Journal of Polymers and the Environment最新文献

This work investigates the molecular interaction between chitosan, an effective and eco-friendly biopolymer, and crude oil components within petroleum emulsions. This mechanistic investigation combines 2D TD-NMR relaxation and computational modeling to understand chitosan’s role as an adsorbent and demulsifier for applications in environmental remediation. We applied a medium molecular mass chitosan to a series of six petroleum emulsions, spanning a representative range of medium and heavy crude oils (viscosities from 32.52 to 182.07 mm².s^-1 at 20 °C). The 2D D-T₂ correlation maps were generated using the PFG-CPMG (Pulsed Field Gradient-Carr-Purcell-Meiboom-Gill) sequence to resolve the changes in oil and water mobility following chitosan addition. The key result is the observation of a characteristic shift in the diffusion coefficient (D) and transverse relaxation time (T₂) of the oil component upon chitosan introduction. This shift provides direct evidence of the molecular interaction and the disruption of the emulsion stabilizing film. Furthermore, molecular modeling confirms strong water binding, complementing the TD-NMR findings. Overall, the study successfully demonstrates the utility of TD-NMR and molecular dynamics for mechanistic assessment, providing crucial, direct insight into the demulsification role of chitosan within petroleum emulsions.

This study determined the cloud point temperatures of a series of poly(2-hydroxypropyl acrylate) (PHPA) copolymers prepared by introducing various acrylamide derivatives using turbidimetry. This study aims to demonstrate the tunability of the cloud point temperatures of HPA-based copolymers by changing the composition of the acrylamide derivative comonomers. N-isobutoxymethyl acrylamide (IBMAAm), N-(3-methoxypropyl)acrylamide (MPAAm), acrylamide (AAm), N-(2-hydroxyethyl)acrylamide (HEAAm), and methacrylamide (MAAm) were used as comonomers to obtain copolymers of PHPA and acrylamide derivatives with different compositions. The cloud point temperatures of the copolymers based on PHPA were found to range from 7.5 to 48.2 °C, depending on the H-bond capacity and quantity of the comonomers in the copolymer. All copolymers exhibited cloud point temperatures higher than the homopolymer of HPA, except those with IBMAAm as the comonomer. Increasing the relative amount of the acrylamide derivative moiety in a copolymer type was found to increase the cloud point temperature, except for copolymers with IBMAAm. AAm and HEAAm were determined to be the most effective comonomers for elevating the cloud point temperature, possibly due to their hydrogen bond capacities and superior solubility in an aqueous medium.

Conventional polymer flooding agents, including commercial biopolymers like xanthan gum, may fail under harsh reservoir conditions due to thermo-oxidative chain scission and mechanical degradation. To bridge this gap, we introduce a novel, eco-functionalized biopolymer derived from Pseudomonas atacamensis M7D1 and functionalized with heavy metal powders from recycled printed circuit boards (PCBs) for enhanced oil recovery (EOR). This functionalization creates stable coordination complexes that act as protective sites, fundamentally enhancing molecular stability. Under extreme simulated reservoir conditions (85°C, 3wt. % NaCl), a 0.5wt. % PCB-biopolymer solution exhibits significant colloidal stability and maintains over 95% of its initial viscosity over 24 hours, directly demonstrating mitigation of the chain scission failure that plagues unmodified biopolymers. Microfluidic visualization in heterogeneous porous media reveals optimized flooding patterns and suppressed viscous fingering, a consequence of the resilient, self-healing viscoelastic character confirmed by a persistent gel-like structure (G’ > G’’) in oscillatory rheology. The 0.5wt. % biopolymer solution delivered 43.6% ultimate oil recovery at ambient temperature and retained strong performance (41% recovery) at 85 °C. Importantly, a 1wt. % solution achieved nearly 4% greater incremental oil recovery than water flooding (22% vs. 17.8%) under a monovalent NaCl salt and high temperature conditions. Consequently, this work establishes metal-functionalized biopolymers as sustainable, high-performance alternatives by uniquely combining extreme salinity/temperature tolerance, colloidal resilience, and efficient pore-scale flow control through deliberate molecular engineering.

