Lamellar Structure Research Articles

Synergic effect between La-MOF and MXene: Revolutionizing TPU with improved mechanical strength and fire safety

Two-dimensional MXene nanosheets with lamellar structure and high specific surface area are considered promising flame retardants for polymers. However, MXene easily accumulates in polymer materials, resulting in the impairment of their mechanical properties. Metal-organic frameworks (MOFs) not only address this issue effectively but also improve compatibility with polymer materials due to their organic components. In this work, lanthanide rare-earth MOF (La-MOF) were successfully grown in-situ on the MXene surface to prepare hybrid flame retardants (La-MOF@MXene), then added to thermoplastic polyurethane (TPU). The La-MOF suppressed the accumulation of MXene in TPU, and the synergistic effect between them improved the fire safety and mechanical strength of TPU composites. The peak heat release rate of the TPU composites with the addition of 3 wt% La-MOF@MXene was 473.3 kW/m2, which represented a 49.4 % decrease compared to that of pure TPU. Besides, due to the synergic properties of MXene and La-MOF, La-MOF@MXene further reduced total smoke, CO2, and CO of TPU composites in fires. Moreover, with the addition of 3.0 wt% La-MOF@MXene, the tensile strength and elongation at break of TPU composites dramatically improved to 42.4 MPa and 686 %, respectively. Therefore, this study provides a novel paradigm for preparing hybrid flame retardants that can improve the fire safety and mechanical properties of TPU composites, exhibiting broad application prospects.

Postnatal hypoxic preconditioning attenuates lung damage from hyperoxia in newborn mice.

Preterm infants frequently require oxygen supplementation at birth. However, preterm lung is especially sensible to structural and functional damage caused by oxygen free radicals. The adaptive mechanisms implied in the fetal-neonatal transition from a lower to a higher oxygen environment were evaluated in a murine model using a custom-designed oxy-chamber. Pregnant mice were randomly assigned to deliver in 14% (hypoxic preconditioning group) or 21% (normoxic group) oxygen environment. Eight hours after birth FiO2 was increased to 100% for 60 min and then switched to 21% in both groups. A control group remained in 21% oxygen throughout the study. Mice in the normoxic group exhibited thinning of the alveolar septa, increased cell death, increased vascular damage, and decreased synthesis of pulmonary surfactant. However, lung histology, lamellar bodies microstructure, and surfactant integrity were preserved in the hypoxic preconditioning group after the hyperoxic insult. Postnatal hyperoxia has detrimental effects on lung structure and function when preceded by normoxia compared to controls. However, postnatal hypoxic preconditioning mitigates lung damage caused by a hyperoxic insult. Hypoxic preconditioning, implemented shortly after birth mitigates lung damage caused by postnatal supplemental oxygenation. The study introduces an experimental mice model to investigate the effects of hypoxic preconditioning and its effects on lung development. This model enables researchers to delve into the intricate processes involved in postnatal lung maturation. Our findings suggest that hypoxic preconditioning may reduce lung parenchymal damage and increase pulmonary surfactant synthesis in reoxygenation strategies during postnatal care.

Nanomechanical behavior of impulse atomized Al-Ce eutectic particles

Al – 20 wt% Ce alloy particles with varying eutectic morphologies and sizes were fabricated using high cooling rate impulse atomization. Nanoindentation and in situ compression in a scanning electron microscope were used to evaluate the hardness, flow strength and plastic deformability of individual phases (Al and Al11Ce3) and various Al11Ce3/α-Al eutectic morphologies. The mechanisms that determine compressive strengths, plastic deformability and fracture of the intermetallic phase are interpreted in terms of the eutectic morphology and spacing. Fine, degenerate eutectic structure facilitated significant strain hardening and delayed onset of cracking, making it highly resilient under compression, while the fine and regular eutectic structure showed relatively lower strengthening and early crack nucleation compared to coarser lamellar eutectic structure. This study reveals the significant effects of microstructure morphology as well as size, specifically focusing on the degenerate eutectic microstructures at submicron scale, in controlling the flow strength and plastic deformability of fine-scale metallic eutectic microstructures containing hard, intermetallic phases.

