The study demonstrates the possibility of direct surface modification of colloidal silicon dioxide with polyantimonic acid without preliminary treatment or functionalization of the silica surface. The porosity values, bulk and pycnometric densities were determined for both mechanical mixtures of colloidal silicon dioxide with polyantimonic acid and for colloidal silicon dioxide particles that were surface-modified with polyantimonic acid. Micrographs and particle size distribution curves reveal that surface modification of colloidal silicon dioxide with polyantimonic acid results in formation of nearly monodisperse particles with size of about 100 nm. IR spectroscopy confirmed the formation of chemical bonds between the surface of colloidal silicon dioxide and polyantimonic acid.

A theoretical study of new polymorphic varieties of boron nitride, which have diamond-like structures with boron and nitrogen atoms in equivalent structural positions, was carried out. The model construction of new phases of boron nitride was performed in the process of crosslinking of precursor nanostructures. Single-walled boron nitride nanotubes with chirality indices (3;0), (4;0), and (6;0) were chosen as precursors for the model construction of diamond-like phases. Using the density functional theory method in the generalized gradient approximation, the possibility of stable existence of three new structural varieties of boron nitride with a diamond-like structure, namely, BN-TA4, BN-TA5, and BN-TA6, was established: the structure of the BN-TA7 diamond-like phase turned out to be unstable and, in the process of geometric optimization, was transformed into the initial structure, a boron nitride nanotube (6;0). As a structural characteristic, the bulk density of new polymorphs was determined to be in the range from 2.613 to 3.0836 g/cm3. The sublimation energy of new polymorphic varieties ranged from 17.16 to 17.63 eV/(BN). The value of the band gap near the Fermi energy varied from 5.37 to 5.74 eV.

Tungsten antimony acids (TAA) with the composition H(2)Sb(2)WXO6·nH2O (0 < x ≤ 1.45; 0 < n ≤ 2.0) have been synthesized by hydrolysis of antimony trichloride pre-oxidized with nitric acid in the presence of varying amounts of Na2WO4. To obtain TAA protonated forms, the samples were kept in a 96% solution of sulphuric acid, the precipitate was washed until reaction became neutral and dried in air. The amount of tungsten, antimony, and silver ions in TAA was determined using energy dispersive analysis. Changes in structural parameters upon doping of AA with tungsten ions were studied using a Bruker D8 ADVANCE X-ray diffractometer (CuKa1-radiation). The number of oxonium ions in TAA was determined by the substitution of these ions by silver ions in equivalent amounts (Ag+-TAA forms). All obtained TAA samples and Ag+ TAA forms had a pyrochlore-type structure, space group symmetry Fd3m. Refinement of the arrangement of atoms in the structure using the Rietveld method showed that tungsten ions replace antimony ions and are statistically located in 16c, oxygen anions in 48f, and oxonium ions and water molecules in 16d and 8b positions, respectively. When tungsten ions were introduced into samples, the structural parameters of the resulting phases changed. There was a decrease in the unit cell parameter and the distance between antimony ions and oxygen anions, while an increase in the distance between oxonium ions and oxygen anions located in 48f positions was observed. This allowed the removal of a proton from oxonium molecules and its transport via a system of hydrogen bonds formed by water molecules

Modification of starch with synthetic polymers under mechanochemical activation is a convenient way to regulate the operational properties of composite materials. The widespread use of this approach is limited by the lack of data on the influence of synthetic polymer nature on the properties of starch and the absence of clear criteria for modifiers selection in the form of aqueous dispersions. To eliminate existing problems, the work proposes to use five integral criteria - polarity, hydrophilicity, and flexibility of synthetic modifiers, as well as particle size and zeta-potential of their aqueous dispersions. To achieve this goal, we studied the dielectric constant, contact angles, IR spectra, and dynamic mechanical properties of four acrylic copolymers and an aliphatic polyurethane. Using the mechanochemical activation, blends and composite films based on corn starch and synthetic modifiers (80:20) were manufactured. Methods of rotational viscometry, X-ray diffraction analysis, DMA, mechanical tests, and moisture permeability allowed us to reveal the influence of the modifier integral parameters on the rheological characteristics of the molding blends and the impact of joint mechanical activation on them, as well as on the crystal structure of the composites, their storage modulus, strength, and transport characteristics.

