Search Results (1,235)

Effective absorption in the S-band usually requires relatively thick absorbing materials. However, growing application demands necessitate the development of high-performance materials with subwavelength thickness. This study presents a broadband absorbing metamaterial for the S-band, based on a novel structural design featuring a nested hexagonal metal resonant layer integrated with a carbonyl iron powder (CIP)/charcoal (CH)/epoxy resin (ER) composite slab. This structural innovation enables exceptional S-band absorption within a subwavelength thickness, effectively overcoming the inherent physical limitations of traditional materials. By combining the arch measurement method and simulations over the 2–18 GHz, we demonstrate that the metal resonant layer of the metamaterial plays a key role in controlling the electromagnetic field vector distribution. This work investigates the mechanism for enhancing S-band absorption in metamaterials through the redistribution of electromagnetic field vectors. Additionally, magnetic loss from CIP/CH/ER and dielectric loss from the resonators further enhance absorption performance. The designed absorbing metamaterial exhibits effective absorption at a thickness of only 2.25 mm, with a reflection loss (RL) below −10 dB from 2.2 to 3.8 GHz. Simultaneously, it can maintain a radar cross-section (RCS) below −10 dBm² in a wide-angle range of ±160°. Furthermore, a superhydrophobic coating with a contact angle of 152° was prepared for absorbing metamaterial. This coating allowed the metamaterial to preserve its microwave absorption performance while imparting self-cleaning capability. This study proposes a multifunctional absorbing metamaterial for efficient absorption in the S-band. Full article

To meet the requirements for passive heat dissipation and self-cleaning of aluminum alloy enclosures used in 5G base-station active antenna units (AAUs), a scalable surface modification strategy involving sandblasting, NaOH etching, and PFTEOS grafting was developed for 6061 aluminum alloy. Microscale rough structures were first constructed by sandblasting, and hierarchical micro/nano structures composed of microscale pits and nanoscale plate-like/coral-like features were subsequently formed through NaOH etching and boiling-water treatment. Finally, a low-surface-energy PFTEOS layer was grafted onto the structured surface to achieve superhydrophobicity. The effects of sandblasting pressure and etching time on surface morphology, chemical composition, wettability, and infrared emissivity were systematically investigated. The results show that sandblasting enhanced infrared emissivity by increasing surface roughness and promoting optical trapping, while NaOH etching further improved emissivity through the formation of hierarchical micro/nano structures and infrared-active AlOOH/Al₂O₃ phases. After PFTEOS grafting, the surface wettability changed from hydrophilic to superhydrophobic, while the high infrared emissivity was maintained. Compared with the untreated aluminum alloy, the modified surface exhibited a remarkable increase in water contact angle from 80.10° to 153.63° and infrared emissivity from 0.0102 to 0.8951. Moreover, the water contact angle remained above 150° after continuous water-jet impact, indicating good preliminary resistance to hydraulic shear. This work provides a feasible surface-engineering route for integrating high infrared emissivity and self-cleaning capability on aluminum alloy surfaces for outdoor thermal management applications. Full article

The anti-corrosion performance of epoxy coatings in saline solution environments is restricted by their surface hydrophilicity and microporous defects. Herein, we developed a modified epoxy (MEP)-based superhydrophobic anticorrosive coating by fluorinated resin matrix and incorporation of polyaniline@expanded graphite (FPANI@MEG) anticorrosive fillers. The FPANI@MEG fillers were fabricated via in situ polymerization of aniline on the surface of dopamine-modified expanded graphite to construct the micro-nano hierarchical structure required for superhydrophobicity, while providing barrier shielding and active passivation functions. The results showed that the final coating exhibited excellent superhydrophobicity with a water contact angle of 156.5 ± 1.8° and sliding angle of 3.0 ± 0.6°, along with excellent adhesion and adaptability to various complex environments. Meanwhile, the coating maintained superhydrophobicity after 400 cycles of Taber abrasion and 450 g of falling-sand impact, demonstrating hydrophobic robustness. Furthermore, the coating exhibited a low-frequency impedance modulus of 2.30 × 10⁷ Ω·cm² after immersion in NaCl solution for 15 days. The synergistic combination of air film shielding, physical barrier, and active passivation endowed the coating with good anticorrosion performance. This work may provide a theoretical reference for improving the corrosion protection of epoxy-based superhydrophobic coatings on carbon steel in aggressive saline solution environments. Full article

