Journal of Polymers and the Environment最新文献

This work introduces a multifunctional wound dressing based on a polyhydroxyurethane (PHU) network primarily crosslinked with oxidized tannic acid (OTA). To tailor its properties, gelatin (GE) was added at different concentrations to improve biocompatibility and exudate management. A secondary crosslinking step, using either Fe(III) coordination or glutaraldehyde vapor, was then applied to enhance the mechanical strength in wet conditions while keeping flexibility. This approach produced two different dressing platforms: glutaraldehyde-crosslinked (GPHU/OTA/GE) and Fe(III)-crosslinked (FePHU/OTA/GE). The resulting materials combined features essential for advanced wound care. The dressings reached tensile strengths of up to ~ 4 MPa and adhered strongly to skin, even on highly mobile joints. The very good adhesion strength of about 15 kPa to tissue imitating substrate (gelatin sheet) was recorded for both categories of these dressings. They could handle fluids at capacities of 2.5–3.6 g/10 cm²/day and had a water vapor transmission rate of 1881–3137 g/m²/day, suitable for low-to-moderate exuding wounds. The OTA crosslinker provided a strong photothermal effect, reaching surface temperatures of > 50 °C under NIR irradiation to kill Gram-positive and Gram-negative bacteria, along with excellent natural antioxidant activity. Cytocompatibility tests confirmed safety, with fibroblast viability exceeding 100% in MTT assays and over 90% wound closure within 24 h in scratch assays. Based on performance evaluations, FePHU/TA/GE series is advised for wounds with moderate exudate levels owing to its excellent mechanical strength and integrity, whereas GPHU/TA/GE series is the optimal choice for low-exudate infected wounds because of its outstanding antibacterial efficacy.

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Heavy metal contamination of aquatic systems is a long-standing threat to both the environment and human health. This issue requires the development of effective, reusable, and clear adsorbents. In this study, we created a rare-earth bimetallic metal-organic framework-hydrogel composite called Ce-Sm-Tz@Alginate Beads. We synthesized it using in situ alginate gelation, followed by the solvothermal incorporation of a nitrogen-rich tetrazole ligand. The hybrid beads combine the structural stability of sodium alginate with the strong binding and adjustable chemistry of cerium and samarium centers. We confirmed the successful formation of a Ce-Sm-tetrazole coordination network embedded in the alginate matrix through comprehensive characterization using FTIR, XPS, SEM-EDAX, and PXRD. Batch adsorption experiments showed that the beads efficiently removed Pb(II), Cu(II), and Cr(VI) ions across various conditions. The maximum adsorption capacities were 2993.82 mg·g⁻¹ for Pb(II), 895.20 mg·g⁻¹ for Cu(II), and 1587.90 mg·g⁻¹ for Cr(VI) under optimized conditions. Kinetic analysis indicated that adsorption followed pseudo-second-order behavior. This means that the uptake was controlled by site availability on a varied surface rather than by strong chemical bonding. Isotherm modeling showed that the Freundlich, Sips, and Hill models best described the adsorption behavior, while Dubinin-Radushkevich energies (less than 0.4 kJ·mol⁻¹) indicated that physisorption was the main mechanism. The thermodynamic parameters suggested a spontaneous and endothermic process, with Pb(II) and Cr(VI) adsorption mainly driven by physical interactions, while Cu(II) showed some stronger interactions. To better understand the factors driving adsorption, we used explainable artificial intelligence techniques, including Principal Component Analysis (PCA) and Local Interpretable Model-agnostic Explanations (LIME). PCA identified the initial metal concentration and adsorption capacity as the main contributors, while LIME analysis showed that the sensitivities to contact time and adsorbent dosage varied by metal. Reusability studies demonstrated excellent stability for Pb(II) and moderate retention for Cr(VI), emphasizing the practical use of the composite beads. Overall, this work presents a scalable, clear, and sustainable rare-earth MOF-hydrogel system for multi-metal wastewater treatment.

