Journal of Polymers and the Environment最新文献

With the growing demand for energy worldwide, energy storage devices like supercapacitors have been extensively researched due to their several advantages, including high power density, fast charging, and excellent cyclic stability. Synthetic polymer-based electrolytes exhibit high mechanical stability and tuneable ionic conductivity; however, these materials still suffer from low ionic conductivity at room temperature and poor interfacial compatibility with electrodes. Biopolymers, especially polysaccharides are naturally abundant and can be sustainably extracted from renewable resources. Biopolymer-polymer blending enhances the mechanical strength of solid, gel, and composite electrolytes while improving electrode-electrolyte interfacial properties, making them suitable for next generation supercapacitors. This review provides fundamental insights about biopolymers and its potential applications for energy storage device. On the basis of growth mechanism, biopolymer electrolytes are classified and discussed according to materials composition and recent developments. Furthermore, the importance of electrochemical impedance spectroscopy (EIS) in optimizing electrolyte formulations and elucidating ion conduction mechanisms is highlighted. In addition, the classification of supercapacitors according to electrode and electrolyte compositions, along with the influence of solid, gel, and plasticized composite biopolymer electrolytes on electrochemical performance, is comprehensively explored. Lastly, it highlights the key findings, challenges, and future outlook of biopolymer electrolytes in energy storage devices.

The incorporation of castor oil as a bio-based polyol offers a sustainable alternative to petroleum-derived polyols in rigid polyurethane (PU) production, supporting efforts to reduce fossil resource dependency. In this study, rigid PU was synthesized from a blend of castor oil and polyether polyol for orthopedic educational model applications. The effect of varying the NCO/OH molar ratio (1.3–2.5) on the resulting foam’s physical and mechanical properties was evaluated. Additives including silicone glycol, triethylenediamine and stannous octoate, and calcium carbonate were used to control foam characteristics. The materials were processed via a one-shot method and characterized through density measurement, compressive strength testing, Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). Results showed that increasing the NCO/OH ratio improved density and compressive strength up to an optimal value at 1.9, reaching 484.09 kg/m³ and 22.74 MPa, respectively, aligning with the standards applicable for orthopedic applications. Higher NCO/OH ratios led to excess unreacted isocyanate, acting as a reactive diluent, reduced crosslink density, and caused greater void formation ultimately compromising mechanical performance. FTIR confirmed urethane formation with minimal residual isocyanate, while SEM analysis revealed that PU1.9 samples had smaller, uniform cell structures with thicker walls. These findings highlight the need to optimize the NCO/OH ratio and show that blending castor oil with the formulation can produce bio-based rigid polyurethane that meets orthopedic performance requirements, thereby improving the sustainability of orthopedic simulation materials.

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Sustainable polyurethane (PU) coatings were synthesised from a 50/50 polyol blend of poly(ethylene glycol) (PEG3000) and modified used palm oil (mUPO) with toluene diisocyanate (TDI) at an NCO index of 100. Ethylene glycol (EG) was used as a chain extender (0–5 mol) to investigate its effects on structure and performance. The developed PUs are intended as bio-based adhesive and structural coatings for glass and polymer substrates, with a focus on bonding strength, flexibility, and thermal stability. FTIR spectra provided clear evidence of urethane linkage formation and intermolecular hydrogen bonding. Mechanical tests demonstrated improvements in adhesion strength and elongation with EG, reaching 26.2 MPa and 284%, respectively, at a concentration of 2 mol. SEM demonstrated rougher bonded surfaces at moderate EG, consistent with the enhanced toughness. Surface analysis revealed that a higher EG content promoted phase separation, increased the water contact angle, and reduced the surface energy from 127 to 12 mJ/m². DSC/TGA indicate improved hard-soft interactions and thermal stability at moderate EG, but performance decreased at higher EG due to plasticisation. In addition, the activation energy (E_a), determined using the Coats–Redfern method, increased progressively from 22.58 kJ/mol (EG0) to 225.19 kJ/mol (EG5), confirming enhanced thermal stability with increasing EG content. These results suggest that EG is a crucial factor in tailoring environmentally friendly PU coatings that balance adhesion, flexibility, wettability, and stability.

