Boosting the Strength and Toughness of Polymer Blends via Ligand-Modulated MOFs

Tuning polylactic acid performance using green citrate plasticizers of varying chain lengths

The addition of these plasticizers increases the chain mobility of PLA, enhancing its deformability while reducing both tensile strength and elastic modulus. Mechanical testing identified TEC at 20 wt% as the most effective formulation, achieving an elongation of 307 % and a reduction in tensile strength from 70.6 MPa (PLA) to 25.2 MPa. Formulations containing 10 wt% exhibited anti-plasticization effects, with a slight reduction in elongation from 3.4 % to 3.2 %. Thermal and thermomechanical analyses corroborated the plasticizing effect, demonstrating a decrease in glass transition temperature from 59.6 °C to 19.3 °C, which indicates sufficient chain mobility to attain a rubber-like state at room temperature. Enhanced mobility also promoted crystallization by modifying nucleation behavior, altering crystal growth dimensionality, and reducing the activation energy required. Shape memory characterization revealed a rapid initial recovery in plasticized samples; however, total recovery diminished at higher plasticizer contents near 20 %, while lower concentrations exhibited recovery rates close to 90 %. Due to their low molecular weight of the plasticizers, migration is anticipated, resulting in measurable weight loss when exposed to food simulants. This migration phenomenon is associated with an increase in free volume, which also contributes to the improved ductile properties observed in plasticized PLA.

Facet Engineering of Metal-Organic Frameworks for Triboelectric Nanogenerators-Based Self-Powered Water Splitting

Metal-organic frameworks (MOFs) are highly versatile materials with tunable chemical and structural properties, making them promising for triboelectric nanogenerators (TENGs) and electrocatalysis. However, achieving precise control over MOF coordination structures to optimize facet-dependent properties remains challenging. Here, a facile and scalable dual-solvent synthesis strategy is presented to fabricate dendrite Co-2-methylimidazole MOF (ZIF-67-D), enabling tailored preferred facet and coordination environments. Using density functional theory (DFT) calculations and synchrotron-based X-ray absorption spectroscopy, it is demonstrated that ZIF-67-D, enriched with (112) facets, features a reduced Co coordination number and enhanced electron-donating ability compared to the conventionally (011) facet-dominated rhombic dodecahedron ZIF-67 (ZIF-67-R). This facet engineering boosts TENG charge density by 2.4-fold, OER current density by 9.9-fold (@1.65 V), and HER current density by 1.9-fold (@-0.3 V). The (112)/(011) facet ratio can be also tuned to precisely alter TENG output. Moreover, the optimized ZIF-67-D shows excellent stability, maintaining electrolyzer performance for 72 h and enabling TENG devices even in high humidity. Consequently, ZIF-67-D-based TENG (D-TENG) devices exhibit robust energy generation and power ZIF-67-D||ZIF-67-D electrolyzers for continuous hydrogen (H2) production. These findings introduce a new paradigm for converting mechanical energy into sustainable chemical energy, offering insights into facet engineering for high-performance energy harvesting systems.

Fabrication and performance of biodegradable poly (lactic acid)/poly (butylene adipate-co-terephthalate) composites by regulating the dispersed rice husk with the silane coupling agent and alkaline

Mixing poly (lactic acid) (PLA) with another biodegradable resin, poly (butylene adipate-co-terephthalate) (PBAT), is a simple strategy to toughen PLA, but its effectiveness is limited, and stiffness is usually compromised. As a consequence, the simultaneous enhancement of strength and toughness in PLA has become of significant challenge in materials driven by growing demand for green polymers in expanded biodegradable fields. In this study, we design and fabricate a novel PLA composites based on a facile processing route consisting of rice husk modified with the silane coupling agent and alkaline (RHM) as the reinforcing agent, and PBAT grafting glycidyl methacrylate (GMA) as the toughening agent. The results indicated RHM promoted the crystalline behavior of the composites and improved the thermal stability, dimensional stability, melt strength and hydrophilicity. PBAT grafted by GMA greatly increased the compatibility of RHM with PLA, which was confirmed in rheological and DSC tests. The toughness of the composites increased by 199 %-237.6 % while maintaining better stiffness and degradability. This work presents a simple and effective strategy for preparing low-cost, and well-balanced stiff and tough PLA, thereby expanding the application range of PLA.

