Search Results (167)

This paper introduces a novel method for producing planar electrochemical devices by combining multi-material 3D printing with metal leaves (3D-MLEs). The fabrication process is based on the use of two polymeric materials, polylactic acid (PLA) and polycaprolactone (PCL), leveraging their different melting points. The approach exploits the thermoadhesive properties of polyesters, which can act as bonding layers upon heating, enabling a direct-writing and low-step fabrication strategy. The device was fabricated using a dual-extruder 3D printer to produce a PLA support containing PCL tracks, followed by selective thermal adhesion of the metal leaf onto the PCL. This process exploits the different melting temperatures of the two polymers: PCL softens and becomes adhesive at the selected temperature, while the PLA support remains structurally unaffected. A final brushing step enables the definition of a well-controlled three-electrode geometry. Following optimization of the fabrication parameters, a platinum leaf-based device (3D-PtLE) was assembled and evaluated using potassium hexacyanoferrate(II) and hexaammineruthenium(III) chloride as redox probes. The optimized device was subsequently applied to hydrogen peroxide detection in phosphate buffer (pH 7), exhibiting a linear response in the concentration range of 0.25–5 mM, with a limit of detection of 67 μM and good repeatability (RSD = 4.2%). The analytical applicability of the device was further demonstrated through the analysis of a real sample consisting of washing water prepared from a sodium percarbonate-based cleaning tablet, with good agreement (98 ± 6%) with the standard titration method. The proposed strategy provides a simple, low-cost, and customizable approach for fabricating planar electrochemical platforms based on pure metal electrodes, combining high analytical performance with straightforward manufacturing. Full article

Aluminum nitride (AlN) ceramics are highly regarded for their excellent thermal and electrical properties, making them highly suitable for numerous applications in high-power electronic devices. However, directly bonding copper to AlN substrates remains a significant challenge, mainly due to the strong covalent bonds inherent in AlN, which result in poor wettability of copper on the AlN ceramic surface. To address this issue, the present study proposes a method for directly depositing a dense copper layer on AlN substrates through the atmospheric plasma spraying (APS) process, thereby obtaining a thick copper layer (~30 µm) with excellent comprehensive performance on the AlN substrates. In this study, before performing APS coating, the AlN substrates were first subjected to pre-oxidation treatment to enhance their wettability with the copper layer. Under the optimized atmospheric plasma spraying process parameters, the maximum adhesion strength of copper on the AlN substrates reached 17.56 MPa, along with a low surface resistivity of 2.66 × 10⁻³ Ω·mm and a relatively high room-temperature thermal conductivity of 135 W/m·K. High-resolution transmission electron microscopy (HR-TEM) was used to characterize the interface structure, and the results showed that chemical bonding was formed between the copper layer and the pre-oxidized AlN surface—this bonding effectively enhanced the interface adhesion. In addition, this paper also reports that the atmospheric plasma spraying technology can be used to precisely fabricate copper circuits directly onto AlN substrates. Full article

Wood-based composite panels are renewable and low-carbon materials, but their inherent flammability limits their broader use in applications requiring improved fire safety. In this study, expanded graphite (EG) was incorporated into a melamine–formaldehyde (MF) adhesive system to fabricate fire-retardant Japanese cedar (Cryptomeria japonica) plywood. Two EG types with different expansion ratios, 200-fold expanded graphite (200EG) and 450-fold expanded graphite (450EG), were added to the bonding layer at 10, 20, 30, and 40 phr. The effects of EG expansion ratio and content on the physicomechanical properties, combustion behavior, char morphology, and pyrolysis gas evolution of plywood were investigated. EG had limited effects on air-dried density and moisture content, but increasing EG content reduced bonding shear strength and parallel-direction flexural properties, particularly in the 450EG series. Cone calorimeter analysis showed that EG reduced the heat release rate and total heat release by promoting the formation of an expanded carbonaceous barrier layer. Among the tested formulations, 30 phr 200EG provided the most favorable balance between mechanical performance and fire-retardant efficiency, showing a visually more continuous char coverage while maintaining acceptable bonding properties. High-temperature furnace–FTIR analysis indicated that excessive EG loading or high-expansion-ratio EG increased CO₂ and CO-related signals at 400–700 °C, probably because of a visually looser char morphology, structural disruption during expansion, and gas release from EG intercalating agents. Although the tested panels did not fully meet the CNS Grade 3 fire-retardant requirement, the results provide a useful basis for the modification and performance optimization of halogen-free fire-retardant wood-based composite panels. Full article