Effect of eutectic microstructure on load transfer and creep resistance in Al-Ce alloys

This study investigates the compressive creep response of hypo- and near-eutectic Al-Ce alloys via finite-element modeling (FEM), by considering the composite response of a weak, fast-creeping Al matrix containing slow-creeping Al11Ce3 eutectic reinforcement. In the as-cast microstructure of an eutectic Al-12.5 wt%Ce alloy, the Al11Ce3 eutectic phase is lamellar, regardless of the various cross-sectional geometries (Chinese-script, fish-bone, and comb-like). FEM models based on these various lamellar microstructures investigate the effect of Al11Ce3 reinforcement volume fraction, orientation, and geometry on load transfer performance between matrix and reinforcement during creep deformation. FEM predicts that, when the lamellar Al11Ce3 phase is continuous along the loading direction (where load transfer is most effective), the creep resistance of the alloy is barely affected by cross-sectional geometry of the Al11Ce3 reinforcement or by the solid-solution strengthening of the Al matrix, at constant Al11Ce3 volume fraction. However, alloy creep resistance and load transfer between phases are significantly reduced when applying load parallel to aligned, discontinuous lamellae, and they can be improved by matrix solid-solution strengthening. Furthermore, Al11Ce3 short plates (as created in Al-12.5Ce by coarsening of lamellae upon over-aging at 590 °C/24 h) provide the least creep resistance and load transfer. Lastly, multi-colony FEM models are created by combining colonies with various lamellar orientations to approximate the creep performance of polycrystalline hypo- and near-eutectic alloys which, when compared to experimental data for hypoeutectic Al-7Ce and for near-eutectic Al-(10–13)Ce, provide better predictions than single-colony FEM models or analytical solutions.

Crafting Nanostructured Hybrid Block Copolymer-Gold Nanoparticles by Confined Self-Assembly in Evaporative Droplets.

Hybrid organic-inorganic nanostructures offer significant potential for developing advanced functional materials with numerous technological applications. However, the fabrication process is often tedious and time-consuming. This study presents a facile method for fabricating block copolymer-based photonic microspheres incorporating plasmonic gold nanoparticles. Specifically, the confined self-assembly of poly(styrene)-b-poly(2-vinylpyridine) in emulsion droplets allows the formation of spherical, noniridescent, concentric lamellar structures, i.e., onion-like particles that are subsequently infiltrated with gold salt. Using ethanol as a preferential solvent allows the loading of metal ions exclusively into the poly(2-vinylpyridine) domains, which are subsequently reduced, leading to the in situ, spatially controlled formation of gold nanoparticles. The hybrid structures exhibit a well-defined photonic bandgap and plasmonic resonance at low gold concentrations. These results demonstrate the feasibility of fabricating optically active photonic structures comprising metal nanoparticles in a block copolymer array via a simple two-step fabrication process.

Effect of α‐Ferrite on Plasticity and Fracture Mechanisms of Dual‐Phase Ultrastrong Heterolamellar Steels

Lamellar heterostructure design is widely recognized as a potential method to improve strength and ductility simultaneously of high‐performance steel. However, the high mechanical contrast among soft/hard phase and inharmonic plastic deformation lead to complex fracture mechanisms and limit the improvement of plasticity. Herein, the plasticity and tensile fracture mechanisms of two types of δ‐ferrite and lath martensite heterolamellar steels with and without α‐ferrite are investigated. The sample without α‐ferrite shows a combination of cleavage in δ‐ferrite and dimple zones in the martensite. The microcracks initiate in the martensite early and the then the cleavage fracture occurs in the δ‐ferrite due to the stress concentration. In contrast, the sample with α‐ferrite has lower plasticity. Failure of the samples with α‐ferrite is govern by the microcracks initiating in the interface of martensite/α‐ferrite. Eliminating the impact of the effect of α‐ferrite, the total elongation increases from 8.9% to 11.6%, and the ultimate tensile strength (UTS) increases from 1567 to 1652 MPa. This study investigates the critical factor in plasticity control of dual‐phase heterostructure and promotes the development and application of lamellar structure.

