Journal of Polymers and the Environment最新文献

Ulvan, a biodegradable sulfated polysaccharide from Ulva papenfussii, was obtained using hot water (neutral pH) and alkaline (pH 13) methods to evaluate how extraction conditions modulate its molecular dynamics and dielectric behavior. While compositional changes due to extraction pH are well documented, their impact on the relaxation processes and segmental mobility of ulvan remains largely unexplored. Here, we provide a comprehensive characterization of dielectric permittivity and dielectric loss over a wide frequency (10⁻²-10⁶ Hz) and temperature range (-150 °C to 150 °C), supported by differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). The alkaline-extracted ulvan showed a lower glass transition temperature (31.6 °C vs. 47.9 °C), higher molecular mobility, and enhanced dielectric response. In contrast, the hot water-extracted sample exhibited greater thermal stability and a more defined dipolar relaxation processes, including a β-relaxation characterized using the Havriliak–Negami model. These findings suggest that hot water-extracted ulvan is more suitable for applications like biodegradable packaging or biomedical films, while alkaline-extracted ulvan is better suited for electroactive materials such as polymer electrolytes. This study highlights the role of extraction strategy in designing ulvan-based sustainable materials. The results underscore the relevance of broadband dielectric spectroscopy as a powerful tool for guiding the design of polysaccharide-based functional materials.

The development of cushioning material with excellent resilience, high compressive strength, and sustainability is essential for engineering development, and environmental protection. In this study, we report a simple and effective method to produce poly (butylene adipate-co-terephthalate) (PBAT)/poly(lactic acid) (PLA) foams with excellent resilience and thermal stability by introducing a small amount of poly (D-lactic acid) (PDLA) through melt blending and supercritical CO₂ foaming. PDLA interacts with poly (L-lactic acid) PLLA chains to form stereocomplex (SC) crystals, which act as rheological modifiers and through tuning the PLLA/PDLA ratio, promote the formation of a rigid co-continuous PLA network within PBAT matrices. The incorporation of SC microcrystals significantly improved the mechanical strength and thermal stability of the foams compared to conventional PBAT/PLA blends that exhibit island-like morphology. The main findings include the production of foams with high cell density (~ 1 ± 0.5 × 10⁹ cells/cm³), uniform bubble size (~ 15 μm), maximum stress at 50% strain of 0.3 MPa, permanent deformation rate of less than 10%, and minimum buffer coefficients of ~ 3.0. In addition, SC crystals considerably retarded the dimensional changes at elevated temperatures, thus improving the stability of the foams. This study highlights a practical strategy for designing high-performance, biodegradable polymer foams, with potential applications in sustainable packaging and protective materials.

In this research, a Pickering nanoemulsion (PNE) coating was successfully created using carboxymethyl cellulose (CMC) and chitosan (C) combined with Pelargonium essential oil (PEO) at quantities of 0.5%, 1%, and 2%. The essential oil compounds were analyzed using GC–MS data, revealing their beneficial effects against the activities of microorganisms like Staphylococcus aureus, Escherichia coli O157:H7, Alternaria alternata, and Aspergillus flavus. Additionally, SEM images revealed that the addition of PEO to the solution enabled the Pickering chitosan (PC) particles to directly stabilize the emulsion and incorporate the oil phase into the polymer matrix, ultimately leading to the formation of oil-loaded nanocapsules. Average particle size of 147.5 d.nm, zeta potential of − 44 mV, and PDI of 0.25 indicated the successful formation of a complex with Pickering CMC-C-PEO, resulting in a stable and antioxidant-rich PNE. The physicochemical properties of fig samples were assessed over 6 days at 25 °C, including weight loss, decay percentage, Juicability, titratable acidity, pH, total soluble solids, total phenol content, total anthocyanin, and total ascorbic acid amounts. As regards the results, the highest content of total phenol (23.93 ± 1.32 mg/100 g sample), total anthocyanin content (52.04 ± 1.81 mg/100 g sample), and the lowest decay percentage (12.50 ± 12.50%) were associated with the sample coated with PNE of CMC-C-PEO 2%. In contrast, the control samples exhibited the opposite trend for these factors, respectively (17.87 ± 2.62 mg/100 g sample, 13.70 ± 1.60 mg/100 g sample, and 87.50 ± 12.50% mg/100 g sample). This study presents a novel, plant-based, PNE system that integrates natural polymers and essential oils to enhance postharvest quality and microbial safety of perishable fruits. The coating not only extends shelf life but also preserves nutritional and functional attributes, offering a sustainable alternative to synthetic preservatives.

