Stanislav Makhno

The review analyzes and summarizes the results of research covering a wide range of topical issues in chemistry, physics, medicine (in particular oncology), photopharmacology, biology, and ecology. Examples of promising developments for practical use are considered, related to the chemical design of multi-level core-shell nanocomposites with the functions of medical and biological nanorobots. An example of a structural model of a nanocomposite is given, which includes four hierarchical levels, namely: core – a single-domain magnetite nanoparticle (1), shell – chemically modified surface of the core (2), immobilized biofunctionalized layer (3) and nanocapsule (4). A new generation of magnetic adsorbents with different surface properties for medical, technical, technological, and environmental applications has been developed and presented. New magnetic fluids based on physiological solution, containing magnetosensitive multifunctional nanocomposites with relevant antitumor drugs and antibodies have been developed. A nanotechnological basis has been developed for minimally invasive methods of photodynamic antitumor therapy and non-invasive controlled pharmacological effects of a given direction on biological cell systems, etc. The identified features of the developed magnetic fluids include the synergistic antitumor action of their active components and the overcoming of drug resistance in malignant cells and tumors. The example of MR based on physiological fluid, magnetite, and cisplatin shows that, according to general and biochemical blood indicators, it does not have a more toxic effect on the body compared to the official antitumor drug cisplatin in traditional use. X-ray luminescent nanostructures can be used in photodynamic antitumor therapy as part of magnetite-lanthanum fluoride nanocomposites for controlled targeted delivery of a photosensitive pharmacological drug and its fixation in the body, while those integrated into a bioactive ceramic medium can be used in bone surgery complicated by tumor processes. The promising prospects of new effective protective materials capable of absorbing electromagnetic radiation in specified spectral ranges for use in electronics and combating electromagnetic smog are demonstrated, as well as the creation of coatings active in the infrared and ultra-high frequency ranges of the spectrum. Broadband absorption and transmission in this case are important factors determining the operational suitability of materials.

Hybrid composites of carbon component/nanosized FeCo particles were synthesized from solution by the co-precipitation method (multiwalled carbon nanotubes, graphene nanoplates, carbon black and carbon fiber were used as the carbon component, and the presence of phases of carbon substrates, cobalt, iron and its oxide forms was found. FeCo nanoparticles with sizes from 5 nm form agglomerates of 50–100 nm on the surface of carbon substrates; the localization of metal particles is characteristic of each substrate, which is associated with the distribution of active functional groups on the surface. The dielectric behavior of the composites in the microwave range and at low frequencies has been studied. It has been shown that carbon fiber/FeCo composites with ?? and ?" significantly exceeding the values of individual components have a significant interface between the components in the composite and a more uniform distribution of metal particles on the surface of carbon fiber compared to other substrates. All the composites obtained have pronounced magnetic properties and thermally stable to a temperature of 250 °C. The frequency dependences of absorption and reflection coefficients in the range from 1 to 40 GHz for the composites obtained are calculated. Several absorption mechanisms are realized simultaneously in the composites (absorption above -12 dB), which makes them an attractive component for creating effective electromagnetic radiation absorbers for different ranges.

The aim of this work was to determine the anisotropy of the electrophysical and mechanical properties of rubber reinforced with a hybrid filler CNTs&CB (carbon nanotubes and carbon black) as a function of CNT content and the technological parameters of the production process. A significant difference in electrical conductivity (σ) and dielectric permittivity (ε) in three perpendicular directions was found for CNT concentrations ranging from 0 to 0.007 in volume fraction. The highest values of σ and ε were observed in the calendering direction, with slightly lower values in the perpendicular direction. This effect was attributed to the orientation of polymer molecules and CNTs along the direction of movement during calendering, as well as the disruption of the cluster structure in the transverse direction. Although the calculated percolation threshold values of the investigated system differed slightly, a correlation was observed between the mechanical and electrophysical properties of CNTs&CB rubber. This correlation enables rubber products to be designed with optimal properties tailored to the desired direction.

