Vladimir Vladimirovich Volkov

First evidence by X-ray diffraction of supermolecules of organometallic compounds (specifically, a vitamin B ₁₂ derivative) created in LS films. Their helix and supercoiled structures, as well as ultra-high sensitivity to O ₂ were demonstrated.

Silver nanoparticle (AgNP) formation in oligomers (epoxy resins and oligoxypropylenediamine) and epoxy–amine systems based on them were studied in detail using UV-visible spectroscopy, small-angle X-ray scattering, dynamic light scattering, and X-ray diffractometry. The reduction of silver ions in the oligomeric media was carried out at near-room temperatures, which is why it was called “cold”. A fundamental difference in the behaviour of Ag⁺ ions in oligomers, depending on the nature of their terminal groups, has been established, and assumptions have been made about the mechanism of stabilisation of Ag⁺ ions and nanoparticles based on reduced Ag⁰ silver atoms. The kinetics of Ag⁰ nanoparticle formation in epoxy systems has been the subject of investigation, and the influence of the system composition (precursor and solvent concentrations) on this process has been demonstrated. The evolution of Ag⁰ nanoparticle sizes in epoxy and epoxy–amine systems is discussed, and a hypothesis is put forward about the formation of an oligomeric hydrodynamic shell around these nanoparticles. It is suggested that, depending on the nature of the oligomer's terminal groups, this contributes to either the stabilisation or aggregation of nanoparticles. The present study investigates the influence of temperature on the ratio of Ag⁺ ion coordination/reduction processes and Ag⁰ nanoparticle stabilisation/aggregation. The results of this research will be used for the purpose of the targeted regulation of polymer–silver nanocomposite production processes.

New promising materials for biomedical applications based on a collagen--chitosan matrix containing conjugates of Ag nanoparticles and gramicidin S were obtained using metal--vapor synthesis. The analysis of the morphology, surface composition and electronic state of the metal in nanocomposites was carried out.

This article reports a new straightforward method for producing hydrophobic GeO₂ aerogels in a one-pot synthesis. For the first time, the epoxide-induced sol–gel process was combined with the co-precursor method to create hydrophobic aerogels. The application of a complex of analytical methods like SEM, TEM, low-temperature nitrogen adsorption–desorption, SAXS and contact angle measurements enabled us to determine that varying the GeCl₄:(C₂H₅)₂GeCl₂ ratio allows for targeted adjustments in the morphology, porous structure, and surface properties of aerogels. As the proportion of (C₂H₅)₂GeCl₂ grows, the surface area increases from 45 to 123 m²∙g⁻¹ and the contact angle changes from 22.1 to 140.1°. Luminescent properties of the hydrophobic GeO₂ aerogels are reported for the first time, and it is established that the ratio of green and blue bands in the luminescence spectra when excited under 390 and 235 nm varies depending on the GeCl₄:(C₂H₅)₂GeCl₂ ratio used for the aerogel preparation.

The behavior of silver nitrate in non-aqueous liquid oligomeric media—aromatic and aliphatic diglycidyl ethers and aliphatic diamine—has been investigated. By employing UV–visible spectrophotometry and dynamic light scattering, it has been shown that in diglycidyl oligomers, regardless of the nature of the monomeric unit, the formation of silver nanoparticles occurs, and the kinetics of this process has been studied. At the same time, in the medium of aliphatic diamine, the reduction of silver ions is absent, indicating the formation of a complex compound. XANES and EXAFS confirmed the formation of such a complex, established the probable coordination number of silver equal to three, and characterized the nearest atomic environment of silver. The SAXS results indicate the formation of complexes of extended conformation environment associated oligodiamine molecules, which favors the formation of an extended network of associates. The SAXS data were used to calculate the composition of the mixture of complexes and associates of diamine molecules for a saturated solution of silver nitrate in diamine. The results of this work will be used to develop new oligomer–silver nanocomposites with unique optical and bactericidal properties.

