Polymer Science, Series B最新文献

Conditions for the synthesis of polymer–metal complexes incorporating zinc oxide nanoparticles differing in the size and shape, via chemical methods from solutions of purified sodium carboxymethylcellulose (degree of substitution 0.97 and degree of polymerization 850) and zinc nitrate crystal hydrate at temperature 80°C, have been determined. Physico-chemical properties of the samples of sodium carboxymethylcellulose containing stabilized zinc oxide nanoparticles differing in the size and shape have been investigated by means of FT-IR spectroscopy, atomic force microscopy, and X-ray diffraction analysis. It has been found that an increase in initial concentration of Zn(NO₃)₂ in the solutions of sodium carboxymethylcellulose subject to chemical reduction leads to the formation of zinc oxide nanoparticles differing in the size and shape. Solutions of sodium carboxymethylcellulose containing zinc oxide nanoparticles can be widely used in medical practice as biomaterials with antibacterial properties.

To reduce the flammability of polymers, functional flame retardants have become widespread, among which phosphorus-containing methacrylates occupy a special place. Despite the well-developed issues of their synthesis and use, the search for new monomers of this class remains a demanding task due to their efficiency, environmental friendliness, and a number of other reasons. This review systematizes the results of recent research concerning phosphorus-containing polymerizable monomers of the methacrylate series, the use of which makes it possible to reduce the flammability of the resulting materials and composites.

In recent years, magnetic-responsive hydrogels, alongside other smart hydrogel materials, have emerged as a focal point of research owing to their exceptional responsive properties and their wide array of biomedical applications. This study introduces an innovative approach involving the use of a biocompatible, carboxymethyl cellulose (CMC) hydrogel crosslinked with non-toxic fumaric acid and loaded with iron oxide nanoparticles (Fe₃O₄) as a novel carrier for magnetic-responsive curcumin drug delivery. Structural characterization of the CMC hydrogel and Fe₃O₄ nanoparticles was conducted through rigorous analysis, utilizing techniques such as Fourier-transform infrared spectroscopy, scanning electron microscopy, and dynamic light scattering. Our results indicate an intriguing inverse relationship between Fe₃O₄ nanoparticle concentration and the swelling ratio of the hydrogel, revealing an interesting relationship between nanoparticle concentration and hydrogel properties. Furthermore, our investigation revealed that the 3.3% Fe₃O₄-loaded magnetic CMC hydrogel exhibited a notably higher curcumin release percentage in comparison to other magnetic CMC hydrogel formulations. This underscores the efficacy of our magnetic CMC hydrogel nanocomposite as a vehicle for curcumin drug delivery, especially when subjected to external magnetic field stimulation. Significantly, our data substantiates that the presence of Fe₃O₄ nanoparticles within the hydrogel network results in a sustained and prolonged release of curcumin when exposed to magnetic stimulation and underscores the potential of magnetic CMC hydrogel nanocomposites as a promising platform for controlled drug delivery.

A two-step nucleophilic substitution mechanism was used and described to prepare liquid amine-terminated fluoroelastomers (LTAFs) by using liquid hydroxy-terminated fluoroelastomers (LTHFs) as raw materials, benzenesulfonyl chloride as an activator, and hexanediamine as an amine source. A reaction time of 24 h at 18°C and a molar ratio of groups –NH₂/–OH = 6.00 is an optimal condition for obtaining LTAFs with a yield of amino groups of 51%. The resulting LTAFs has a higher viscosity and lower thermal stability than LTHFs, while the molecular weight and distribution, as well as the glass transition temperature, remain essentially similar. Aziridine cured LTAFs has the best comprehensive mechanical properties and excellent chemical solvent resistance.

For the first time, it was proposed to use aniline derivatives with a skeleton monoterpene fragment at the nitrogen atom (N-(het)aryl-substituted camphan-2-amines and N-aryl-substituted fenchan-2-amines) as antioxidants for rubbers. Using nitrile butadiene rubber as an example, the kinetics of accumulation of carbonyl groups in macromolecules was studied using IR spectroscopy and the potential ability of these compounds to inhibit the process of thermal-oxidative aging was revealed. N-[(1RS,2RS)-Camphan-2-yl]-4-methoxyaniline and N-[(1RS,2RS)-camphan-2-yl]-4-ethoxyaniline, which differ in the presence of polar ethoxy and methoxy substituents at the p-position at aniline and characterized by the lowest bond energy >N–H. The results of a comprehensive assessment of the retention of elastic-strength properties, hardness, and degree of cross-linking of samples after thermal-oxidative aging in laboratory conditions, as well as long-term full-scale climatic tests in the tropical climate of southern Vietnam, allow us to conclude that after additional testing these compounds can be used as antioxidants in rubber formulations.

