Heterophase Systems Research Articles

Study of Se-based microgel catalyst for heterophase benzaldehyde oxidation

Benzaldehyde was oxidized with hydrogen peroxide in the heterophase system with different ratios of benzene and water using selenium-based catalysts. For the reaction, which was carried out in the ratio of benzene:water = 4:1, Se-microgel proved to be a highly active colloidal catalyst and allowed to achieve 94.1 % yield of benzoic acid at 60 °C. The synthesized Se-modified microgel demonstrates exceptional catalytic activity in oxidation reactions at the interface in various heterophase systems at different temperatures.

THEORETICAL AND EXPERIMENTAL APPROACHES IN THE STUDY OF ELECTROCHEMICAL AND THERMODYNAMIC PROPERTIES OF POLYFUNCTIONAL ORGANIC COMPOUNDS IN LIQUID-PHASE AND HETEROPHASE SYSTEMS

The publication reflects the experimental substantiation and fundamental development of some important ideas of the theory of the mutual influence of functional substitution in complex molecules of macrocyclic and chelating compounds on their coordination, solvation and redox properties, as well as the formation of algorithms for searching useful functions of these compounds. Researchers of the Analytical Chemistry Department of the Ivanovo State University of Chemistry and Technology have been studying the electrochemical and thermodynamic behavior of porphyrins, complexones, amino acids, peptides and the corresponding complexes with d- and f-metal ions, their influence on coordination, solvation and catalytic processes for a number of years. The results obtained together with the literature data are discussed in the review. For citation: Bazanov M.I., Berezina N.M., Gridchin S.N., Krutova O.N., Gorboletova G.G., Bychkova S.A., Lytkin A.I., Chernyavskaya N.V., Chernikov V.V., Volkov A.V. Theoretical and experimental approaches in the study of electrochemical and thermodynamic properties of polyfunctional organic compounds in liquid-phase and heterophase systems. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2023. V. 66. N 7. P. 98-110. DOI: 10.6060/ivkkt.20236607. 6839j.

Rate Constants of Reactions in Liquid–Gas and Liquid–Liquid-Gas Heterophase Systems in the Hydroformylation of Isobutylene, the Hydrocarboxylation of Cyclohexene, and the Hydrogenation of N-Benzylideneaniline

Rate Constants of Reactions in Liquid–Gas and Liquid–Liquid-Gas Heterophase Systems in the Hydroformylation of Isobutylene, the Hydrocarboxylation of Cyclohexene, and the Hydrogenation of N-Benzylideneaniline

On the possibility of regulation of rheophysical properties multicomponent mixtures based on rheotechnology

The article deals with the regulation of the rheophysical properties of multicomponent mixtures on the basis of the purposeful application of a new direction in science-rheotechnology. The data of rotoviscometry once again confirmed that the sequence of mixing the constituent components of the oil-water-sand mixture directly affects the rheology of the newly formed systems. The method of changing the order of entering the constituent components shows the prospects for increasing the efficiency of the processes of extraction, collection and transport of oils and their mixtures based on the creation of new rheological methods based on the regulation of the rheophysical properties of the heterophase systems under consideration. Keywords: constituent components of the mixture; rheology; structural viscosity; anomalous index; graph-analytical method.

Особенности получения пленок MnXSiY на кремнии твердофазной реакцией

Recently, in the development of new device structures, structures with various metals on silicon have been used. Numerous studies have shown that as a result of solid-phase reactions of Mn and Si, it is possible to create heterophase systems from various manganese silicide. Such films possessing a unique set of thermoelectric properties. At the present time, obtaining a film with high values of a sufficient thermo-EMF, the maximum thermoelectric figure of merit of these materials of the pack has not yet been achieved. In this regard, there is a need for a detailed study of the structure and perfection of manganese silicide – silicon films obtained on a silicon substrate. In this work, we study the solid-phase reaction in the Mn-Si diffusion system and the process of the formation of manganese silicide phases on a silicon substrate.

