Objectives. In comparison with methyl tert-butyl ether (MTBE) and methanol mixtures, the separation of MTBE and tert-butanol (tert-butyl alcohol, TBA) mixtures represents a relevant challenge in chemical technology due to limited research in this area. Our aim was to evaluate the potential and efficiency of using choline chloride-based deep eutectic solvents (DESs) as green extractants for the separation of the MTBE–TBA system via liquid–liquid extraction (LLE).

Methods. DESs were prepared by mixing and heating a hydrogen bond acceptor (choline chloride, ChCl) with hydrogen bond donors (HBDs) as follows: malonic acid (1 : 1 molar ratio), glutaric acid (1 : 1), urea (1 : 2), and glycerol (1 : 2). Liquid–liquid phase equilibrium was experimentally studied in four ternary systems containing MTBE, TBA, and DES at temperatures of 293.15 and 313.15 K and atmospheric pressure. The compositions of the equilibrium liquid phases were determined using ¹H nuclear magnetic resonance spectroscopy (500 MHz, dimethyl sulfoxide-d₆).

Results. The experimental data allowed the key extraction parameters to be calculated: distribution coefficients for TBA and selectivity for MTBE–TBA separation for each investigated DES. A comparative analysis of the extraction capacity of the synthesized solvents toward the separated components was performed. The experimental phase equilibrium data confirm the fundamental possibility of using the ChCl-based DESs under study as extractants for separating the MTBE–TBA system. The calculated selectivity and distribution coefficient values allow the efficiency of various HBDs within the DES composition to be evaluated for solving this separation task. The comparative analysis of the DES extraction capacity showed a dependence of selectivity on the HBD and a slight dependence of selectivity on temperature. The highest selectivity values were observed for DESs based on ChCl/glycerol (1 : 2) and ChCl/urea (1 : 2) systems.

Conclusions. The feasibility of using DESs based on choline chloride with malonic acid, glutaric acid, urea, and glycerol as extractants for separating the MTBE–TBA mixture by LLE method has been experimentally confirmed. The calculated distribution coefficients and selectivity values enable a quantitative assessment and comparison of the efficiency of different DESs for this task, identifying the most promising compositions. The results obtained can be used as the basis for further development and optimization of the LLE process for MTBE and TBA using promising green solvents.

Objectives. To investigate the specific features of tetraethoxysilane (TEOS) hydrolysis in associated media of saturated diols and their esters in acidic media. Propylene- and butylene glycols and ethylcarbitol were selected as associated systems.

Methods. Association, hydrolysis, and condensation processes in the TEOS–diol system were studied by potentiometry, infrared spectroscopy, and dynamic light scattering in liquid media. The acidic environment was created by adding HCl in the amount not exceeding 0.3 wt %.

Results. The hydrolysis of TEOS in associated alcohol media is limited by the reaction that yields silanol (RO)₃SiOН, which further interacts with the associated diol. This results in the incorporation of (RO)₃SiO groups into the hydrogen bond network of diols. This is confirmed by a decrease in the self-association of diols with a decrease in size in the diol–(RO)₃SiO domains of up to 1–7 μm.

Conclusions. The use of diols as a reaction medium for TEOS with a low content of H₂O in acidic media limits the depth of hydrolysis and condensation, which increases the possibility of esterification reactions of diol with alkoxy derivatives of silanols. The decreased number of hydroxyl groups during the transition from diols to their esters has a significant effect on the degree of association.

Objectives. To analyze the properties, dispersion structure, and intermolecular interactions in oil disperse systems (ODSs) of various component compositions, and to consider the possibilities of controlling phase transitions in an ODS to achieve the most favorable dispersion properties for carrying out technological processes of refining hydrocarbons, upgrading petroleum products, or recycling oil waste. Phase transitions are proposed to be controlled by low-energy wave action (low-frequency ultrasound, constant magnetic field with low induction).