Gallium (Ga)-based liquid metal (LM) composites, particularly those based on eutectic gallium–indium (EGaIn) and related alloys, have emerged as a promising materials platform for soft and deformable energy storage owing to their unique combination of metallic conductivity, fluidic deformability, and adaptive interfaces. Despite rapid advances in LM-enabled devices, binders remain insufficiently understood and are still commonly regarded as passive structural components. Here, we present a comprehensive binder-centered perspective for LM composites, establishing the binder as a key regulator of electro-chemo-mechanical coupling, interfacial stability, transport behavior, and processability in soft energy systems. We show that tailored binder chemistries in Ga-based LM systems—including stretchable batteries, printable conductors, and soft electrochemical devices—govern LM droplet dispersion, suppress coalescence and leakage, and preserve conductive percolation under large deformation, while enabling room-temperature fabrication and printability through rheological regulation and interfacial wetting. Beyond mechanical confinement, emerging binder functionalities—including dynamic bonding, supramolecular interactions, ionically conductive networks, and reversible polymer architectures—enable self-healing interfaces, adaptive transport pathways, and robust adhesion in deformable devices. By integrating recent advances in stretchable batteries, flexible supercapacitors, printable electronics, and multifunctional soft energy systems, we establish a unified multiscale framework linking binder molecular design to device-level electrochemical and mechanical performance. We further discuss sustainability and manufacturing considerations, including recyclable polymer networks, low-temperature fabrication, and scalable processing strategies. Finally, we outline current challenges and future opportunities toward programmable binder systems with tunable viscoelasticity, interfacial reactivity, and adaptive functionality. This Review establishes binder-centered engineering as a key pathway for transforming LM composites from proof-of-concept materials into resilient, manufacturable, and multifunctional soft energy technologies for wearable, stretchable, and biointegrated electronics. Full article

Polyester (PET) fibers are widely used to reinforce asphalt materials; however, their smooth and hydrophobic surfaces limit interfacial bonding and restrict their reinforcing efficiency. This study develops an eco-friendly surface modification method based on the chemical modification of gallic acid (GA) and aminosilane (KH792) to enhance the compatibility between PET fibers and asphalt. Modified fibers with various molar ratios of GA/KH792 were prepared and incorporated into asphalt mastic. Their performance was evaluated using softening point, cone penetration, dynamic shear rheometer (DSR), multiple stress creep recovery (MSCR), linear amplitude sweep (LAS), and bending beam rheometer (BBR) tests, combined with interfacial interaction analysis and scanning electron microscopy (SEM). The results show that surface modification significantly improves the reinforcing effect of PET fibers. In particular, the co-modified fiber with a GA/KH792 ratio of 1:1 exhibits the best performance, with increases of 27% in softening point and 105% in shear strength, as well as notable improvements in rutting resistance, fatigue performance, and temperature stability. Interfacial indices and SEM observations confirm enhanced adhesion, dispersion, and load transfer capacity. However, the improvement in low-temperature performance is limited. Overall, GA/KH792 chemical modification effectively enhances fiber asphalt interfacial interaction and provides a simple and sustainable approach for developing high-performance asphalt materials. Full article

