Vol 57, No 3 (2023)

The effect of gadolinium on the luminescence of europium in mixed complexes with thenoyltrifluoroacetylacetone and 1,10-phenanthroline in poly(methyl methacrylate) and polyethylene films has been studied. The scale of change in light resistance with varying the proportion of gadolinium and the concentration of the complex in the polymer has been estimated. An increase in the relative intensity of luminescence in polyethylene with an increase in the proportion of gadolinium in the complexes has been revealed, the
magnitude of which corresponds to a similar effect for complexes in the crystalline state. This effect is absent in poly(methyl methacrylate) films; however, the presence of gadolinium lowers the rate of decrease in luminescence intensity during photolysis.

Colloidal quantum dots of perovskites having the chemical composition CsPbBr3 have been synthesized. For these particles, the average size of an ensemble of particles and sample polydispersity have been determined by steady-state spectrofluorometry. Conducting layers were made from the obtained particles, and the electrophysical characteristics of these layers were measured. The hole nature of the conductivity was
established, and the layer conductivity (0.04 S/m), mobility (0.8 cm2/(V s)), and number concentration of free charge carriers (3.01 × 1021 m−3) were measured. In accordance with published data, the measured mobility value is higher by one to two orders of magnitude than published typical values. It is shown that high polydispersity has a weak effect on the electrophysical and transport characteristics in the resulting layers.

Nanocomposites based on aqueous polyurethane latex and graphene oxide have been synthesized and characterized. The structure and composition of the nanocomposites were studied using elemental analysis, optical microscopy, IR spectroscopy, DSC, and thermogravimetry. The nanocomposites showed higher thermal stability and increased mechanical strength compared to those of the original polymer. It has been established that the Young’s modulus of latex films after the introduction of 2 wt % graphene oxide increased by a factor of almost 6. In this case, the fracture stress decreased only slightly by 10–15%. The influence of the particle size of graphene oxide on the mechanical properties of the composites was found, namely: composites with larger particles of graphene oxide had a higher Young’s modulus, and their relative elongation at break decreased

Steady state radiolysis showed a decrease in the reactivity of quercetin in free radical reactions with the 1-hydroxyethyl radical and the superoxide radical anion as a result of the formation of a complex with a copper ion. The negative effect of copper ions can be reduced via destroying the resulting complex by introducing chelating compounds, such as tartaric acid and EDTA. The nature of the change in reactivity corresponded to the change in the radioprotective activity of quercetin in relation to yeast cells.

The γ-radiolysis of 2-fluoroethanol-1, 2,2,2-trifluoroethanol-1, 3-fluoropropanol-1, and 4,4,4- trif luorobutanol-1 in aqueous solutions in an inert atmosphere or in the presence of oxygen has been studied. It has been found that the dehalogenation of hydroxyl-containing organic compounds is induced by •ОН and Н• radicals rather than hydrated electrons. The carbon-centered α-hydroxy-β-fluoroethyl radicals FCH2–•CHOH are def luorinated much more efficiently than α-fluoroalkyl radicals, both vicinal (F–•CHCH2OH) and nonvicinal (F–•CHCH2CH2OH). In the absence of oxygen, α-fluoroalkyl radicals
eliminate fluoride ions by the mechanism of nucleophilic substitution, and this process is enhanced in the presence of alkali. In an oxygenated medium, the dehalogenation of α-fluoroalkyl radicals occurs via the addition of oxygen molecules to them and the subsequent disproportionation of resulting peroxyl radicals. The dehalogenation of the α-hydroxy-β-fluoroethyl radicals FCH2–•CHOH is inhibited by oxygen through their oxidation.

Intramolecular hydrogen bonding has a significant effect on the radiolytic transformations of β- diketones. Using the radiolysis of acetylacetone as an example, it has been shown that a hydrogen bond between the hydroxyl and carbonyl in an enol prevents proton transfer from the primary radical cation to the neighboring molecule. As a result, the radiolytic formation of a keto alcohol (4-hydroxy-2-pentanone) was not observed at room temperature, but it was effective under boiling conditions. The intramolecular hydrogen
bond contributed to a significant structural stress in the radical cation, which increased the yield of C–OH bond cleavage and the inhomogeneous formation of acetate (4-oxopent-2-en-2-yl acetate) under normal conditions

The surface treatment of ultra-high-molecular-weight polyethylene (UHMWPE) in helium
plasma at a pressure of 0.133 mbar has been studied by IR spectroscopy, X-ray photoelectron spectroscopy,a nd atomic force microscopy. It has been shown that the helium plasma treatment leads to the formation of double bonds in the UHMWPE surface layer and the associated formation of intermolecular crosslinks. The crosslinking of the surface layer is accompanied by a decrease in the nanowear of the UHMWPE surface by
more than three orders of magnitude, which is confirmed by measurements using an atomic force microscope in the contact mode