The Cahn–Hilliard model of coherent lamellar microstructure: application to alkali feldspar

The temporal evolution of coherent lamellar microstructures is significantly influenced by their elastic properties, particularly when the exsolved phases are coherent. This research utilizes the Cahn–Hilliard model to examine the morphological and energetic evolution of binary alkali feldspar, integrating anisotropic elastic energy into the Gibbs energy equation. The Cahn–Hilliard model successfully simulated the orientation of lamellae observed in natural samples and the elastic strain was consistent with previous research. We also computed the coherent solvus from the annealing simulation of various precursor compositions and temperatures. The temperature difference (ΔT\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\Delta T$$\\end{document}) between the strain-free solvus and the coherent solvus was ΔT=85∘C\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\Delta T = 85\\,{}^\\circ \ ext {C}$$\\end{document}, which is slightly lower than previously reported values obtained from similar parameters. This discrepancy is likely due to the presence of non-planar lamellae at the onset of phase separation, which are more stable than planar ones. We also simulated the binodal curves of the coherent solvi for different precursor phase compositions. The computed solvi were not unique but varied depending on the precursor composition. Our model is flexible because it does not assume any specific shapes for the lamellar interfaces and is applicable to various coherent binary systems.

Spectroscopic determination of Deborah numbers in membrane-mimetic bolaamphiphile assemblies

The remarkable stability of Archaebacteria and their resistance to extreme environmental conditions, such as high temperature (hot springs), high salinity (salt marsh), high acidity (volcanic environment), or low temperature (Arctic or Antarctic) is mostly due to their very stable membranes. Membranes of Archaebacteria are composed of tetraethers from the lipid family of bolaamphiphiles. The concern in our laboratory is to synthesize bolaamphiphiles that could form vectors with function to carry drugs toward target cells in the body. The new family of bolamphiphiles synthesized has one polar head based on a sugar moiety and the other polar head is glycine betaine, both issued from natural sources (sugar beet, wheat). They are interconnected with a hydrocarbon chain of 12 methylène units. One side hydrocarbon chain, of 8 methylène units is attached to the anomeric position of the sugar moiety. These two molecules are named N-(12-Betainylamino-Dodecane)-octyl β-D-Glucofuranosiduronamide Chloride, abbreviated C8C12 and N-(12-Betainylamino-Dodeca-5,7-diynyl)-octyl β-D-Glucofuranosiduronamide Chloride, abbreviated C8C12X2. These bolaamphiphile molecules organize in membrane-mimetic lamellar structures (Lc, Lα, L). They undergo a thermal phase transition upon heating. When cooled back to room temperature, they remain in the undercooled high-temperature phase. To follow the relaxation back to the thermodynamically stable phase at 20 °C, the small-angle and wide-angle X-ray spectra were recorded every hour. The Deborah number (De), defined as De = time of relaxation/time of observation, is a dimensionless number often used in rheology to characterize the fluidity of materials under specific flow conditions. It was evaluated for supramolecular structures of two type of bolaamphiphiles, as the De(C8C12) = 35 and the De(C8C12X2) = 62. These values are typical for solid-like behavior, which is in accordance with the sticky, paste-like, brownish aspect of these bolaamphiphile assemblies. The time of relaxation was the time for bolaamphiphiles to regain their thermodynamically stable phase at 20 °C and the time of observation was 1 h, the typical time of recording between two subsequent spectra.

Thermal conductivity of 3D-printed block-copolymer-inspired structures

This study primarily focuses on examining the impact that geometric structure has on thermal conductivity of multi-phase constructs in different 3D-printed poly(lactic acid), PLA, samples. The investigated structures are inspired by morphologies formed by diblock copolymers: lamellae, hexagonally packed cylinders, and gyroid. This research also investigates how volume percentage and material combination influence the thermal conductivity of these structures. The samples can be tailored to simulate various thermal management structures observed in practical applications, such as thermal interface materials in electronic devices. Thermal conductivity ratio is controlled using air, the least conductive material at 0.026 W/(m K), PLA at 0.136 W/(m K), and thermal paste at 5.11 W/(m K). Different models were tested against thermal conductivity measurements in order to capture the effect of material type (PLA-Air versus PLA-Thermal Paste), volume percentage, structure, and orientation. Simple, effective medium models were good predictions of thermal conductivity in lamellar structures, but it was necessary to develop models for conduction through cylindrical and gyroid structures. Finally, all results were normalized to find a universal model that is independent of structure and material. This approach provides a simple method to predict how to reduce or enhance transport properties and heat management capabilities of 3D printed objects.

