Doklady Chemistry最新文献

The development of high-performance rubber sealants requires elastomer blends with high strength, elasticity, and long-term chemical stability. In this study, ethylene–propylene–diene monomer (EPDM) and nitrile butadiene rubber (NBR) were compounded at a fixed 60/40 ratio. Standard additives such as carbon black (N330), zinc oxide (ZnO), stearic acid, and a sulfur-based curing system were incorporated. 1-Naphthol was introduced as a reactive compatibilizer in amounts of 0, 2, 4, 8, and 10 phr to improve interfacial adhesion between the non-polar EPDM and the polar NBR phases. Rheological analysis demonstrated that moderate concentrations of 1-naphthol (2–4 phr) increased the maximum torque (MH), complex viscosity, and elastic modulus, indicating enhanced crosslink density and stronger interphase interactions. Higher concentrations (≥8 phr) led to partial network disruption and phase separation. The blend containing 4 phr 1-naphthol exhibited the best mechanical performance, with a tensile strength of 14.6 MPa, elongation at break of 280%, and compression set of 22%. SEM micrographs confirmed the formation of a uniform and finely dispersed morphology at 2–4 phr, while excessive compatibilizer loading resulted in coarser domains. These improvements are attributed to hydrogen bonding and π–π stacking interactions between 1-naphthol and the polymer chains, which enhance interfacial compatibility and overall cohesion. Therefore, the optimum compatibilizer concentration for EPDM/NBR sealing materials lies within 2–4 phr, offering enhanced rheological, mechanical, and sealing performance suitable for automotive, oil and gas, and construction applications.

Antibiotics have been known for decades for the management of microorganisms, and their overuse and irrational applications are causing increased bacterial resistance. This study explores the synthesis of a novel composite material comprising carbon nanofibers (CNFs) and copper (Cu) through the electrospinning technique. The electrospinning allowed precise integration of Cu nanoparticles within the CNF matrix, resulting in a synergistic combination of their distinct properties. Scanning electron microscopy (SEM) and Electron probe microanalysis (EPMA) revealed that CNFs were densely covered by Cu nanoparticles. The study investigated structural characteristics of Cu infused CNFs, emphasizing their potential for dual applications as an antimicrobial agent and as a supercapacitor electrode. The antimicrobial efficacy of Cu infused CNFs (Cu@CNFs), is explored in the context of inhibiting bacterial (E. coli) and Candida albicans growth, indicating that it is a durable candidate for biomedical procedures, such as antimicrobial filters, coatings and wound dressings, etc. Concurrently, the electrochemical performance of CNFs composite is evaluated for its suitability as a supercapacitor electrode, taking advantage of the high conductivity of CNFs and pseudo-capacitance of Cu nanoparticles. The results showed specific capacitance of Cu@CNFs displayed a larger specific capacitance of 496 F/g. Additionally, the presence of Cu nanoparticles in the mat generated robust microbicide action.

Kinetics of polymerization of ε-caprolactone initiated by zirconium acetylacetonate Zr(acac)₄ in the presence of ethylene glycol as a co-initiator was studied. Detailed kinetic analysis was performed using Friedman differential isoconversional method in combination with analysis of the enthalpy–entropy compensation effect, resulting in model-free evaluation of the kinetic triplet of the reaction: ({{E}_{{{alpha }}}}), ({{A}_{{{alpha }}}}), and (fleft( {{alpha }} right)). In addition, the activation energy ({{E}_{{{alpha }}}}) was calculated using the first-order reaction model. The obtained value ({{E}_{{{alpha }}}}) = 65.5 ± 2.3 kJ/mol was consistent with the average ({{E}_{{{alpha }}}}) values calculated by the isoconversional method. It was shown that the sigmoidal nature of polymerization is adequately described by the Kamal autocatalytic model. The effect of reaction temperature and initiator concentration on the molecular-weight characteristics of resulting poly(ε-caprolactone) was investigated. When the reaction temperature is 100–140°C, the molecular weight of the polymer is M_n ≈ 40–50 kDa and the dispersity is Ð ≈ 1.7–2.0.

This study investigates the feasibility of using 1,4H-octafluorobutane as a reaction medium for mild suspension polymerization of propylene using a Ziegler–Natta catalyst. The proposed approach enables propylene polymerization under mild conditions at near-room temperatures and atmospheric pressure. The resulting polypropylene has been characterized by IR and NMR spectroscopy, elemental analysis, and differential thermal analysis. The data obtained demonstrate that the synthesized polypropylene has a predominantly atactic structure. The basic advantage of the proposed approach is the reduction in fire and explosion hazards during propylene polymerization by conducting the reaction at atmospheric pressure, room temperature, and in a nonflammable solvent.

The article presents the results of a study of the effect of phthalocyanine pigments, in particular, α-modification (Blue 15:3) and excessively halogenated chlorin (Green 7) on the crosslinking kinetics and properties of a composite material based on high-pressure polyethylene (LDPE) processed by compression two-stage chemical foaming. The main attention is paid to the analysis of kinetic curves and physico-mechanical parameters: strength and elongation at break. The study was based on a comparison of the kinetics of crosslinking compositions with the addition of a crosslinking agent, a crosslinking agent and a blue pigment (Blue 15:3), a crosslinking agent and a green pigment (Green 7). Experiments show that the addition of phthalocyanine pigments affects crosslinking kinetics and physico-mechanical properties. Given the uniform nature of the pigments, it is worth paying attention to the different effects of each of them, which is presumably explained by the different molecular compositions. The data obtained open new prospects in compounding, in optimizing technological modes, and can also serve to create LDPE materials with predictable characteristics for compositions processed by two-stage pressing. The paper investigates the changes in the nature of the kinetic curve of the crosslinking process with the addition or absence of pigments of a specific nature, as well as their effect on the physico-mechanical properties of the resulting material. The results of the study confirmed the effect of pigments on the stitching process and, as a result, on the performance properties of the material. Kinetic curves indicated an acceleration of the stitching process, as well as an increase in the density of the resulting vulcanization mesh.

