Knife Scratch Research Articles

A superhydrophobic mortar with ultra-robustness for self-cleaning, anti-icing, and anti-corrosion

Superhydrophobic cement-based materials are promising candidates to alleviate the performance deterioration of concrete constructions caused by water penetration. However, the weak mechanical performance of superhydrophobic surfaces, and severe reduction in compressive strength due to bulk modification, present significant challenges for the application of superhydrophobic cement-based materials. In this work, a superhydrophobic mortar (S-mortar) was prepared using a facile and economical method by surface micro-nano roughness construction and matrix silane modification, and nano-silica was introduced to compensate for the strength loss. The obtained S-mortar exhibits superb surface mechanical durability and chemical stability, no significant decrease in superhydrophobic property after sandpaper rubbing, knife scratches, and exposure to extreme temperatures, while even new surfaces exposed by cutting and powders obtained by grinding possess excellent water repellency. Furthermore, the superhydrophobicity endows the S-mortar with self-cleaning, anti-fouling, anti-icing, anti-freezing, and anti-corrosion properties. This approach creates a balance between superhydrophobic property and mechanical performance, broadening application prospects of superhydrophobic cement-based materials.

Fabrication of robust superhydrophobic myristic acid/ZrO2 coating with improved anti-icing and anti-corrosion for concrete via a two-step method

To address the safety concerns associated with icing and corrosion of concrete-based facilities, a facile two-step process of sandpaper covering and spraying for fabricating a robust superhydrophobic myristic acid/ZrO2 coating (MAZ-RSC) on concrete surface was proposed. Sandpaper covering and ZrO2 modified with myristic acid were used to fabricate the superhydrophobic structure. An analysis of the resultant superhydrophobic concrete's surface morphology and chemical structure was performed. The formation mechanism of the obtained MAZ-RSC was discussed. Results indicate that the MAZ-RSC coating exhibited superior superhydrophobic and self-cleaning properties with a contact angle of 161.3° and a sliding angle of 1.2°. The robust ability of the as-prepared MAZ-RSC coating was assessed through knife scratching, tape peeling, and sandpaper abrasion. The presence of ZrO2 enabled the MAZ-RSC to be a superhydrophobic hard coating. Meanwhile, the prepared coating was proven to possess a good active anti-icing ability and a strong anti-corrosion ability and to be easily de-iced. Further tests show that this coating can maintain excellent chemical resistance across a broad pH range because of its superior hydrophobicity and the chemical inertness of the ZrO2 particles. Thus, the as-prepared coating is expected to be adopted in practical areas such as roads, buildings and bridges.

An ultra-thin nickel electrodeposited stainless steel mesh with superhydrophobic property and high mechanical durability for oil-water separation

Oil pollution has a detrimental impact on our water environment. Therefore, developing a durable and high-flux material for separating oil-water mixture is highly desirable. In this study, we present an innovative approach to prepare superhydrophobic-superoleophilic nickel palmitate stainless steel meshes (SNP-SSM) using a one-step electrodeposition method. This method not only creates rough hierarchical micro/nanostructures on the SSM but also reduces the surface free energy of the SSM. The SNP-SSM demonstrates a water contact angle (CA) of 164.98 ± 2.3° and a roll-off angle (ROA) of 4.78 ± 1.3°, enabling effective, long-term separation of oil-water mixtures by gravity. The oil-water separation efficiency (n-hexadecane/water) reaches 98.3%. Furthermore, in various tests, including knife scratching, tape peeling, sandpaper abrasion, bending, heating, and immersion in various liquids, the SNP-SSM exhibits sufficient mechanical, chemical, and thermodynamic robustness, making it suitable for harsh conditions, the as-prepared coatings effectively inhibited the corrosion of the meshes. This study paves the way for advancing technology in challenging oil-water separation scenarios, encompassing mechanical friction, chemical processes, and high-temperature conditions.

Effect of heating self-healing and construction of composite structure on corrosion resistance of superhydrophobic phosphate ceramic coating in long-term water environment

Despite superhydrophobic ceramic coatings have been successfully prepared, there lacks an improvement in their corrosion resistance in long-term saltwater environments due to the porous properties. In this paper, two coatings were prepared again by heat repair treatment and construction of double-layer composite structure, and the surface characteristics of the coatings were determined by scanning electron microscope, infrared spectrometer and contact angle measuring instrument, and the electrochemical performance and corrosion resistance of the coatings were evaluated by electrochemical test and immersion test. The results showed that the original porous ceramic coating had superhydrophobic property, and the water contact angle (CA) and sliding angle (SA) were 150.4°and 8.7°, respectively. Through knife scratching, sandpaper abrasion and tape peeling tests, the coating had good bond strength and mechanical durability. Compared with the original coating, the corrosion resistance of heat repair coating and composite coating had better corrosion resistance and a protective effect on the substrate. This protective mechanism can be attributed to the repair effect of heat treatment on the hydrophobicity of the coating, and the composite structure resists the penetration of external liquids. Based on these results, heat repair and double-layer composite structures can improve the defects of long-term insufficient durability of superhydrophobic ceramic coatings, which have potential marine application prospects.

