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EN
A series of mixed oxides was synthesized by deposition of a guest phase on a highly dispersed oxide matrix. Fumed nanooxides SiO2, Al2O3, SiO2/Al2O3, and SiO2/Al2O3/TiO2 with the specific surface area of 65-91 m2/g were selected as highly dispersed matrices. NiO/FexOy was deposited as a guest oxide using solvate-stimulated modification of a surface of fumed nanocarriers with nickel nitrate and iron(III) formate and subsequent heat treatment up to 600 °C to form NiO/FexOy. The aim of this work was to study the influence of the composition and structure of fumed oxide matrices and deposited guest phase on the behavior of the composites in gaseous and aqueous media using XRD, nitrogen adsorption and SEM/EDX, and quasi-elastic light scattering (QELS) methods. The lowtemperature nitrogen adsorption isotherms have a sigmoid shape with a narrow hysteresis loop characteristic of mesoporous materials. The specific surface area of composites varies from 65 to 120 m2/g. SEM data show denser aggregate structure of nanocomposites compared to the initial carriers. The primary particle size was in the 30-60 nm range. According to QELS data, there is a tendency to form aggregates of 100 nm - 10 µm in size in the aqueous media. The XRD method shows that the deposited metal oxides are in the form of crystalline phases of NiO with crystallites of 7-23 nm in size, but the iron oxide reflexes were not identified for NiO-containing composites.
EN
A method of obtaining yttrium citrate by transformation of freshly precipitated yttrium hydroxide in the solutions of sodium citrate under hydrothermal conditions has been proposed. To determine the synthesis time, transformation kinetics consisted in by taking the solid samples for the C and H contents analysis after 6, 12, 24, 48 and 72 hours of synthesis. Simultaneously these samples were subjected to the thermogravimetric analysis. As follows from the thermogravimetric analysis adsorption of citrate dihydrate on yttrium hydroxide is observed in the initial period up to 24 hours. Later the yttrium citrate dihydrate is formed. The thermogravimetric analysis of the final product i.e. amorphous yttrium citrate showed that the decomposition/oxidation of the sample occurs in six stages the particle size analysis method of static light scattering showed that 45% of the particles had a diameter of 0.1-0.9 µm and 55% of particles with sizes from 0.9 to 5 µm.
EN
The surface morphology, structure and hydrophobicity of low-and high-molecular weight poly(dimethylsiloxane) (PDMS) fluids physically adsorbed onto multi-walled carbon nanotubes (MWCNTs) at different weight percentages (5, 10, 20 and 40 wt.%), were studied employing X-ray diffraction (XRD), attenuated total reflectanceFouriertransforminfrared spectroscopy (ATR-FTIR), scanning electron microscopy (SEM) and measurements of contact angle with water. It was found that MWCNTs agglomerate forming voids between tubes of a broad range, while adsorption of the polymer from a hexane solution results in the expected wrapping of nanotubes withPDMS chains and, further, in filling voids, as represented by SEM data. ATR-FTIR was used to investigate the possible structural changes in the polymer nanocomposites. Based on the contact anglemeasurementsvia water drop shape analysis,MWCNTs/PDMS nanocomposites were characterizedas astable,superhydrophobic materials with the maximum contact angle (CA) equal to 152°at CPDMS=40wt.%.
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