Indole-3-acetic acid (IAA) is a widely used plant growth regulator; however, its rapid environmental degradation limits practical applications. Encapsulation in biopolymer matrices offers a promising strategy to enhance its stability. V-type starch, a single-helical amylose structure, can form inclusion complexes with small molecules. In this study, V-type starch was synthesized from maize starch using an antisolvent precipitation method and employed as a delivery system for IAA. The materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), near-infrared (NIR) spectroscopy, and Fourier-transform infrared (FTIR) spectroscopy. The IAA release profile, photostability, bioactivity in tomato plants, and biotoxicity in Artemia salina were evaluated. IAA release from the complex was pH-dependent: complete (100%) release was achieved after 48 h at pH 3.0, 96 h at pH 5.0 and 120 h at pH 7.0. After 240 min of UV irradiation, the starch-IAA complex exhibited only 18% degradation, compared to 100% for technical IAA. In tomato plants, the starch-IAA complex at 500 µg/mL enhanced growth by increasing leaf number and root biomass, whereas at 1000 µg/mL, it inhibited growth similarly to technical IAA. Biotoxicity tests in Artemia salina showed that at 1000 µg/mL, free IAA caused 60% mortality, while the starch-IAA complex and V-type starch caused only 9.9% and 6.5%, respectively. These results suggest that V-type starch enables controlled IAA release while reducing toxicity, highlighting its potential as a safe and effective delivery system for agricultural applications.

This study investigates the kinetic modeling of castor oil epoxidation via the Prilezhaev reaction using in situ generated peracetic acid, with a focus on optimizing the process through Particle Swarm Optimization (PSO). Experimental procedures involved the use of ZSM-5/H₂SO₄, with reactions monitored by titration, FTIR, NMR, and GPC analysis. FTIR confirmed successful epoxidation through the appearance of characteristic oxirane peaks at 852 cm⁻¹ and the disappearance of alkene bands. NMR spectra showed reduction of olefinic (5.2–5.4 ppm) and allylic protons (1.8–2.0 ppm), and emergence of epoxide ring signals (3.6–3.8 ppm). GPC revealed a drop in weight-average molecular weight (Mw) from 9732 to 1013 g/mol and polydispersity index (PDI) from 7.66 to 1.51, confirming chain scission during epoxidation. The reaction was modeled through a system of second-order differential equations representing peracid formation, epoxide synthesis, and degradation. Two models were compared—one spanning 0–60 min (including reversible reactions) and another from 30 to 60 min (unidirectional). PSO achieved an R² of 0.52 for the full model and R² of 0.98 for the 30–60 min range. The unidirectional model demonstrated superior predictive accuracy, suggesting that inclusion of reversibility introduced noise, especially during early reaction stages. This highlights PSO’s limitations in handling reversible systems and supports the use of simplified forward-reaction kinetics, focusing on epoxide formation and ring-opening steps while excluding the reverse formation of peroxy acid. This approach improves model performance in epoxidation processes while still benefiting from the fast convergence of the PSO algorithm compared to other algorithms.

Bio-based composite films offer a sustainable alternative to synthetic packaging materials due to their biodegradability and functional versatility. In this study, a biodegradable film was developed using gelatin (GA), lignin (LG), and tannic acid (TA), for applications in food packaging and seed preservation. Films were prepared by fixing GA and varying LG and TA, on a weight/weight (w/w) basis relative to GA. The optimized formulation (LGT68) exhibited a tensile strength of 7.59 ± 0.58 MPa, and elongation at break (EAB) of 158.54 ± 15.68%. Scanning electron microscopy (SEM) revealed a dense fibrillar matrix with uniformly dispersed spherical agglomerates, attributed to LG–TA interactions within the GA matrix. Fourier-transform infrared spectroscopy (FTIR) confirmed strong hydrogen bonding. The film also demonstrated complete ultraviolet (UV) blocking, improved hydrophobicity with a water contact angle of 89.4 ± 0.7°, and significant antimicrobial activity with a 23 mm zone of inhibition against Staphylococcus aureus (S. aureus). Real-time application trials using raw beef and mushroom for packaging and seeds of Momordica charantia for coating confirmed the film’s effectiveness in extending shelf life. These results highlight the potential of LGT films as sustainable and multifunctional materials for active food packaging and seed protection applications.