A facile and high-efficient method to fabricate slippery liquid-infused porous surface with enhanced functionality

Inspired by Nepenthes pitcher, slippery liquid-infused porous surface (SLIPS) has been extensively investigated owing to its potential applications required for water repellence. However, the existing preparation methods for SLIPS involve complicated processing technologies and toxic chemical reagents, which seriously restricts practical applications. Herein, we prepared the SLIPS on Al substrates by nanosecond pulsed laser ablation, low surface energy modification, and infusion of lubricant. The optimal laser parameters for the preparation of the SLIPS were explored. The as-prepared SLIPS showed good slippery performance with a sliding angle smaller than 5° for various liquids. A series of performance tests, including knife scratching, repeated tape peeling off, sandpaper abrasion, heating, hot water jet impacting, and long-term water immersion, were conducted to investigate the mechanical strength and durability of the prepared SLIPS, and the SLIPS showed high mechanical strength and good durability. Moreover, the fabricated SLIPS could also resist corrosion solution, avoid contamination, protect the substrates against freezing rain and have superior water collection efficiency in moist environments. Thanks to the excellent performances, the prepared SLIPS has promising potential for practical applications.

Robust metallic-based superhydrophobic composite with rigid micro-skeleton structure for anti-icing/frosting

Superhydrophobic coatings with excellent water-repellent property exhibit unique advantages in anti-icing/frosting but suffer from the problem of low mechanical and environmental durability. Although several strategies have been adopted to tackle this issue, developing an equipment-free, low-cost and scalable strategy for the fabrication of robust superhydrophobic coatings remains a technical challenge. Here, we construct a robust superhydrophobic composite with rigid micro-skeleton structure via mild and equipment-free dip-coating method. The prepared composite consists of Cr microparticles confined in epoxy adhesive layer and stearic acid-modified Cu powders, among which the first dip-coating Cr microparticles function as robust micro-skeleton due to their rigid property. Then smaller-sized Cu powders are filled within the micro-skeleton structure to be modified with low-surface-energy coating to provide superhydrophobic property. The rigid micro-skeleton imparts the superhydrophobic composite great durability to resist long-term abrasion, knife scratching, tape-peeling, water jetting tests, acid/saline corrosion, temperature process and UV irradiation. In addition, the as-designed micro-skeleton structure could “lock” various modified nanoparticles (candle soot, SiO2 nanoparticles, recycled rubber particles) to provide the persistently superhydrophobicity. mportantly, the as-prepared superhydrophobic composite could retard the formation of the ice/frost in − 20 ℃, exhibiting a good anti-icing/frosting property and great durability even after cycled anti-icing/frosting test. We believe that this equipment-free, low-cost and scalable design strategy can provide a novel approach for the fabrication of robust superhydrophobic coatings.

Multifunctional superhydrophobic composite with mechanochemical stability for concrete protection

Chemical or electrochemical corrosion of the concrete-based facilities causes potential safety hazards. Endowing the concrete with a commercial superhydrophobic coating with designed surface topography and chemical composition is an effective way to prevent the corrosion of the internal rebars. Although several methods have been adopted to combat the corrosion problem, developing an equipment-free, low-cost and scalable strategy for fabricating a robust superhydrophobic coating on the concrete surface is still a challenge. In this work, a robust superhydrophobic epoxy fixed corundum-silica-polydimethylsiloxane (ECSP) composite is fabricated as the concrete modification coating through an “armour” protection methodology via a facile and low-cost dip-coating process. The as-prepared ECSP composite consists of corundum microparticles (MPs) confined in the epoxy (EP) adhesive layer and silica nanoparticles (SiO2 NPs) modified with a low-surface-energy coating. The corundum MPs with high rigidness and hardness function as a robust, protective “armour” structure, while the polydimethylsiloxane-modified SiO2 NPs reside within the “armour” structure to provide superhydrophobicity. Benefitting from the armoured structure, the ECSP composite coated concrete exhibits an excellent robustness under various harsh conditions including mechanical abrasion, knife scratching, tape-peeling treatment, water jetting, UV irradiation, temperature treatment and chemical corrosion. Importantly, the ECSP composite coating successfully prevents the concrete (with a rebar in it) from the chemical and electrochemical corrosion. The corrosion current density (4.8 × 10−6 A·cm−2) of the ECSP coated concrete is two orders of magnitude lower than that of the unprotected concrete (1.17 × 10−4 A·cm−2), exhibiting its excellent corrosion resistance. Besides, the superhydrophobic ECSP composite coating can retard the formation of ice on the concrete surface at the temperature of −20 °C, exhibiting good anti-icing performance. This work opens a new avenue for the fabrication and application of the multifunctional superhydrophobic coating for concrete protection.

