Polymer Bulletin最新文献

This study presents a novel approach for environmentally friendly paint removal, focusing on the efficient removal of methylene blue from aqueous environments using iron nanoparticles embedded in polyvinyl alcohol nanofibers. Iron nanoparticles were synthesized via a green method employing green tea extract under optimized conditions and characterized by FESEM, DLS, TGA, DTG, EDS, FTIR, and XRD. The average size of synthesized iron nanoparticles was 22 nm. Two fabrication techniques were employed to embed the nanoparticles into polyvinyl alcohol nanofibers: electrospinning of a solution containing iron nanoparticles, and in situ synthesis of nanoparticles on the PVA nanofibers. Comparative analyses revealed superior methylene blue adsorption rates when nanoparticles were synthesized in situ on the nanofibers. Characterization techniques, including FESEM, XRD, and FTIR, confirmed the successful formation of nanoparticles on the nanofibers. Response surface method using central composite design (CCD) was performed to find the optimal removal conditions. Optimal removal (85%) occurred under adsorption conditions of pH 8.6, an initial methylene blue concentration of 30 mg/L, a nanofiber dose of 1.6 g/L, and a contact time of 100 min. Kinetic studies demonstrated a pseudo-second-order adsorption model, while Langmuir isotherm analysis indicated a maximum adsorption capacity of 24.509 mg/g. Thermodynamic analysis suggested the spontaneous and exothermic nature of the adsorption process. This composite membrane is an efficient and economical method for removal dye from wastewaters.

This study focuses on the evaluation and the drug release characteristics of a new coated matrix membrane (CMM) system, particularly emphasizing drug delivery from porous systems that offer more precise release control, especially for drugs with narrow therapeutic indexes (NTIs), such as theophylline. The parameters affecting the delivery of theophylline from the CMM were systematically studied. In the study, ethyl cellulose (ETC) served as the coating polymer, while poly (ethylene glycol) (PEG) was selected as the pore-forming agent. Poly (vinyl alcohol) (PVA) was used as the base polymer in the preparation of matrix membranes, and poly (vinyl pyrrolidone) (PVP) was preferred as the hydrophilicity balancing guest polymer. The effects of matrix membrane (MM) thickness, heat treatment temperature (HTT), coating layer thickness, drug loading concentration and coating layer porosity on the release rate of theophylline from CMM systems were all investigated. Additionally, the impacts of pH and temperature on theophylline release from CMM systems were examined. All experiments were conducted in vitro. By the study, 150 °C was determined as optimal HTT temperature. At more acidic pH values greater release rates were obtained. The release mechanism consistent with the Case I (Fickian) diffusion model and the activation energy for the permeation of theophylline through CMM systems was found as 62.355 J mol⁻¹. As a result of the study, it was determined that the optimized CMM system with improved release properties can control the released amount of theophylline and it was proposed as a promising material for the dermal delivery of theophylline in vivo.

Graphical abstract

A new drug delivery coated matrix membrane system for theophylline delivery.

In this study, multifunctional wound and burn dressing material was developed to cover open wounds and protect them from external effects. Trimethylolpropane ethoxylate-170 (TMPE)-based polyurethane/polycaprolactone (PU/PCL) dressing materials were prepared with high biocompatibility and ordered nanofiber formation. Prepared PU/PCL dressing materials also contain allantoin additive to accelerate wound healing. Polyurethane structures were synthesized using solution polymerization technique from hexamethylene diisocyanate, polyethylene glycol-200, TMPE and Tween-40 monomers in different mole ratios. The obtained polyurethanes and dressing materials were characterized structurally, thermally and morphologically. Then, PCL, allantoin and gentamicin sulfate were added to these PU structures and converted into wound dressing materials by electrospinning technique. The allantoin release, mechanical analysis, antibacterial properties and biodegradability of the produced dressing materials were investigated. The obtained PU/PCL dressing materials were seen as flexible, durable and structural stable. These dressing materials have fiber diameter of approximately 500 nm. The tensile strength and Young's modulus of PU/PCL dressing materials are 2.22 ± 0.39 MPa and 1.04 ± 0.11 MPa. They released allantoin regularly for about 70 h and showed antibacterial properties. In addition, the prepared dressing materials have grade 1 biocompatibility. As a result, these dressing materials provide a good alternative to existing wound dressing materials.

