Journal of Polymers and the Environment最新文献

The synthesis of nanoscale metal-organic frameworks (MOFs) is emerging as a promising method for targeted drug delivery in cancer therapy. In this study, unlike conventional solvothermal methods that require high temperatures, room-temperature synthesis of two Zn-MOF-74 variants was achieved using zinc nitrate and zinc acetate with triethylamine (TEA). The use of different anions allows precise control over the morphology and particle size of the MOF, optimizing drug loading in nanocarriers. Drug loading and release were evaluated using 5-fluorouracil (5-FU) as a model drug in both aqueous and ethanolic environments. The results showed that Zn-MOF-74 prepared with zinc acetate (R_A-MOF-74) at a 1:1 drug-to-nanocarrier ratio in ethanol exhibited superior drug adsorption and release characteristics. To enhance biocompatibility and controlled release, R_A-MOF-74 nanocarriers were coated with two biodegradable polymers, sodium alginate (ALG) and polydopamine (PDA), to improve stability at low pH and enhance release control. The release profiles of 5-FU from R_A-MOF-74 and its coated samples (PDA and ALG) were evaluated at different pH levels. In uncoated R_A-MOF-74, drug release at pH 7.4 and 8 was 48.4% and 59.1%, respectively, reaching 100% at pH 1.5. For the coated samples, 5-FU@R_A-MOF-74/ALG released 19.8% and 45.9% at pH 1.5 and 8, respectively, while 5-FU@R_A-MOF-74/PDA showed 25.2% and 40.8% release at pH 7.4 and 5.5. These results clearly highlight pH-sensitive release and the role of biocompatible coatings in enhancing controlled drug release, demonstrating the potential of Zn-MOF-74 with controlled morphology for pH-responsive delivery of 5-FU in cancer therapy, paving the way for future in vivo applications.

The quest for sustainable materials in offshore renewable energy is critical for mitigating the environmental concerns associated with the use of conventional composites. This study explores the potential of vegetable oil-based polyurethanes (BIO-PUR) as a sustainable alternative to petrochemical-based resins in offshore structural applications. BIO-PUR composites were fabricated, mechanically characterized, and subjected to real-world marine environments in the HarshLab floating laboratory, with exposure durations of 3 and 5 months in both atmospheric and immersion zones. Comprehensive testing, including dynamic mechanical analysis (DMA), thermogravimetric analysis (TGA), Fourier-transform infrared spectroscopy (FTIR), and interlaminar shear strength (ILSS) assessments, showed no significant degradation in the mechanical, thermal, or chemical properties of the composites. Notably, water absorption remained minimal, and the glass transition temperature of the material (T_g) and interlaminar strength remained unchanged after exposure, highlighting the exceptional durability of BIO-PUR in harsh marine environments. These results suggest that BIO-PUR composites could not only meet but potentially surpass the performance requirements for long-term offshore applications, offering a highly promising eco-friendly alternative to traditional composites. This study provides a foundation for future research into the long-term viability of biobased materials in offshore energy systems, paving the way for more sustainable solutions in renewable energy infrastructures.

Graphical Abstract

The growing global population, climate change and dietary patterns, and the demand for waste-free food production have increased the need for environmental protection. Packaging materials that have become more important to avoid food waste and environmental pollutants. Edible coatings and films used for preserving food are gaining popularity due to their eco-friendly nature and ability to carry active ingredients. Their use as antioxidant effectively help prevent quality deterioration by reducing oxidation and food spoilage. Edible packaging is now seen as a promising solution to extend shelf life of food products and reduce dependence on petroleum-based resources. Proteins are versatile materials suitable for producing edible and non-edible coatings and films. This article aims to provide a thorough overview of research on the use of proteins in food and edible packaging, including their modification, anti-oxidative, antimicrobial, and antifungal properties, as well as their economic implications.

Graphical Abstract

Vitrimers possess the dual advantages of thermoplastics and thermosets, combining reprocessability with excellent mechanical property, heat resistance, and solvent resistance. Ethylene acrylic acid copolymer (EAA) is a widely used semicrystalline thermoplastic that suffers from low Vicat softening point and poor creep resistance. Previously, we demonstrated a simple, efficient and scalable avenue to EAA derived vitrimer with excellent creep resistance and reprocessability. Yet the overall mechanical properties were suboptimal. In order to address this issue, dual cross-linked EAA vitrimers, namely, EAA-GDE-ZnO (GDE and ZnO represent ethylene glycol diglycidyl ether and zinc oxide, respectively), based on dynamic β-hydroxy ester covalent bonds and zinc carboxylate ionic bonds were designed and prepared through a simple and one-step reactive blending approach starting from low-cost commercial grade raw materials. The formation of covalent and ionic cross-linking networks were evidenced by torque rheometer, FTIR, and gel fraction testing. DMA tests demonstrated that clear rubbery plateaus for EAA-GDE-ZnO showed up above the melting temperature, serving as a hallmark that distinguishes vitrimer from its thermoplastic precursor. Meanwhile, EAA-GDE-ZnO exhibited excellent creep resistance even at elevated temperatures. The mechanical properties of dual cross-linked EAA-GDE-ZnO were significantly enhanced compared to its single cross-linked counterpart. Owing to the dynamic features of β-hydroxy ester and zinc carboxylate cross-linkages, the mechanical properties of EAA-GDE-ZnO were well maintained after 3 times reprocessing, proving the excellent (re)processability of EAA-GDE-ZnO.