Results. The following features of oil disperse systems are considered and substantiated with literature data and the results of our own research: multiplicity of phases; diversity of hydrocarbon components and heteroatomic compounds contained in them; the nature of intermolecular interactions (the absence of charge interactions and the presence of charge–polarization and exchange spin-spin interactions); spin activity or paramagnetism of oil, petroleum products, and their various components; homolytic dissociation of highmolecular-weight and heteroatomic organic compounds, resulting in an increase in paramagnetism; as well as the presence of trace elements contained in organometallic compounds and in salts dissolved in emulsified water. An equation is presented for intermolecular interactions in ODSs, in which a decisive role is played by the exchange interactions caused by the presence of spin and spin-polarized molecules. Two-component models are described for the shells of complex structural units of the oil disperse system, their structure, and their interaction with the dispersion medium. Methods for controlling phase transitions and dispersity of ODSs are shown. Special attention is paid to low-energy wave technologies (ultrasonic waves with a frequency of 20–100 kHz with an intensity of up to 0.4 W/cm² and a constant magnetic field with an induction of less than 0.4 T). Examples are given for the intensification of such technological processes as separation of water–oil emulsions, removal of mechanical impurities, atmospheric and vacuum distillation, selective purification of oil fractions, degassing of heavy fuel oil to remove hydrogen sulfide, visbreaking, and others. Positive results are demonstrated for the application of low-energy technologies for reduction of the viscosity and pour point of oil and petroleum products in oil refining equipment. The study proposes a mechanism of the influence of a constant magnetic field on the flow of petroleum product or hydrocarbon raw material.

Conclusions. The study of the features of ODSs is key to the qualified colloid-chemical approach to processes of production, transportation, and processing of hydrocarbon raw materials. They are seen from the standpoint of ODS theory on the basis of the consideration of the dispersion structure and phase transitions in ODSs. Low-energy technologies in the petroleum industry are an effective tool for resource saving in various processes and optimization of their parameters without significant material costs.

Objectives. Gene therapy involves the administration of various types of therapeutic nucleic acids into the organism, in order to treat severe hereditary diseases, as well as cancer. Furthermore, the COVID-19 pandemic demonstrated the possibility of rapid development and the effectiveness of both DNA and mRNA vaccines for the prevention of viral diseases. Numerous studies in the field of gene therapy have revealed that in most cases successful delivery of nucleic acids requires a special delivery system which protects nucleic acids from the effects of external and internal biological factors. Among the various types of such tools, non-viral delivery systems have proven to be the most versatile and safe ones. In the case of mRNA delivery, such systems are usually called mRNA vaccines, consisting of cationic or ionizable lipids. The purpose of this review is to justify the choice of the optimal structure of lipid components of mRNA vaccines and highlight the current prospects for their clinical use.

Results. In this review, we have considered the evolution of lipid structures, from cationic to ionizable, as the main components of mRNA delivery systems. Furthermore, the study demonstrated the necessity to use other types of lipids in mRNA vaccines. It also presents a review of clinical trials of mRNA vaccines against viral and oncological diseases, and provides recommendations for the design of the optimal structure of both cationic and ionizable lipids.

Conclusions. The most promising lipids for the development of mRNA vaccines are ionizable. They do not have a permanent positive charge which reduces their cytotoxicity and undesirable binding to components of the immune system. In general, mRNA vaccines can be universal and effective means for treating various types of diseases. However, their composition needs to be careful optimized.

Objectives. To investigate the properties of intumescent fire-retardant materials based on plasticized polyvinyl chloride and oxidized graphite as functions of their content of nitrile butadiene rubber.

Methods. Intumescent fire-retardant materials with different contents of nitrile butadiene rubber (from 0 to 20 wt %) were obtained. The materials were prepared in the form of a sheet 38–52 mm wide and 1.5–1.9 mm thick by means of flat-die extrusion using a twin-screw compounding extruder. The raw materials used were plasticized polyvinyl chloride with a K-value of 71, nitrile butadiene rubber with a bound acrylonitrile content of 31–35%, oxidized graphite, and ultrafine aluminium hydroxide. The properties of the raw materials and the resulting fire-retardant materials were investigated using infrared spectroscopy, thermal analysis, scanning electron microscopy, as well as mechanical tests, flammability tests, and thermal shock foaming tests.