The possibility of synthesising ion-substituted forms of hydrated silver antimonates has been studied. For the synthesis, the method of mechanochemical activation of the components of an inorganic mixture consisting of polyantimonic acid (PAA) with composition and silver nitrate with the concentration range from 0.0 to 1.0 has been applied. The results of studies of the phase composition of the synthesized compounds and their structural features are presented. Using the Rietveld method, the parameters of the crystal lattice of PAA hydrated ionsubstituted silver forms with a pyrochlore-type structure have been refined. The model for the occupation of metal ions by crystallographic positions has been proposed: the framework of the structure of the compounds is formed by 16c- and 48f-positions, in which Sb5+ and O2- are statistically located; hydrated oxonium ions (H3O+) and silver ions occupy 16d- and 8b-positions respectively. It has been shown that the synthesis of silver forms of PAA is preferably carried out by the mechanochemical synthesis, which results in the complete substitution of proton groups by silver ions in the structure of the compounds.

The rheological properties of starch-latex blends mechanically activated in a rotary-pulse apparatus were studied. Several integral criteria—flexibility, polarity and hydrophilicity of macromolecules, particle size and electrokinetic potential—were chosen to evaluate the effectiveness of starch modification with synthetic copolymer latexes. An increase in the blends viscosity was shown to observe for more flexible polymers Binder RA, Binder AF, Ruzin with a glass transition temperature (Tg) below 25°C. Polymers BAK-R and Aquapol with high values of the modulus E′ reduce viscosity. The hydrophilicity of synthetic copolymers and their particle size promote an increase in the blends viscosity.

A review of the work in the field of design, study of properties, and application of liquid crystal materials and acrylamide porphyrin polymers, performed at the Department of Chemistry and Technology of High-molecular Compounds, in the laboratory of Supramolecular and liquid crystal systems and in the laboratory of Polymer materials of the Research Institute of Macroheter-ocyclic compounds of the Ivanovo State University of Chemical Technology over the past 10 years, is presented. Synthetic methods were developed, mesogenic compounds and mixed liquid crystal compositions based on classical and supramolecular mesogens doped with additives containing polar, amphiprotic and chiral groups were obtained and studied. The mechanisms of chiral transport in the mesophase were studied. The results on the use of liquid crystals as light and heat stabilizers of polymeric materials are presented. Stationary phases for gas-liquid chromatography based on supramolecular mesogens, macroheterocyclic compounds with high structural selectivi-ty with respect to various isomers were developed. Methods have been developed for the synthesis of water-soluble porphyrin polymers and porphyrin-containing hydrogels based on acrylamide and synthetic porphyrin monomers, realizable both under thermal heating and under microwave radiation. It is shown that a change in the ratio and nature of the components, as well as the polymerization conditions in the synthesis of porphyrin polymers provides targeted control of the properties of the resulting compounds. The molecular-mass and spectral characteristics of the ob-tained polymers, their surface morphology and sorption properties of porphyrin-containing acrylamide hydrogels are investigated.

The mesomorphic, optical, dielectric, and orientation properties of nematic mixture CB-2 doped with chiral bis(camphorylidene)ethylendiamine were studied. The cleaning temperatures of mixtures were measured by polarization microscopy. The destabilization of the mesophase upon the introduction of a dopant was assessed. The helix pitch of the induced chiral nematic in mixtures was measured. The effect of a chiral dopant on the anisotropic characteristics of the mesophase was studied.

A theoretical study of the structure and electronic properties of three new polymorphic varieties of diamond-like phases of boron nitride, the atoms of which are in equivalent crystallographic positions, was carried out by the density functional theory (DFT) method in the generalized gradient approximation (GGA). The primary structures of these phases were built modelically from the corresponding carbon diamond-like phases by replacing carbon atoms with alternating boron and nitrogen atoms, so that an atom of one kind was surrounded by atoms of another kind. As a result of the calculations, the possibility of stable existence of new structural varieties of boron nitride was established: BN-TA1, BN-TA2, BN-TA3. The sublimation energy of new BN phases varies from 17.08 to 17.59 eV(BN)−1. The new BN polymorphs are wide-gap semiconductors with a band gap at the Fermi energy level from 3.6925 to 5.4565 eV.