Waste plastics have attracted widespread attention in asphalt modification because of their environmental and economic benefits. However, the incorporation of waste plastics may weaken asphalt–aggregate interfacial adhesion, thereby increasing the risk of moisture damage in asphalt pavements. Although liquid anti-stripping agents have been widely used in conventional asphalt systems, their effectiveness and performance evolution in waste plastic-modified asphalt (WPA) remain insufficiently understood. To address this gap, this study systematically investigated the effects of two liquid anti-stripping agents, AJ-1 and AMR-II, on the adhesion, rheological properties, and aging behavior of WPA. Specifically, asphalt–aggregate adhesion was evaluated using water-boiling and binder bond strength tests, rheological properties were characterized by dynamic shear rheometer and bending beam rheometer tests, and aging behavior was analyzed through rolling thin-film oven test, pressurized aging vessel, and Fourier transform infrared spectroscopy. The results show that waste plastics reduce the adhesion performance at the asphalt-aggregate interface, whereas anti-stripping agents compensate for this loss. Compared with AJ-1, AMR-II showed stronger adhesion enhancement, increasing the asphalt residual coating ratio by approximately 1.5%–3.5% and the pull-off tensile strength by 17.4%–28.1%, while the corresponding improvements for AJ-1 were approximately 1.3%–2.7% and 13.0%–25.0%, respectively. As the dosage of both anti-stripping agents increased, the penetration index decreased, the temperature susceptibility increased, the softening point generally decreased, and the ductility increased markedly. Temperature sweep results show that both AJ-1 and AMR-II reduce the high-temperature performance of WPA. According to the bending beam rheometer results, AMR-II also enhances the low-temperature performance of WPA. Aging test results indicate that both anti-stripping agents increase the aging sensitivity of WPA to some extent, but the adverse effect of AMR-II on aging resistance is smaller than that of AJ-1, and AMR-II better preserves the low-temperature ductility and adhesion performance after aging. Overall, this study provides a binder scale evaluation showing that 0.4% AMR-II may offer a more balanced strategy for improving the adhesion and service performance of WPA. Full article

Silicon micromachining serves as the foundational enabling technology for high-precision MEMS inertial sensors. However, the relentless pursuit of enhanced sensitivity and multi-functionality in emerging applications encounters a fundamental bottleneck when confined to two-dimensional scaling. The evolution toward complex three-dimensional (3D) stacking architectures is an inevitable trajectory for devices including MEMS inertial sensors, yet performance is constrained by the limitations of conventional processes in fabricating and integrating intricate 3D hollow structures. Specifically, uniformity in large-area deep silicon etching, structural integrity of convex corners in wet etching, and residual stress induced by multi-layer wafer bonding have emerged as critical, shared challenges. To address these issues, this paper proposes a triple-layer wafer-level stacking scheme that synergistically combines wet/dry hybrid etching with low-temperature adhesive bonding. This stacking scheme incorporates an innovative linear compensation model for wet-etched convex corners, enabling high-precision fabrication of complex corner structures under deep etching conditions. Furthermore, a collaborative strategy involving temporary bonding and plasma flow-field optimization improves the uniformity and integrity of dry etching for large perforated structures. A low-temperature triple-layer wafer-level stacking process is developed, encompassing precise adhesive dispensing, optical alignment, and a stepped low-temperature curing profile, thereby achieving highly symmetric 3D integration with controlled adhesive distribution. The efficacy of this stacking scheme is validated through the fabrication of a symmetrically stacked triple-layer MOEMS accelerometer sensing element. Test results demonstrate a noise floor as low as 0.40 µg/√Hz and a bias instability of 1.81 µg over 10 min. Compared with a double-layer counterpart, improved performance is obtained. The wafer-level stacking scheme established in this work not only provides a viable pathway for pushing the manufacturing limits of high-precision inertial devices but also offers a generic methodology for tackling complex hollow structure formation and low-temperature integration, holding referential value for broader applications in high-precision 3D microsystems. Full article