Thermal stability of a newly developed Mn containing β-solidifying γ-TiAl intermetallic compound at 750 °C

A newly low-cost β-solidifying γ-TiAl alloy Ti-44Al-3Mn-0.4Mo-0.4W-0.1B-0.1C (in at. %, named as TMMW) was invented. The rolled bars with a diameter of 12 mm were successfully fabricated by conventional hot rolling process, directly carrying out from the ingot without the pre-forging or hot-packing. The heat-treated TMMW rolled bar, which had a fine-grained nearly lamellar (NL) microstructure, was then air-exposed at 750 °C for up to 3000 h. The changes of the microstructure during this exposure were characterized using electron probe X-ray micro-analyzer (EPMA), transmission electron microscope (TEM), electron backscattered diffraction (EBSD) and high-energy X-ray diffraction (HEXRD). The tensile properties of the samples before and after thermal exposure were also tested. The fine-grained NL microstructure is found to be thermodynamically stable during the exposure. Meanwhile, the combined addition of Mo and W shows a positive effect on the stabilization of βo phase at colony boundaries, with only slight precipitation of the nanometer βo phases with no other brittle phases, such as Laves, in the metastable α2 lamellae. It is found that the thickness of the α2 lamellae decreases after 500 h exposure, while remains basically unchanged from 500 h to 3000 h, which is contributed by the effective pinning effect of the precipitated βo phase in α2 lamellae. As a result, the exposure-induced embrittlement under room temperature and elevated temperature does not take place. Interestingly, the ductility tested at 800 °C improves significantly after exposure. As for the tensile strength, it is only reduced by less than 10 % after 500 h exposure, while it remains essentially unchanged when increasing the exposure time from 500 h to 3000 h. Finally, the mechanisms of the precipitation of βo phases in the α2 lamellae and the tensile properties evolution during the exposure were carefully discussed.

Enhanced piezoelectric properties of additively manufactured BCZT with an oriented ceramic lamellar structure formed via vat photopolymerization

Advances in additive manufacturing have enabled the creation of piezoceramic materials with complex architectures. However, the lack of a clear structural design strategy limits their performance and application in high-performance piezoelectric transducer devices. This work outlines the additive manufacture of a novel sandwich architecture based on a porous (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3 (BCZT) layer containing oriented ceramic lamellae. The d33 charge coefficients and g33 voltage coefficients of the optimized porous ceramic were 1.16 times and 2.11 times higher than those of the dense counterparts respectively. After electroding the aligned lamellar ceramic with an indium tine oxide film a piezoelectric sensor was obtained which, when subject to a pressure of 7.5 MPa, produced a open circuit voltage of 173 V. This paper provides a new structural design strategy to effectively improve the performance of piezoelectric ceramics, and provides new opportunites for the design and production of additive manufactured piezoelectric sensors and energy harvesting devices.

Nanoindentation behaviors of the AlCoCrFeNi2.1 eutectic high-entropy alloy: The effects of crystal structures

The AlCoCrFeNi2.1 eutectic high-entropy alloy (EHEA), as a kind of in-situ composite materials, have achieved good match of strength and plasticity due to its typical eutectic lamella structures. Although many previous studies have investigated the indentation behaviors of the AlCoCrFeNi2.1 EHEA, there are still some controversies about the hardness characteristic of different crystal structures, requiring further clarification. Accordingly, in this study, nanoindentation tests were conducted to investigate the indentation behaviors of different crystal structures (primary L12 phase, primary B2 phase, and the eutectic phase region). The residual indentation and the crystallographic orientations were characterized by the laser scanning confocal microscope, scanning electron microscope, and electron backscatter diffraction. The hardness in different crystal structures were comparatively analyzed and the material deformation mechanisms were discussed correspondingly. The statistic results showed that the eutectic phase region had the lowest hardness, and primary B2 phase had the highest hardness. Furthermore, the slip lines in the primary L12 phase were evenly distributed near the residual indentation, but the slip lines in the eutectic phase region were concentrated near the phase boundaries. These findings are expected to deepen the understanding of the microscale deformation behaviors of EHEAs.