UV-C and UV-C/H₂O-Induced Abiotic Degradation of Films of Commercial PBAT/TPS Blends

The environmental impact of conventional plastics has spurred interest in biopolymers as sustainable alternatives, yet their performance under abiotic degradation conditions still remain unclear. This study investigated the effects of ultraviolet C (UV-C) irradiation and its combination with water immersion (UV-C/H2O) on films of commercial poly(butylene adipate-co-terephthalate)-thermoplastic starch (PBAT/TPS) blends. Changes in structural, chemical, morphological, and thermal properties, as well as molar mass, were analyzed. The results showed distinct degradation mechanisms during exposure to UV-C irradiation either in dry or during water-immersion conditions. UV-C irradiation disrupted PBAT ester linkages, inducing photodegradation and chain scission, leading to a more pronounced molar mass decrease compared to that under water immersion, where a more restrained impact on the molar mass was ascribed to diffuse attenuation coefficient of irradiation. Nevertheless, under UV-C/H2O conditions, erosion and disintegration were enhanced by dissolving and leaching of mainly the TPS fraction, creating a porous structure that facilitated the degradation of the film. Blends with higher TPS content exhibited greater susceptibility, with pronounced reductions in PBAT molar mass. In conclusion, exposure of films of PBAT/TPS blends to ultraviolet/water-assisted environments effectively initiated abiotic degradation, in which fragmentation was accentuated by the contribution of water immersion.

High Barrier and Flexible Biodegradable PLA/CNC Based Multilayer Films via Large-Scale Forced Assembly Layer Multiplication Coextrusion: Role of Crystalline Polymer Layers Under Confinement

In this work, a novel and pioneering route was developed for the large-scale fabrication of PLA-based multilayer films with high barrier properties by forced assembly layer multiplication coextrusion. The process involved coextruding cellulose nanocrystal (CNC)-filled polylactide (PLA) biocomposite, obtained by a liquid feeding method, with highly crystalline poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) into alternating multilayer structures with a number of layers up to 513. The degree of CNC dispersion in the PLA/CNC-based composite and the multilayer architecture were first evaluated by TEM observations. Subsequently, the role of PHBV layers under confinement on the crystallization behavior and gas permeability was thoroughly investigated. It was found that the obtained films basically maintained their multilayer structure and architectures, with CNC particles overall well-dispersed at a mean length of 318 nm. Nevertheless, layer instability and breakup began to occur at 129 layers due to the formation of microscale CNC aggregates. The geometric confinement effect resulted in a gradual restriction of crystallization behavior of both PLA and PHBV phases/layers as the number of layers increased. Notably, an increase in the oriented edge-on lamellar/crystal structure in the PHBV layer along the normal direction was detected. Consequently, a remarkable reduction in oxygen transmission rate (OTR) was realized when increasing the number of layers and confinement. Additionally, multimicro/nanolayers with the large number of layers exhibited higher flexibility, while maintaining a considerable tensile strength. In conclusion, this study provides the innovative and novel solution for the continuous melt-processing of biodegradable flexible films with enhanced barrier properties, making them highly suitable for food packaging applications.

A Hydrogel Electrolyte-Based Zn-CO2 Battery with Improved Life

Environmental-friendly aqueous Zn-CO2 batteries present bifunctional potentials of achieving carbon neutrality and energy storage. Nonetheless, anode corrosions derived from H2O molecules and high risks of volatilization and leakage hinder the advancement of Zn-CO2 batteries. In this work, polyvinyl alcohol (PVA)-based hydrogel electrolyte with fast ion diffusion kinetics, high mechanical strength, and flexibility is developed to replace liquid electrolyte. Since hydroxyl radicals in the polymer chain can interact with H2O and Zn2+, electrode corrosion from free H2O and active H2O around Zn2+ is significantly inhibited, facilitating the uniform deposition of Zn2+ cations. The introduction of an ionic liquid plasticizer further enhances the interaction between Zn2+ and polymer backbone, as well as amorphous extent of the electrolyte. The hydrogel electrolyte possesses adequate self-healing ability, whose ionic conductivity reaches 7.95 × 10-3 S cm-1. The symmetric Zn metal batteries containing the electrolyte remain steady for >2000 h under different current densities. Furthermore, the Zn-CO2 battery based on Ru nanoparticles cathode and hydrogel electrolyte realizes a discharge capacity of 6028 mAh g-1 and stable cyclicity for 90 times. The reaction path of hydrogel electrolyte-based Zn-CO2 battery is that CO2 is reduced to ZnCO3 and C species followed by reversible decomposition of discharge products on recharge.

Construction of a Heterostructured Alloy-Molybdenum Nitride Catalyst for Enhanced NH3 Production via Nitrate Electrolysis

Here, we reported a highly efficient nitrate electroreduction (NO3RR) electrocatalyst that integrated alloying and heterostructuring strategies comprising FeCo alloy and Mo0.82N (FeCo-Mo0.82N/NC). Notably, the maximum NH3 Faraday efficiency (FE) of 83.24%, NH3 yield of 12.28 mg h-1 mgcat.-1, and good stability were achieved over FeCo-Mo0.82N/NC. Moreover, a Zn-NO3- battery assembled with FeCo-Mo0.82N/NC exhibited a power density of 0.87 mW cm-2, an NH3 yield of 14.09 mg h-1 mgcat.-1, and a FE as high as 76.31%.