Surface and Antibacterial Properties of Titanium Dioxide Nanoparticles Synthesized in Plasma Discharge under Ultrasonic Cavitation

In this work, it is shown that intensive treatment of dispersed systems with ultrasound is an effective method for enhancing the interaction of particles and polymer with the subsequent formation of adsorption layers of high thickness and strength. This makes possible to obtain highly stable dispersed systems with a modified surface of the solid phase. The studies proved the important role of intensive ultrasonic action for controlling the properties of the nanoparticles surface in heterophase systems. It is shown that an increase in the activity of the surface of nanoparticles as a result of ultrasonic treatment is of great importance for the study of their antibacterial activity: after ultrasonic activation, nanoparticles are more active in interaction with cell membranes.

Phase Segmentation in Atom-Probe Tomography Using Deep Learning-Based Edge Detection

Atom-probe tomography (APT) facilitates nano- and atomic-scale characterization and analysis of microstructural features. Specifically, APT is well suited to study the interfacial properties of granular or heterophase systems. Traditionally, the identification of the interface between, for precipitate and matrix phases, in APT data has been obtained either by extracting iso-concentration surfaces based on a user-supplied concentration value or by manually perturbing the concentration value until the iso-concentration surface qualitatively matches the interface. These approaches are subjective, not scalable, and may lead to inconsistencies due to local composition inhomogeneities. We introduce a digital image segmentation approach based on deep neural networks that transfer learned knowledge from natural images to automatically segment the data obtained from APT into different phases. This approach not only provides an efficient way to segment the data and extract interfacial properties but does so without the need for expensive interface labeling for training the segmentation model. We consider here a system with a precipitate phase in a matrix and with three different interface modalities—layered, isolated, and interconnected—that are obtained for different relative geometries of the precipitate phase. We demonstrate the accuracy of our segmentation approach through qualitative visualization of the interfaces, as well as through quantitative comparisons with proximity histograms obtained by using more traditional approaches.

On the Phase Composition, Morphology, and Optical and Electronic Characteristics of AlN Nanofilms Grown on Misoriented GaAs(100) Substrates

Thin AlN nanofilms are produced by reactive ion-plasma deposition onto GaAs(100) substrates misoriented with respect to the 〈100〉 direction to different degrees. It is shown that growth on substrates misoriented with respect to the 〈100〉 direction to different degrees results in the formation of AlN films with different phase compositions and crystal states. An increase in the degree of misorientation of the GaAs(100) substrate used for growth influences both the structural quality of AlN nanofilms and their electronic structure, surface morphology, and optical properties. Thus, the morphology, surface composition, and optical functional characteristics of AlN/GaAs(100) heterophase systems can be controlled using differently misoriented GaAs(100) substrates.

Фазовый состав, морфология, оптические и электронные характеристики наноразмерных пленок AlN, выращенных на подложках GaAs(100) с разориентацией

Thin nano-sized aluminum nitride films on GaAs (100) substrates with varying degrees of misorientation with respect to the <100> direction can be obtained by reactive ion-plasma deposition. It is shown that growth on substrates with different degrees of mismatch from the <100> direction leads to the growth of an AlN film with different phase composition and crystalline state. An increase in the degree of misorientation in the GaAs substrate used for growth is reflected both in the structural quality of nanoscale AlN films and in their electron structure, surface morphology, and optical properties. Thus, the management of the morphology, surface composition and optical functional characteristics of AlN/GaAs heterophase systems can be achieved by using the degree of misorientation of the GaAs substrates.

Effect of vibration on structure and properties of polymeric membranes

The effect of structural memory in a wave field has been exemplarily studied by the IR-spectroscopy method on films made from mixtures of butadiene-styrene and acrylic latex as models of polymeric membranes. The strengthening of the interphase interaction in heterophase systems that can cause change of their local and transmitting mobility has been observed. It has been shown, that the response of polymeric dispersed systems and compositions on influence of nonlinear vibrations proves their influence on deformation properties, like orientation phenomena in solid polymers (where Rebinder's effect can take place) that it is possible to consider as a way of polymer modifications, including the obtaining of nanocomposites, polymeric biocarriers, etc.