In vivo absorption, in vitro digestion, and fecal fermentation properties of non-starch polysaccharides from Chinese chestnut kernels and their effects on human gut microbiota

Non-starch polysaccharides are major bioactive components in chestnuts, and can serve as water-soluble polysaccharides with potential prebiotic properties. This study aims to establish an in vitro digestion and fermentation model to reveal the digestive and fermentative characteristics of Non-starch polysaccharides from chestnut kernels (NSPCK). The results indicated that under simulated digestion, NSPCK was partially digested in gastric juice but remained significantly undigested in saliva and intestinal juice, demonstrating considerable resilience against hydrolysis. After digestion, NSPCK still exhibited stable rough, lamellar, and porous structure and maintained strong antioxidant capacity. Animal experiments revealed positive effects of NSPCK on blood lipid level, and colon tissue of mice. Moreover, NSPCK enhanced the accumulation of short-chain fatty acids during fermentation, particularly acetic acid, propionic acid, and butyric acid. Furthermore, NSPCK intervention increased the abundance of beneficial bacteria such as Lactobacillus and Bifidobacterium, and at the same time reduced that of harmful bacteria such as Enterococcus.

Heterostructure ZIF-8@MXene with sieving effect in mixed matrix membranes for CO2 separation

At the present time, the realm of gas separation membranes is predominantly centered on the development of membrane materials that simultaneously exhibit exceptional gas permeability and selectivity. Mixed Matrix Membranes (MMMs) hold significant promise in addressing the long-standing challenge of balancing membrane selectivity with permeability. By incorporating a molecular sieving mechanism, an enhanced gas separation process is achieved. In this research endeavor, single-layer MXene nanosheets serve as an ideal substrate for the direct growth of ZIF-8 nanoparticles, yielding heterogeneously structured nanofillers, coined ZIF-8@MXene. The composite filler, ZIF-8@MXene, maintains a two-dimensional lamellar structure reminiscent of MXene, while also integrating ZIF-8 nanoparticles with their optimal pore size of 3.4 Å. This optimal pore size efficiently facilitates the unimpeded passage of CO2 molecules through the channels, creating a preferential pathway. Conversely, N2 molecules encounter greater difficulty traversing these channels, effectively coupling the solubility-diffusion mechanism with the molecular sieving mechanism to enhance selectivity in gas separation processes. Consequently, the mixed matrix membrane exhibits a remarkable enhancement in gas selectivity. Particularly, under sub-ambient conditions (−20 °C), the PEO/ZIF-8@MXene-0.3 % membrane achieves an exceptional CO2/N2 selectivity of 294.1, accompanied by a high CO2 permeability of 115.58 Barrer. This outstanding performance surpasses the 2019 upper bound, underscoring the significant potential of heterostructured nanofillers to be harnessed in advancing various mixed matrix membranes (MMMs) towards high-performance gas separation capabilities.

Measuring Oxygen Solubility in Amorphous and Semicrystalline Polyolefins Using Test Particle Insertion: A Comparative Study of Polyethylene and Isotactic Polypropylene.

The test particle insertion method is used to study the solubility of oxygen in two commonly used polymers: polyethylene (PE) and isotactic polypropylene (iPP). Amorphous samples for both polymers were prepared by means of Monte Carlo and molecular dynamics simulations, and the oxygen solubility was measured across different temperatures. The solubility-temperature dependence for iPP proved to be nonmonotonic due to the interplay between binding and reorganizational enthalpy, while for PE, it appeared to be monotonic based on the available data in the studied temperature range. A broad comparison to experiments and simulations is included. Further oxygen insertions were also performed in semicrystalline PE and iPP samples at ambient temperature, and the obtained values were compared to a linear relationship which correlates the solubility in the purely amorphous phase with the solubility in the crystalline phase. The solubility of PE closely follows the linear relationship, while iPP exhibits some divergence. All the semicrystalline samples were previously annealed at elevated temperatures for long periods (a few μs), and a strong effect of annealing was observed on the structure and the solubility of iPP. A well-developed iPP lamellar structure emerged at longer annealing times, while PE develops that structure already in the early crystallization stages. The solubility of semicrystalline iPP samples with lamellar morphology exhibited better agreement with extrapolated solubility values of the amorphous state─the extrapolation was made using a linear relationship connecting solubility in the purely amorphous phase and solubility in mixed phases (amorphous and crystalline). Results on the correlation of the solubility with the local structural ordering are also present.

