A mixture of bulk hexagonal boron nitride (h-BN) with hydrazine, 30% H(2)O(2), HNO(3)/H(2)SO(4), or oleum was heated in an autoclave at 100 °C to produce functionalized h-BN. The product formed stable colloid solutions in water (0.26-0.32 g L(-1)) and N,N-dimethylformamide (0.34-0.52 g L(-1)) upon mild ultrasonication. The yield of "soluble" h-BN reached about 70 wt%. The dispersions contained few-layered h-BN nanosheets with lateral dimensions in the order of several hundred nanometers. The functionalized dispersible h-BN was characterized by IR spectroscopy, X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, UV/Vis spectroscopy, X-ray diffraction (XRD), dynamic light scattering (DLS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and atomic force microscopy (AFM). It is shown that h-BN preserves its hexagonal structure throughout the functionalization procedure. Its exfoliation into thin platelets upon contact with solvents is probably owing to the attachment of hydrophilic functionalities.

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A simple model of a dry reversed micelle of ionic surfactants is proposed, according to which during the optimization procedures the ions move over certain closed surfaces in a vacuum at T = 0 K .The electrostatic interactions of discrete ions in dry, reversed micelles of AOT are calculated as a function of the sizes of the ions, ion charges, and the optimum positions of the ions in the polar cavity of the micelles. It is shown that when the counterions penetrate the layer of the potential-determining ions, the electrostatic interaction begins to favor the self-organization of the ionic surfactants over that of the reversed micelles. The distribution of the electrostatic potential in the polar cavity of micelles of different shapes (a sphere, a spheroid, a prolate ellipsoid) is calculated. In the models in which the charge is taken to be discrete, the electrostatic field extends beyond the double electric layer (DEL); the sign of the potential coincides with that of the counterion. It is shown that in the analysis of structures of dry, reversed micelles the possibility of the formation of voids (in the surface layer of polar groups and in the center) as well as the density of packing should be taken into account by using a specially developed approach. The most probable structural parameters of AOT micelles are determined for different counterions (Li+, Na+, Cs+, [Co(H2O)6]2+, La3+).

Bulk NbS3and NbSe3were stably dispersed in a number of organic solvents to yield colloids containing thin well-crystallized nanoribbons of NbS3and NbSe3.

The electrophoretic mobility of nanoparticles of gold in reversed micelles of AOT was determined, and the nanoparticle electrokinetic potential was calculated. The electrokinetic potential of the particles decreased from 43 to 17 mV with the fall in the solubilization capacity from 1 to 0.2 vol. %. Correspondingly, the hydrodynamic radius decreased from 2.9 to 1.8 nm. On the basis of the electrokinetic studies, a new concentration method was developed, allowing concentration of metal particles with an enrichment factor of ∼10 3 . A simple model of the concentration has been proposed as a process of electrophoretic separation of micelles with gold nanoparticles from the empty ones. The limiting gold concentration in the liquid cathode concentrate (∼1 mol/L) and the concentrate volume have been calculated depending on the organic-phase volume, the solubilization capacity of the micellar solution, and the initial metal ion concentration.

In this work, we tried to combine the advantages of microemulsion and emulsion synthesis to obtain stable concentrated organosols of Ag nanoparticles, promising liquid-phase materials. Starting reagents were successively introduced into a micellar solution of sodium bis-(2-ethylhexyl)­sulfosuccinate (AOT) in n-decane in the dynamic reverse emulsion mode. During the contact of the phases, Ag+ passes into micelles and Na+ passes into emulsion microdroplets through the cation exchange AOTNaOrg + AgNO3 Aq = AOTAgOrg + NaNO3 Aq. High concentrations of NaNO3 and hydrazine in the microdroplets favor an osmotic outflow of water from the micelles, which reduces their polar cavities to ∼2 nm. As a result, silver ions are contained in the micelles, and the reducing agent is present mostly in emulsion microdroplets. The reagents interact in the polar cavities of micelles to form ∼7 nm Ag nanoparticles. The produced nanoparticles are positively charged, which permitted their electrophoretic concentration to obtain liquid concentrates (up to 30% Ag) and a solid Ag–AOT composite (up to 75% Ag). Their treatment at 250 °C leads to the formation of conductive films (180 mOhm per square). The developed technique makes it possible to increase the productivity of the process by ∼30 times and opens up new avenues of practical application for the well-studied microemulsion synthesis.

A simple photometric method for determining the electrophoretic mobility of nano- and microparticles in reverse micelles and in solvents with a low dielectric permittivity (2-5) has been developed. The method is based on the use of a thermostatically controlled diaphragm-based optical cell (length 2 cm) with three vertical plane-parallel electrodes (2 x 3 cm; interelectrode gap, 0.3 cm) placed into a standard photocolorimeter. When an electrostatic field (100-600 V) is applied, the particles begin to move away from the electrode of the same polarity. The path traveled by the particles for a given time (2-30 s) is calculated from the change in the optical density of the solution in the near-electrode zone. The electrophoretic potential of nanoparticles in the model systems, calculated from the values of electrophoretic mobility by Huckel-Onsager theory, varied from 70 (Ag nanoparticles in AOT micelles in decane) to -73 mV (aggregated SiO(2) nanoparticles in a decane-chloroform mixture). Calculations by the classical Deryaguin-Landau-Verwey-Overbeek (DLVO) theory determined the contribution of the electrostatic interaction to the stability of the studied systems. We have shown that the surface charge of nanoparticles permits: (1) an electrophoretic concentration of the charged nanoparticles (Ag) with an enrichment factor of up to 10(4), (2) the separation of nanoparticles with zero (C(60)) and a high (Ag) electrokinetic potentials, and (3) the formation of electrostatically bound aggregates (Ag-SiO(2)) through the heterocoagulation of oppositely charged particles.

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