Constructing inverted wedge-shaped hydrophilic channels with a small apex angle on surfaces with wettability patterns is an effective strategy to promote efficient and complete droplet detachment, which is crucial for applications such as condensation heat transfer and self-cleaning. However, a comprehensive understanding of how wedge geometry parameters affect droplet dynamics has not been established. In this study, we systematically investigate the dynamics of droplet formation and detachment within inverted wedge-shaped superhydrophilic channels fabricated by laser etching on hydrophobic or superhydrophobic substrates. Four distinct droplet detachment mechanisms are revealed. Our results indicate that, within the experimental parameters tested, a slender channel geometry—featuring a narrow upper base, a minimized lower base, and sufficient height—combined with a superhydrophobic substrate, promotes high-position droplet formation, extends the droplet sliding distance, and significantly reduces resistance. This synergy leads to the most efficient detachment mechanism: inertia-driven direct shedding. For the tested configurations, the C1.2/0/40 channel achieved the highest recorded detachment frequency of 318 min⁻¹ at a flow rate of 0.5 mL/min. Furthermore, droplet rebound at the channel tip is observed in some configurations, where two to three droplets must form sequentially and coalesce to trigger a single detachment event. This work provides actionable geometric design strategies for engineering surfaces capable of directional and highly efficient droplet detachment. Full article

This review examines how plant polyphenols enable multifunctional textiles, offering a sustainable alternative to synthetic dyes and nanomaterial-based treatments. A literature search (2001–2025) identified 105 peer-reviewed studies across eight functional areas. Abundant in agricultural and industrial byproducts, plant polyphenols act as natural colorants, bio-adhesives, and performance enhancers—providing coloration, antibacterial activity, UV protection, flame retardancy, deodorization, antioxidant capacity, superhydrophobicity, and more. Their catechol and pyrogallol groups bind strongly to natural and synthetic fibers via hydrogen bonding, π–π stacking, and metal chelation, ensuring durable, nontoxic functionality. We analyze structure–function links and scalable methods, including pad-dry-cure and metal–phenolic network (MPN) assembly, which were validated against ISO, ASTM, and AATCC standards. Polyphenol-based textiles match or exceed conventional ones in key metrics, with added benefits: full biodegradability, low ecotoxicity, and skin compatibility. Key advances include enzymatic polymerization for wash-stable color, MPN tuning for customizable functions, and using waste-derived polyphenols. However, major challenges remain: narrow color range (mostly yellow, brown, black) and poor wash/UV resistance, leading to rapid fading and loss of antibacterial/UV protection after laundering. Solving these is a top priority for future work. Overall, this review delivers a practical, science-based roadmap for high-performance, sustainable textiles that align with the Sustainable Development Goals and meet real-world needs in healthcare, sportswear, and smart wearables. Full article

