Journal of Polymer Science最新文献

A metal-free and sustainable strategy for the synthesis of graft copolymers was developed by combining ring-opening polymerization (ROP) of ε-caprolactone with atom transfer radical polymerization (ATRP) at ambient temperature. Polycaprolactone (PCL) backbones bearing initiating sites were first prepared and subsequently employed for ATRP of two different vinyl monomers, methyl methacrylate (MMA) and poly(ethylene glycol) methyl ether acrylate (PEGA). This tandem polymerization approach enabled the controlled preparation of well-defined PCL-g-PMMA and PCL-g-PPEGA graft copolymers without the use of transition-metal catalysts. The successful incorporation of side chains was confirmed by ¹H-NMR and FT-IR spectroscopy, while molecular weight distributions were evaluated by gel permeation chromatography (GPC). Differential scanning calorimetry (DSC) revealed the influence of grafting on the thermal properties of the copolymers, and water contact angle (WCA) measurements demonstrated surface wettability changes associated with PEGA incorporation.

Highly porous polylactic acid (PLA) electrospun fibrous membranes loaded with thyme oleoresin (TOR) (0–20 wt%) were fabricated via electrospinning using a non-solvent induced phase separation (NIPS) mechanism for active food packaging. Scanning electron microscopy (SEM) analysis revealed uniform, bead-free fibers with high surface porosity across all samples. Among different membranes, the PLA/TOR 15% membrane showed comparatively superior mechanical strength, thermal stability, surface hydrophobicity, and water vapor barrier properties. Antioxidant evaluation using the DPPH assay confirmed strong activity, with 20% TOR-loaded membranes showing the highest scavenging (93% ± 2.7%). Antibacterial analysis revealed selective activity; no inhibition against Escherichia coli , while increasing TOR content enhanced inhibition against Staphylococcus aureus . The PLA/TOR 15% membrane was further evaluated for meat preservation over 15 days, assessing quality parameters such as color, pH, peroxide value (PV), free fatty acid (FFA) content, and thiobarbituric acid reactive substances (TBARS). These results demonstrated that the PLA/TOR membrane effectively delayed lipid peroxidation, thereby extending the shelf life of meat, highlighting its potential for active food packaging applications.

Rapid industrialization has resulted in the discharge of significant amounts of dye-contaminated wastewater, raising serious environmental concerns. Addressing this, the current study focuses on developing eco-friendly, rationally designed alginate-based composite hydrogel beads (ACHBs) for the efficient removal of both cationic (methylene blue, MB) and anionic (Congo red, CR) dyes from aqueous solutions. The ACHBs were synthesized and thoroughly characterized using FTIR, XRD, SEM–EDX, BET, TGA, and XPS analyses to confirm their structure and composition. Batch adsorption experiments were conducted to evaluate the dye removal efficiency under varying conditions including adsorbent dosage, dye concentration, contact time, pH, and temperature. Optimal adsorption capacities reached 47.8 mg g⁻¹ for MB at pH 7.0 and 32.5 mg g⁻¹ for CR at pH 4.5 with 50 mg of adsorbent and 90 min contact time. The incorporation and crosslinking of the composite components with Zr⁴⁺ ions provided the ACHBs with mechanical integrity and enhanced performance. Distinct mechanisms facilitated the simultaneous removal: MB was primarily adsorbed by electrostatic attraction, while CR was captured via host–guest inclusion within beta-cyclodextrin. The adsorption process was endothermic and spontaneous, and the Langmuir isotherm and pseudo-second-order models fit the data well. Regeneration studies confirmed the material's reusability for multiple cycles, demonstrating promise for sustainable water treatment.

The strength and hydrophilicity of nanofiber materials for tissue engineering have always been a significant challenge. This paper presents the design and preparation of PLA&Gel/PHBV core–sheath nanofibers that combine strength and super hydrophilicity using electrospinning technology. Compared to the original materials, the addition of gelatin simultaneously enhances both the strength and hydrophilicity of the materials, with the mechanical and hydrophilic properties of PLA&20 wt%Gel/PHBV nanofibers reaching optimal values of 7.45 MPa and 2.2°, respectively. The increase in strength is attributed to the entanglement effect caused by the gelatin molecular chains, which hinders the relative sliding of the molecular chains. The enhancement in hydrophilicity is due to the introduction of a large number of hydrophilic groups from Gel, improving the material's hydrophilicity. Additionally, the polar groups in gelatin and the emergence of a network pore structure significantly increase the material's water absorption rate. This work provides new insights into the design and preparation of nanofiber materials.

The experimental results showed that the limiting oxygen index (LOI) value of the THPON3-THPC-treated cotton fabric increased significantly (by up to 32.5%), and the length of damage in the vertical burning test was reduced to 8.1 cm with no afterflame. Cone calorimeter tests revealed a significant reduction in combustion efficiency, with the peak heat release rate (PHRR) decreasing from 283.1 to 112.9 kW/m² and the total heat release (THR) decreasing from 21.8 to 4.6 MJ/m². Compared to the traditional Proban ammonia curing process, THPON3-THPC demonstrated greater flame-retardant effectiveness. This treatment improved both the comfort and environmental sustainability of the flame-retardant cotton fabric. Furthermore, experimental results showed that THPON3 achieved formaldehyde removal rates of 92.5% (E2 grade) and 68.3% (NAF grade) from plywood, outperforming urea and demonstrating significant formaldehyde removal capabilities. As an efficient formaldehyde scavenger, THPON3 significantly inhibited and delayed the release of formaldehyde from plywood. Additionally, cytotoxicity tests showed that THPON3 exhibited no significant toxicity to Hacat and BEAS-2B cells at a concentration of 800 μM, indicating a very low risk to human health in the event of accidental ingestion or inhalation. These findings are important for the application of THPON3 in flame-retardant and residential building materials.

Technologies for formation of polymer materials with a given spatial distribution of properties are widely in demand in both scientific and industry applications. Various chemical or physical effects are used to control the formation of polymers and influence their properties, enabling the creation of materials with controlled property gradients. Among the physical effects the use of centrifugal field is one of the most effective ways. Usually it is believed that this mechanism is able to form only a monotonous distribution of properties in the radial direction. In our work, the possibility of obtaining a non-monotonic distribution of optical and mechanical polymer properties during polymerization in centrifuge is demonstrated by the example of acrylamide polymer. The use of interferometry in real-time visualization of the polymerization process allowed us to demonstrate a key role of convective motion in the final distribution of polymer properties. The magnitude of the refractive index inhomogeneity turned out to be on the order of 10⁻³. We propose a physical mechanism responsible for the formation of a non-monotonic distribution of polymer properties based on the competition of several effects at once: free convection, convection in a porous medium, and edge effects.