Polymer Science, Series B最新文献

Polypropylene-g-N-phenylmaleimide was prepared by melt grafting reaction of polypropylene and N-phenylmaleimide and was added to the polypropylene matrix in different match ratios. After that the base films were fabricated by casting of the mixture of polypropylene and polypropylene-g-N-phenylmaleimide, and then separators were obtained by stretching. Adoption of N-phenylmaleimide is a key technique to ensure separators with excellent heat resistance. It was also found that polypropylene-g-N-phenylmaleimide played an important role in improving the overall performance of those base films and separators. Compared with the polypropylene base film, the crystallinity, crystalline orientation, and elastic recovery of base films containing polypropylene-g-N-phenylmaleimide increased obviously. The prepared separators showed good pore structure and hydrophilicity. The heat shrinkage of separators measured at 130°C reduced from 18.8 to 10.6% while the content of polypropylene-g-N-phenylmaleimide increased from 0 to 10%. Coin cells assembled with separators also show higher battery capacity than the cells assembled with pure polypropylene separators.

In this study, 4-amino-3-hydroxy-1-naphthalenesulfonic acid was polymerized by the oxidative polymerization method. Copper nanoparticles of the synthesized PSa were prepared with copper sulfate solution. Structural analysis of the synthesized compounds were determined by FTIR, ¹H NMR and ¹³C NMR measurements. Its optical properties were measured by UV–Vis spectrophotometer, thermal analysis by Thermogravimetric Analysis (TG) device, morphological properties by scanning electron microscope (SEM) device, and crystallographic properties by X-ray Diffraction (XRD) device. Additionally, HOMO–LUMO band gaps were calculated by determining oxidation-reduction peak potential values with the Cyclic Voltammetry (CV) device. Since CuNPs@PSa shows very good antimicrobial properties against some yeasts and bacteria, its usability in drug release was investigated. For this, Ch–CuNPs@PSa encapsulation study was carried out by coating CuNPs@PSa with chitosan (Ch). Encapsulation efficiency, loading capacity, and in vitro release kinetics were calculated. As a result, it was observed that chitosan encapsulation increased the antimicrobial effect against bacteria and yeasts and achieved the release in a controlled manner. It has been determined that Ch–CuNPs@PSa can be used in drug delivery systems as it has an Encapsulation Efficiency (EE) of 98.70%, a Loading Capacity (LC) of 78.96% and a cumulative release of 98.84%. In this case, it can be said that the obtained Ch–CuNPs@PSa can be evaluated as effective in drug release studies.

In this study, the effect of titanium dioxide (TiO₂–H100) on the electrical properties of polypyrrole (Ppy), a conductive polymer known for its promising application in various fields, is investigated. Pure Ppy is synthesized via chemical oxidative polymerization method, and a Ppy/TiO₂–H100 composite is prepared with 10% TiO₂–H100 by weight. The samples are characterized using Fourier Transform InfraRed spectroscopy (FTIR), X-ray Diffraction (XRD), Thermogravimetric analysis (TGA), and Scanning Electron Microscopy (SEM). The key finding is a significant structural change in Ppy upon the incorporation of TiO₂–H100, as confirmed by XRD and SEM, which reveal enhanced crystallinity and a more compact morphology in composite. Regarding the electrical properties, conductivity measurements revealed that the electrical conductivity of pure Ppy at 300 K was 4.81 × 10^–7 S/cm, whereas the Ppy/TiO₂–H100 composite exhibited a higher conductivity of 5.08 × 10^–7 S/cm, likely due to the interfacial interaction between TiO₂–H100 and Ppy. Electrochemical impedance spectroscopy (EIS) results showed similar trends, where the composite exhibited semiconductor behavior, reflecting the influence of TiO₂–H100 on the electrical properties. These results highlight the potential of TiO₂–H100 to modify the electrical and structural properties of Ppy, making it a promising material for semiconductor applications.

Poly(N-isopropylacrylamide) has been synthesized for the first time by reversible addition-fragmentation chain transfer polymerization in supercritical carbon dioxide. It has been shown that the molecular weight distribution of the polymer is narrower and its average molecular weights are lower than those of poly(N-isopropylacrylamide) synthesized in supercritical СО₂ (scСО₂) according to the conventional radical mechanism. Both polymers are branched and contain a minor proportion of the gel fraction. The form factors determined by light scattering are 1.35 (conventional polymerization) and 1.11 (reversible addition-fragmentation chain transfer polymerization), which is typical for branched and hyperbranched polymers, respectively. Aqueous solutions of the polymers are thermoresponsive and characterized by a cloud point of 30–31°С.