Superhydrophobic coatings are regarded as a promising passive anti-icing strategy; however, their practical engineering application, particularly in electrical insulation, is severely hindered by the performance deterioration caused by mechanical damage and a lack of theoretical understanding of microscopic ice adhesion mechanisms. In this study, a layered polymer composite coating was designed to resolve the trade-off between abrasion resistance and low ice adhesion. The chemistry of the coating relies on a synergistic “primer–topcoat” design: the primer consists of an epoxy resin matrix chemically modified by amino silicone oil to lower its surface energy and improve toughness, while the topcoat features hierarchical SiO₂ clusters functionalized with hexamethyldisilazane (HMDS) and silane coupling agents. This architecture was fabricated via a controllable layer-by-layer spraying method. Systematic investigations revealed that the hierarchical micro/nanostructure, composed of microscale protrusions and nanoscale SiO₂ clusters, provides excellent superhydrophobicity (contact angle of 155.2°, sliding angle of 2°). Crucially, the crosslinked polymer network and stable siloxane (Si-O-Si) covalent bonding ensure that the coating maintains its functionality after a cumulative sand impact of 3 kg, demonstrating superior mechanical durability. Furthermore, differentiated theoretical models for ice adhesion in Cassie–Baxter and Wenzel states were established based on intermolecular interactions, identifying that maintaining a stable Cassie–Baxter state is key to reducing adhesion. This study offers a robust approach to balancing functionality and durability in polymer composites through synergistic structural design, providing both a scalable fabrication strategy and a quantitative theoretical framework for understanding interfacial ice adhesion. Full article

Superhydrophobic fiber films, as a typical superhydrophobic material, have advantages such as self-cleaning, non-wettability, and pollution resistance. They can be widely used in oil-water separation, antibacterial, anti-pollution, anti-icing, and self-cleaning fields. Traditional electrospun superhydrophobic fiber films face difficulties in fabricating fibers with large contact angles due to the non-Newtonian fluid flow and Taylor cone jet trajectory limitations. To address this challenge, this study develops a novel ultrasonic-magnetic field coupling electrospinning strategy for fabricating poly(methyl methacrylate)-polystyrene (PMMA-PS) fibrous films with enhanced superhydrophobicity. Physical, chemical, and contact angle measurements were used to analyze the morphology, composition, and hydrophobic properties of the fabricated films. The results showed that by controlling the blend ratio of PMMA and PS and optimizing the electrospinning process with ultrasonic vibration and magnetic field coupling, PMMA-PS fibers with better fiber refinement, closer spindle-shaped arrangements, and significantly increased roughness were successfully fabricated. When using 15% PMMA and 15% PS solutions, the static contact angle of the resulting fiber films reached 173.1°, demonstrating the best superhydrophobicity. The study suggests that optimizing the surface morphology of the nanofibers is an effective method to improve hydrophobicity and provides a new approach for fabricating superhydrophobic fiber films. Full article

Water-induced deterioration of silty soil subgrade in the lower Yellow River floodplain poses a critical, long-standing engineering challenge. Most existing studies on silty soil modification prioritize strength enhancement via traditional cementitious binders (i.e., cement, lime), yet these strategies fail to fundamentally block water migration in the soil matrix. A distinct scientific gap persists: the capillary water inhibition mechanism of nano-superhydrophobic modified Yellow River alluvial silt, along with the correlation between its microstructural evolution and macroscopic engineering performance, has yet to be systematically elucidated. To fill this gap, we conducted hydrophobic modification of the targeted silt using a nano-superhydrophobic material (NSHM), and performed a systematic suite of laboratory tests to characterize its hydrophobicity, mechanical properties, water stability, and microstructural characteristics. Quantitative experimental results demonstrate that NSHM imparts remarkable water resistance to the silt: at an NSHM dosage ≥0.5%, the modified soil exhibits stable superhydrophobicity across all tested compaction degrees, with over a 99% reduction in saturated hydraulic conductivity. Notably, the hydrophobic modification only incurs a <12% reduction in the dry unconfined compressive strength (UCS) of the silt. Microscopic characterization results reveal that NSHM modifies the silt via two core pathways: uniform particle encapsulation and pore infilling, without altering the inherent mineral functional groups of the soil. This microstructural regulation reduces the average pore diameter by 38.2% and total porosity by 15.6%, while optimizing the uniformity of pore size distribution. Based on comprehensive evaluation of overall performance, a minimum NSHM dosage of 0.5% is recommended for in situ application in local silty soil subgrade. This study provides critical theoretical guidance and technical support for water damage mitigation in alluvial silty soil subgrade. Full article