Herein, the novel bio-based co-polymer was synthesized using only natural fibers by way of co-dissolving cellulose extracted from Luffa Cylindrica (LC) and silk fibroin (SF) in formic acid in different weight ratios (3SF/1LC, 2SF/2LC, and 1SF/3LC). The prepared bio-composite films were investigated by morphological, vibrational, structural, thermally, and wettability with Scanning electron microscope (SEM), Fourier transform-infrared spectroscopy (FT-IR), X-ray diffraction spectroscopy (XRD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and water contact angle (WCA). The surface and cross-section SEM images of samples indicate that all films have homogeneous structures, and by varying the ratio of silk fibroin in blend films, a smoother and glassier appearance was obtained, as also proved by XRD and DSC results. The results of the FT-IR test reveal that the changing and shifting of peak intensities in the spectroscopy of bio-composite films indicate interactions between luffa cellulose and silk fibroins. XRD results show that silk fibroin enhances the crystallinity of bio-composite specimens. In addition, thermogravimetric analysis demonstrates that increasing the cellulose ratio in bio-composite films extends their thermal stability. The glass transition value provided by the DSC test proves that the flexibility of hybrid bio-composite films increases as the ratio of luffa increases. As a final analysis, WCA states that when blended with luffa and silk fibroin, although both are hydrophilic, the hybrid bio-composite films display hydrophobic properties, and LC increase enhances this behavior against water. The combination of these two materials can be used in environmentally friendly in medical applications (tissue engineering, wound dressings, etc.) and agricultural fields.

The increasing global demand for sustainable and effective food preservation methods has prompted the development of novel technology. The utilization of biomass generates valuable compounds that can be applied in innovative technologies like next-generation packaging, thereby enhancing environmental quality through the recycling of materials previously considered as waste. In this study, melanin was isolated from Pecan nut shells (Carya illinoensis Koch), with an optimized extraction process that enables the extraction of around 88 g of melanin per kilogram of Pecan shells. Melanin was electrospun with concentrations of 1.0 and 3.0 wt% using a hybrid mixture of polycaprolactone (PCL) and gelatin (Gel). Polycaprolactone-gelatin (PG)/melanin membranes showed an antioxidant capacity associated with efficient behavior as a hydrogen atom donor. The presence of -OH functional groups and catecholic compounds in melanin allows interaction with water molecules, enabling the transition from highly hydrophobic to hydrophilic behavior. Additionally, fibers showed antifungal activity against three phytopathogenic fungal strains isolated from commercial strawberries (Fragaria x ananassa L.) due to the release of H₂O₂ from the oxidation of catechols. All these active properties are intended to be used in food packaging.

Improving the accessibility of cellulose is essential for the production of derivative products. This can be achieved by modifying its physicochemical properties. This research aimed to investigate the properties of cellulose extracted from the torch ginger stem. The cellulose was pretreated with FeCl₃ and then hydrolyzed using HCl vapor at a 37% concentration. Hydrolysis was conducted in a pressurized HCl vapor system at 27.60 kPa and 30 °C for 0–24 h. Similar treatment was conducted to cellulose without FeCl₃ (unpretreated). The results show that FeCl₃ pretreatment significantly decreased degree of polymerization (DP) from 0 to 24 h compared to unpretreated cellulose. The hydrolysis reaction occurred above the saturation point of HCl. When the cellulose was hydrolyzed with HCl vapor, cellulose morphology, thermal properties, and functional groups remained largely unchanged, respectively, as observed by FESEM, TGA, and FTIR methods. However, the X-ray diffractograms and FTIR spectra revealed that decrystallization of FeCl₃ pretreated cellulose occurred after 10 h of hydrolysis. The 24 h hydrolysis yield for FeCl₃ unpretreated and pretreated cellulose was 90.6% (DP of 118) and 86.8% (DP of 76), respectively. Therefore, this hydrolysis system can be considered an important pretreatment method for preparing cellulose derivatives.

In this work, highly porous biodegradable poly(lactic acid) (PLA) foams with bi-modal architecture were prepared by using the melt-compounding process in a twin-screw extruder and filler leaching technique. The highly-filled composites of PLA/salt porogen were extruded and then, subjected to distilled water to obtain lightweight inter-connected nano- and micro-cellular structure for foams with 100% open cell content. The density of PLA diminished from 1.14 g/cm³ to 0.3 g/cm³ by using these simple and economical preparation methods. In the presence of poly(ethylene glycol) (PEG) plasticizer, the void content of open-cell PLA foam reached 72%. The bi-modal cell size distribution of foams was created by the partial miscibility of PLA/PEG phase and salt. The cell density of prepared foams rose to 6 × 10⁷ cells/cm³ by adding 15 wt% PEG to the PLA melt. The presence of PEG in the PLA melt affected the microstructure and mechanical properties of foams by altering the melt viscosity and surface tension. These open-cell bi-modal porous foams, which are biocompatible and biodegradable, can be applied in biomedical and pollutant adsorption applications. The adsorption capacities of the open-cell foams were measured for different solvents and marine pollutants. The adsorption capacity of these foams reached 4 g/g for carbon tetrachloride.

In this study, carboxymethyl chitosan/gelatin/Akermanite (CMC/GEL/AK)-based scaffolds were prepared for bone tissue regeneration via 3D printing method. The bioactive AK was synthesized and used to fabricate the scaffolds. The AK powder was analysed through scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FTIR), dynamic light scattering (DLS), and X-ray diffraction (XRD). The porous scaffolds were fabricated and characterized to show their ability in bone tissue engineering (BTE). Degradation rate, swelling ratio, and mechanical properties of the scaffolds containing AK have been significantly increased. The scaffolds possess the interconnected networks with the pore size of about 300–900 μm. The mechanical strength increased up to 2.6 MPa by adding 20% AK to the scaffolds. In addition, cell viability and cell attachment studies exhibited the viability of up to 80%. This study confirms the potential of fabricated biocomposites in non-load-bearing bone defect regeneration.