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Understanding the physical behavior of polymers during processing is crucial for developing new materials suitable for emerging technologies. Rotational molding (RM), a low-shear manufacturing method, requires a distinct approach to material characterization, as polymer behavior under these conditions differs from that observed in conventional melt mixing and laboratory-scale molding techniques. This study investigated the miscibility of poly(lactic acid) (PLA) and poly(ethylene 2,5-furandicarboxylate) (PEF) blends. The RM processability of bio-polymeric blends was evaluated using dry-blending and melt-mixing procedures. The influence of the multi-stage preparation procedure for PLA-PEF blends on melt-mixed RM was verified. The blends containing up to 50 wt% PEF exhibited good RM-processability, and the introduction of 25 wt% PEF enabled the manufacture of a product with a uniform RM-part wall structure. Moreover, it was demonstrated that the fine, dispersed structure of the pre-extruded blends could be preserved despite partial coalescence and structural relaxation of the polymers during cryogenic grinding and the subsequent long-duration RM process. Correlated rheological, structural, thermal, and thermomechanical analyses enabled a comprehensive description of the phenomena and limitations, providing support for the further upscaling of novel thermoplastic bio-polyester blends. This work addresses the knowledge gap on forming polymeric blends under shaping conditions in RM technology based on polymer sintering, with almost complete exclusion of shear forces during processing.

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Fused deposition modeling (FDM) is a versatile and cost-effective technique for producing personalized pharmaceutical dosage forms. Advancing this approach requires the development of novel excipients to overcome the limitations of conventional drug formulation additives. Naturally derived excipients, valued for their biocompatibility, are increasingly explored in drug design, with soy protein products emerging as promising candidates due to their low cost and availability. This study investigated the possibility of incorporation of soy protein concentrate (SPC) into filaments prepared via hot-melt extrusion (HME) for FDM 3D printing of ketoprofen tablets. Additionally, the effects of SPC content, sodium starch glycolate (SSG) content and tablet geometry on ketoprofen release rate were evaluated. SPC was successfully incorporated at 10% w/w and demonstrated greater potential as a release-rate enhancer compared to the traditional superdisintegrant SSG, in both pH = 1.2 and pH = 6.8 dissolution media. Drug release kinetics were influenced by both formulation composition and dosage form geometry, highlighting the complex interplay between material properties and printing design. FTIR and DSC analyses suggested the formation of a solid dispersion of ketoprofen within the hydroxypropyl cellulose polymer matrix, with no evidence of chemical interactions with any of the excipients. These results confirm the successful processability of SPC by both HME and FDM 3D printing and emphasize the value of a holistic approach in designing 3D-printed pharmaceutical dosage forms, integrating excipient selection, formulation composition, and printing parameters to optimize drug release performance and enable the production of tailored, effective therapies.

This study investigates the epoxidation of sunflower oil using lactic acid as an oxygen carrier, with emphasis on reaction kinetics under varying conditions of temperature, hydrogen peroxide-to-oil molar ratio, and stirring speed. The reaction progress was monitored through oxirane oxygen content (OOC) measurements and analyzed using pseudo-first-order and consecutive first-order kinetic models, with MATLAB R2023A employed for parameter estimation. The results showed that the highest relative conversion to oxirane (RCO) was achieved at the most intense conditions tested. The maximum relative conversion of oxirane (RCO) reached about 27%, with an apparent pseudo-first-order rate constant of 6.8 × 10⁻³ min⁻¹ and consecutive model rate constants of k₁ = 0.0307 min⁻¹ (epoxy formation) and k₂ = 0.0351 min⁻¹ (epoxy degradation).These findings confirm that increasing temperature, oxidant loading, and agitation enhances both the epoxidation rate and peak oxirane yield. However, the accelerated degradation of oxirane groups at these extreme conditions also highlights the trade-off between rapid conversion and product stability. Overall, the study demonstrates that lactic acid can serve as an effective and safer oxygen carrier for epoxidation, with kinetic modeling providing valuable insights into the design of optimized green processes for producing epoxidized oils and polyols.

