Journal of Polymers and the Environment最新文献

The increasing demand for efficient water purification technologies has accelerated the development of advanced adsorbents for dye removal. In this study, a novel high-performance adsorbent was synthesized by grafting 2,5-dimercapto-1,3,4-thiadiazole (DMTD) onto a chitosan (CS)–glutaraldehyde–trimesic acid (TMA) framework (CS@TMA@DMTD) through a straightforward two-step process. Comprehensive physicochemical characterization, including Fourier Transform Infrared Spectroscopy (FTIR), Thermogravimetric Analysis (TGA), X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Brunauer–Emmett–Teller (BET) surface area analysis, and X-Ray Photoelectron Spectroscopy (XPS), confirmed the successful incorporation of functional thiol (–SH) and carboxyl (–COOH) groups, which synergistically enhance the adsorption performance of the composite. The adsorption capacity of pristine crosslinked chitosan was evaluated at 96.3 mg/g, while the modified CS@TMA@DMTD composite exhibited a significantly enhanced capacity of 218.4 mg/g and achieved 96.5% removal under optimal conditions (298 K, pH 8, initial MB concentration 25 mg/L, and contact time 60 min), demonstrating the effectiveness of the functional modifications. Batch adsorption studies demonstrated a strong pH dependence, with optimal performance under neutral to slightly alkaline conditions. Kinetic data were best described by the pseudo-first-order model, suggesting that physical adsorption dominates the process. In contrast, the equilibrium data were fitted to the Langmuir isotherm model, indicating monolayer coverage on a homogeneous surface. Thermodynamic parameters (ΔG° < 0, ΔH° < 0) confirmed that the adsorption process is spontaneous and exothermic. Reusability tests demonstrated the stability and efficiency of CS@TMA@DMTD over five cycles, with only a ~ 5% performance loss. Its high capacity, fast kinetics, and recyclability make it a promising eco-friendly adsorbent for dye-contaminated wastewater, surpassing many conventional chitosan-based materials.

Poly(lactic acid) (PLA) is a promising biopolymer valued for its degradability and versatility. Conventional ring-opening polymerization (ROP) methods, which involve multistep processes under high temperature and vacuum conditions, often require high energy input and prolonged reaction times. In this study, ultrasonic-assisted ROP was first optimized using the conventional metal catalyst stannous octoate (Sn(Oct)₂) to evaluate the effects of ultrasonic power and reaction time. The optimal conditions (99.29 W, 3.66 h) produced PLA with a molecular weight of 88.18 kg/mol, 44.76% crystallinity, and a melting temperature of 165.64 °C, while reducing energy consumption by 49.98% compared to the conventional thermal process. Following this optimization, creatinine was employed as a metal-free biocatalyst to explore a greener catalytic alternative. In addition, methanol was introduced as a co-initiator at different ratios (0%, 0.5%, 1%, and 1.5%). The presence of methanol, particularly at 1.5%, enhanced chain initiation and propagation, leading to higher molecular weight and improved physical and thermal properties of PLA synthesized with creatinine. These findings suggest that the combined use of ultrasonic irradiation, biocatalyst, and co-initiator provides a potential pathway toward more energy-efficient and sustainable PLA production.

This research focuses on creating an innovative pH-sensitive nanocarrier for targeted paclitaxel delivery to breast cancer cells. The nanocarrier, consisting of hyaluronic acid grafted poly (acrylic acid-co-allyl glycidyl ether) conjugated mesoporous magnetic graphene quantum dots, is engineered to release the drug specifically in the acidic tumor environment. The study examined key factors affecting paclitaxel measurement. The Langmuir model provided the best fit, with a maximum sorption capacity of 15.851 mg g⁻¹. Kinetic modeling aligned well with the pseudo-second order kinetic model, supporting physisorption in the adsorption process, facilitated by a high density of active sites. Thermodynamic analysis revealed that drug adsorption onto nanocomposite was endothermic and spontaneous. The drug-loaded nanocomposite exhibited limited release in simulated physiological conditions (pH 7.4, 37 °C), but increased release in tumor tissue conditions (pH 5.6, 37 °C), enabling sustained drug release at the target site. The zero-order kinetic model best described drug release from the nanocarrier at pH 5.6, indicating non-Fickian diffusion transport control. The cytotoxicity results demonstrated that the nanocarrier was more toxic to MCF-7 cells than nanocomposite without the drug. Based on the collected data, the developed nanocarrier with appropriate pH-responsiveness shows significant potential as an anticancer agent.