A generalized O-element approach for analyzing interface structures

A correct description of interfacial dislocations is critical to the understanding of physical and mechanical properties of the interfaces and their impact on phase transformation and deformation mechanisms. The O-lattice theory provides a general theoretical framework for determining interfacial dislocation structures. However, for systems having an invariant line (IL) or an invariant plane, the O-elements do not always exist in the three-dimensional (3D) space, which impedes the capability of the O-lattice theory to the interfaces in these systems. To determine the dislocation structures in interfaces for which the O-elements do not extend in the 3D space, we introduce a generalized O-element approach by employing the Moore-Penrose pseudoinverse. The generalized O-elements, as the least square solutions to the O-lattice, play a parallel role as that of the ideal O-elements and extend the candidate locations for the coherent regions between dislocations. Worked examples for dislocation structures in both homo-phase and hetero-phase systems are presented. The predicted interface structures are in good agreement with experimental observations and molecular statics (MS)/molecular dynamics (MD) simulations.

Morphological Features and Rheological Properties of Combined Cellulose and Polyacrylonitrile Solutions in N-Methylmorpholine-N-oxide

The combined solutions of cellulose and PAN in N-methylmorpholine-N-oxide at total polymer contents of 18 and 25% are obtained by solid-phase dissolution. The investigation of phase composition and morphology of these systems via optical methods shows that the solutions of cellulose and PAN in N-methylmorpholine-N-oxide are incompatible and form emulsions. The action of deformation on the emulsions leads to the appearance of orientational effects. If PAN predominates in droplets of the dispersed phase of cellulose solutions, this leads to the formation of fibrillar structures under shear stress, while in the case of PAN dispersion medium double emulsions are formed, in which internal droplets of the cellulose solution are most easily extended under shear. The rheological behavior of the combined systems is the direct consequence of structural-morphological transformations proceeding during deformation of the system. An analysis of the morphological and rheological features of heterophase systems reveals the concentration interval for the moldability of composite fibers from spinning emulsions.

MgFe2O4 phase effect on magnetic properties of BiFeO3 in ceramic composites of (1-x) BiFeO3–x MgFe2O4

A two-stage ceramic technology was used for producing a family of (1-x) BiFeO3 - x MgFe2O4 heterophase systems. The study of the magnetic hysteresis loop revealed the presence of a ferrimagnetic response. The experimentally obtained concentration and temperature dependences of the magnetic permeability made it possible to consider the influence of the BiFeO3 phase on the magnetic response of the studied samples.

Structural and optical studies of thin films of aluminum nitride grown via ion-plasma sputtering on gallium arsenide substrates with different orientations

IR and UV spectroscopy is used to study the properties of nanostructured aluminum nitride films obtained via reactive ion-plasma sputtering on GaAs substrates with different orientations. Nanostructured thin (100–200 nm) films of cubic aluminum nitride with optical bandgaps of ~5 eV and refractive indices varying from 1.6 to 4.0 in the wavelength range of ~250 nm are fabricated. Growth on a misoriented GaAs(100) substrate (4° with respect to the [110] plane) makes it possible to synthesize AlN films with smaller grains and higher refractive indices (n ~ 4). It is shown that misoriented GaAs substrates allow us to control the morphology, surface composition, and optical functional characteristics of AlN/GaAs heterophase systems.

Optical properties of composite heterophase objects with liquid crystal material for different display applications

AbstractLiquid crystal (LC) director distribution and optical transmission for different types of heterophase systems with different LC boundary conditions is simulated. The first type is a transparent isotropic material with spherical or cylindrical liquid crystalline objects. There are polymer dispersed liquid crystal, LC fiber, lyotropic LC in polarizing films, LC in microgroove and nanogrooves and pores. The second type is an LC layer incorporating an isotropic transparent or non‐transparent object like microparticles and nanoparticles, spacers, protrusions in multi‐domain vertical alignment LC display et al. The system parameters' influence on LC display performances is discussed.