Colorectal cancer (CRC) continues to rank among the most prevalent and clinically significant malignancies on a global scale. Traditional chemotherapy often leads to systemic drug dispersion, culminating in deleterious off-target effects on healthy, non-malignant tissues. This highlights the critical need for designing targeted drug delivery platforms that improve therapeutic accuracy by limiting off-target exposure. In this context, a temperature and pH responsive co-polymer, Alg-g-P(NIPAAm-co-NVP), was fabricated and evaluated for its potential to deliver Capecitabine specifically to colorectal tumour sites. Alg-g-P(NIPAAm-co-NVP) co-polymers were synthesized and 2² factorial design was employed to optimize sodium alginate and NVP concentrations to achieve tumour-specific responsiveness for co-polymer. Capecitabine was loaded into the optimized formulation and assessed for release behaviour, cytotoxicity and stability studies. Drug release studies revealed significantly enhanced release under tumour-like pH and temperature conditions (~ 82.62%) compared to physiological conditions (~ 38.24%), with MTT assay results corroborating increased drug release in the tumour microenvironment as CAP-loaded nanoparticles exhibited lower cytotoxicity than free Capecitabine (IC₅₀; 30 ± 1.2 µg /mL), under physiological conditions (IC₅₀; 27 ± 1.4 µg/mL), but higher cytotoxicity in the tumour-like environment (IC₅₀;23 ± 2.1 µg/mL). The biocompatibility of the co-polymer and Capecitabine-loaded nanoformulation was validated via MTT assay using human fibroblast (NIH) cell lines. Stability studies indicated that the optimized formulation exhibits excellent stability when stored at 4–8 ± 2 °C. The developed Alg-g-P(NIPAAm-co-NVP) nanoparticles exhibit considerable potential for Capecitabine to achieve tumour specific targeting, offering an innovative strategy for controlled and site-specific delivery in oncology.

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Polyhydroxyalkanoate (PHA) represents a promising biodegradable alternative to conventional plastics, yet its extraction from mixed microbial cultures (MMC) remains challenging owing to low intracellular accumulation (< 35% of cell dry weight) and robust cell envelopes. Notably, the use of short-term acclimated sludge, while reducing cultivation time and cost, results in such low-PHA-content biomass (LPCB), further complicating extraction. The present study addresses these limitations by establishing an optimized and scalable recovery protocol for PHA derived from LPCB obtained from activated sludge acclimated under short-term anaerobic-aerobic conditions (24.6% PHA content). This focus on short-term acclimated sludge is pivotal for industrial scalability, as it leverages readily available wastewater treatment sidestreams and eliminates the need for costly, dedicated long-term acclimation reactors. To facilitate efficient cell disruption, pretreatment strategies were systematically investigated to weaken the hydrolysis-resistant MMC cell walls and reduce the dominance of the non-PHA cellular matrix (NPCM). Subsequent extraction employed dimethyl carbonate (DMC) as a green solvent. Critical extraction parameters—including solvent concentration, temperature, and reaction time—were optimized using a Taguchi orthogonal array design, with Minitab^® employed to quantify the relative contribution of each parameter to recovery efficiency. The optimized process not only significantly enhanced PHA recovery from LPCB but also preserved polymer quality. Scale-up experiments demonstrated consistent performance under extended operational conditions, confirming the method’s potential for industrial application. This work thus proposes a scalable, cost-effective, and environmentally benign downstream strategy for PHA production from waste-derived biomass, contributing to more sustainable bioplastic manufacturing.