The use of synthetic scaffolds as an alternative strategy for repairing bone defects has garnered significant attention in bone tissue engineering. Human mesenchymal stem cells (MSCs) play a crucial role in the body’s regeneration processes, making the identification of suitable inducers for treating osteogenesis disorders essential. This study is the first report in the world on the induction of differentiation of human adipose-derived mesenchymal stem cells (hAD-MSCs) into osteoblast-like cells on an innovative scaffold of carboxymethylcellulose, polyglycerol, and sebacic acid, containing vitamin D2 and chondroitin-4 sulfate. Initially, the scaffolds were created using molding and salt washing techniques. Their morphology, structure, and mechanical characteristics were examined through techniques such as scanning electron microscopy (SEM), X-ray diffraction (XRD), Thermogravimetric Analysis (TGA), and Fourier-transform infrared spectroscopy (FTIR). The optimal concentrations of vitamin D2 and chondroitin sulfate (CS) in the differentiation medium and scaffold structure were determined using the MTT assay. Viability and morphology were assessed through acridine orange-ethidium bromide (AO/EB) staining. Differentiation experiments were conducted with various concentrations of inducers both in the medium and on the scaffolds. Cell differentiation into osteoblasts was quantified through alkaline phosphatase (ALP) enzyme activity assays and calcium content deposition (C.C). Qualitative assessments included staining the mineralized matrix with Alizarin Red and Kossa staining. Finally, the expression of bone marker genes, including RUNX-2, collagen I, osteocalcin, osteonectin, and ALP, was quantitatively evaluated using Real-Time PCR. The results of the osteogenic differentiation experiments demonstrated that scaffolds containing vitamin D2 and chondroitin-4-sulfate effectively induced osteogenic differentiation in mesenchymal stem cells. These scaffolds significantly increased alkaline phosphatase (ALP) activity and calcium deposition, as confirmed by specialized staining methods such as Alizarin Red and von Kossa. Furthermore, the expression levels of key genes involved in osteogenic differentiation were significantly upregulated, confirming the efficacy of these scaffolds in promoting osteogenesis.

Developing an affordable, stable, and efficient photocatalyst is essential for addressing environmental pollution. In this study, A Sulfur-doped Zinc oxide(S@ZnO) and sulfur-doped Zinc oxide/Chitosan (S@ZnO/Chitosan) composites with enhanced photocatalytic capabilities for degrading tetracycline under visible light was synthesized. The synthesized composites were characterized using techniques such as X-ray diffraction (XRD), Field-Emission Scanning Electron Microscopy (FESEM), and energy-dispersive X-ray spectroscopy (EDX) to confirm their structure and composition. The photocatalytic activity was assessed by measuring tetracycline degradation under visible. Machine learning (Random Forest regression) is employed to model and predict degradation efficiency. It evaluated by a 10 fold cross-validation, and the results clearly show that an average R² of 0.978 and a relatively low average MSE of 15.334 across the 10 folds, indicating strong predictive performance and accuracy. Importance of individual features (TC concentration, pH, dosage, and time) and their products are evaluated using Random Forest Average Feature Importance (Gini) and SHAP(SHapley Additive exPlanations) Global Feature. Our findings reveal that the S@ZnO/Chitosan nanocomposite achieved a 95% degradation rate of tetracycline in 120 min, compared to 50% degradation using S@ZnO alone. Kinetic modeling confirmed pseudo-first-order behavior, with rate constant for the chitosan composite was 0.016 min⁻¹, significantly higher than 0.005 min⁻¹ for S@ZnO. These results demonstrate that incorporating chitosan into S@ZnO. substantially enhances photocatalytic efficiency by improving electron-hole pair separation and increasing the lifetime of photogenerated charges. This innovative S@ZnO. /chitosan nanocomposite shows significant potential for practical applications in environmental remediation.

