Polymer Science, Series B最新文献

In this study, we employed two distinct branching coagents to optimize the topology structure of long-chain branched polylactide (LCB-PLA) via melt grafting with 3,6,9-triethyl-3,6,9-trimethyl-1,4,7-triperoxonane (Trigonox301) and PLA. Our findings reveal that an impressive 22.8% degree of branching degree in PLA was attainable with the addition of merely 2 wt % allyl glycidyl ether (AGE) and 0.75% Trigonox301. Three mathematical models were applied to quantitatively assess the degree of branching based on molecular weight distribution, zero-shear viscosity η₀, and phase angle. Notably, the presence of gel complicated the precise determination of the branching degree when using LCB_G derived from molecular weight distribution fitting. Comparatively, the η₀ and LCB_C, derived from complex viscosity fitting for LCB-PLA samples enriched with 2 wt % AGE, saw a marked escalation from 2140 Pa s and 0 mol % to 13286 Pa s and 22.8 mol %, respectively.

Furthermore, the preferential end-group reaction between the epoxy group of AGE and the carboxyl group of the PLA molecule chain indicated that AGE was more efficacious in enhancing the branching degree than trimethylolpropane triacrylate (TMPTA).

The possibility of using oxirane and imidazole rings as “anchor” functional groups in the structure of flexible-chain polymers for their reactive mixing has been demonstrated. It has been shown that the obligatory condition for the crosslinking of oxirane- and imidazole-containing polymers is the presence of water in the reaction system. Polymer networks formed similarly from linear water-soluble lactam- and imidazole-containing polymers form stimulus-sensitive hydrogels with ionic conductivity upon swelling in water.

Conductive polymer-based adsorbent such as polyaniline has a great potential in replacing conventional adsorbent to remove heavy metal. In this research, different polyanilines were synthesized by modifying synthesis methods and parameters in expectance to yield different properties, which may affect nickel removal efficiency. Besides, titanium dioxide and carboxymethyl cellulose were added to further improve Ni removal efficiency. All synthesized samples were examined with FTIR and UV–Vis to confirm their chemical structures and oxidation states. The electrical conductivities of the samples were measured on a four-point probe and their crystallographic information and incorporation of metal oxide were confirmed using XRD and EDX respectively. The samples’ thermal stability and morphologies were investigated using TGA and FESEM respectively. Among the different morphologies obtained, nanotubes showed highest Ni removal efficiency of 31.250% as its longitudinal structure allowed easier access of polyaniline active sites to interact with Ni ions. With the incorporation of TiO₂ and carboxymethyl cellulose, the Ni removal efficiency of polyaniline/TiO₂/carboxymethyl cellulose significantly improved to 66.8% with TiO₂ improving the charge transport network and surface roughness while carboxymethyl cellulose provides additional active sites and improved hydrophilicity for the transfer of Ni ions from solution to adsorbent surface.

High-density polyethylene (HDPE) was synthesized using a Ziegler-Natta catalyst in two different ways: one step and two-step processes in a hexane slurry polymerization. The study explored the impact of adding hydrogen as a chain-terminating agent on various properties of the polymer, such as productivity of catalyst, molecular weight distribution variation, melt flow index (MFI) and resin average particle size distribution. The results revealed that increasing hydrogen concentrations led to the production of low-molar mass and high MFI polyethylene in the one-step process. Conversely, decreasing hydrogen concentration and increasing ethylene concentration produced higher molar mass/low MFI polyethylene in the same one-step process. In the two-step process, low-molar mass PE was formed first, followed by high-molar mass PE, resulting in broad molecular weight distribution (MWD). This research provides insights into controlling the molecular weight of polyethylene in slurry polymerization processes, which is significant for industrial polymerization technology.

The synthesis of porous polymeric materials with a high proportion of micropores, including ultramicropores, from a multifunctional branched monomer by the Ni-catalyzed cyclotrimerization reaction followed by heat treatment at 500°C is presented. The textural surface properties of these polymeric materials have been studied. It has been shown that heat treatment at 500°C leads to an increase in the proportion of micropores, including ultramicropores, in the material. The specific surface area was determined, and the adsorption capacity of the obtained compounds was found to be linearly related to the volume of ultramicropores. A sample with the largest volume of ultramicropores had the highest CO₂ adsorption, being 3.12 mmol/g at 273 K and 100 kPa.

Amphiphilic and polyelectrolyte crosslinked polymer products with different types of network structure capable of limited swelling in aqueous media to form hydrogels exhibiting pH-sensitive properties were synthesized by the interaction of tetrazole-containing polysaccharides with the epoxy resin and oxirane-containing carbon chain polymers.

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.