Quantum-Chemical Estimating Interaction of <i>sp²</i>-Carbon Nanoclusters with PE and PP Oligomers

The purpose of this work was to examine the interaction of graphene-like nanoclusters with fragments of polymers of the same nature, but somewhat different structure, for example, polyethylene (PE) and polypropylene (PP) by means of quantum chemistry. By method of density functional theory with the exchange-correlation functional B3LYP, the basis set 6 - 31 G (d, p) and the Grimme’s dispersion correction, the energy values have been calculated of interaction between nanocarbon fragments and oligomers of PE and PP, the most probable structures of their intermolecular complexes being optimized. A graphene-like plane of 40 carbon atoms and 16 atoms of hydrogen was chosen as a model for the surface of the graphene and carbon nanotubes (CNT). In order to take into account the dimensional effect of the surface of the nanotube fragment model on the interaction energy, in addition to the above described, two larger models were used, with the general formula C54H18 and C96N24. It has been found that the interaction energy of nanocarbon fragment with an oligomer of PP is greater, compared with PE, which is consistent with the experimental data on melting temperatures of pure polymers and nanotube-polymer composites. The polymer with a surface of nanocarbon fragment forms an intermolecular complex not bound covalently and retained by intermolecular dispersion forces. Oligomers of polymeric matters and carbon surfaces in formed nanocomplex are placed closer to each other than separate polymeric links between them.

Modification of Operational Characteristics of Cold Curing Silicon Rubber

Technological aspects of modifying the operational characteristics of cold cured silicate rubbers have been developed. The effect of chromium oxide on the resistance of cold-curing silicone compounds to thermal aging, as well as on the physic mechanical properties and dielectric characteristics has been studied. The various content of ultrafine chromium oxide in cold-cured silicone compositions has been investigated, it’s optimal content in an amount of 2 - 5 mass at 100 mass, including low molecular weight rubber. Chromium oxide has been proven to improve the thermal stability of cold-cured silicone compositions. The manufacturing technology and component composition of the composition with high performance.

Resistance of Epoxypolymer with 2 - 5 wt% Nanosilica in Aggressive Acid Medium

The swelling dynamic and epoxy resin structure changes of nanosilica (NS) with different specific surface in concentrated nitric acid were studied. It is established that with increasing of specific surface area of unmodified NS swelling degree decreases and stability of the composite in the acid goes up. Resistance of NS to the HNO3 can be achieved by choosing the optimal concentration and modifications of NS’s surface. According to electron microscopy and X-ray diffraction, the structure of composite can be changed due to appearance of ordered structural zones.

Study of Thermolysis of Hydrogenated Carbon Molecules as Products of Fullerenization of Benzene, Xylene, Ethanol and Pyridine

Novel essentially distinct from already known (methods of hydrogenation of fullerenes (C60 and C70) or fullerite) method for the synthesis of highly hydrogenated carbon molecules is developed;such approach is perspective hydrogen capacity accumulators. First, the reactionary conditions are created for the realization of the process of fullerenization as direct transformation of molecules of aromatic hydrocarbons, pyridine and ethanol into carbon molecules, fulleranes (С60Н8-С60Н60 and С70Н8-С70Н44) and quasi-fulleranes (CnHn-6-CnHn-2 (n = 20 - 46)) containing up to 5.7 wt% hydrogen. X-ray amorphous powders of hydrogenated carbon molecules in gram amounts are obtained. Appreciable dehydrogenation of such samples of fulleranes and quasi-fulleranes at ~50&degC is began, while dehydrogenation of synthesized from fullerene (or fullerite) fulleranes is observed only at temperatures above 400&degC. Methods of NMR, IR spectroscopy, mass spectrometry MALDI and temperature-programmed desorption mass spectrometry EI are used for the study of condensed products of fullerenization of precursors molecules.

Nanocoatings on 2D Macroporous Silicon Structures

Macroporous silicon formed by photoanodic etching with high aspect ratio and large effective surface is one of the promising materials for the development of 2D photonic structures. We fabricated nanocoatings of CdTe, ZnO, CdS surface nanocrystals and SiO2 layers on macroporous silicon surface. The near-IR optical absorption was investigated and well-separated oscillations with giant amplitude were observed in the spectral ranges of surface level absorption. This process is because of resonance electron scattering on the surface impurity states with the difference between two resonance energies equal to the Wannier-Stark ladder. Macroporous silicon structures with SiO2 nanolayers and CdS nanocrystals are proposed to enhance the photoluminescence of CdS nanoparticles with quantum yield 28%. Addition functionalization of 2D macroporous silicon is a result of the high-pressure oxidation. The structural SiO2 reorganization to orthorhombic phase increases the concentration of paramagnetic Pb centers, EPR signal amplitude and GHz radiation absorption.