The main objective of the present work is to get insight into the polarization switching and dielectric response of PVDF-TrFE with incorporation of BaTiO₃ (BTO) nanoparticles. For this purpose, cost-effective solvent casting technique was used, to prepare PVDF-TrFE/BaTiO₃ composite free-standing films. It is necessary to prepare films in which BTO nanoparticles are distributed homogenously without agglomeration. Surface functionalization technique is reported to be useful in homogenous distribution of the nanofiller in polymer matrix. However, addition of surface modifier causes reduction in the permittivity of the polymer nanocomposite and deteriorates the desired properties. Therefore, the main aim of the present work is to obtain homogenous free-standing PVDF-TrFE/BaTiO₃ composite films in which filler is dispersed without any use of surface modifier. Hence ferroelectric particles are dispersed in the ferroelectric polymer matrix. It has been observed that nanocomposite is much more complex compared to the simple models based on spheres dispersed in a medium. Complexities arise due to the strain and interfacial effects of the BTO nanoparticles on the ferroelectric matrix which exhibits marked effect on structural and electrical response of the system. Consequently, specific concentration of filler has been identified at which optimum ferroelectric and dielectric properties of PVDF-TrFE/BaTiO₃ composite have been achieved. Incorporation of more than a desired concentration of filler affects the chain alignment and causes reduction in the β-phase content. Correlation between structural and electrical response has been discussed in detail to explain the non-monotonic trend of polarization as a function of BTO content.

The widespread use of sodium carboxymethyl cellulose (CMC) in the production of edible coatings is returned to its biodegradable, biocompatible, and non-toxic nature. However, neat CMC edible coatings lack UV-shielding activity and have poor antimicrobial properties. This study aimed to develop a CMC-based coating with optimal UV-barrier properties by incorporating aloe vera (AV) and green synthesized zinc oxide nanoparticles (ZnO-NPs). The composition and synergistic effects of CMC, AV, and ZnO-NPs were optimized using central composite design to achieve the best UV-barrier properties. When using the optimized compositions of CMC (1.0 g), AV (3.0 g), and ZnO-NPs (5.0 wt%), the minimum UV-transmittance achieved was 4.75%. Fourier transform infra-red and wide-angle X-ray diffraction were used to confirm the interactions between the coating components. The incorporation of ZnO-NPs into CMC/AV was validated through surface morphology analysis via scanning electron microscopy and by examining the distribution of ZnO-NPs using transmission electron microscopy. CMC/AV/ZnO-NPs coatings showed excellent water barrier, mechanical, thermal, and antimicrobial properties when compared with the neat carboxymethyl cellulose coating. In addition, CMC/AV/ZnO-NPs coatings significantly resisted both mass loss and spoilage of green capsicum for a 15-day storage period. These results proved that the optimized coating could replace the plastic packaging candidates and be used potentially to preserve food products.

Polycaprolactone/polybutylene adipate terephthalate blends (PCL/PBAT) (90/10, 75/25, and 50/50 wt/wt) containing 1, 3, and 5 phr hydroxyapatite (HA) nanoparticles were prepared using solvent-casting technique. Scanning electron microscopic studies confirmed a homogeneous morphology for the blends and nanocomposites. Some agglomeration can be recognized using energy-dispersive spectroscopy mapping in the blends containing 5 phr HA. The DSC results confirmed the presence of nanoparticles in each phase, particularly in the crystalline region, and wetting coefficient confirmed the localization of nanoparticles at the interface. Thermal stability and degradation kinetics were analyzed using thermogravimetric analysis (TGA). Based on the TGA results, a multi-step degradation process resulted in the blends and blend nanocomposites and the PCL/PBAT blends showed better thermal stability and exhibited higher T_max and residual mass. PCL/PBAT blends were more stable at higher temperatures compared to PCL and PBAT. Various kinetics evaluation techniques, including Friedman, Flynn–Ozawa–Wall, and Kissinger–Akahira–Sunose methods, were utilized to determine the activation energy of degradation. PCL/PBAT blends were more difficult to thermally degrade and showed the highest degradation activation energy. Incorporating HA led to lower thermal stability and, therefore, lower degradation activation energy. Incorporation of only 5 phr of HA resulted in greater thermal stability at higher temperatures (T_90%).

The study explores the novel use of jute nanofibers as environmentally friendly modifiers to enhance the mechanical and thermal properties of waste polypropylene/polystyrene/natural rubber (wPP/PS/NR) ter-blends. It aligns with the sustainable development goal (MDG 7) to ensure environmental sustainability. Nanofiber was produced from jute fiber via a ball milling process after freezing with liquid nitrogen. The produced nanofibers were analyzed using Fourier transform infrared (FTIR) spectroscopy and dynamic light scattering (DLS). Ter-blend, produced via melt blending using two-roll mills, was modified with the nanofibers at different weight percentages (2–10 wt%) at 2 wt% intervals. The modified polymer blends were characterized by their mechanical, thermal, physical, and morphological properties. FTIR revealed the removal of hemicellulose, lignin, and other impurities from the jute fiber due to chemical treatment. DLS analysis revealed an average size distribution of 85.54 nm, for which an intensity and polydispersity index (PDI) of 0.353 was achieved. Additionally, thermogravimetric analysis (TGA) confirmed that the jute nanofibers were thermally stable up to 282 °C. The polymer blends modified with 2 wt% nanofibers had the highest average impact and tensile strength. The percentage water absorption (%WA) showed that sp10% absorbed the highest amount of water after 24 h. The weight loss of the modified blend at various temperatures increased with the addition of nanofibers. Scanning electron microscopy (SEM) revealed cracks, voids, and blend separation as the amount of jute nanofibers increased. Dynamic mechanical analysis (DMA) revealed that the T_g of the modified blend improved, while the loss factor improved greatly by 43%, but the storage and loss moduli remained unchanged.

