Russian Journal of Applied Chemistry最新文献

The study of the influence the type of plasticizing organic/inorganic agents on structural-mechanical properties (plastic strength, molding pressure, limit shear stress, greatest plastic viscosity, plasticity and etc.) of the pseudoboehmite pastes is presented. Samples of the pastes were prepared using plasticizing agents of organic nature (acetic, malic, tartaric, oxalic and citric acids and diethyelen glycol) and inorganic nature such as nitric and phosphoric acids, aqueous ammonia solution and ammonium hydrocarbonate. Our results suggest the pastes plasticized with nitric/phosphoric acids or with diethylene glycol demonstrate the highest plastic strength in the set. Plastic strength values were found to correlate well with the molding pressure necessary for the paste shaping through a piston extruder. The structural-mechanical type of paste was determined using a modulus of elasticity, viscosity and limit shear stress. All pastes were found to be suitable for extrusion molding and did not belong to SMT types 0 and III. The plasticizing agent was found to affect SMT type of paste. Paste types I, II, IV, and V were obtained by changing the plasticizing agent. Alumina granules without visible defects and with sufficient crush strength value were prepared using the investigated pastes. This allows them to be used as supports/adsorbents/catalysts for industrial processes.

A novel calix[4]arene-bonded nano silica gel (C4A–SiO₂) is prepared by covalent attachment of a calix[4]arene derivative to nano silica gel. The structure and properties of C4A–SiO₂ were studied by Fourier Transform Infra-Red (FTIR), thermogravimetric (TG), elemental analysis (CHN), scanning electron microscopy (SEM), and surface area analysis (BET). In addition, the organocatalytic activity of C4A–SiO₂ for synthesis of some biologically active cores xanthenes was investigated by comparison of the yields and reaction times. The results prove that utilization of catalyst causes the reaction time reduction and yield expansion. Xanthene structures have been proved by FT-IR, ¹H NMR, ¹³C NMR and comparison of melting points. Easy work-up, acceptable reaction times, eco-friendly solvent, recyclable of catalyst and high yields are remarkable advantages of these processes. The catalyst C4A–SiO₂ is recyclable for at least five cycles without substantial loss of activity. Thus, C4A–SiO₂ can be introduced as an efficient organocatalyst in synthesis of xanthenes.

Protonated diallylammonium polymers attract attention due to a number of properties, in particular high antimicrobial activity, including activity against the mycobacterium M. tuberculosis. To reduce the cytotoxic effect of polymers in the case of practical use, samples with a low MW are required. The work investigated the free radical polymerization of protonated diallylammonium monomers, diallylammonium trifluoroacetates, in excess of the initiator ammonium persulfate (10^–1 M) and at average polymerization temperatures (40 and 50°C) to obtain polymers with a low degree of polymerization. It has been shown that under such conditions it is possible to obtain polymers with values suitable within the aim: 16000 < MW < 28000 g/mol. Using NMR and IR spectroscopy, it was shown that with an increase in the concentration of the initiator and, accordingly, a decrease in the molecular mass of polymers, the relative number of characteristic terminal vinyl groups decreases, and the terminal groups formed by the interaction of macroradicals with primary radicals of the initiator become predominant, in this case, sulphate groups of ammonium persulfate. The data obtained indicate that at high concentrations of the initiator, the characteristic reactions of chain transfer to the monomer are largely kinetically suppressed by the interactions of macroradicals with the primary radicals of the initiator. The approach used, which makes it possible to synthesize polymers with a low MW and terminal groups of the initiator, can be applicable in the future to vary the properties of antimicrobial activity and toxicity of polymers.

A new method for producing glassy carbon microspheres in solutions containing furfuryl alcohol, ethylene glycol, isooctylphenol decaglycol ether (OP-10), and sulfuric acid was developed. The morphology of the microspheres was examined. Their electrochemical tests in a solution containing 0.1 M KCl, 0.005 M K₃[Fe(CN)₆], and 0.005 M K₄[Fe(CN)₆] were performed. The relationship between the solution temperature during the synthesis (the heat released in the polycondensation reaction) and the volume of the acid added was established using a noncontact thermometer. The polymer microspheres obtained in the solution were washed, dried, and calcined at 900°C. The materials obtained were examined by scanning electron microscopy and X-ray fluorescence elemental analysis. The elemental analysis showed that the materials contained about 98% carbon and less than 2% potassium, copper, oxygen, sulfur, and iron. Scanning electron microscopy revealed that the microspheres had a regular spherical shape, a developed surface, and the diameter ranging from 0.5 to 10 μm. The characteristic microsphere size was determined by dynamic light scattering, and the dependences of the size on the reactant ratio during the synthesis were constructed. A paste with the microsphere to vacuum oil weight ratio of 80 : 10 was prepared for the electrode fabrication. This mixture was stirred to obtain a homogeneous paste and stuffed into a tubular electrode 3 mm in diameter. The peak current and peak potential values determined using cyclic voltammetry for the electrodes with pure microspheres and, for the best sample, with the addition of barium hexaferrite as an electrochemical catalyst. Among the nineteen solutions studied, the solution containing 100 mL of ethylene glycol, 5 mL of furfuryl alcohol, 5 mL of OP-10, and 50 mL of sulfuric acid is the most promising.