The mesomorphic, dielectric, orientational and rheological properties of the induced chiral nematic phase on the base of 4-butyl-4'-octanoyloxyazoxybenzene (C4-AB-OCOC7) doped with 1R(+)-1',7',7'-trimethyl bicyclo[2.2.1]heptane[2',3'-b]-2,3-dicyanopyrazine ((R+)CDCP) and (2R,3R)()2,3 butanediol (R-)BD were studied. The clearing temperatures and the pitch were measured, and the value of the helical twisting power were calculated. A strong influence of the dopants structure on the thermal stability of the spiral phase and the dielectric anisotropy was shown. An increase in the orientational order parameter LC upon doping with a chiral diol and the formation of its H-bond with the ester group of the terminal substituent were established by H-1 NMR. Stable structures of dopant - LC solvates, their dipole moments, anisotropy of polarizability and formation energy have been established by DFT simulation. The determining influence of local dipole-dipole contacts and H-bonds on the structure and properties of solvates has been substantiated. The calculated data allowed to establish the reasons for the effect of dopants on the physical properties of the spiral phases. The effect of (2R, 3R) (-) 2,3 butanediol on the kinematic viscosity of two nematic solvents - C4-AB-OCOC7 and a binary mixture of alkoxycyanobiphenyls (CB-2) was investigated. The influence of the dopant was shown to be determined by the geometry of solvates formed due to local H-bonds with electron-donor moieties of nematic solvents. (C) 2021 Elsevier B.V. All rights reserved.

To search for new effective inducers of helical liquid-crystalline phases, chlorin e6 13 (N)-methylamide-15,17-dimethyl ester (MADMECl) and its nickel complex (Ni-MADMECl) were studied. An increase in the optical activity of the chlorin e6 derivative upon complexation with nickel, associated with a distortion of the macrocycle structure, was established by circular dichroism spectroscopy and quantum chemistry. The introduction of a macrocyclic complex into binary LC mixtures based on cyanobiphenyls (CB-2) and Schiff bases (SB-2), as well as the macrocyclic ligand MADMECl in CB-2, was shown to induce the formation of helical LC phases with high helical twisting power (maximum HTP = 409 mu m(-1) for the mixture CB-2 + Ni-MADMECl). The HTP decreases with an increase in the additive concentration. The assessment of the dopant influence on the LC thermal stability was carried out. The temperature dependences of the permittivity components of the studied liquid-crystalline solutions were obtained at different dopant concentrations. The relationship between the dielectric anisotropy and the helical pitch is established due to the 3D compensation of molecular dipoles. Quantum-chemical simulation of dopant-LC solvates was performed. The influence of the energy of intermolecular interaction on the efficiency of nematic phase twisting was ascertained. The contribution of supramolecular chirality to the process of chiral induction was detected. (C) 2021 Elsevier B.V. All rights reserved.

The molecular polarizability and dipole moments of the fragments of copolymer fluoroelastomers was evaluated by the quantum chemical method. It was shown that the polarity of fluororubbers is provided by the presence of vinylidene fluoride units. The dynamic mechanical analysis method was used to obtain the frequency and temperature dependencies of the storage modulus E′ and the mechanical loss tangent tan δ of fluororubbers and vulcanizates on their basis. The characteristic features of the influence of the rubbers composition and vulcanization on the mechanical and thermophysical characteristics of elastomers were established. The values of tensile strength and elongation at break were obtained for vulcanizates of the studied fluoroelastomers, as well as the Mooney viscosity and the compression set values. The crucial influence of the rubber polarity and the vulcanization network parameters on the specified parameters was identified. The swelling kinetics of rubbers and vulcanizates on their basis in 1,2-dichloroethane at 50°С was studied. The sorption limitation degree of the solvent at the appearance of the vulcanization network and its parameters were evaluated. It was found that with regard to the reduction in their equilibrium degree and swelling rate in dichloroethane, elastomers go in the following order: SKF-26 > Elaftor 3061R > Elaftor 7075 > Elaftor 1000R, symbatically to the decrease in their polarity.