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The pervasive accumulation of plastic waste in terrestrial and aquatic environments has become a critical environmental issue, largely due to the resistance of petroleum-derived polymers to microbial degradation. This persistence leads to the long-term generation of microplastics and widespread ecosystem contamination. As a response, biodegradable and bio-based materials such as polyhydroxyalkanoates (PHA) have emerged as promising sustainable alternatives. Among them, poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P(3HB-co-4HB)) is a microbial polyester that exhibits excellent biodegradability, biocompatibility, and tunable mechanical properties. Owing to these characteristics, P(3HB-co-4HB) can be employed in a wide range of applications, from environmentally friendly packaging to biomedical devices. However, its processing has traditionally relied on toxic solvents such as chloroform. In this study, acetic acid is evaluated as a green alternative solvent for producing P(3HB-co-4HB) films and porous gels. Compared with chloroform, acetic acid caused moderate reductions in molecular weight (–12% for 10 mol% 4HB and − 5% for 34 mol% 4HB) and slight decreases in thermal stability, while degradation kinetics remained unaffected. DSC analyses revealed enhanced melting enthalpy for P(3HB-co-10 mol%4HB) films and the emergence of additional crystalline populations for P(3HB-co-34 mol%4HB). Mechanical tests showed moderate reductions in ductility and modulus at low 4HB content, whereas high 4HB content was unaffected. FTIR spectra confirmed the absence of solvent-induced chemical modifications. In addition, a simple thermally induced phase separation method produced highly porous (≈ 90%) gels. Overall, this study demonstrates that acetic acid offers a sustainable processing route for P(3HB-co-4HB), while preserving key material properties comparable to those obtained with chloroform.

This study investigates the effect of polylactide (PLA) molecular weight on the reactivity of multifunctional epoxy-based chain extender, Joncryl. PLA samples with low (L-PLA), medium (M-PLA), and high (H-PLA) molecular weights, each with D-lactic acid contents below 1.5 mol%, were melt-processed with 0.5 and 1.0 wt% Joncryl ADR 4468. The melt rheological behavior, molecular weight, and crystallization kinetics of the processed samples were evaluated using a rheometer, gel permeation chromatography (GPC), and differential scanning calorimetry (DSC), respectively. Small-amplitude oscillatory shear rheology and GPC analyses showed that Joncryl reactions with higher molecular weight PLA resulted in more dramatic enhancements. This enhanced long-chain branching in turn provided stronger improvements to the melt rheological properties and to final molecular weight. Non-isothermal DSC analysis demonstrated that Joncryl modification suppressed crystallization more noticeably in high-molecular weight PLAs. Isothermal DSC analysis further revealed that long-chain branching nearly doubled the crystallization time while significantly reducing the final crystallinity.

The synthesis of a tropoelastin-based polypeptide (PP), poly(AAGVP) (where A denotes Alanine, G for Glycine, V for Valine, and P for Proline), is performed using a solution-phase approach. The miscibility of PP and polyvinyl alcohol (PVA) is examined in various ratios to develop membranes for suitable biomedical applications. Miscibility in the solution phase was evaluated using viscometric parameters (K_H, ∆[η]_m, ∆B, μ, α, β, ΔK as proposed by Huggins, Garcia, Chee, Sun, Jiang, and Han, individually), indicating that PVA is miscible with PP up to 60% of PP at 25 °C. Viscosity increased with polymer concentration, being higher in PVA-rich systems but decreasing with increasing PP content. Intermolecular interactions between PP and PVA were confirmed by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), X-ray diffraction (XRD), and atomic force microscopy (AFM). Thermal stability of the blends, assessed by thermogravimetric analysis (TGA), showed improvements compared to pure PP. In vitro assays demonstrated α-amylase inhibition with IC₅₀ values of 0.81–0.85 µg, outperforming the standard inhibitor acarbose (1.22 µg). Enzyme kinetics (K_m and V_max) determined from Michaelis–Menten and Lineweaver–Burk plots confirmed this activity. These findings suggest that PP–PVA blends may be suitable candidates for biomedical applications.

To address the growing demand for biodegradable materials with superior reflective properties across various applications, poly(vinyl carbazole) (PVK), synthesized via radical polymerization, was melt-blended with biodegradable poly(butylene succinate) (PBS). The properties of the resulting composites were comprehensively investigated. The findings indicate that PVK and PBS interact through intermolecular forces. The incorporation of PVK did not affect the crystalline structure of PBS. However, the thermal decomposition temperature of the composite increased, and its thermodynamic properties were enhanced, despite a decrease in crystallinity. Notably, the introduction of PVK significantly improved the reflective performance of the composite. When the addition of PVK reached 5%, the water contact angle of the composite measured 100°, while the water vapor transmission rate was recorded at 14.72 [g·(m²·d)⁻¹]. The degradation rate over a period of six months was found to be 40.09%, and the reflectance was determined to be 92.91%. At this concentration, the effects of pepper color, fruit length, capsaicin content, capsanthin levels, peroxidase activity, and malonaldehyde content were also observed to be most significant. This indicates its potential as an environmentally friendly material for agricultural reflective films.

