Kinetics of thermal degradation of polymeric materials is usually studied by weight loss at a constant temperature or during heating. Hence, the activation energy and other kinetic parameters of the thermal destruction process are determined. One of the fastest and most accessible methods for studying the kinetics of these processes is TGA. Weight methods of TGA do not provide an opportunity to judge the proportion of gaseous degradation products. This is especially true for processes associated with the release of hydrogen and other substances with low molecular weights, the accuracy of determining the amount of which by the weight method is low. Meanwhile, the study of the gas evolution process can provide additional information about the kinetics and mechanism of thermal destruction processes. Of great interest is also the joint study of the total weight loss and gas evolution during the polymer heating. Using mass spectrometry, IR spectroscopy combined with thermal analysis (TGA/DSC-IR and TGA/DSC-MS) we have defined product composition and thermal destruction kinetics. As a result of the TGA/DSC-MS study of gaseous products of thermolysis in nitrogen atmosphere, there were found products with 44, 45, 59, 60, 68, and 88 phr. Quite a similar pattern for p-PGFPh:AA copolymers is also observed in TGA/DSC-IR studies: the same products and the same temperature range. However, in contrast to the TGA/DSC-MS study, CO release was also recorded by this method (weak signal). Kinetic characteristics of the processes were determined based on Friedman, Ozawa-Flynn-Wall and modified NPC methods. Obtained values of the activation energy and thermodynamic characteristics make it possible to predict the composition of polymers, which make a significant contribution to the development of theoretical ideas about the features of the physicochemical properties of polymers.

This research presents the results of a combined numerical and experimental study of the thermal decomposition behavior of copolymers based on polypropylene glycol fumarate phthalate. The thermal decomposition of polymers plays a key role in various fields, such as waste recycling and energy recovery, and in the development of new materials. The objective of this study is to model the degradation kinetics using thermogravimetric data, matrix-based numerical methods, and quantum chemical calculations. To solve the resulting systems of linear algebraic equations (SLAEs), matrix decomposition algorithms (QR, SVD, and Cholesky) were employed, which enabled the determination of activation energy values for the process. Comparison of the activation energy (E_a) results obtained using the decomposition method of Cholesky (207.21 kJ/mol), normal equations (205.22 kJ/mol), singular value decomposition (206.23 kJ/mol), and QR decomposition (206.23 kJ/mol) showed minor changes that were associated with the features of each method. Quantum chemical calculations based on density functional theory (DFT) at the B3LYP/6-31G(d) level were performed to analyze the molecular structure and interpret the IR spectra. This study establishes that the content of functional groups (ether and ester) and the type of chemical bonds exert critical influences on the decomposition mechanism and associated thermal parameters. The results confirm that the polymer’s structural architecture governs its thermal stability. The scientific novelty of this work lies in the integration of numerical approximation methods and quantum chemical analysis for investigating the thermal behavior of polymers. This approach is applied for the first time to copolymers of this composition and may be employed in the design of heat-resistant materials for agricultural and environmental applications.

The data on the synthesis of N-aminomorpholine hydrazones are presented. It is shown that the interaction of N-aminomorpholine with functionally substituted benzaldehydes and 4-pyridinaldehyde in isopropyl alcohol leads to the formation of corresponding hydrazones. The structure of the synthesized compounds was studied by ¹H and ¹³C NMR spectroscopy methods, including the COSY (¹H-¹H), HMQC (¹H-¹³C) and HMBC (¹H-¹³C) methodologies. The values of chemical shifts, multiplicity, and integral intensity of ¹H and ¹³C signals in one-dimensional NMR spectra were determined. The COSY (¹H-¹H), HMQC (¹H-¹³C), and HMBC (¹H-¹³C) results revealed homo- and heteronuclear interactions, confirming the structure of the studied compounds. The antiviral, cytotoxic, and antimicrobial activity of some synthesized hydrazones were investigated. It is shown that 2-((morpholinoimino)methyl)benzoic acid has a pronounced viral inhibitory property, comparable in its activity to commercial drugs Tamiflu and Remantadine. A docking study was performed using the influenza virus protein models (1930 Swine H1 Hemagglutinin and Neuraminidase of 1918 H1N1 strain). The potential binding sites that are complementary with 2-((morpholinoimino)methyl)benzoic acid were found.

This study aimed to create new composite materials based on diatomite—a non-organic porous compound—through its surface modification with bioactive organic compounds, both synthetic and natural. Chloramphenicol, tetrahydroxymethylglycoluril and betulin were used as modifying substances. Composite materials were obtained by covering the diatomite surface with bioactive substance compounds as a solution and material dispersion in it. The materials were characterized by IR spectroscopy, SEM and X-ray photoelectron spectroscopy. For the biocomposites, the hemolytic effect, plasma proteins’ adsorption on the surface and the antibacterial activity of the obtained materials were studied. Results show that the obtained materials are promising for medicine and agriculture.