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The development of multifunctional scaffolds with improved mechanical strength, swelling resistance, antibacterial activity and cytocompatibility is crucial for tissue engineering. In this study, chitosan–gelatin (CH GT) scaffolds were reinforced with curcumin (Cur), nano-curcumin (nCur), and PLGA-encapsulated curcumin (PLGA_Cur) to enhance physicochemical and biological properties. SEM micrographs confirmed uniform, interconnected pores with reduced pore wall disruption upon Cur incorporation. Mechanical testing revealed that the highest tensile strength and tensile modulus for CH GT nCur were observed at 34 kPa and 58 kPa, respectively. Swelling studies showed a significant reduction in equilibrium swelling ratio from ~ 675% (CH GT) to ~ 340% (CH GT_nCur), correlating with enhanced hydrogen bonding and physical crosslinking. Antibacterial assays indicated significant inhibition against S. aureus (~ 94%) and E. coli (~ 92%) for CH GT_nCur. Cytocompatibility tests showed > 85% cell viability across all formulations, with CH GT_nCur supporting superior cell attachment and cell migration capabilities compared to controls. Cur release from CH GT Cur and CH GT nCur hydrogel scaffolds resulted in antioxidant activity; however it was slightly impeded by rapid release. In the PLGA-based system, antioxidant activity is enhanced with sustained release. CH GT Cur and CH GT nCur enhanced M2 macrophage polarization (p < 0.001) compared to CH GT Cur hydrogels, which successfully decreased inflammation and oxidative stress. Notably, despite a delayed M2 response, the PLGA-encapsulated Cur system (CH GT PLGA_Cur) demonstrated sustained decrease of ROS levels and iNOS expression, suggesting extended anti-inflammatory effect. These results demonstrate the promise of CH GT-based hydrogels, particularly the PLGA_Cur system, for oxidative stress management and regulated immunomodulation in therapeutic settings.

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Recently, hydrogel films, due to their biocompatibility, high drug and encapsulation efficacy, and adjustable physicochemical features, have emerged as promising candidates for delivering therapeutics in the treatment of human cancers. Therefore, this study aimed to design dialdehyde starch-crosslinked chitosan hydrogel films modified zeolitic imidazolate framework-8 (ZIF-8) for controlled release of doxorubicin (DOX) to HeLa cancer cells. For the preparation these hydrogel films, the dialdehyde starch (DS) in different percentages was utilized to crosslink chitosan (CS) through the Schiff base imine reaction, which 5% was chosen as the optimal content for preparing CS hydrogel films with higher swelling capacity (1000% at pH 7.4 for 72 h). Then, a subsequent in-situ synthesis method was employed to grow antibacterial ZIF-8 nanoparticles on the DS-CS hydrogel films (DS-CS/ZIF-8). To elucidate the effectiveness of the DS-CS/ZIF-8 nanocomposite hydrogel films as a pH-responsive drug carrier, DOX was loaded as a model anticancer drug (97.6%) by soaking in a solution of the drug. The in-vitro DOX release study indicated a time-dependent, pH-sensitive controlled release profile (< 35% at pH 7.4 and about 90% at pH 5 over 72 h). Notably, the MTT assay demonstrated good cytocompatibility and significant cytotoxicity against the HeLa cancer cells (cell viability < 50% at 6 µg/mL) for both the DS-CS/ZIF-8 and DOX-loaded DS-CS/ZIF-8. The DS-CS/ZIF-8 showed improved antibacterial properties toward both S. aureus (MIC: 31.2 µg•mL^–1) and E. coli (MIC: 62.5 µg•mL^–1) bacteria. Based on the obtained results, the synthesized biocompatible nanocomposite hydrogel films with pH-sensitive features have the potential for use as an implantable anticancer treatment.