Access to clean water remains a critical global challenge, particularly in arid and fog-rich regions where conventional resources are limited. Fog water harvesting has emerged as a low-energy alternative; however, the performance of traditional collectors (typically 3–10 L m⁻² day⁻¹) remains constrained by inefficient droplet capture and transport. This review provides a systematic and critical analysis of recent advances in membrane-based fog harvesting technologies, focusing on material design, surface engineering, and structural optimization. The analysis shows that nanostructured and electrospun membrane systems can enhance water collection rates to ~20–60 L m⁻² day⁻¹, representing up to a 5–6 times improvement over conventional meshes. Furthermore, biomimetic and Janus wettability designs significantly improve droplet nucleation and directional transport, while hierarchical micro/nanostructures accelerate coalescence and runoff dynamics. At the structural level, optimized collector geometries (vertical harp designs) demonstrate ~3–4 times higher collection efficiency compared to traditional Raschel mesh due to reduced clogging and enhanced drainage. Despite these advances, key challenges remain, including material durability, fouling resistance, lack of standardized testing protocols, and limited large-scale validation. This review identifies critical design–performance relationships and proposes a framework linking surface wettability, morphology, and environmental parameters to harvesting efficiency. Future directions emphasize the development of durable, scalable membrane systems and the integration of fog harvesting with hybrid water supply technologies. Full article

The corrosion protection of copper in acidic urban rain environments was studied using self-assembled hydrophobic layers (SAHLs) based on stearic acid (SA), with and without rosehip seed oil (RH). The limited durability of fatty acid-based self-assembled layers under acidic conditions was addressed by correlating surface wettability, morphology, and electrochemical behaviour. Contact angle and SEM analyses showed that SA alone forms a moderately hydrophobic but structurally irregular layer, whereas the addition of 2.0 wt.% RH produces a hierarchical micro/nanostructure with near-superhydrophobic characteristics (CA ≈ 149°). Electrochemical measurements in simulated acid rain solutions (pH 5, 3, and 1) revealed a strong pH dependence of protective performance. While SA-derived layers provided effective protection at pH 5, they deteriorated at lower pH due to protonation of carboxylate anchoring groups and electrolyte ingress. In contrast, SAHLs containing 2.0 wt.% RH maintained polarisation resistance in the MΩ cm² range and inhibition efficiencies above 99% at pH 3, and remained effective even at pH 1. Long-term EIS results indicate a predominantly diffusion-controlled, barrier-type inhibition mechanism associated with defects sealing and interfacial reorganisation. Notably, the rosehip seed oil used is a commercially available, bio-based material with expired shelf life, highlighting the potential of waste-derived resources for sustainable corrosion protection. Full article

The inefficient utilization of industrial by-product phosphogypsum, coupled with the increasing global demand for cooling, has spurred the development of sustainable radiative cooling materials. Compared with conventional cooling coatings that primarily rely on expensive synthetic materials or complex fabrication processes, this study provides a promising cost-effective and sustainable route for integrating industrial solid waste valorization with zero-energy cooling technologies. In this study, we fabricated a composite coating (β-HPG@CA/SiO₂@OTS) consisting of β-hemihydrate phosphogypsum (β-HPG), a derivative product of phosphogypsum, cellulose acetate (CA), SiO₂ particles and octadecyltrichlorosilane (OTS) by a facile combination of blade coating and spraying, which exhibited strong solar reflectivity (90.9%), high mid-infrared emissivity (98.7%) and satisfactory superhydrophobicity (157°). The as-prepared composite achieved an ambient temperature drop of 18.7 °C under direct sunlight during sunny weather, achieving a net cooling power of 92.23 W/m². Meanwhile, the composite coating exhibits excellent durability after prolonged immersion in strongly acidic and alkaline solutions, ultraviolet radiation and outdoor testing. Owing to its simple fabrication process and robust cooling performance, this coating shows promise for scalable production and practical outdoor applications, such as building envelopes and equipment enclosures. Full article