Efficient fabrication of poly(vinylidene fluoride)/graphene composite actuators with robust superhydrophobicity and excellent photothermal performance for controllable light-driven motion

The Marangoni effect has garnered significant interest as a promising method for non-contact, remote-controlled actuation. Despite the numerous advantages it offers, the high cost and complex fabrication procedures associated with the technology have limited its widespread application. To address these limitations, an industrialized polymer processing strategy that combines melt blending and hydrophobic modification is proposed for the large-scale and cost-effective production of lightweight poly(vinylidene fluoride)/graphene nanosheets foam with a three-dimensional interconnected network. The foam displays excellent superhydrophobic properties, including a contact angle of 155 ± 2° and a rolling angle of 7 ± 3°. Furthermore, the foam is durable under a variety of conditions, including dynamic impact, high temperatures, acidic and alkaline environments, knife scratching, abrasion damage, and tape peeling. Additionally, the foam displays stable photothermal conversion performance due to the uniform dispersion of graphene nanosheets throughout the polymer matrix. When used as a light-driven actuator, the foam demonstrates the ability to achieve on-demand driving as well as swimming route planning at the water–air interface. The proposed method offers a promising solution for the efficient fabrication of light-driven actuators that are both adapted to practical applications and resistant to external damages.

Amidation reaction to derive waterborne, tolerant, and optically transparent solid slippery and superhydrophobic coatings

Separate and lubrication-free association of low surface energy with hierarchically featured and highly smooth interfaces yield two distinct and prospective bio-inspired wettability—superhydrophobicity and solid slippery properties, respectively. However, the derivation of such bio-inspired wettability with high optical transparency—following a simple, completely waterborne, non-fluorinated and scalable fabrication approach is an extremely challenging task to achieve. Here, a simple amidation reaction between thioester and amine groups is rationally extended for aqueous processing of strategically selected small molecules to attend desired outputs through formation of nanoparticles. An aqueous reaction mixture of selected non-fluorinated small molecules provided a stable (for 30 days) dispersion of nanoparticles (size ∼210 nm). While the ‘in-situ’ deposition of the reaction mixture yielded completely waterborne, optically transparent, physically and chemically durable lubrication-free solid slippery coating on a planar substrate, a highly deformable superhydrophobic coating on porous and fibrous substrates was obtained following a rapid and facile post-deposition of the prepared nanoparticles. The prepared solid slippery coating remained efficient in sliding the beaded droplets of various (e.g., polar and non-polar) liquids having a wide range (70.2 mN/m to 22.3 mN/m) of surface tension. The embedded slippery property remained unaltered even after exposure of prepared coating to extremes of temperatures and severe abrasive conditions—including continuous drop of 250 g of sand, sandpaper abrasion with a distance of 500 cm under an applied load of 25 KPa, adhesive tape peeling for 500 cycles, pencil (6H) & knife scratching, and prolonged (15 days) treatments of extremes of pH, seawater, river water, etc. The synthesized superhydrophobic coating on porous and fibrous-substrate remained efficient in sustaining repetitive and large physical deformations and other relevant abrasive exposures.

Fabrication of a durable brass mesh capable of rapid transformation between two modes of liquid transportation

Low cost, process controllability, and durability have been the key problems in the application of superhydrophobic materials, and there are many difficulties in achieving these goals. A simple ultrasound-assisted nitric acid etching method is now described for the construction of coral-like metal structures on the surface of a brass mesh pipe. The structures are formed by the different corrosion rates of the two metals in the alloy during etching. These structures exhibit superoleophobic characteristics in water and, following modification by immersion in aqueous sodium laurate solution, superhydrophobic characteristics in air. The surface wettability of the pipe can be converted multiple times within one hour to facilitate two modes of liquid transportation, in water and in air. The pipe material has excellent durability, withstanding severe mechanical contact including fingertip friction, arbitrary folding, knife scratching, and load friction, without significantly altering the surface wettability. This novel material can be prepared using a simple, controllable, low-cost, and environmentally friendly method and offers a new direction for the development of multi-interface liquid transportation devices.