Results. The mechanical, thermal, and fire-retardant properties of the obtained materials were studied as functions of their contents of nitrile butadiene rubber. The dynamics of foaming in the temperature range from 300 to 800°C were also explored. The flammability rating was determined. The dependence of fire-retardant properties on the melt viscosity of fire-retardant materials was described. The thermal properties were found to be in the temperature range of 40 to 900°C.

Conclusions. The study found that the introduction of nitrile butadiene rubber into fire-retardant materials leads to a change in a number of properties: a decrease in density and hardness; a decrease in tensile strength; an increase in relative elongation; an increase in melt viscosity by 16 times; and, accordingly, a decrease in foaming rate by a factor of 1.43–1.65. It was established that the foaming rate has a linear dependence on the viscosity of the melt of fire-retardant materials. The introduction of rubber leads to an increase in the strength of foamed char by a factor of 4.8. Thermal analysis showed that increasing the rubber content leads to an increase in heat resistance from 222 to 236°C, and resistance to oxidation of foamed graphite in the composition of foamed char from 601 to 659°C. The presence of rubber does not have a noticeable effect on flammability. The established flammability rating for all compositions is V-0.

Objectives. To study the effect of shape on the intensity of surface-enhanced Raman light scattering when depositing nanoparticles on track membranes. The resulting composite material can be further used as a substrate for sensors. The efficiency of such sensors is determined by the effect of surface-enhanced Raman scattering of light.

Methods. Silver nanoparticles were obtained by reduction of silver ions in solution under various conditions. Nanoparticles from the obtained colloidal solutions were deposited on polyethylenimine-modified polyethylene terephthalate track-etched membranes. The samples were examined using absorption spectroscopy in the ultraviolet and visible region, scanning and transmission electron microscopy, dynamic light scattering, and Raman spectroscopy.

Results. Silver nanoparticles of spherical, triangular, and nanowire shape were synthesized. The sizes and zeta potential of the nanoparticles were determined. The obtained nanoparticles were deposited on the surface of track-etched membranes. For the composite membrane samples, the relative enhancement factors of the Raman light scattering signal of the 4-aminothiophenol test substance were calculated based on the substrate with a known enhancement factor.

Conclusions. The effect of surface-enhanced Raman light scattering was found to be greater when transitioning from spherical to various nonspherical-shaped nanoparticles. The highest value of the relative enhancement factor was 4 · 10⁷ on the composite membrane with silver nanowires.

Objectives. To obtain data on the compatibility of a polymer blend based on poly-3-hydroxybutyrate and butadiene-nitrile rubber for the development of a biodegradable polymer with improved mechanical properties.

Methods. Film samples of biodegradable plastic–elastomer blends, using mixtures of poly-3-hydroxybutyrate and butadiene-nitrile rubber as a case study, were investigated by means of optical and scanning electron microscopy with computer-aided image analysis, differential scanning calorimetry, mathematical analysis, and Fourier transform infrared spectroscopy.

Results. The mixtures studied herein were found to have a heterogeneous heterophase structure. The interaction between the carbonyl group of poly-3-hydroxybutyrate and the nitrile group of acrylonitrile block of acrylonitrile butadiene-nitrile rubber is shown due to kinetic compatibility. A change in the crystalline regions of poly-3-hydroxybutyrate when it is mixed with rubber was also noted. The results of the Gibbs energy calculation of mixing confirmed the interaction of carbonyl and nitrile groups. Microscopy results show the localization of poly-3-hydroxybutyrate particles around rubber particles. The reasons for this phenomenon are discussed here.

Conclusions. Studies have shown a relationship between morphology and component content of the samples. The change in composition affects the structure and properties of the surface and volume. The formation of associates leads to the formation of an interface which attracts the second component. The Flory–Huggins theory, Avrami equations, and microscopic data established a complex interaction mechanism: convergence and formation of chemical bonds, rearrangement of crystalline regions, transition of spherulitic particles into lamellar particles, diffusion of rubber macromolecules, association of poly-3-hydroxybutyrate particles around the rubber, and completion of chemical bonds.