The formation of a chiral nematic mesophase by doping a liquid crystalline mixture of 4-alkyloxy-4′-cyanobiphenyls with chiral 4-[(S)-2-methyl-3-hydroxypropyloxy]-4′-cyanobiphenyl was determined by polarizing thermomicroscopy. The temperature dependences of the mixtures permittivity were measured. A decrease in the dielectric anisotropy was shown with an increase in the chiral dopant concentration associated with a change in the mesophase associative state and induction of the chiral mesophase.

The mesomorphic and anisotropic properties of the induced chiral nematic phase in a mixture of substituted cyanobiphenyls (CB6) doped with chiral (1S, 2R, 5S) - (+) - menthol and its acetate are studied. The clearing temperatures and the pitchweremeasured, and the value of the helical twisting power beta were calculated. An insignificant effect of chiral menthol, its racemate and acetate on the clearing temperature of the LC mixture, bire-fringence, and orientational ordering is shown. At the same time, the dielectric anisotropy of the helical phase CB6 + chiral dopant was found to strongly depend on the degree of mesophase twisting and the intensity of the magnetic field applied to the sample. Similar effects were shown in the study of kinematic viscosity. Based on the results of the Kirkwood's correlation parameter analysis and quantum-chemical calculations, it was shown that the introduction of the chiral mentol and menthyl acetate dopant leads to a change in the associative state of the LC matrix due to the formation of hydrogen bond of menthol and dipole-dipole contact of menthyl acetate with host molecules. (C) 2020 Elsevier B.V. All rights reserved.

Induction of helical mesophases by incorporating chiral dopants into the nematics matrix is the promising modern trends in the chemistry of liquid crystals. This process is associated with a unique phenomenon - an amplification of chirality in liquid-crystalline phases, which ensures the detection of enantiomers by their chiral induction, much more sensitive than other methods. The relevance of this approach is due to the need to create perspective electro-optical devices operating with ultra-low control voltages based on twist effects, chromatographic stationary phases with high chiral selectivity, flexible magnets, photo-sensitive nanostructures, and other smart LC materials. The successful solution of these problems is impossible without experimental research and theoretical comprehension of the mechanisms of third level chiral transfer optically active dopant – nematic liquid crystal. In the last decade, a large number of works have appeared on the solution of these problems. This review is devoted to a generalization of the experimental results and a theoretical description of the transfer of molecular chirality to orientationally ordered systems with the participation of both chiral molecular substituents with an asymmetric carbon atom and planar or quasi-planar fragments chirally distorted relative to each other. The stereochemical aspects of induction associated with the structural correspondences of the dopant and nematic liquid crystal, as well as the main classes of optically active additives, are discussed. Application of metal complexes, both Werner and macroheterocyclic, are presented. Special attention is paid to the results of the mechanisms study of chiral transfer due to various intermolecular interactions: hydrogen bonding, axial coordination, and the formation of inclusion compounds. The high efficiency of induction of spiral mesophases has been demonstrated with a combination of different self-assembly mechanisms in liquid crystal - chiral additive systems.