Eucommia ulmoides gum (EUG), a sustainable plant-derived natural polymer, was functionalized via three distinct routes, including vulcanization, epoxidation, and hydroxylation to yield vulcanized (VEUG), epoxidized (EEUG), and hydroxylated EUG (HEUG), respectively. We systematically characterized the effects of modification route and degree on the chemical structure, crystallization behavior, thermal stability, hydrophilicity, and mechanical properties of functionalized EUG and further evaluated the high/low-temperature performance, microstructure, and mechanical properties of the corresponding modified asphalt binders (VEMA, EEMA, HEMA) as a function of modifier type and loading. For VEUG, C-S cross-linking networks formed during vulcanization suppress EUG crystallization, enabling a rigid-plastic to elastic transition, while high-temperature cleavage of C-S bonds reduces its initial thermal stability. For EEUG, epoxidation breaks C=C double bonds and introduces epoxy groups to strengthen intermolecular interactions; subsequent ring-opening grafting of hydroxyl groups onto EEUG yields HEUG, which forms additional cross-links via dynamic hydrogen bonds. Increasing modification degree for both EEUG and HEUG reduces their number- and weight-average molecular weights with narrower distribution, diminishes crystallinity, enhances thermal stability and hydrophilicity, and drives a rigid-plastic to elastic transition, characterized by decreased strength (0.65 MPa < σ_HEUG < σ_EEUG < 10.18 MPa) and markedly improved ductility (143.6% < ε_EEUG < 262.0%, 679.9% < ε_HEUG < 1360.3%). In asphalt binders, VEUG’s cross-linked network endows VEMA with refined more abundant bee-like microstructures, drastically boosting high- and low-temperature performance: relative to pristine EUG-modified asphalt (EUGMA), VEMA’s DMT modulus decreases by 94%, and adhesion increases by 87%. EEMA forms covalent bonds with polar asphalt components via epoxy groups, while HEMA constructs a hydrogen-bonded cross-linked network; both effectively inhibit asphaltene aggregation. With increasing modifier loading, EEMA and HEMA exhibit increased modulus, reduced adhesion, and gradually improved high- and low-temperature performance, except for the non-significant high-temperature enhancement of HEMA at higher loadings. Full article

With the shortage of natural aggregates and the massive accumulation of iron tailings (ITs) solid waste restricting the sustainable development of asphalt pavement engineering, replacing natural aggregates with ITs has become a promising low-carbon solution with prominent economic and social benefits. However, the poor interfacial adhesion between ITs and asphalt severely restricts the engineering application of tailings, and the micro-interaction mechanism at their interface still lacks systematic clarification, which is the key research gap addressed in this work. Different from conventional macro road performance tests, this study innovatively combined molecular dynamics (MD) simulation with microscopic characterization, including Fourier transform infrared spectroscopy (FT-IR) and atomic force microscopy (AFM), to comprehensively reveal the interfacial interaction mechanism between ITs and asphalt at the molecular and microscales. The results indicate that asphalt molecules exhibit higher aggregation concentration and diffusivity on Al₂O₃ and Fe₂O₃ surfaces than on SiO₂ surfaces, proving stronger interfacial interaction between asphalt and iron-rich oxide minerals. Moderate temperature optimizes the adhesion performance of asphalt with Al₂O₃ and Fe₂O₃, while the interfacial bonding of asphalt on CaCO₃ and SiO₂ weakens as temperature rises. The silane coupling agent KH-550 can effectively react with acidic minerals, SiO₂ minerals in ITs, which significantly increases the concentration, diffusion coefficient, and distribution uniformity of asphalt molecules at the interface. FT-IR results verify that the combination of ITs and asphalt mainly relies on physical adsorption without generating new chemical bonds. AFM tests further confirm that alkaline minerals improve the surface roughness of asphalt mastic, and KH-550 greatly enhances the micro-adhesion force of the interface. The novelty of this work lies in clarifying the mechanism of typical mineral components in ITs and revealing the modification enhancement law of silane coupling agent and alkali minerals at the micro level. This study provides a scientific theoretical support for the high-value engineering utilization of ITs in asphalt pavement, and offers a reference for optimizing the interfacial modification design of solid waste aggregate. Full article