Biopolymeric scaffolds with the ability to retain their morphology and mechanical properties while promoting cell growth in three-dimensions (3D) similar to that of the extracellular matrix (ECM) were developed using a blend of a natural protein and a natural polysaccharide without using any crosslinking agents. Sericin, the protein used is a byproduct of silk processing and similarly, the polysaccharide chitosan is obtained from chitin which is a byproduct obtained after processing crustaceans. Both of these natural polymers are available in large quantities at affordable cost. Further, sericin is a unique water soluble and biocompatible protein which also has inherent autofluorescence. However, sericin is highly hydrophilic and hence susceptible to degradation under aqueous conditions, making it difficult to develop materials for medical applications. Attempts at blending with other polymers or chemical modifications to improve stability of sericin based biomaterials have had limited success. Chitosan is a versatile polymer commonly used in various biomaterials due to its mechanical and biological properties that are suitable for medical applications. Chitosan also contains fluorophores which provide fluorescence across a wide wave length. Utilizing these unique features of sericin and chitosan, we have developed scaffolds with stability, biocompatibility and other properties essential for tissue engineering. In this study, various proportions of sericin and chitosan were combined and converted into scaffolds. Chemical and physical interactions between sericin and chitosan led to the formation of scaffolds with high porosity, good mechanical properties (94 ± 0.3 kPa), excellent compressibility and stability in DMEM media for over two weeks at 37 °C. Fibroblast cells seeded on the scaffolds were able to attach, grow and proliferate, as evidenced by MTT assay and further corroborated by optical and fluorescence images where the penetration and three-dimensional growth of the cells within the scaffolds was observed. This study demonstrates that blending and lyophilization of sericin and chitosan induces self-crosslinking and results in scaffolds with properties suitable for medical applications, specifically tissue engineering.

To reduce carbon dioxide (CO₂) emissions, membranes such as poly(ether-block-amide) (PEBA) are utilized; however, their laboratory synthesis and evaluation can be costly and time-consuming. This study employs molecular simulation (MS) to investigate the transport and physical properties of different PEBA membranes, aiming to streamline the synthesis process in order to decrease time and cost. Specifically, the molecular weight and content of poly(ethylene glycol) (PEG) affect the structure and performance of nine PEBA membranes were assessed. It was found that increasing PEG content made the membrane chains more polar, enhancing their interactions and reducing the fractional free volume (FFV). Also, CO₂ diffusivity and radial distribution function (RDF) of CO₂ in the membranes were improved by increasing PEG content in the copolymer. The simulation results corroborate earlier experimental findings for Pebax® 1657 membranes, and the X-ray diffraction results align with these simulations. Notably, the CO₂ permeability values for the copolymer containing 40 wt% of PEG 1000 (P₁₀₀₀-40) and the copolymer containing 40 wt% of PEG 1500 (P₁₅₀₀-40) were 300.6 and 494 Barrer, respectively. The carbon dioxide/nitrogen (CO₂/N₂) selectivity values for P₁₀₀₀-40 and P₁₅₀₀-40 were 167 and 145.29, respectively. The separation performance results of these two copolymers demonstrate crossing of the 2019 Robeson upper bound. This indicates that these copolymers have excellent separation performance, making them suitable for commercial and industrial applications. Among all samples, P₁₅₀₀-40 and P₁₀₀₀-40 demonstrated the highest CO₂ permeability (494 Barrer) and CO₂/N₂ selectivity (167), respectively.

