Yu. M. Korolev

X-ray powder diffraction study of polytetrafluoroethylene

Samples of polytetrafluoroethylene were studied by X-ray diffraction. A quantitative X-ray powder diffraction analysis of three components of the polymer was performed for the first time. All samples of polytetrafluoroethylene were found to be three-phase and consist of one crystalline and two amorphous phases. One of the amorphous phases is composed of low-molecular-weight products. The structure of the latter phase was established for the first time by X-ray diffraction methods and computer simulation.

Nanocomposites based on layered silicates and ultrahigh-molecular-mass polyethylene prepared via in situ polymerization

Nanocomposites based on ultrahigh-molecular-mass PE and layered silicates are prepared via in situ polymerization. The process is conducted in the suspension mode under mild conditions with the use of a conventional Ziegler-Natta catalyst and a bifunctional complex containing a nickel oligoallene component along with a titanium component. The fillers are four types of montmorillonite: nonmodified montmorillonite and three montmorillonites modified with various organic intercalants. In their presence, the activities of the catalysts appreciably increase (by a factor of 2–3). Composites containing 10–40 wt % aluminosilicates are prepared. The structures of the polymer matrix and composites are studied via X-ray diffraction. It is found that the degree of exfoliation of the filler depends not only on its amount but also on the type of modifier and the type of catalytic system. The PE matrix with a molecular mass of (1.5–1.6) × 106 has a melting point of T m = 141–143°C, a high enthalpy of melting, and a high degree of crystallinity. The IR-spectral studies of the polymers synthesized with the bifunctional complex reveal the presence of branches in a chain, thereby suggesting the formation of linear PE with a medium density (0.938–0.946 g/cm3). Nanocomposites containing 10% aluminosilicate possess the best complex of mechanical properties relative to that of unfilled polyethylene.

Anisotropic electroconducting polymer-silicate composites based on polyaniline

Approaches for the development of anisotropic electroconducting composite materials based on polyaniline and Na-montmorillonite prepared by the me thods of boundary and intercalation polymerization of aniline and mechanical blending are proposed. Parallel plane compression of solid and plasticized dispersions is shown to lead to the development of primarily planar ordering of anisometric clay particles with sorbed or intercalated polymer; as a result, nanocomposites with anisotropic electrical conductivity are formed. In the prepared polymer-silicate films, the parameter of anisotropy in electrical conductivity achieves 6 × 103.

Catalytic Activity of Tetraarylporphyrins in the Oxidation Reactions of Saturated Hydrocarbons

The oxidation of cyclic hydrocarbons by potassium peroxymonosulfate catalyzed by the iron and manganese complexes of tetra-(4-N-butylpyridinium)porphyrin, tetraphenylporphyrin, and mixed porphyrins containing phenyl and butylpyridyl substituents was studied in an aqueous acetonitrile medium. The test catalysts were dissolved in the reaction medium or adsorbed on layered aluminosilicates. It was found that the immobilization of metal complexes on layered aluminosilicates, as well as the bromination of porphyrins, decreased the activity of catalysts in a number of cases, although it improved their stability. The addition of pyridine in an equimolar amount with respect to metal complexes to the reaction mixture increased the activity of dissolved manganese complexes. An increase in the number of butylpyridyl meso-substituents in a porphyrin molecule improved the catalytic activity of a metal complex.

Obtainment of a metal-polymer coating via the simultaneous combination of electrodeposition on the cathode of oligomeric electrolytes and electrodeposition of metals

The example of a nickel-polymer system is used to propose a new way to obtain an original metal-polymer coating via the simultaneous (in situ) combination of electrodeposition on the cathode of oligomeric electrolytes and electrodeposition of metals. The properties, structures, and morphologies of the resultant coating were examined. It was found that the novel metal-polymer coating exhibits significantly improved protective anticorrosive capabilities and unusual hardness, while preserving its high elasticity.

Formation of nanoparticles of a new metastable copper compound in the copper acetate hydrate/poly(acrylonitrile) heterogeneous system

AbstractWe use X-ray powder diffraction to study heterogeneous solid-phase reactions induced by IR radiation in the system Cu(OOCCH3)2·H2O/PAN and intermediate copper compounds in the synthesis of copper nanoparticles. The composite Cu(OOCCH3)2 · H2O/PAN after annealing contains crystallites of copper (lCu = 16 nm), a new metastable compound Cux>2O (

The effect of the physicomechanical characteristics of the polymer matrix and structure of a filler on the stress-strain behavior of polymer-montmorrilonite nanocomposites

l_{Cu_{x > 2} O}

Manufacture of Synthesis Gas by the Methane Combustion Process: The Formation of Soot and Its Physicochemical Characteristics

= 20 nm), and Cu2O (