Enhanced Lithium Extraction from Brines: Prelithiation Effect of FePO4 with Size and Morphology Control.

Extracting lithium resources from seawater and brine can promote the development of the new energy materials industry. The electrochemical method is green and efficient. Iron phosphate (FePO4) crystal, with its 1D ion channel, holds significant potential as a primary lithium extraction electrode material. Li+ encounters a substantial concentration disadvantage in brines, and the co-intercalation of Na+ diminishes Li+ selectivity. To address this issue, this work enhances the energy barrier for Na+ insertion through prelithiation strategies applied to the 1D channels of FePO4 crystal, thereby improving Li+ selectivity, and further investigating the prelithiation effect with particle size and morphology control. The results indicate that the Li(4C-40%)FePO4// Activated carbon(AC) system enhances selectivity of lithium. The Li(4C-40%)FePO4 with size diameter of 2500nm demonstrates an energy consumption of 0.79Whmol-1 and a purity of 97.94% for lithium extraction at a unit lithium extraction of 5.93mmolg-1 in simulated brine. Li(4C-40%)FePO4-nanoplates demonstrate the most optimal lithium extraction performance among the three morphologies due to their lamellar structure's short ion diffusion path in the [010] channel, favoring Li+ diffusion. The diffusion energy barriers of Li+ and Na+ are calculated using Density Functional Theory (DFT) before and after prelithiation, showing good agreement with experimental results.

Assembly of Chitosan/Caragana Fibers to Construct an Underwater Superelastic 2D Layer-Supported 3D Architecture for Rapid Congo Red Removal.

Developing environmentally friendly bulk materials capable of easily and thoroughly removing trace amounts of dye pollutants from water to rapidly obtain clean water has always been a goal pursued by researchers. Herein, a green material with a 3D architecture and with strong underwater rebounding and fatigue resistance ability was prepared by means of the assembly of biopolymer chitosan (CS) and natural caraganate fibers (CKFs) under freezing conditions. The CKFs can randomly and uniformly distribute in the lamellar structure formed during the freezing process of CS and CKFs, playing a role similar to that of "steel bars" in concrete, thus providing longitudinal support for the 3D-architecture material. The 2D layers formed by CS and CKFs as the main basic units can provide the material with a higher strength. The 3D-architecture material can bear the compressive force of a weight underwater for multiple cycles, meeting the requirements for water purification. The underwater compression test shows that the 3D-architecture material can quickly rebound to its original shape after removing the stress. This 3D-architecture material can be used to purify dye-containing water. When its dosage is 3 g/L, the material can remove 99.65% of the Congo Red (CR) in a 50 mg/L dye solution. The adsorption performance of the 3D architecture adsorbent for CR removal in actual water samples (i.e., tap water, seawater) is superior than that of commercial activated carbon. Due to its porous block characteristics, this material can be used for the continuous and efficient treatment of wastewater containing trace amounts of CR dye to obtain pure clean water, meaning that it has great potential for the effective purification of dye wastewater.

Interfacial Stabilization of Organic Electrochemical Transistors Conferred Using Polythiophene-Based Conjugated Block Copolymers with a Hydrophobic Coil Design.