The development of advanced methods for the synthesis of nano- and microparticles in the field of biomedicine is of high interest due to a range of reasons. The current synthesis methods may have limitations in terms of efficiency, scalability, and uniformity of the particles. Here, we investigate the synthesis of submicron calcium carbonate using a microfluidic chip with a T-shaped oil supply for droplet-based synthesis to facilitate control over the formation of submicron calcium carbonate particles. The design of the chip allowed for the precise manipulation of reaction parameters, resulting in improved porosity while maintaining an efficient synthesis rate. The pore size distribution within calcium carbonate particles was estimated via small-angle X-ray scattering. This study showed that the high porosity and reduced size of the particles facilitated the higher loading of a model peptide: 16 vs. 9 mass.% for the particles synthesized in a microfluidic device and in bulk, correspondingly. The biosafety of the developed particles in the concentration range of 0.08–0.8 mg per plate was established by the results of the cytotoxicity study using mouse fibroblasts. This innovative approach of microfluidically assisted synthesis provides a promising avenue for future research in the field of particle synthesis and drug delivery systems.

The challenge of continuous CaCO₃ particle synthesis is addressed using microfluidic technology. A custom microfluidic chip was used to synthesize CaCO₃ nanoparticles in vaterite form. Our focus revolved around exploring one-phase and two-phase synthesis methods tailored for the crystallization of these nanoparticles. The combination of scanning electron microscopy, X-ray diffraction, dynamic light scattering, and small-angle scattering allowed for an evaluation of the synthesis efficiency, including the particle size distribution, morphology, and polymorph composition. The results demonstrated the superior performance of the two-phase system when precipitation occurred inside emulsion microreactors, providing improved size control compared with the one-phase approach. We also discussed insights into particle size changes during the transition from one-phase to two-phase synthesis. The ability to obtain CaCO₃ nanoparticles in the desired polymorph form (∼50 nm in size, 86–99% vaterite phase) with the possibility of scaling up the synthesis will open up opportunities for various industrial applications of the developed two-phase microfluidic method.

Condensation of hexakis-2-(formylphenoxy)cyclotriphosphazene with malonic acid yielded hexakis-2-(β-carboxyethenylphenoxy)cyclotriphosphazene (2-CEPP), whose structure was confirmed by ³¹P, ¹H, ¹³C NMR spectroscopy and MALDI-TOF mass spectrometry. A quantum-chemical calculation for the 2-CEPP molecule using the ab initio methods in the 6-311G^** basis set and the DFT-PBE0/6-311g** method was performed with geometry optimization of all parameters by the standard gradient method. The acid strength of 2-CEPP was theoretically estimated. Using the small-angle X-ray scattering method, it was found that 2-CEPP is an amorphous substance, which, when heated, can transform into a crystalline state. However, when heated at 370 °C, 2-CEPP undergoes decarboxylation and polymerization to form an insoluble heat-resistant product. The occurrence of decarboxylation and polymerization reactions in the formed styrene fragments was confirmed by thermal (differential-scanning calorimetry) and spectral (solid-state ¹³C NMR spectroscopy) analysis.

A central point of validity of computer X-ray diffraction micro tomography is to improve the digital contrast and spatial resolution of the 3D-recovered nano-scaled objects in crystals. In this respect, the denoising issue of the 2D image patterns data involved in the 3D high-resolution recovery processing has been treated. The Poisson-noise simulation of 2D image patterns data was performed; afterwards, it was employed for recovering nano-scaled crystal structures. By using the statistical average and geometric means methods of the acquired 2D image frames, we showed that the statistical average hypothesis works well, at least in the case of 2D Poisson-noise image data related to the Coulomb-type point defect in a crystal Si(111). The validation of results related to the de-noised 2D IPs data obtained was carried out by both the 3D recovery processing of the Coulomb-type point defect in a crystal Si(111) and using the peak signal-to-noise ratio (PSNR) criterion.