Production of materials with periodically arranged microparticles by photopolymerization of patterns formed at parametric excitation of capillary surface waves

It is experimentally demonstrated that parametric excitation of capillary waves in a liquid polymer can result in a spatially periodic distribution of microparticles. The distribution of the particles follows the pattern of the waves excited on the surface of the liquid. It is shown that photopolymerization allows positions of microparticles to be fixed and materials with controlled spatially periodic inhomogeneity to be produced.     

Influence of the phase and elemental compositions and defect structure on the physicomechanical properties and tribotechnical characteristics of nanostructural Ti-Hf-Si-N coatings

A new approach to preparing superhard nanostructural Ti-Hf-Si-N coatings with high physicomechanical performance is developed and tested. Samples with Ti-Hf-Si-N nanocoatings obtained under different deposition conditions were investigated using nuclear physical analysis methods, namely, Rutherford backscattering, energy-dispersive X-ray analysis, secondary-ion mass spectrometry, and the slow positron beam method, as well as by conducting X-ray diffraction analysis and microhardness measurements and testing the tribotechnical performance of the films. It is found that the grain size varies from 3.9 to 10.0 nm depending on the bias applied to the substrate and the residual pressure in the chamber during nanocoating deposition. It is shown that the microhardness varies considerably (from 37.4 to 48.6 ± 1.2 GPa) according to the percentage and number of phases, grain size, and material transfer along nanograin boundaries and interfaces. In tribological tests of the Ti-Hf-Si-N nanocoatings, the mechanism of cohesive and adhesive fracture changes and the friction coefficient may vary from 0.46 to 0.15.     

New Hybrid Material Based on Multiwalled Carbon Nanotubes Decorated by Rhenium-Tungsten Nanodendrites

Re–W nanoparticles are deposited onto multiwalled carbon nanotubes by the metal organic chemical vapor deposition technique. A mixture of dirhenium decacarbonyl and tungsten hexacarbonyl is used as a precursor. Nanoparticles of hybrid materials are studied by scanning electron microscopy, high-resolution transmission electron microscopy, and X-ray phase analysis. It is found that in a wide range of ratios of the precursors (dirhenium decacarbonyl and tungsten hexacarbonyl), the crystalline component is a Re–W phase, and the morphology of the nanoparticles is the same as that of the nanodendrites.     

Effect of Impurities on Results of Redoxometric Determination of Molecular Oxygen in Natural and Waste Water by Winkler Method

The possibility of determining dissolved oxygen in natural and waste water by the potentiometric variant of the Winkler method, with samples prepared using the Ross procedure and blank sample technique employed, was studied.     

Formation,properties, and thermal decomposition of bisarene chromium(i) and molybdenum(i) fullerides

Fullerides [(⁶-Ph₂)₂Cr]⁺[C₆₀]^·–, [(⁶-C₁₀H₁₂)₂Cr]⁺[C₆₀]^·– (C₁₀H₁₂ is tetralin), and [(⁶-PhCH₃)₂Mo]⁺[C₆₀]^·– were synthesized. The molecular structure of [(⁶-Ph₂)₂Cr]⁺[C₆₀]^·– was established. In this compound at 100 K, radical anions C₆₀ ^–· are linked by an ordinary bond to form dimers, whereas at 293 K they are disordered and do not form dimers. The [(⁶-tetralin)₂Cr]⁺[C₆₀]^·– fulleride is stable in vacuo (10^–2 Torr) below 429 K, and [(⁶-toluene)₂Mo]⁺[C₆₀]^·– is stable below 581 K.Based on the materials presented at the International Conference Modern Trends in Organoelement and Polymer Chemistry (Moscow, May 30–June 4, 2004) dedicated to the 50th anniversary of the A. N. Nesmeyanov Institute of Organoelement Compounds of the Russian Academy of Sciences.Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1973–1976, September, 2004.     

The liquid–gas interface of oxygen–nitrogen solutions: 1. Surface tension

The capillary method of surface tension measurement has been used to measure the surface tension of oxygen–nitrogen solutions in the temperature range from 80 to 132 K. At temperatures below the nitrogen critical temperature (T_c = 126.2 K) the capillary constant and the surface tension of solutions are smaller than their additive values and vary linearly with the temperature. Experimental data are compared with the results of calculating the surface tension by the theories of Pinnes and Rowlinson.     

The hydeosilylation of functional olefins on nickel catalysts

Russian Chemical Bulletin -     

MOCVD modification of the surface of multiwalled carbon nanotubes to impart to them necessary physicochemical properties

Multiwalled iron-containing carbon nanotubes were synthesized by the MOCVD method with pyrolysis of ferrocene and toluene mixtures in an argon flow at atmospheric pressure. Using the MOCVD method with vacuum pyrolysis of bis-arene-chromium compounds onto the surface of multiwalled carbon nanotubes (MWCNTs), pyrolytic chromium films were deposited and new composite materials MWCNT/pyrolytic chromium were obtained. The composite morphology depends on the conditions of pyrolytic chromium deposition. Regular bead-shaped structures were detected. The mechanism of their appearance due to the formation of bis-arene chromium compounds of the intermediate viscoplastic polymer phase and the onset of Plateau-Rayleigh instability during pyrolysis is discussed.