The recent interest in developing low-cost, biocompatible, and lightweight bioelectronic devices has focused on organic electrochemical transistors (OECTs), which have the potential to fulfill these requirements. In this study, three types of poly(3-hexylthiophene) (P3HT)-based block copolymers (BCPs) incorporating different insulating blocks (poly(nbutyl acrylate) (PBA), polystyrene, and poly(ethylene oxide) (PEO)) were synthesized for application in OECTs. The morphological, crystallographic, and electrochemical properties of these BCPs are systematically investigated. Accordingly, P3HT-b-PBA demonstrates superior performance in the KCl-based aqueous electrolyte, with a higher product of mobility and capacitance (μC*) at 170 F s-1 cm-1 V-1 than that of the P3HT homopolymer at 58 F s-1 cm-1 V-1. P3HT-b-PBA exhibits better stability over 50 ON/OFF switching cycles than do other BCPs and P3HT homopolymers. With regard to the performance in the KPF6-based aqueous electrolyte, P3HT-b-PBA outperforms with a higher μC* of 9.2 F s-1 cm-1 V-1 than that of 8.6 F s-1 cm-1 V-1 observed from P3HT. Notably, both polymers exhibited almost no decay in device performance over 110 ON/OFF switching cycles. The strongly different performance of polymers in these two electrolytes is due to the side chain's hydrophobicity and interdigitated lamellar structures, thereby retarding the doping kinetics of the highly hydrated Cl- ions compared with the slightly hydrated PF6- ions. Concerning the improved performance of P3HT-b-PBA, this is attributed to its soft and hydrophobic backbone. Our morphological and crystallographic analyses reveal that P3HT-b-PBA experiences minimal structural disorder when swelled by the electrolyte, maintaining its original structure better than the P3HT homopolymer and the hydrophilic BCP of P3HT-b-PEO. The hydrophobic nature of P3HT-b-PBA contributes to the stability of its backbone structure, ensuring enhanced capacitance during the operation of the OECT operation. These findings provide reassurance about the stability and performance of P3HT-b-PBA in the field of OECT applications. In summary, this study represents the first exploration of P3HT-based BCPs for OECT applications and investigates their structure-performance relationships in mixed ionic-electronic conductors.

Effect of laser remelting treatment on the tribological properties of plasma sprayed WC–Cr3C2–Ni reinforced NiCrBSi coatings

The incorporation of single hard phases, such as tungsten carbide (WC), and chromium carbide (Cr3C2), into NiCrBSi coatings effectively enhances their performance, thereby fulfilling the tough requirements of high-temperature friction condition. To investigate the collaborative reinforcing effect of multiple hard phases and further enhance the high-temperature wear resistance of the coating, a novel WC–Cr3C2–NiCrBSi binary hard phase reinforced coating was developed and subjected to laser remelting treatment. The as-sprayed coatings demonstrate a distinct lamellar structure that diminishes upon remelting, resulting in significant densification of the coatings and a reduction in porosity to 0.3 %. The microhardness of the remelting coatings is reduced by about 10 % due to dilution of the coating by the lower hardness of the base material. However, during the laser remelting process, WC and Cr3C2 decompose and dissolve into the alloying binder phase of the coating, serving as solid solution agents. In cases where the concentration of W elements is elevated, a considerable precipitation of W-rich carbide is observed within the coating. Notably, N30 coatings demonstrate remarkable were resistance at both ambient and 700 °C, resulting in a significant reduction in wear volume by 86.5 % and 55.2 % respectively in comparison to original NiCrBSi coatings. The remelting treatment enhances the densification of the coating, improves the homogeneity of the microstructure, and reduces the coefficient of friction of the coating. The laser-remelted coating exhibits a decreased wear volume, attributed to a transition in its wear mechanism from fatigue-dominated to abrasive wear at room temperature. Conversely, under frictional conditions at 700 °C, the remelted coating experiences an augmented wear volume, attributed to severe abrasive wear.

Improving the electrochemical performance of nickel-cobalt organic framework by hybridizing with carbon quantum dots

To improve the electrochemical properties of nickel-cobalt metal-organic skeleton materials, two carbon quantum dots (CQDs), namely, CQD-CA and N-doped CQD-CAn, were prepared by using citric acid as carbon source and then introduced into NiCo-MOF to prepare CQDs/NiCo-MOF composites. Through the application of physical characterization and electrochemical analysis methods, such as SEM, TEM, XRD, XPS and BET, it was found that NiCo-MOF@CA and NiCo-MOF@CAn exhibited a nano thinner lamellar structure, higher specific surface area, larger pore structure, and excellent electron transport ability. Especially, by introducing CQDs, the charge could transfer from oxygen to Ni and Co, and there was some higher electron cloud density around active metals Ni and Co in NiCo-MOF@CAn than in NiCo-MOF, effectively activating the metal center Ni and Co. As the result, the specific capacitance of NiCo-MOF@CAn reached 1917.7 F·g−1 at the potential scan rate 5 mV·s−1, significantly higher than that of NiCo-MOF (1173.4 F·g−1) and NiCo-MOF@CA (1489.3 F·g−1). The method might provide an alternative strategy for modulating the morphology, porous structure and the partial electron structure of the target materials by introducing various CQDs.