHP and water solution in decane–microemulsion, microemulsion–liquid crystals, NaSDEHP and water solution in decane–microemulsion–liquid crystals, and NaSDEHP and water solution in decane–liquid crystals. The viscosity of NaSDEHP microemulsion was measured. It was shown that the viscosity increases significantly with an increase in the ratio of sodium hydroxide and di-2-ethyhexyl phosphoric acid molar concentrations from 0.6 to 1.0. Formation of the third liquid (microemulsion) phase in the vicinity of the oil–water interface was found upon the transfer of NaSDEHP from one phase to the other.     

Gelation in Extraction Systems with Basic Copper(II) and Neodymium(III) Alkyl Phosphates

Gelation in extraction systems containing purified or commercial di(2-ethylhexyl) hydrogen phosphate (HDEHP), copper(II) or neodymium(III) hydroxides, hydrocarbon solvent, and water was studied at different ratios of the metal and extractant. The region was determined in which gelation caused by formation of basic neodymium(III) di(2-ethylhexyl) phosphates occurs in decane. Some characteristics of organogels in the HDEHP (commercial)-Cu(OH)₂-organic diluent (decane, hexane or toluene)-H₂O extraction systems were studied.     

Microemulsions in Sodium Dodecyl Sulfate–1-Butanol–Extractant–Kerosene–Water Systems for Extracting Nonferrous Metals from Oxide Raw Materials

Russian Journal of Applied Chemistry - Areas of existence and properties of extractant-containing microemulsions in sodium dodecyl...     

The Stability of Highly Concentrated Water-in-Oil Emulsions and Structure of Highly Porous Polystyrene Produced from Them

The porosity of polymer materials produced by polymerizing dispersion media of highly concentrated emulsions may be predicted, provided that the emulsions are stable. The study of the stability of water-in-oil (W/O) emulsions containing styrene as a dispersion medium at 25 and 65°C has shown that emulsions with a dispersed phase fraction of 0.75 and sorbitan monooleate concentrations of 1.5–20.0 vol % are stable to coalescence but are unstable to sedimentation. Emulsions with a dispersed phase fraction of 0.95 are stable to both coalescence and sedimentation at sorbitan monooleate concentrations of 10–20 vol %. Open-pore polymer materials are formed from emulsions with dispersed phase fractions of 0.75 and 0.95 at sorbitan monooleate concentrations of 2.0–3.5 and 10–12 vol %, respectively. At a dispersed phase fraction of 0.75 and a sorbitan monooleate concentration of <2 vol %, a multiple O/W/O emulsion is formed, the polymerization of which yields a porous polymer material containing spherical polystyrene particles inside pores. At higher surfactant concentrations in emulsions with dispersed phase fractions of 0.75 and 0.95 partly destroyed porous materials are formed.     

Ejection of Particles from the Free Surface of Shock-Loaded Lead into Vacuum and Gas Medium

The presence and behavior of a gas–metal interfacial layer at the free surface of shock-wave driven flying vehicles in gases of various compositions and densities has not been sufficiently studied so far. We present new comparative data on “dusting” from the free surface of lead into vacuum and gas as dependent on the surface roughness, pressure amplitude at the shock-wave front, and phase state of the material. Methods of estimating the mass flux of ejected particles in the presence of a gas medium at the free metal surface are proposed.