The healing of wounds is still a difficult clinical issue, and effective wound management is necessary to promote wound healing. Fabrication of highly developed dressings for wounds exhibiting biologically active properties and possessing favorable mechanical characteristics to accelerate the period of healing to avoid sideways bacterial infection. Hyaluronic acid (HA) inserted with loaded metal oxides such as silver phosphate (Ag₃(PO₄)), CNT and samarium oxide (Sm₂O₃) by film casting technique. The prepared films were examined by XRD, SEM, FTIR, and TGA. The surface topography showed a rough surface with low porosity for pure HA, while the addition of nanoparticles caused an incredible increase in the roughness with pores in diameter of 4–15 µm. The smooth surface appeared due to the addition of carbon nanotubes (CNT) and the mixing of the HA with polyvinyl alcohol (PVA). The contact angle was determined with water drops to determine the wettability of the prepared films, and it showed different changes varying between 67.72° for pure HA and then increased to 73.33° with the addition of Ag₃(PO₄), while the addition of Sm₂O₃ reduced the angle to 54.76° and 46.59° with mixing the ratios of nanoparticles. On the other hand, the Ag₃(PO₄)/Sm₂O₃/CNT@PVA/HA film represented a slight increase in the angle to 53.77° which has a hydrophilic tendency. The antibacterial test was done, and it was shown that the inhibition zone reached 20.5 ± 1.5 and 17.5 ± 1.5 against E. coli and S. aureus, respectively, for Ag₃(PO₄)@HA. The generated data display that the biological behavior of the mentioned nanocomposites (NCs) is promising.

A hybrid film that exhibits reversible fluorescence (FL) is prepared by embedding a conjugated polymer, having an intramolecular stacking structure of the side phenyl rings, in a highly dispersed state into a silicone elastomer. The hybrid film experiences significant FL quenching during stretching and restores its original FL when the external stress is removed. In particular, the hybrid film manufactured using a shadow-masked, plasma-treated silicone elastomer provides a high-resolution FL image, which disappears when the film is stretched and reappears when the external stress is removed. The hybrid film can be applied as a strain-gauge sensor or a security film with embedded images that can be mechanically erased and regenerated.

Graphical abstract

The purpose of the current research study was to formulate and evaluate a fenugreek (FG) and agarose (AG) base hydrogel exploiting pH-responsive attributes and colon targeting of 5-fluorouracil (5-FU). A novel 5-FU loaded fenugreek (FG) and agarose (AG) base hydrogel was formulated via free radical polymerization by employing N’, N’methylene bisacrylamide (MBA) as a crosslinker and methacrylic acid as a monomer. The influence of substrate concentrations (FG, AG, MBA, and MAA) was studied on the swelling index, sol–gel fraction, and drug release rate (%). It was also evaluated that as the concentration of fenugreek and agarose increases, drug release increases to 94.35 ± 0.34 (%) at pH 7.4 and 13.34 ± 0.34 (%) at pH 1.2. However, an increase in MAA concentration further leads to an increase in swelling, 95.87 ± 0.23 at pH 7.4 and 14.35 ± 0.74 at pH 1.2. Moreover, MBA concentration could significantly and directly influence the swelling of hydrogels owing to the variation of crosslinking density. An increase in MBA concentration results in a significant decrease in swelling. Fourier transform infrared spectroscopy (FTIR) depicted the grafting of polymers (FG and AG) and monomers (MAA). Thermal behavior showed that the formulated nexus protects the drug and substrate from degradation. The X-ray diffraction analysis (XRD) revealed that the entrapment of the drug within the nexus mimicked its crystalline behavior. The scanning electron microscope (SEM) elucidates the porous, rough, irregular, and asymmetric nature of the nexus. Toxicity studies showed that the best-selected optimized formulated nexus (F9) is biocompatible, non-toxic, and promising for targeted delivery of 5-FU for curing colorectal cancer.

Graphical Abstract