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Ultraviolet radiation exerts detrimental effects on skin health, necessitating the use of sunscreen products for effective protection. However, conventional sunscreens encounter limitations due to their susceptibility to photo-instability, skin irritation, and environmental impact. The primary objective of this study is to circumvent these limitations by substituting plastic microspheres and conventional sun protection agents with enzyme-modified natural porous corn starch microspheres and Xanthoceras sorbifolium bunge (X. sorbifolia) oil composites. The average particle size of enzyme-modified porous corn starch microspheres was 13.24 μm, and they possess a porous structure, enabling adsorption and shielding effects. The SPF value of the sunscreen product formulated by substituting an equivalent quantity of UV shielding agent TiO₂ with porous microspheres was 23.75 ± 0.15, which was comparable to the TiO₂ sunscreen product. Following the reduction of the UV absorber in the sunscreen product by half and the incorporation of microspheres and the X. sorbifolia oil composite, the SPF value of the product retained a higher level compared to its predecessor (30.5 ± 0.07 vs. 16.44 ± 0.02). When this natural composite synergistically worked with conventional UV absorbers benzophenone-3 (BP-3) and ethylhexyl methoxycinnamate (EHMC), the photostability of BP-3 and EHMC was effectively enhanced. Embryotoxicity studies conducted on zebrafish demonstrated that natural porous starch and X. sorbifolia oil exhibited reduced toxicity compared to conventional sunscreen agents, particularly at elevated concentrations. These findings suggest novel ideas for the development of safe and effective sunscreen products in the future.

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Mesoporous silica nanoparticles (MSNs) have emerged as promising carriers in drug delivery systems due to their high surface area, tunable pore structure, excellent chemical stability, and biocompatibility. However, their practical application is often hindered by premature drug leakage and limited targeting capability. To address these challenges, a hybrid nanocarrier was developed by coating MSNs with a lipid bilayer (ML) and subsequently with a chitosan-polyethylene glycol-folic acid copolymer (CPF), yielding CPF-coated ML nanoparticles (MLCPF). Characterization confirmed successful layer-by-layer assembly with nanoscale size, spherical morphology, positive surface charge, and good colloidal stability. Doxorubicin (DOX) was efficiently loaded into MLCPF (DOX@MLCPF), exhibiting pH-responsive release with slower drug release at neutral pH and faster release under acidic conditions. In vitro studies showed blank MLCPF was biocompatible, while DOX@MLCPF displayed stronger anticancer activity than free DOX. Confocal microscopy revealed efficient cellular uptake of CPF-functionalized nanoparticles. These findings suggest MLCPF as a promising platform for controlled and targeted cancer therapy.

The escalating environmental challenges posed by organic dye pollution necessitate the development of efficient and sustainable remediation technologies. This study presents a novel strategy to enhance the visible-light photocatalytic performance of TiO₂ through the synthesis of hyperbranched polyglycerol (HPG)-modified nanocomposites functionalized with photosensitizers (hemin and Eosin Y (EY)). A sol-gel method was employed to graft HPG with tailored polymerization degrees and branching architectures onto TiO₂ surfaces, enabling systematic investigation of the effects of modifier content, polymer structure, and light source on photocatalytic activity. The grafted polymers significantly narrowed TiO₂’s bandgap energy (from 2.82 eV for pure TiO₂ to as low as 0.73 eV for HPG2-hemin/TiO₂), extending its light absorption to the visible spectrum. Under optimized conditions, 1% HPG5-EY/TiO₂ achieved a methylene blue (MB) degradation rate of 73.22% within 120 min of visible-light irradiation—a 2.11-fold enhancement compared to pristine TiO₂. The composite also demonstrated exceptional recyclability, retaining over 95% of its initial activity after four recycling cycles. The catalyst has exhibited excellent degradation performance in visible light compared to most of the recently reported systems. Mechanistic studies revealed that the abundant hydroxyl groups in HPG facilitated the generation of reactive oxygen species (•OH and •O₂⁻), which synergistically accelerated MB degradation. This work establishes a robust framework for designing high-performance TiO₂-based photocatalysts by leveraging polymer structural engineering and photosensitizer integration. The approach not only addresses the inherent limitations of TiO₂’s UV-dependent activity but also provides a scalable strategy for sustainable wastewater treatment under solar illumination.

Insoluble starch-chitosan foams were produced through a novel plasticization process that integrates glycerol via a post-expansion soaking and freeze-drying process. Starch foams incorporating 4% and 8% chitosan were first expanded and cross-linked using microwave heating, then soaked in a 7.5% glycerol solution, frozen, and freeze-dried to retain glycerol within the foam matrix. This process uniquely preserves the position of the glycerol in the foam by sublimating water during freeze-drying, allowing for internal plasticization without structural collapse. The resulting foams showed up to a 43% reduction in compressive modulus, yielding mechanically soft yet stable structures. Rheological characterization revealed that chitosan-starch polyelectrolyte complexation helped reduce retrogradation with the presence of glycerol. Increasing chitosan content enhanced foam integrity, while swelling behavior confirmed that both chitosan and glycerol concentrations influenced solution uptake. This study demonstrates a promising method for producing soft, insoluble, stable and retrogradation-resistant starch-based foams for a wide variety of diverse applications.

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