Tunable NiSe-Ni3Se2 Heterojunction for Energy-Efficient Hydrogen Production by Coupling Urea Degradation

Urea-assisted water splitting is a promising energy-saving hydrogen (H2) production technology. However, its practical application is hindered by the lack of high-performance bifunctional catalysts for urea oxidation reaction (UOR) and hydrogen evolution reaction (HER). Herein, a heterostructured catalyst comprising highly active NiSe and Ni3Se2, along with a conductive graphene-coated nickel foam skeleton (NiSe-Ni3Se2/GNF) is reported. The heterostructured NiSe-Ni3Se2 originates from the in situ selenization of graphene-coated nickel foam, allowing for careful regulation of the NiSe to Ni3Se2 ratio by simply adjusting the calcination temperature. Theoretical calculations of the charge transfer between NiSe and Ni3Se2 components can optimize the reaction pathways and reduce the corresponding energy barriers. Accordingly, the designed catalyst exhibits excellent UOR and HER activity and stability. Furthermore, the NiSe-Ni3Se2/GNF-based UOR-HER electrolyzer requires only 1.54 V to achieve a current density of 50 mA cm-2, which is lower than many recent reports and much lower than 1.83 V of NiSe-Ni3Se2/GNF-based OER-HER electrolyzers. Moreover, the UOR-HER electrolyzer exhibited negligible cell voltage variation during a 28-h stability test, indicating satisfactory stability, which provides a new viable paradigm for energy-saving H2 production.

Boosting the Strength and Toughness of Polymer Blends via Ligand-Modulated MOFs

Mechanically robust and tough polymeric materials are in high demand for applications ranging from flexible electronics to aerospace. However, achieving both high toughness and strength in polymers remains a significant challenge due to their inherently contradictory nature. Here, a universal strategy for enhancing the toughness and strength of polymer blends using ligand-modulated metal-organic framework (MOF) nanoparticles is presented, which are engineered to have adjustable hydrophilicity and lipophilicity by varying the types and ratios of ligands. Molecular dynamics (MD) simulations demonstrate that these nanoparticles can effectively regulate the interfaces between chemically distinct polymers based on their amphiphilicity. Remarkably, a mere 0.1 wt.% of MOF nanoparticles with optimized amphiphilicity (ML-MOF(5:5)) delivered ≈1.1- and ≈34.1-fold increase in strength and toughness of poly (lactic acid) (PLA)/poly (butylene succinate) (PBS) blend, respectively. Moreover, these amphiphilicity-tailorable MOF nanoparticles universally enhance the mechanical properties of various polymer blends, such as polypropylene (PP)/polyethylene (PE), PP/polystyrene (PS), PLA/poly (butylene adipate-co-terephthalate) (PBAT), and PLA/polycaprolactone (PCL)/PBS. This simple universal method offers significant potential for strengthening and toughening various polymer blends.

Crafting "brick-mud" segregated nanocomposites: a novel approach to superior electromagnetic interference shielding, electrical insulation, and thermal conductivity in biopolymers

As electronic devices continue to be integrated, miniaturized, and operated at higher frequencies, the demand for green, advanced polymer nanocomposites with superior electromagnetic interference (EMI) shielding, thermal conduction, and electrical insulation properties significantly increases. However, achieving such multifunctional nanocomposites is challenging due to the inherent contradiction between electrical and magnetic properties. Biopolymer nanocomposites of polycaprolactone (PCL)/boron nitride (BN)@polylactic acid (PLA)/multi-walled carbon nanotubes (CNTs) ((PCL/BN)@(PLA/CNTs)) exhibit a unique "brick-mud" segregated double-network structure. This configuration effectively separates high-melting-point PLA/CNTs conductive phase from the PCL/BN insulating matrix. PLA/CNTs particles contribute to enhanced EMI shielding by attenuating electromagnetic waves, while also improving insulation by disrupting electron transfer within the PCL/BN phase. Additionally, incorporating conductive CNTs and thermal conductive BN further boosts the thermal conductivity (TC) of the nanocomposites. The structured sample (s-8B8C), which contains 8 wt% BN and 8 wt% CNTs, achieves an EMI shielding effectiveness (SE) of 31.4 dB in the X-band, a TC of 0.6 W m-1 K-1, and a volume resistivity of 7.2 × 1011 Ω cm. In summary, the "brick-mud" segregated structure facilitates the development of advanced biopolymer nanocomposites for electronic applications, leveraging sustainable materials for broad potential use.