This study shows the creation of an intelligent orthopedic device for arthrodesis using a 4D-printing method. This device has great potential for use in veterinary medicine. The key purpose of such a product for veterinary medicine is to position the joint at a natural angle for the animal, which in modern practice is performed manually by the surgeon. Polylactide (PLA) is selected as the polymer matrix of the composite materials as a biodegradable and bioresorbable polymer obtained from renewable resources that meets the goals of sustainable development by reducing the environmental impact of medical implant production. The effect of secondary temperature treatment and 3D-printing features PLA on the implementation of the shape memory effect (SME) was studied. For a better understanding two well-known dispersed fillers – nanoparticles of hydroxyapatite (HA) and microparticles of silicon dioxide (SiO₂) were chosen. Analyzing the effects of multiple thermal cycling (extrusion followed by 3D-printing), we demonstrate how 4D-printing conditions alter the microstructure, crystallinity, and shape-recovery ability of these materials. The importance of choosing a filler for these technologies is shown, since HA nanoparticles improve interlayer adhesion, while SiO₂ causes cavitation defects. Consequently, 4D-printed PLA/HA showed a high degree of shape recovery (~ 85% recovery coefficient and ~ 3.2 MPa recovery stress) and was used to manufacture orthopedic structures. The attachment and activation of self-positioning of the arthrodesis are demonstrated for the accuracy of limb angles and shortening the recovery time of the animal.

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As an alternative to petroleum based raw materials, bio-based bisphenol (TC) was derived from thymol (T) and citronellal (C) emphasizing two principles of green chemistry by employing safer solvents and auxiliaries for synthesis and utilization of renewable feedstocks are justified. The novelty of this work lies in demonstrating the dual utility of this renewable bisphenol (TC) for the first time in the synthesis of two commercially significant thermosets polybenzoxazines and epoxy resins establishing a sustainable possible replacement for conventional petrochemical monomers. Benzoxazines (TC-fa, TC-la and TC-sa) were synthesized using TC with three different primary amines viz. furfurylamine (fa), laurylamine (la) and stearylamine (sa) separately. Also, TC was epoxidized to obtain bio-based epoxy (TC-E). The molecular structure of the targeted benzoxazines and epoxy were confirmed by spectral analysis. TC-fa showed lowest temperature of 205 °C to undergo polymerization. Whereas, poly(TC-sa) was found to possess highest water contact angle of 144^o with a corrosion inhibition efficiency of 98.8% which was further supported by DFT studies. On comparing the antimicrobial activity and cytotoxic effects of TC with benzoxazines, TC exhibited greater bacteriostatic property with 30 and 20 mm inhibition zone against E.coli and S.aureus. Also, TC coated cotton fabric exhibited 99.9% bacterial growth inhibition efficiency. Mild toxicity with IC50 value of 138.81 µg/mL was exhibited by TC when compared to benzoxazine. The epoxidized bisphenol (TC-E) was cured with different curing agents and found the suitable catalyst to cure the epoxy resins at a least temperature of 141 °C. Thermally cured epoxy material was subjected to flexural test which revealed a maximum flexural stress of 0.77 MPa and a modulus of 40.20 MPa.

Chronic wounds are often characterized by persistent inflammation and oxidative stress, which impair fibroblast function, disrupt extracellular matrix formation, and delay tissue regeneration. Bioactive hydrogels that incorporate natural polyphenols and functional nanomaterials offer a promising strategy to accelerate healing through synergistic antioxidant and anti-inflammatory effects, creating a favorable microenvironment for tissue repair. Building on previous work with a ZnO–CuO nanocomposite–embedded PEG–chitosan hydrogel, this study developed a novel polyphenol-loaded ZnO–CuO polysaccharide hydrogel (CPZCH-X) for advanced wound dressing applications. Structural and chemo-mechanical characterization using FTIR, XRD, SEM, UV–Vis spectroscopy, and tensile testing confirmed successful polyphenol incorporation, resulting in improved structural integrity and mechanical stability. The functional assays showed favorable cytocompatibility, hemocompatibility, and wound closure activity, along with regulated inflammatory, oxidative, and repair biomarkers, demonstrating enhanced wound-healing potential. Overall, CPZCH-X is a multifunctional, polyphenol-enriched hydrogel with superior physicochemical and mechanical properties, showing strong potential as a bioactive wound dressing. Future in vivo studies are warranted to validate its therapeutic efficacy and clinical applicability in chronic wound management.

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