To address the drag reduction requirements of superhydrophobic surface coatings for underwater vehicle hulls, this study designed a synthesis method based on resin substrate modification and filler modification according to superhydrophobic coating synthesis techniques. Three types of superhydrophobic microstructured surface coatings were prepared: polyurethane resin, silicone resin, and fluororesin. The coatings were fabricated by incorporating fluorine-modified SiO₂ nanoparticles into the modified resin matrices to construct hierarchical micro/nanostructures. The main components and synthesis processes for each coating were determined. Performance tests were conducted to evaluate mechanical properties (thickness, hardness, adhesion, wear resistance), functional characteristics (surface morphology, static/dynamic hydrophobic angles), and environmental resistance (seawater immersion, salt spray stability, thermal stability). Five surface coating test plans for underwater vehicle hull models were proposed, and drag reduction experiments were carried out to compare total drag, drag coefficient, and drag reduction rate across coating plans. Experimental results indicated that the silicone resin superhydrophobic coating with F660 + 8% SiO₂ exhibited the best comprehensive performance, while the PU + 6% SiO₂ superhydrophobic coating achieved optimal drag reduction at speeds below 9 m/s, meeting the performance criteria for underwater vehicle hull applications. Full article

Polymer films and coatings play an increasingly critical role in extending material functionality across industrial, biomedical, and environmental applications. Recent advances in surface engineering have enabled precise control of interfacial properties, leading to enhanced durability, cleanliness, and protection. This review summarizes state-of-the-art strategies for modifying polymer surfaces, with an emphasis on plasma-based surface modification and plasma-induced polymerization as versatile, solvent-free methods for tailoring wettability, chemical functionality, and adhesion. Furthermore, it examines emerging classes of self-cleaning and self-sterilizing coatings that leverage photocatalytic, hydrophobic, or antimicrobial mechanisms to mitigate contamination, biofouling, and pathogen transmission. Additionally, developments in high-performance barrier films designed to protect food products and electronic devices through improved resistance to gases, moisture, and chemical agents are highlighted. By integrating insights from materials chemistry, surface physics, and nanostructured coating design, this review provides a comprehensive overview of current achievements and future directions in functional polymer films and coatings aimed at anti-pollution, antibacterial, and anti-corrosion performance. Full article

Micro- and nano-plastic pollution caused by the mismanagement of plastics waste is a significant problem worldwide, causing severe impacts in aquatic and terrestrial environments. The purpose of this study was to evaluate the adsorption capacity of a thermally stable and superhydrophobic bio-substrate to remove microplastic particles (MPPs) from aqueous systems. In this work, the adsorption efficiency of cattail fluff towards MPPs from pristine PP, PVC, PA6, LDPE, HDPE, and their blend was evaluated. The effect of temperature (30 °C, 40 °C, and 50 °C) and two binding environments (distilled water and industrial wastewater) on adsorption was determined. Non-linear regressions of seven adsorption isotherm models including Langmuir, Freundlich, Temkin, Dubinin–Radushkevich (D–R), Redlich–Peterson (R–P), Toth, and Sips were applied to fit the experimental data. Error function analysis confirmed that the D–R adsorption isotherm model offers the best fit of the experimental data. The results show that the bio-substrate is very effective in adsorbing MPPs from aqueous systems with adsorption capacities of q_e = 3597 mg/g and q_e = 2807 mg/g in distilled water and synthetic industrial water, respectively. The composition of the MPPs determines the effect of temperature and binding environment on the adsorption performance of the bio-substrate. Physisorption dynamics for the MPP/bio-substrate system are also provided and discussed. Overall, the hydrophobic bio-substrate is highly effective in removing MPPs from aqueous systems, with the added advantages of low cost, sustainability, and scalability for practical applications. Full article