In extreme scenarios such as nuclear explosions and high-energy radiation detection in space, UV-cured adhesives are usually used as coupling media to bind tapered optic fiber arrays with intensified charge-coupled devices or complementary metal–oxide semiconductors and a tapered optic fiber array for effective optical signal transmission. To address the issue of weak bonding strength caused by the small binding area between charge-coupled devices or complementary metal–oxide semiconductors and TOFA, a stage-wise curing process was investigated and proved to be efficient through comparison with the single curing process. The effect of interval time between the initial and final curing on coupling strength was characterized by tensile strength, shear strength and shock acceleration testing, and the samples were exposed to high and low temperatures for evaluation of their environmental adaptability. The curing mechanism was analyzed by surface morphology of the adhesive layer after decoupling and an energy-dispersive X-ray spectroscopy elemental analysis of interface layer. The results show that when the interval time is extended from 5 min to 60 min, the shock acceleration of the coupling device decreases by 26.1%, while the tensile and shear strengths also decrease by 49.4% and 60.7%, respectively. The decline in coupling strength is attributed to oxygen inhibition during interval time. The exposure of the adhesive surface to the air allows oxygen to diffuse into and react with active the free radicals that remain from the initial curing, which inhibits further polymerization and generates a thin, incompletely cured weak boundary layer. These findings provide insights for optimizing stage-wise curing processes and improving the reliability of coupled imaging devices. Full article

Efficient heat dissipation is crucial for semiconductor devices; however, conventional thermal management materials often cannot meet practical demands because of inadequate thermal conductivity and mismatched coefficients of thermal expansion with semiconductor materials. In this study, we develop a synergistic process integrating magnetron sputtering and annealing to fabricate a composition-controllable Cr/Cr₃C₂ composite interlayer on diamond surfaces. By regulating the annealing temperature from 700 to 1100 °C, three key parameters of the Cr/Cr₃C₂ composite interlayer can be tailored: the thickness varies from ~200 to 800 nm, the Cr/Cr₃C₂ fraction is adjustable, and the surface roughness ranges from 33.3 to 61.6 nm. In the current research, the sample that was annealed at 900 °C for 2 h exhibited the highest coating uniformity, with carbide coverage exceeding 98% and no discernible porosity. This optimized annealing process produces an interlayer with robust coverage, moderate thickness (~300 nm), and low surface roughness (Ra = 33.3 nm), thereby markedly enhancing interfacial bonding and thermal-transport performance. The resulting composite achieves a maximum thermal conductivity of 605.27 W·m⁻¹·K⁻¹, corresponding to 211% of the experimentally measured value for the uncoated sample. Analyses combining the diffusion mismatch model and experimentation indicate that the enhancement originates from improved phonon spectral matching and increased interfacial adhesion energy. This work provides processing guidance for precise interface engineering in high-thermal-conductivity diamond/copper composites. Full article

One promising innovative joining process for non-oriented electrical sheets is based on an electro-insulating layer combined with a self-bonding varnish. The aim of this study was to investigate the adhesion of the self-bonding varnish as evaluated by a lap-shear test. During the experiments, non-oriented electrical steels with low to high silicon content were analyzed and tested. The Si content, the bond thickness, and the surface roughness Ra, as well as the selected steel production parameters—such as the radiation tube furnace temperature (RTF), the grain growth temperature (i.e., heating temperature (HF)), the peak metal temperature (PMT), and the annealing atmosphere (dry or humid, controlled by dew point)—were considered as the variables. The results showed that the lap-shear strength was independent of the surface roughness within the investigated range. In contrast, the bond thickness exhibited a weak positive effect on the lap-shear strength, while the Si content showed condition-dependent behavior. The RTF and the HF resulted in a relatively stable mechanical performance, whereas the PMT and the humid annealing atmosphere were identified as critical factors influencing adhesion. Full article