The packaging industry needs to develop new materials to replace conventional plastics. This is where bioplastics, primarily derived from biopolymers such as proteins, come into play in addressing this problem. However, given their overall mechanical properties, cross-linking methods are needed to improve their performance compared to synthetic counterparts. Thus, this article proposes the development of bioplastics using pea protein as a biopolymer and glycerol as a plasticizer in different ratios (60/40 and 70/30), and incorporating transglutaminase as a natural cross-linking agent (0.25% and 0.50% concentrations), using compression molding as a processing technique for the development of prototypes. Therefore, the mechanical, thermal, optical, physicochemical, and functional properties were analyzed, demonstrating, first of all, the obtention of a material with a glass transition temperature of approximately 65–70 °C lower than that of conventional plastics such as PET. In this way, the materials showed an improvement in flexural properties (obtaining an elastic modulus of 1–2 MPa), at the expense of a deterioration in tensile tests (with a Young’s Modulus of 20–30 and 45–50 MPa for the 60/40 and 70/30 formulations, respectively). Similarly, opacity was increased by incorporating the enzyme into the formulation, highlighting its role in the 70/30 formulation with 0.50% of the enzyme. Moreover, this enzyme also reduced the water absorption capacity by approximately 13%. This demonstrates the potential application of this type of material in dry product packaging, which maintains its properties after a period of 125 min with a moisture content of 3–5%, highlighting its viability for the development of more environmentally responsible packaging solutions.

In this study, we introduce a one-step semi-solid extrusion 3D printing strategy to fabricate gelatin-polyvinylpyrrolidone (GAG-PVP) scaffolds loaded with a low dose (0.5 wt%) of alendronate (ALN) and crosslinked in situ with 1 wt% genipin. The genipin-crosslinked ALN scaffold (GAG-PVP-GEN-ALN) demonstrated enhanced functional performance compared to both non-crosslinked GAG-PVP and GAG-PVP-ALN controls. Its peak swelling reached 462% at 5 h, surpassing the 362% of the unmodified scaffold and preventing the rapid dissolution observed for GAG-PVP-ALN, before gradually deswelling for 96 h. Water contact angle measurements confirmed that genipin fully restored surface hydrophobicity (101.9°), counteracting the pronounced wettability induced by ALN (47.8°) and exceeding the 78.2° of the GAG-PVP matrix, which is consistent with swelling ratio. Differential scanning calorimetry (DSC) indicated enhanced thermal stability of the crosslinked gelatin, with shifts in both glass transition and denaturation temperatures reflecting greater molecular rigidity despite the presence of glycerol as a plasticizer. Mechanical testing showed that while alendronate alone reduced mechanical performance, the combined inclusion of alendronate and genipin significantly enhanced scaffold properties compared to gelatin-polyvinyl pyrrolidone blend: tensile strength increased from 19.7 MPa to 39.8 MPa, elastic modulus rose from 805 MPa to 1174 MPa, and microhardness improved from 9.24 MPa to 22.3 MPa, values nearing those of native cancellous bone. The sustained ALN release profile extended from an abrupt 3 h burst in GAG-PVP-ALN to a controlled 48 h delivery in GAG-PVP-GEN-ALN, following first-order kinetics. Both direct and indirect cytotoxicity assays confirmed high cell viability (> 85%) without morphological abnormalities. These results highlight that embedding low-dose ALN within a genipin-crosslinked gelatin-PVP network results in a mechanically robust, biocompatible scaffold with tunable swelling and prolonged drug release, offering a versatile platform for localized bone tissue engineering.