Pectin and gelatin are used in skin tissue engineering applications due to their excellent biocompatibility; however, the low mechanical properties limit their functionality. To address this, we developed a nanocomposite system by incorporating tannic acid-derived carbon dots (TCDs) into a pectin-gelatin scaffold to enhance its physicochemical and biological performance for skin tissue engineering. Tannic acid was used to synthesize carbon dots via an environmentally benign hydrothermal method. Physical, chemical, and optical characterizations confirmed the successful synthesis of nanoparticles with a mean hydrodynamic diameter of 9.7 ± 1.27 nm and a Zeta potential of -20.5 ± 1.43 mV. Optical analysis confirmed the photoluminescent features of the nanoparticles, with peak emission observed at 431 nm under excitation at 345 nm. The scaffolds were synthesized through a freeze-drying process, and SEM imaging confirmed their highly porous structure. The influence of TCD incorporation on the mechanical, antioxidant, and biocompatibility properties of the scaffold was evaluated. Mechanical and thermal assessments revealed significant enhancements in tensile strength and thermal stability with the addition of 3% (w/w) TCDs. The 2, 2-diphenyl-1-picrylhydrazyl (DPPH) assay of the scaffolds showed up to 71.28 ± 2.83% free radical scavenging activity. The scaffolds demonstrated favorable biocompatibility on L929 fibroblasts, as evidenced by MTT and 4′,6-diamidino-2-phenylindole dihydrochloride (DAPI) assays, along with improved collagen production in Sirius Red staining and enhanced cell adhesion and migration behaviors. Overall, these findings indicate that TCD-reinforced pectin/gelatin scaffolds provide a sustainable and effective platform for skin tissue regeneration and wound healing applications.

Polyhydroxyalkanoates are a microbial storage polymer that presents similar characteristics to plastics, therefore are usually referred to as bioplastics. The key enzyme involved in the synthesis of polyhydroxyalkanoates is called PHA synthase, but it is always forming a synthesis cassette of three to five enzymes. In this work, we present a novel class III polyhydroxyalkanoate synthesis cassette identified using a sequence-based metagenomics approach. From two metagenomes from dairy industries stabilization ponds, we found four complete synthesis cassettes. One of them was successfully cloned into Escherichia coli CGSC: 6576, a bacterial strain able to grow in lactose and whey permeate, a by-product of dairy industries that represent an environmental risk. This recombinant strain grown in lactose was able to accumulate nearly 40% of dry weight as insoluble material identified by Fourier Transform Infrared Spectroscopy (FT-IR), Gas Chromatography with Flame Ionization Detection (GC-FID) and characterized by Nuclear Magnetic Resonance (NMR) as poly(3-hydroxybutyrate), one of the main polyhydroxyalkanoates commercially used. This research presents the complete process, from the identification of novel enzymes from uncultured microorganisms to the synthesis at laboratory scale of compounds of industrial interest.

Treatment of wound infections has been a matter of concern due to the emergence of antimicrobial resistance (AMR) in Pseudomonas aeruginosa (PA). As an alternative to antibiotics, phage therapy has proven to be an effective strategy to combat AMR. The present study aimed to fabricate PA phage (PAΦ)-gentamicin (GeN)-loaded dressing made from chitosan and alginate, to thwart wound infections associated with PA. Various chitosan-alginate (CA) scaffolds (1 C:1 A/1 C:3 A/3 C:1 A) were prepared by physical crosslinking and subjected to parametric analysis for screening, followed by functionalizing using PAΦ-GeN combination. The findings revealed that 1 C:1 A dressing exhibited high swelling index (1887%), protein adsorption ability (845.8 µg.cm^− 2), and in vitro biodegradability within 7 days. FTIR spectroscopy and thermogravimetric analysis supported biophysical characterization and electron microscopy revealed microporous structure of the dressing. Functionalized CA dressings demonstrated broad-range antibacterial potential against standard strains of Escherichia coli, Staphylococcus aureus, Acinetobacter baumannii, Klebsiella pneumoniae, and clinical strains of PA, while displaying a biocompatible/non-allergenic nature. The therapeutic potential of functionalized CA dressing was further validated in vivo using a thermal injury murine model infected with PA. Topical application of PAΦ-GeN-loaded CA dressing significantly lowered bacterial burden on day 3 post-infection (p.i.) and completely eradicated pseudomonal infection by day 21 p.i. Furthermore, the functionalized CA dressing significantly enhanced skin re-epithelialization and resulted in complete wound closure in BALB/c mice on day 21 p.i. Overall, the present study reinforces the application of functionalized wound dressings as promising alternative to traditional wound care products for management of skin infections.

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