Molecular imprinting technology is a specialized technique used to create selective recognition sites within synthetic polymers. It has been employed in the removal of environmental contaminants like pesticides. In this research, a magnetic molecularly imprinted polymer (MMIP) centered on chlorpyrifos as the template molecule was successfully synthesized. Ethyleneglycol dimethacrylate (EGDMA) was the crosslinker, functional monomer used was methacrylic acid (MAA) and initiator was AIBN (2,2′-azobis-isobutyronitrile). The MMIP was successfully characterized using Fourier-transform infra-red (FTIR), scanning electron microscope (SEM), energy dispersive X-ray (EDX), and X-ray diffraction (XRD). The MMIP recorded a high adsorption capacity and selectivity for chlorpyrifos. The MMIP was then used as a dispersive solid phase extraction (D-SPE) adsorbent for isolating and extracting chlorpyrifos from water samples. A gas chromatograph coupled with an electron capture detector (GC-ECD) was used to quantify the extracts. When compared to C-18 solid phase extraction (SPE), the MMIP recorded spiked chlorpyrifos recoveries between 82 and 104% while that for C-18 SPE ranged between 64 and 81%. The limits of quantification (LOQ) and detection (LOD) were 4.91 and 1.62 mg/L respectively.

Nitrogen-oxygen co-doped porous carbon microspheres were synthesized through hydrothermal and carbonization processes using polyimide (PI) as the carbon precursor and a nitrogen-oxygen source. ZIF-8 was also used as the template. When the carbonization temperature reached 800°C, the porous carbon microspheres displayed a unique 3D sea urchin-like morphology, a high specific surface area (782.3 m²/g), and good nitrogen and oxygen doping contents (6.62 and 11.92 at %, respectively). Electrochemical testing showed that when the scanning rate was 0.5 A/g, the material achieved a specific capacitance of 330.5 F/g, and the capacitance retention rate of the electrode material was 73.5% when the current density reached 10 A/g. Furthermore, the symmetrical supercapacitor assembled with this electrode had an operating voltage window that extended to 1.8 V and provided an energy density of 20.5 W h/kg at a power density of 400 W/kg. This method of preparing high performance nitrogen-oxygen co-doped carbon electrode materials provides an idea for the application of insulating polymers in the field of energy storage.

Urea formaldehyde (UF), melamine formaldehyde (MF) and melamine urea formaldehyde (MUF) resins are the most common thermosetting resins. The most obvious advantage of MUF resin over urea formaldehyde resin is that it has much higher resistance to water. MUF resins, synthesized by condensing precursors such as melamine, urea and formaldehyde, have good flame-retardant properties as they release nitrogen gas when burning. Improving the mechanical, thermal and barrier properties of MF and MUF resins by adding various nanoparticles has become very interesting. One of the promising areas of use of MUF resin is their use as insulation foams. In particular, organo clay MUF nanocomposite foams have the potential to offer significant advantages such as improved mechanical and thermal properties as well as reduced water sensitivity. This study aims to prepare and characterize melamine urea formaldehyde organo-clay nanocomposite foams, as well as to examine their properties such as thermal insulation and compressive strength, by using the microwave irradiation technique together with thermal treatment, which can offer advantages such as high reaction rate, yield and purity, and short curing time. Characterization of virgin polymer and melamine formaldehyde organo clay nanocomposite foams prepared by in situ polymerization method, was made using XRD, FTIR, SEM, and HRTEM methods. Spectroscopic and microscopic analyzes showed that the organo-clay platelets exhibited an exfoliated distribution in the melamine-urea-formaldehyde polymer matrix, which did not change with increasing clay content. Although the highest compressive strength values were obtained in virgin MUF foam (0.44 MPa), the values, which partially decreased in nanocomposites, increased with increasing clay ratio and reached 0.38 MPa in the nanocomposite prepared with the highest clay ratio of 0.45 wt %. On the other hand, thermal conductivity coefficients decreased regularly with increasing clay content. Thus, it was concluded that the nanocomposite containing 0.45 organo clay by weight had optimal properties in terms of both strength and thermal insulation.

A new approach to the synthesis of polyrotaxanes from the polyethylenimine‒block‒poly(ethylene glycol)‒block‒polyethylenimine copolymer and alpha-cyclodextrin has been proposed. It has been shown that the acylation of free amino groups of polypseudorotaxane effectively blocks decomposition of the complex in solution. The structure of the synthesized copolymers has been studied in detail by ¹Н and ¹³С NMR spectroscopy, IR analysis, and GPC. It is assumed that the observed abnormally high optical activity of the resulting rotaxanes is probably associated with the formation of chiral helical supramolecular structures.

Novel catalytic systems based on complexes of copper(II) bromide with polydentate nitrogen-containing ligands, tris[(2-pyridyl)methyl]amine and tris[(2-dimethylamino)ethyl]amine, and salts of organic acids (Rochelle salt, sodium oxalate, sodium lactate, and sodium pyruvate) acting as catalyst regenerating agents have been developed for the radical polymerization of acrylonitrile. It has been shown that the polymerization of acrylonitrile carried out in the presence of these systems and halogen-containing initiators occurs by the atom transfer mechanism, affording polymers with target molecular weight values. Effect of the nature of reducing agent and initiator on the process of polymerization and the degree of control over molecular weight characteristics of the resulting samples has been studied. It has been found that Rochelle salt and sodium oxalate are the most efficient reducing agents allowing for a high rate of polymerization while maintaining control over the process.