Objectives. In this work, we consider the relationship between the tracer (k^*) and chemical (k^δ) oxygen exchange coefficients for Ba_0.5Sr_0.5(Co_0.8Fe_0.2)_1−xMe_xO_3−δ (Me = Ta, W) oxides. The aim is to analyze the experimental dependencies of the chemical (k^δ) and tracer (k^*) coefficients of oxygen exchange, evaluate the surface thermodynamic factor w₀|_x=±L , and compare its value with the bulk thermodynamic factor w₀|_x=0 determined from the dependence of oxygen content in oxides on the temperature and partial pressure of oxygen. Possible reasons for the discrepancy between these two thermodynamic factors are discussed.

Methods. The oxygen exchange kinetics between the gas phase and the surface of oxide materials under nonequilibrium conditions was studied using the method of oxygen pressure relaxation. The surface thermodynamic factor was calculated based on data obtained under both equilibrium and nonequilibrium conditions.

Results. Comparison of the tracer (k^*) and chemical (k^δ) oxygen exchange coefficients allowed the w₀|_x=±L surface thermodynamic factor to be estimated by the k^δ = k^*w₀|_x=±L equation.

Conclusions. The surface thermodynamic factor was found to differ from the bulk thermodynamic factor of the oxide material, w₀ = [1^∂ln(p_O2 )] / [2 ∂ln (3−δ)], which can be calculated from the dependence of oxygen content in oxides on the temperature and partial pressure of oxygen. This difference can be explained by the difference in the defect structure of the surface layers of oxide materials.

Objectives. To summarize the results from studies of plasma processes for the production of specified composition powder materials; to implement plasma processes: plasma-chemical synthesis of nanopowders, granulation of nanopowders, plasma spheroidization of microgranules and micropowders in order to perform nanotechnologies and additive technologies tasks.

Methods. Thermal plasma generation was used at the A.A. Baikov IMET RAS by means of direct-current electric arc plasmatrons with a rated power up to 45 kW with self-adjusting arc length and gas stabilization of discharge, as well as plasmatrons with an interelectrode insert. In order to carry out the processes of nanopowders synthesis and metal powders spheroidization, the plasma reactor design with confined jet flow using thermal plasma of reducing, oxidizing, and inert media was used.

Results. The use of electric arc plasmatron in the processes of plasma chemical synthesis of nanopowders and plasma spheroidization of powders enabled productivity of 0.5 and 10 kg/h, respectively, to be achieved for various metals, alloys, compounds, and their compositions. In the case of the implemented processes of producing nanopowders, where the formation of particles depends on various macro-mechanisms, it was established that the average size of the particles obtained is controlled. This also depends on the synthesis parameters—the initial concentration of the precursor, enthalpy, and flow rate of the plasma jet, cooling rate and vapor condensation. The study shows the results of examining the processes of producing spheroidized powders in thermal plasma flows. These include (Ti, Ta, Fe, Ni, Mo, W), alloys (based on Fe, Ti, Ni, Co, Nb, W, Mg, including stainless, heat-resistant, refractory, hard), compounds (borides, oxides) and compositions (W–Ni–Fe, ZrB₂–SiC, Ni–TiCN, etc.). The possibility of obtaining nonporous spherical powders of various dispersity was also shown: for particles of about 10–100 μm and for granules having a particle size of less than 1 μm. The study described the main process parameters determining the quality of spheroidization, including dispersity of precursor, plasma enthalpy, gas composition, characteristics of plasma flow, and their mixing with initial powders.

Conclusions. The research and development results presented here show the possibilities of plasma processes and apparatuses for producing nanopowders of various metal, inorganic compounds and compositions with given properties. The study also confirmed that powders of metals and alloys, compounds and compositions obtained by a variety of methods can be spheroidized in a plasma reactor with confined jet flow in a wide range of melting points, particle sizes, and morphology. The demonstrated approach using successive stages of plasma-chemical synthesis of nanopowders, their granulation and subsequent plasma spheroidization of microgranules enables tungsten-based composite micropowders with dense spherical particles and submicron structure to be obtained.