In the present study we have synthesized interpenetrating polymer network (IPN) of fullerene (C₆₀) and N-vinyl carbazole (NVC). The IPNFC was characterized using infrared (IR) spectroscopy, scanning electron microscope (SEM) and conductivity techniques which reveals desirable and interesting results. IR spectroscopy reveals presence of fullerene at 527 and 1600 cm^–1 and poly (N-vinyl carbazole) at 1101 cm^–1. A thin polymeric interconnected film is seen via SEM technique, revealing transparent and dual phase morphology. IPN is also analyzed for permeability and permittivity, which reveals maximum value of ε_r', ε_r'' and tan δ_ε at 2.77, 0.48, and 0.11, respectively, and maximum values of μ'_r of μ''_r, and tan μ _r ranging from 0.99 to 1.50, 0.01–0.103, and 0.01–0.08, respectively. Moderate values of permeability and permittivity reveals electromagnetic property of the IPN. Conductivity IPN was calculated and found to be 4.98 S/m, which describes the semiconducting nature of the polymeric network.

This study impregnated polyurethane (PU) into a nonwoven polyethylene terephthalate (PET) fabric. Polyurethane was prepared by a facile and green method using polyols with different ratios of polyethylene glycol (PEG)/(Polyvinyl butyral (PVB) + waste sodium lignosulfonate (SLS)) and hexamethylene diisocyanate. Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and X-ray diffraction (XRD) were used to examine the non-woven PET-treated and untreated samples. The results indicated that the treated solution was successfully impregnated on the nonwoven polyester surface, which affected the morphology. Derivative thermogravimetric analysis (DTG), thermogravimetric analysis (TGA), mechanical properties, and antifungal properties were studied. The results depicted that the treated nonwoven PET became more thermally stable than untreated nonwoven PET with an increasing percentage of (PVB + SLS). The mechanical properties showed a noticeable improvement in tensile strength and Young’s modulus, while elongation decreased by increasing the (PVB + SLS) ratio. It was discovered that weight loss decreased after researching the impact of UV light. PU modified with PVB+SLS exhibited enhanced antifungal activity of nonwoven PET due to the natural antimicrobial properties of SLS. This modification not only improves the resistance of the material to fungal growth but also expands its application potential in various industries, including healthcare, construction, and consumer goods. The sodium lignosulfonate examined in this study exhibits promise for use as a reactive polyol component in the synthesis of PU.

The features of forming film materials based on acid-soluble chitosan are investigated. The dependence of the physicomechanical and sorption properties of the film materials on the amount of the introduced cross-linking agent (glutaraldehyde) and plasticizer (polyoxyethylene glycol) was found. The use of glutaraldehyde is proposed to control the sorption of aqueous media by chitosan-based film materials due to the formation of cross-links that afford the films with water absorption of 200–650% (without adding cross-linking agents and plasticizers—up to 40%). Non-toxic chitosan film materials with more than 90% cell survival rate during incubation with the studied materials were fabricated. The obtained materials have required level of hydrophilic-hydrophobic properties (wetting angle was up to 90°) and physicalmechanical properties (strength and relative elongation were 10–12 MPa and 4–10%, respectively). The possibility of biodegradation of the fabricated films under conditions of soil degradation is shown, which can be applied to create materials with programmed degradation.

This manuscript presents a novel approach for green hydrogen production through ethanol electrolysis using Co/Ni bimetallic nanoparticles-incorporated carbon nanofibers (CNFs). The synthesis method involves the electrospinning of a sol-gel comprising nickel acetate, cobalt acetate, and poly(vinyl alcohol), followed by vacuum drying at 60°C overnight and subsequent calcination in a vacuum atmosphere. X-ray diffraction (XRD) analysis revealed the decomposition of acetate precursors, resulting in the formation of zero-valent metal nanoparticles (NPs). Transmission electron microscopy (TEM) confirmed the alloy composition of the NPs. Electrochemical measurements demonstrated the effective utilization of the proposed nanofibers as anode materials in ethanol electrooxidation reactions for hydrogen production at low voltage. Optimization of the metallic nanoparticle composition was found to significantly enhance performance. For instance, Ni- and Ni_0.9Co_0.1-doped CNFs exhibited current densities of 37 and 142 mA/cm², respectively. Especially, Ni_0.1Co_0.9-doped CNFs displayed a remarkably low onset potential of -50 mV vs. Ag/AgCl. Moreover, Ni_0.9Co_0.1-doped CNFs exhibited the ability to recover hydrogen from ethanol solutions from 0.1 to 5 M, attributed to the observed active layer regeneration. The versatility of ethanol as a feedstock, derived from biomass fermentation, positions the proposed anode materials as sustainable catalysts for green hydrogen production from agricultural sources. This work underscores the potential of Co/Ni bimetallic nanoparticles-incorporated CNFs in advancing the field of renewable energy and promoting sustainable H₂ generation.