This paper presents the synthesis of first- to fourth-generation (G1–G4) oligohydroxyethylaminoethylurethane dendrimers using a two-stage divergent method. The dendrimers were obtained by the reaction of triethanolamine with dimethyl carbonate and diethanolamine in strictly stoichiometric ratios, which ensured high product yields (97.4% for G1, 98.2% for G2, 98.4% for G3, 98.8% for G4). The resulting compounds are resinous substances with a colour range from reddish-brown (G1) to rich amber (G2) to dark brown (G3, G4), with a characteristic sweetish odour. Dendrimers (G1-G4) are soluble in water, dimethyl sulfoxide, dichloromethane, acetone, dioxane, dimethylformamide and alcohols, but are insoluble in chloroform, tetrachloromethane, aromatic and aliphatic hydrocarbons. The structure of dendrimers has been proven by ¹H, ¹³C NMR, IR, titrimetry, and elemental analysis. An increase in molecular weight (498, 1152, 2504, and 5164 g/mol) and the number of hydroxyl groups (6, 12, 24, and 48) has been established with the increase in generation from 1 to 4, as well as the transformation of 1 (G1), 3 (G2), 5 (G3), and 11 (G4) urethane groups into amino groups due to the elimination of carbon dioxide. The thermal stability of dendrimers is in the range of 104–106°C. Prospects for further research are related to the study of the use of these dendrimers as effective platforms for catalysts, which opens up new opportunities in the field of chemical synthesis.

This study was aimed at modifying the surface of aromatic phthalide-containing polymers, promising for use in membrane technologies, with aliphatic polymer brushes of varying polarity. Mono- and polyfunctional vinyl monomers with various side groups, including reactive ones, were used: hydroxyl, ether, ester, acid, epoxy, and nitrile. The possibility of graft copolymerization of acrylates and methacrylates, as well as some other vinyl monomers, on the surface of brominated polydiphenylenephthalide (PDP-Br) was investigated. The influence of the degree of halogenation of PDP-Br and irradiation dose and duration on the degree of grafting was studied. It has been shown that brominated PDP is a polymeric photoinitiator for a wide range of vinyl monomers, the use of which in graft copolymerization processes allows the production of grafted aromatic–aliphatic copolymers of various chemical structures with different hydrophilic/hydrophobic ratios.

We present our kinetic study of tin–zinc (Sn–Zn) alloy electrodeposition from an alkaline electrolyte using potentiodynamic polarization curves and a rotating disk electrode (RDE). The joint tin and zinc discharge is controlled by a mixed diffusion–kinetic mechanism, confirmed by the linear dependence of the inverse current density on the inverse square root of angular RDE rotation velocity. Diffusion coefficients of tin ions D(Sn) ≈ 1.77 × 10^–8 cm²/s and zinc ions D(Zn) ≈ 1.97 × 10^–7 сm²/s were determined, significantly lower than those for simple ions in aqueous solutions due to complexation to form stannates and zincates in alkaline solutions and the influence of additives (sodium citrate and sodium lauryl sulfate). Polarization curves featured zinc depolarization (deposition at –1.10 V instead of –1.20 V), while tin reaches its limiting current at –1.40 V due to diffusion limitations. The alloy composition depends on the deposition potential and RDE rotation velocity: the velocity increasing from 100 to 1600 rpm raises the zinc content from 55 to 65% at –1.45 V. The hydrogen evolution side reaction is significant below –1.8 V, reducing the current efficiency. Thermal studies showed the activation energy to decrease from 18.73 kJ/mol at –1.1 V to 14.42 kJ/mol at –1.4 V, indicating enhanced diffusion control with a negative shift of the deposition potential. Potentiodynamic measurements at sweep rates of 1–100 mV/s confirmed nonstationary factors’ influence on curve shifts. The obtained results are crucial for developing environmentally friendly technologies for protective coatings with controlled compositions and enhanced properties. Future directions include exploring new additives and optimizing the electrolyte composition for providing improved efficiency.

This study investigated the potential corrosion inhibition of a series of eight chalcone derivatives using in silico analysis on Fe (110) and Cu (111) surfaces. The compounds examined include six cyclic chalcones (C1–C6) and two acyclic analogues (C7–C8). The electronic properties of these chalcone derivatives were analyzed using Density Functional Theory (DFT) and Natural Bond Orbital (NBO) analysis. With the B3LYP hybrid functional and 6-311++G(d,p) level of theory. The geometry optimization was performed to identify the most stable molecular structures, followed by calculations of molecular electrostatic potential surfaces, dipole moments, and electronic characteristics. Molecular Electrostatic Potential (MEP) mapping was performed to understand the molecule’s chemical reactivity and intermolecular interactions. Monte Carlo (MC) simulations were used to model the adsorption behavior of chalcone derivatives on Cu (111) and Fe (110) metallic surfaces, offering insights into their interactions with these metals. According to the results, the chalcone derivative C5 has the lowest adsorption energy on the Fe (110) surface and a significantly lower adsorption energy – roughly half – on the Cu (111) surface. This disparity is attributed to the planar configuration of the C5 molecule, where both chalcone fragments engage with the Fe (110) surface, but only one interacts with the Cu (111) surface. This study improves our understanding of chalcone derivative corrosion inhibition, enabling the development of ecologically benign and effective corrosion inhibitors.