In compounds, crystallized within the pyrochlore-type structure (sp.gr. Fd3m) of the А2В2X6X’ general formula, there could be doubly or triply charged ions in the place of A cations, quadruply or quintuply charged ions in the place of B cations. Most works are devoted to the formation of these structures, depending on the nature and sizes of A and B cations, while little attention has been paid to determining the temperature ranges of their stability. The aim of this work was to study the thermolysis of substitutional solid solutions H2Sb2–xVxO6·nH2O in the range of 25–700 °C and the determination of the infl uence of the nature of B (Sb, V) cation on the stability of pyrochlore-type structures during heating. Substitutional solid solutions have been obtained by the co-precipitation method. The samples, containing 0; 5 (x = 0.10); 15 (x = 0.30); 20 (x = 0.40); 24 (x = 0.48) at% of vanadium have been chosen as subjects of the present research. The changes in the proton hydrate sublattice in samples, containing different amounts of V+5 were analysed by IR spectroscopy. The modelling of the thermolysis process and determination of the phase compositions at each stage was possible using X-ray phase and thermogravimetric analysis of the samples It was shown that at temperatures of 25–400 °C, proton-containing groups are removed from the hexagonal channels of the pyrochlore-type structure. The increase in number of V+5 ions in solid solutions changed the proton-binding energy with oxygen ions [BO3] –-octahedron, which led to the shift of stage boundaries: oxonium ions and water molecules were removed at higher temperatures, while hydroxide ions were removed at lower temperatures. An increase in temperature to over 500 °C led to the structure destruction due to the oxygen removal from [BO3] –-octahedrons. The model for the atomic fi lling of crystallographic positions in the pyrochlore-type structure for phases, formed during H2Sb2–xVxO6·nH2O thermolysis at 25–400 °C, has been proposed. According to the thermogravimetric analysis, the structural formulas of solid solutions under the air-dry condition has been determined. (H3O)Sb2–xVxO5(OH)·nH2O, where 0 < x £ 0.48, 0 <n £ 1.1. It has been shown that the temperature ranges of thermolysis stages were affected by the proton-binding energy with oxygen ions [BO3] –-octahedron temperature ranges, where B = V, Sb, forming the structural frame. It has been found that the studied solid solutions are stable up to 400 °C within the framework of the pyrochlore-type structure.

The present work is devoted to the study of crystalline polyantimonic acid (CPA) structural properties in conditions of ion exchange and heat treatment of its substituted Ag+, H+-forms. According to the obtained data of X-ray diffraction qualitative phase analysis, the compounds analyzed crystallize within the framework of the pyrochlore type structure (space group Fd-3m). For phases being isomorphic to this structural type, it was shown that with an increase in the degree of substitution α, a relative intensity redistribution of the group of reflections with even and odd indices and decrease of unit cell parameter a were observed.. The data of thermogravimetric analysis allows to conclude that the thermolysis of CPA’s ion-substituted forms proceeds in a wide temperature range from 297 to 973 K being accompanied by a decrease of samples weight. Applying the Rietveld method, the structural characteristics of CPA and its derivatives were refined, and a model of populating the corresponding metal ions by crystallographic positions within a pyrochlore-type structure was proposed. Using a complex of physicochemical methods (thermogravimetric and X-ray diffraction analyses), the effect of hydration of CPA compounds with a pyrochlore type structure on transport properties was determined. It is shown that with an increase of substitution degree α in samples of CPA’s Ag+, H+-forms in conditions of alternating current the value of the specific conductivity decreases monotonically. An increase of silver ions content in the phases of Ag+, H+-forms leads to the change of proton-binding energy with the crystal lattice. In the condition of elevated temperature in hydrated CPA compounds, charge transfer is performed by silver ions. It was found that the electrical conductivity in the samples analyzed can also rise with a silver ions amount decrease (16d-positions are partially filled with Sb3+).

The effect of composition and mechanoactivation in the rotor-stator device on the rheological and film-forming properties of casting blends based on corn starch and chitosans with high (HDC) and low (LDC) deacetylation degree was studied. Films were characterized using optical and atomic force microscopy, X-ray diffraction, FTIR-spectroscopy and by tensile and moisture permeability testing data. An increase in chitosan content was found to result in the blends viscosity increase as well as the tensile strength, elongation and moisture permeability of films. Mechanoactivation was shown to cause an increase in the homogeneity, smoothness and transparency of the films, and an increase in the tensile strength by 1.5 and 2.5 times for the HDC and LDC based films, respectively. It is concluded that the developed eco-friendly and easily implemented method, which allows improving the unsatisfactory properties of starch-chitosan films without the introduction of additional chemicals, can be used on an industrial scale.