In polymer optics for LED luminaires, materials are lacking which combine properties needed for a modern, circular, and biobased economy and the high technological demands. With respect to this the photostability of optical-grade polylactide (PLA) compounds with fatty acid amides as clarifiers was evaluated. Clouding of the PLA is avoided by the incorporation of two fatty acid amides with favorable performance, namely N, N′-ethylenebis(stearamide) and N, N′-ethylenebis(12-hydroxystearamide). To enable the application of such novel PLA compounds in compact LED luminaires, high photostability at elevated temperatures is essential. The compounds were irradiated with high radiant fluxes at 450 nm for a total of 5000 h. Earlier studies have already attributed high photostability to neat PLA under those conditions, whereas optical-grade polycarbonate showed signs of aging after a few hundred hours. The present study demonstrates identical photostability for the PLA compounds containing fatty acid amides. During the first thousand hours, the UV–Vis transmission of all tested PLA samples increased, while haze levels remained unchanged. Furthermore, thermal and infrared spectroscopic analyses reveal no signs of incipient photodegradation. Although a decrease in the molecular weight of the samples was identified by size exclusion chromatography, fatty acid amides are proven to have no adverse effects on the photothermal aging of PLA. These findings confirm the high photostability of optical-grade PLA compounds, making them viable eco-friendly alternatives for the replacement of fossil-based polymers in optics.

Nowadays, the development of flexible electrodes through green processes for sustainable development has received much attention. Hence, the objective of this work is to fabricate a novel, free-standing polyaniline/polyvinyl alcohol/cellulose (PANI/PVA/cellulose) electrode using gamma irradiation as an efficient green technology for practical production. Cellulose was extracted from sugarcane bagasse through alkaline treatment, then combined with PVA and PANI to form a composite film via gamma irradiation at a dose of 40 kGy at ambient temperature, with a dose rate of 9.18 kGy/h, followed by hydraulic pressing. The chemical and crystalline structures, thermal stability, morphology, wettability and mechanical properties of the flexible electrode were characterized by FTIR, XRD, TGA, FE-SEM, contact angle measurement, and a universal testing machine respectively. Four-point probe and EIS measurement were employed to investigate the electrical conductivity. The ternary composite PANI/PVA/cellulose film formed a three-dimensional network with porosity ranging from 24.2 ± 0.5% to 67.6 ± 5.1%. In the presence of PANI improved the morphology and porosity of the composite films, resulting in enhanced ion transfer and electrical conductivity. Furthermore, the tensile strength and elongation at break increased to 22.1 ± 1.1 MPa and 25.0 ± 5.0%, respectively with the addition of 0.5 wt% PANI. The obtained PANI/PVA/cellulose composite film is considered as a potential candidate to replace the commercial electrode in energy storage devices due to its cost-effectiveness, eco-friendliness, and flexibility.

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An innovative solvent casting method was used to develop a series of biodegradable PCL/APTES-functionalized bioactive glass (F-BG) nanocomposites, with the goal of creating bone scaffolds that provide both robust mechanical support and a favorable biological environment. The study systematically evaluated composites with BG content ranging from 15% to 45%. Mechanical testing showed that the PCL/32% F-BG composite exhibited the highest flexural strength (25.8 MPa), while the PCL/45% F-BG composite achieved the highest elastic modulus (1793 MPa). This enhanced mechanical performance is crucial, as it allows the scaffold to more closely match the mechanical properties of adjacent bone tissue, a key factor for successful osteointegration. Microstructural analysis confirmed the uniform dispersion of the 56 nm BG nanoparticles, which underpinned the superior properties. Furthermore, comprehensive biological evaluations) including hydrophilicity, controlled degradation, and cytocompatibility using NIH3T3 cells (demonstrated the composite’s excellent biological response. The biocompatibility of the nanocomposites was confirmed by the MTT assay, which showed a notable increase in cell viability from approximately 84% for neat PCL to over 92% for the optimal 32% F-BG composite.

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