To create materials that interact effectively with electromagnetic (EM) radiation, new nanosized substituted ferrites (NiZn)_1−xMn_xFe₂O₄ (x = 0, 0.5, and 1) anchored on the surface of multi-walled carbon nanotubes (CNTs) have been synthesized. The concentration of CNTs in the (NiZn)_1−xMn_xFe₂O₄/CNT system was from 0.05 to 0.07 vol. fractions. The dielectric and magnetic characteristics of both pristine (NiZn)_1−xMn_xFe₂O₄ ferrites and (NiZn)_1−xMn_xFe₂O₄/CNT composite systems were studied. The introduction of (NiZn)_1−xMn_xFe₂O₄/CNT composites into the amorphous epoxy matrix allows to tailor absorbing properties at the high-frequency by effectively shifting the maximum peak values of the absorption and reflection coefficient to a region of lower frequencies (20–30 GHz). The microwave adsorption properties of (NiZn)_1−xMnxFe₂O₄/0.07CNT–ER (x = 0.5) systems showed that the maximum absorption bandwidth with reflection loss below −10 dB is about 11 GHz.

A new proton conducting membrane has been developed by impregnation of porous polyimide Matrimid® (PI) with hydrophobic protic ionic liquid triethylammonium bis(trifluoromethylsulfonyl)imide (TEA‐TFSI). According to the results of dynamic mechanical analysis (DMA), PI/TEA‐TFSI membrane has satisfactory viscoelastic properties in the temperature range 25–100°C. However, the sharp drop in storage modulus (E') occurs at higher temperatures that is probably caused by the plasticizing effect of ionic liquid. To improve the mechanical properties of PI matrix, it was impregnated with the solution of polyetheramine Jeffamine® D‐400 in the TEA‐TFSI. This approach allowed to obtain a partially cross‐linked PI which is more resistant to deformation at elevated temperatures. Thus, DMA study revealed a storage modulus around 400 MPa for PI/Jeffamine/TEA‐TFSI membrane up to 150°C, like neat porous Matrimid®. Thermogravimetric analysis results indicate high thermal stability of PI/Jeffamine/TEA‐TFSI composite with thermal degradation point of 343°C. The ionic conductivity of the composite membrane is 4·10⁻³ S/cm at room temperature and reaches the level of 10⁻² S/cm above 100°C. Overall, the results of this study indicate that partially cross‐linked porous PI impregnated with hydrophobic protic ionic liquid is a promising polymer electrolyte membrane for fuel cells operating at elevated temperatures in water‐free conditions.

New proton exchange membrane based on polyimide Matrimid® (PI) and hydrophobic protic ionic liquid, 1-methylimidazolium bis(trifluoromethylsulfonyl)imide (MIM-TFSI), has been prepared by casting from methylene chloride/dimethylformamide solution. Infrared analysis revealed physicochemical interactions between 1-methylimidazolium cations and imide groups of PI. The results of mechanical testing indicate significantly reduced tensile strength of PI/MIM-TFSI composite membrane compared to neat polymer. Moreover, the dynamical mechanical analysis results revealed sharp drop in storage modulus (E´) of the polymer film above 60 °C. To improve the elastic properties of the membrane, PI was successively cross-linked with polyetheramine Jeffamine® D-2000 (10 mol. %) in methylene chloride/dimethylformamide solution, as well as in solid film at 100 °C. This approach allowed to prepare PI/Jeffamine/MIM-TFSI (70 wt. %) composite film which has an acceptable E' value of 210 MPa at 140 °C. According to thermal gravimetric analysis data, PI/Jeffamine/MIM-TFSI composite has a thermal degradation point (i.e. 5 % weight loss) of 286 °C. The ionic conductivity of PI/Jeffamine/MIM-TFSI composite membrane is around 10–4 S/cm at room temperature and reaches the minimal level of 10–3 S/cm, required for fuel cell applications, above 100 °C. Overall, the results of this study indicate that the cross-linking of polyimide Matrimid with flexible polyetheramine Jeffamine is an efficient approach for preparing dense composite membrane with high content of the protic ionic liquid. Such polymer-electrolyte membrane has the reasonable combination of good stiffness, thermal stability, and ionic conductivity and therefore is a promising candidate for use in fuel cells operating at elevated temperatures in water-free conditions.