Effect of cation substitution in Cs1–2x Ba x H2PO4 on structural properties and proton conductivity

We synthesized compounds with partial substitution of Cs+ cations in CsH2PO4 by Ba2+ cations. The structural, electron transport and thermodynamic properties of Cs1–2x Ba x H2PO4 (x = 0–0.15) were studied for the first time with the help of a set of physicochemical methods: infrared and impedance spectroscopy, X-ray diffraction and synchronous thermal analysis. The proton conductivity of Cs1–2x Ba x H2PO4 at 50–230°C was investigated in detail by impedance measurements. The formation of solid substitution solutions isostructural with CsH2PO4 (P21/m) is observed in the range of substitution degrees of x = 0–0.1, with a slight decrease in the unit cell parameters and some salt amorphization. The conductivity of disordered Cs1–2x Ba x H2PO4 in the low-temperature region increases by two orders of magnitude at x = 0.02 and increases with an increasing fraction of barium cations by three or four orders of magnitude at x = 0.05–0.1; the superionic phase transition practically disappears. At x = 0.15, heterophase systems based on salts are formed, showing high conductivity and a further decrease in the activation energy of conductivity to 0.63 eV. The conductivity of the high-temperature phase of Cs1–2x Ba x H2PO4 does not change with increasing fraction of the substituent.

Light Propagation Through Composite Heterophase Objects with Liquid Crystal Material

We simulate LC director distribution and optical transmission of heterophase systems with different LC boundary conditions. The first type is a transparent isotropic material with spherical or cylindrical objects. The second type is an LC incorporating an isotropic transparent or non-transparent object. Systems parameters influence on LCD performances are discussed.

Amphiphilic Ferrocene-Containing PEG Block Copolymers as Micellar Nanocarriers and Smart Surfactants.

An important and usually the only function of most surfactants in heterophase systems is stabilizing one phase in another, for example, droplets or particles in water. Surfactants with additional chemical or physical handles are promising in controlling the colloidal properties by external stimuli. The redox stimulus is an attractive feature; however, to date only a few ionic redox-responsive surfactants have been reported. Herein, the first nonionic and noncytotoxic ferrocene-containing block copolymers are prepared, carrying a hydrophilic poly(ethylene glycol) (PEG) chain and multiple ferrocenes in the hydrophobic segment. These amphiphiles were studied as redox-sensitive surfactants that destabilize particles as obtained in miniemulsion polymerization. Because of the nonionic nature of such PEG-based copolymers, they can stabilize nanoparticles even after the addition of ions, whereas particles stabilized with ionic surfactants would be destabilized by the addition of salt. The redox-active surfactants were prepared by the anionic ring-opening polymerization of ferrocenyl glycidyl ether, with PEG monomethyl ether as the macroinitiator. The resultant block copolymers with molecular weights (Mn) between 3600 and 8600 g mol-1 and narrow molecular weight distributions (Mw/Mn = 1.04-1.10) were investigated via 1H nuclear magnetic resonance and diffusion ordered spectroscopy, size exclusion chromatography, and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Furthermore, the block copolymers were used as building blocks for redox-responsive micelles and as redox-responsive surfactants in radical polymerization in miniemulsion to stabilize model polystyrene nanoparticles. Oxidation of iron to the ferrocenium species converted the amphiphilic block copolymers into double hydrophilic macromolecules, which led to the destabilization of the nanoparticles. This destabilization of nanoparticle dispersions may be useful for the formation of coatings and the recovery of surfactants.

Growth features and spectroscopic structure investigations of nanoprofiled AlN films formed on misoriented GaAs substrates

Nanostructured aluminum-nitride films are formed by reactive ion-plasma sputtering onto GaAs substrates with different orientations. The properties of the films are studied via structural analysis, atomic force microscopy, and infrared and visible–ultraviolet spectroscopy. The aluminum-nitride films can have a refractive index in the range of 1.6–4.0 at a wavelength of ~250 nm and an optical band gap of ~5 eV. It is shown that the morphology, surface composition, and optical characteristics of AlN/GaAs heterophase systems can be controlled using misoriented GaAs substrates.

Distinctions of the growth and structural-spectroscopic investigations of thin AlN films grown on the GaAs substrates

Using X-ray diffraction analysis, atomic force microscopy, IR and UV spectroscopy, the properties of thin aluminium nitride films (<200nm) that were obtained by ion-plasma reactive sputtering on GaAs substrates with different orientations were studied.The films of aluminium nitride can have a refractive index within the range of 1.6–4.0 for the wavelength band around ~250nm and an optical band-gap of ~5eV. It was shown that the morphology, surface composition and optical functional characteristics of AlN/GaAs heterophase systems can be controlled owing to the use of misoriented GaAs substrates as well choice of the technological parameters used for the film growth.