Graphical Abstract

Innovative electrospun films were developed utilizing ZnO/α-, β-, and ɣ-cyclodextrin-metal-organic frameworks (Zn@CD-MOFs) with varying molar ratios of CD to ZnO (1:1, 3:1, 5:1, and 7:1). The 5:1 molar ratio combined with ɣ-CD exhibited the highest loading efficiency (2.84 ± 0.020%) and was thus chosen for subsequent investigations. The synthesis of Zn@γ-CD-MOFs, along with their thermal stability, crystalline structure, and nanoscale crystal morphology, was validated through Fourier transform infrared (FTIR), thermal gravimetric analysis (TGA), X-ray Diffraction (XRD), and Field Emission Scanning Electron Microscope (FESEM) tests. The effective integration of Zn@γ-CD-MOFs nanostructures into the zein electrospun fiber matrix at concentrations of 5, 10, and 15% w/w was confirmed via FESEM imaging. The interactions between Zn@γ-CD-MOFs and zein-based electrospun matrices were clearly evidenced by FTIR and XRD. The electrospun films containing Zn@γ-CD-MOFs demonstrated the highest antimicrobial efficacy against Saccharomyces cerevisiae, Escherichia coli, and Bacillus cereus. The mechanical properties of the electrospun films were significantly improved with the inclusion of 10% w/w Zn@γ-CD-MOFs. The release kinetics of Zn²⁺ ions was best described by the Korsmeyer-Peppas model, while the Fickian diffusion mechanism was identified as the primary mode of ion transport. The bioactive electrospun films containing 10% w/w Zn@γ-CD-MOFs hold promise for application as active packaging materials in direct contact with food, potentially extending their shelf-life.

Poly(butylene adipate-co-terephthalate) (PBAT) is an emerging eco-friendly polymer characterized by its biodegradability and superior mechanical properties. However, the preparation of high-strength and functional PBAT foams remains a challenge due to severe shrinkage and poor dimensional stability. This study reports an ultrasonic-enhanced microcellular foaming strategy integrating mica nanosheets to fabricate PBAT foams with high expansion ratio, superior open-cell content, and dimensional stability. Through the incorporation of mica nanosheets as heterogeneous nucleating agents, the method significantly improves cell density and suppresses coalescence, while the ultrasonic intervention enhances cell wall interconnectivity, resulting in an expansion ratio of 24.5, an open-cell content of 91.0%, and a shrinkage rate less than 10%. Cyclic mechanical tests demonstrate outstanding resilience, retaining > 85% shape recovery after 20 compression cycles and 38% tensile strength retention across a 15℃ foaming temperature range. The dimensional stability is attributed to a two-tier mechanism: rapid gas exchange through highly interconnected cells and elastic energy dissipation during cell wall rupture. The integration of mica nanosheets and ultrasonic field modulation provides new insights into enhancing foam dimensional stability, offering potential solutions for other thermoplastic elastomers. This green manufacturing approach provides a scalable solution for biodegradable foam applications in precision packaging, cushioning and oil-water separation.

To enhance the hydrolytic degradability of poly(L-lactide) (PLA), a series of biodegradable triblock copolymers containing a cleavable moiety and hydrophilic midblock were synthesized via ring-opening polymerization (ROP). A cleavable trithiocarbonate-based initiator (BSCD) possessing terminal hydroxyl groups was first synthesized by the reaction of dibromobenzothiazole, carbon disulfide, and mercaptoethanol. Using BSCD, poly(δ-valerolactone) (PVL) or poly(ε-caprolactone) (PCL) midblock, which exhibits hydrophilicity and promotes water diffusion, was polymerized. This PVL or PCL midblock subsequently served as macroinitiators for the ROP of L-lactide, yielding triblock copolymers of PLA-b-PVL-b-PLA or PLA-b-PCL-b-PLA containing a cleavable trithiocarbonate moiety at the center. Introducing both hydrophilic midblock and trithiocarbonate linkages significantly improved the hydrolytic degradation of PLA, which is otherwise resistant under mild conditions. The cleavable moiety enabled aminolysis-triggered main chain scission, accelerating molecular weight reduction. After five weeks at 50 °C under aerobic conditions, the molar mass of PLA-b-PVL-b-PLA decreased by approximately 50%, confirming the enhanced degradability conferred by the incorporated cleavable structure and water-permeable midblock.