To mitigate the issue of brittleness and cracking in epoxy resin (EP) anti-skid systems, this study investigates four key aspects tailored to application scenarios: toughening, low shrinkage, strong adhesion, and rapid curing at ambient temperature. 1,4-Butanediol diglycidyl ether (BDDE) was used to extend the chain of triethylenetetramine (TETA), followed by a Mannich reaction with formaldehyde (F) and cardanol to prepare a flexible aliphatic amine Mannich base curing agent containing flexible segments (Curing Agent B). The influence of composition ratios on the mechanical properties of the cured product was studied. The curing performance of the epoxy system under various temperature conditions and its adhesion to asphalt substrates were characterized. The thermal shrinkage behavior of the epoxy system under temperature-variable environments was also investigated. The results indicated that the elongation at break of the epoxy curing system, after chain extension and toughening, increased from 28.7% to 40.4%, representing a 28.9% increase. When n (Cardanol):n (TETA):n (F):n (BDDE) = 1:1.4:0.8:0.7 (molar ratio of reactants), m (EP):m (Curing Agent B) = 1:1 (mass ratio), and epoxy-terminated polyurethane (EPU) prepolymer constituted 10% of the epoxy resin mass; the epoxy curing system exhibited an elongation at break of 44.3%, a tensile strength of 7.0 MPa, a bond strength of 6.9 MPa, and an impact toughness of 1.77 J/cm². Furthermore, it exhibited rapid curing at a low temperature (0~5 °C) and at room temperature (25 °C). Additionally, when bisphenol F epoxy resin was used, the system demonstrated optimal thermal expansion properties. Full article

Flexible conductive hydrogels hold great promise in wearable electronics and biomonitoring applications, yet their practical use is constrained by issues such as poor low-temperature tolerance, susceptibility to dehydration, and limited multifunctional sensing capabilities. This study successfully synthesized a dual-conductive lithium-ion and calcium-ion hydrogel based on acrylamide/gelatin via a simplified low-temperature one-pot polymerization method. At 60 °C, mixing acrylamide, gelatin, lithium chloride, and calcium chloride within 40 min constructed a network structure featuring covalent bonds, ionic bonds, and hydrogen bonds. The resulting material exhibited exceptional extensibility with a break elongation of 1408.5% and tensile strength of 134.2 kPa while maintaining strong adhesion to nine different substrates. It retained flexibility at −20 °C and demonstrated minimal mass loss (3% of initial value) after 10 days of aging. As a sensor, this hydrogel reliably responds to pressure, temperature, large-amplitude body movements, and subtle physiological signals like pulse and vocal cord vibrations. In animal simulation monitoring, its electrical resistance signals increased linearly with model body weight and remained stable between −20 °C and 20 °C. These results demonstrate the hydrogel’s broad application potential in wearable sensing, ecological monitoring, and smart agriculture. Full article

Ultra-low-formaldehyde medium-density fiberboard (MDF) is commonly produced using low-molar-ratio urea-formaldehyde (UF) resins; however, the reduced formaldehyde-to-urea ratio also lowers resin reactivity and can complicate curing. The aim of this research work was to investigate and evaluate the performance of ammonium bisulfite and urea–metabisulfite as formaldehyde scavengers for a low-molar-ratio UF resin (F/U = 1.06) at 1, 3, and 5 wt% (based on dry UF resin solids) used for MDF panel manufacturing. The modified adhesive systems were first screened by simultaneous thermal analysis in air to determine changes in the curing profile, and laboratory panels were then produced and evaluated for formaldehyde content by the perforator method (EN ISO 12460-5:2015) and for the main physical and mechanical properties. Ammonium bisulfite shifted the main curing peak to higher temperatures, indicating stronger retardation of the principal polycondensation stage, whereas urea–metabisulfite generated a broader, multi-peak curing profile. Despite these differences, both additives reduced the perforator values substantially. The control MDF already met the E0 level (3.84 mg/100 g oven-dry board), while 3 wt% ammonium bisulfite and 5 wt% urea–metabisulfite reached the super E0 levels (<1.5 mg/100 g; 1.36 and 1.26 mg/100 g, respectively). To note, scavenger addition up to 5 wt% (based on dry UF resin solids) did not significantly affect density, water absorption/thickness swelling, or bending and internal bond properties. The results demonstrate that sulfite-based scavengers can be incorporated into low-molar-ratio UF adhesives to obtain ultra-low-formaldehyde MDF while maintaining the main panel properties. Full article