This paper is the first generalization of the material accumulated in the kinetic study of the ring-opening polymerization of cyclic ketene acetals. The main attention is focused on the difference between the kinetics of radical polymerization of these monomers and the kinetics of polymerization of vinyl monomers. The difference in the mechanisms of elementary events of chain initiation and termination is revealed. Kinetic features of the controlled polymerization of cyclic ketene acetals occurring by reversible inhibition, atom transfer, and reversible-addition fragmentation chain-transfer mechanisms are considered.

The synthesis of polyethersulfones of various chemical structures from commercially available starting materials is described. Quantitative characteristics of the dependences of the polycondensation degree and the molecular weight of the obtained polyethersulfones to the reactant ratio have been determined. The dependenses of the heat resistance of the obtained materials on the molecular weight and rigid-chain moieties introduced into the structure of the polymers have been revealed. The effect of the concentration and the reactivity of the end groups of macromolecules on the thermo-oxidative stability of the product polyethersulfones is shown. The particular attention is paid to the synthesis of polyethersulfones with phenolic end groups and a polycondensation degree of n = 25‒30. Such polymers have a high (up to 20 wt %) solubility in epoxy oligomers upon heating without a significant increase in the viscosity of the epoxy resins and do not form an insoluble phase upon binder cooling, thereby opening up broad prospects for their further use as epoxy modifiers.

The influence of external donor nature on propylene polymerization reactions with titanium-magnesium catalyst activated with AlEt₃ is studied. The use of cyclohexylmethyldimethoxysilane as the donor increases the content of isotactic polymer and the use of 2,6-dimethylpyridine promotes the formation of syndiotactic component in polypropylene. By combining different donors, it is possible to regulate the site distribution in catalytic system with respect to stereospecificity and to modify stereoregularity, molecular weight characteristics and mechanical properties of polypropylene.

Cross-linking of polymer is a simple way to improve stability of dyes into a polymer matrix according to using in different application. In this study spherical poly(methacrylic acid-ethylene glycol dimethacrylate) microparticles consisting of curcumin, rhodamine B and crystal violet were synthesized by precipitation polymerization to obtained possible synergistic effect and Förster resonance energy transfer in a single platform. The synthesized microparticles were characterized using scanning electron microscopy, X-ray diffraction, fluorescence spectroscopy, dynamic light scattering, and differential scanning calorimetry. Microparticles containing curcumin and crystal violet showed 2.7 times higher intensity than microparticles containing curcumin and rhodamine B and 14 times higher fluorescence intensity compared to microparticles containing curcumin only. Also, the most unpredictable result belonged to the microparticles containing crystal violet and rhodamine B. It showed approximately 5 and 2 times higher fluorescence intensity compared to microparticles containing curcumin and rhodamine B and microparticles containing curcumin and crystal violet, respectively. This finding enabled us to design microparticles with minimum toxic effect due to low contents of rhodamine B for bioimaging applications with high sensitivity.

Polymer-based soil ameliorants are considered effective tools to protect soil from wind and water erosion. In the article, five promising modern ameliorants were examined: hydrolyzed polyacrylonitrile (HYPAN, synthetic polyanion), two commercial humic products (potassium humates) and two binary mixtures composed of HYPAN and humates at 10/1 wt/wt ratio, with a special attention to their effects on soil structuring, anti-erosion and hydrophysical properties. The polymers were dissolved in water and the resulting aqueous formulations were 1) sprayed on the surface or 2) injected into the sandy loam soil. The obtained polymer-soil constructs were comprehensively tested for mechanical strength, aggregate composition, anti-erosion stability, water retention capacity and biocompatibility with the following main conclusions. When sprayed over the soil, the formulations penetrate the soil to a depth of 0.5 cm. Drying the soil with deposited polymers results in polymer-soil coatings with mechanical strength varied from 0.7–1.3 kg/cm² for humates to 4.1–6.7 kg/cm² for HYPAN-based formulations. HYPAN coatings provide a 100% soil resistance at an air flow speed of 72 km/h and only 5–7% loss of soil when re-watering. Treatment of soil with HYPAN-based formulations results in a higher water capacity, better retention of water and increased content of agronomically valuable aggregates 0.25–1 mm in size from 34 to 51 wt %. Addition of humates to HYPAN solutions stimulates plants growth. The results obtained are important to develop polymer ameliorants with anti-erosion, water-retaining and biostimulating properties.