Waterborne superhydrophobic coating with abrasion and corrosion resistant capabilities

Superhydrophobic materials have been extensively exploited for corrosion protection because of their unique non-wetting properties, but restricted by the complicated fabrication process, fluorinated chemicals usage, weak interfacial binding force, low hardness, and poor abrasion/scratch resistance. In this paper, we designed a waterborne superhydrophobic coating based on modified Al2O3 nanoparticles (M-Al2O3) and waterborne epoxy resin through a versatile spray-coating approach. When the mass ratio of epoxy/M-Al2O3 was 1.5, the coating features both superhydrophobic properties (water contact angle ∼ 150.8 ± 0.6° and sliding angle ∼ 4.9 ± 0.2°) and optimal abrasion-resistant stability. The coating can maintain its water-repellent superhydrophobicity after 90 abrasion cycles and 120 tape-peeling cycles, indicating reinforced interfacial robustness. Moreover, the coating exhibits excellent self-cleaning, anti-fouling, and corrosion-resistant behaviors with greatly enhanced charge transfer resistance (Rct) and lowest frequency impedance values (|Z|0.01Hz). The corrosion inhibition efficiency of the original coating, coating after 90 abrasion cycles and coating after 120 tape-peeling cycles were 99.99 %, 97.54 %, and 97.52 % respectively, confirming a durable anti-corrosion stability. In addition, the coating retains its superhydrophobic properties after a 6 H pencil hardness test and knife scratch test, which demonstrates its robustness and stability against mechanical damage.

Enhanced corrosion resistance and self-cleaning properties of superhydrophobic nickel coating fabricated by one-step electrodeposition

In order to fabricate the stable superhydrophobic coatings with antifouling and anticorrosion functions. In this study, a series of nickel-coated superhydrophobic surfaces were designed on carbon steel (CS) using a one-step electrodeposition route. The structures of the prepared superhydrophobic Ni (SN) coatings were identified by scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FTIR), and the wettability was also tested by contact angle goniometer. The findings displayed that the hierarchical micro-flower structures of the optimal SN coating (0.64 A of circuit density and 9.5 min of deposition time) imparted it excellent superhydrophobic property; the water contact angle (CA) and sliding angle (SA) were 168 ± 1.1° and 4.7 ± 0.6°, respectively. The optimal SN coating was found to have superior mechanical and chemical stabilities, as tested by knife scratching, adhesive tape peeling, sandpaper abrasion, and chemical corrosion resistance. Additionally, the optimal SN coating exhibited outstanding self-cleaning property, anti-corrosion, and superhydrophobic stability. Based on these results, it appears that SN coating prepared by one-step electrodeposition can solve the defect of insufficient long-term durability of electrodepositied superhydrophobic coatings, and has potential industrial application prospects.

Facile fabrication of robust epoxy resin monolithic superhydrophobic materials with excellent mechanical-chemical stability, biocompatibility and photothermal conversion capacity

Improving the durability of superhydrophobic materials is the key factor to promote their practical application. Here, a facile one-pot synthesis procedure is used to prepare epoxy resin monolithic superhydrophobic materials (ER-MSM) with excellent mechanical strength, chemical stability, oil-water separation, stain liquids repellency, biocompatibility and excellent photothermal conversion capacity. The mechanical strength and hydrophobic durability of ER-MSM are improved by synchronously processes of bubbles impact, high temperature curing and chemical bonding of epoxy resin to form micropores. The prepared monolithic material can maintain water repellency even after sandpaper abrasion, ultrasonication, multiple knife scratch, finger wiping, and exposure to UV irradiation and high-temperature calcination. The biocompatibility of ER-MSM was further proved by the 95 % cell viability of the PC12 cells after contacting with ER-MSM for 70 min. ER-MSM has excellent photothermal conversion ability by dopamine coreaction in the one-pot synthesis procedure (named as PER-MSM). The photothermal conversion capacity of PER-MSM can be regulated by adjusting the concentration of dopamine. The surface temperature easily exceeds 70 °C after 808 nm laser irradiating for 200 s under power density of 1 W/cm2 and dopamine concentration larger than 10 mg/mL or under power density of 2 W/cm2 and dopamine concentration larger than 2 mg/mL. The alcohol-based reaction system without complex fabrication steps, expensive, or toxic fluoride, satisfies the environment-friendly requirements. Therefore, the prepared mechanochemically stable and photothermal superhydrophobic materials have great potential applications in oil-water separation, self-cleaning and other industrial fields.

Robust superhydrophobic composite fabricated by a dual-sized particle design

Superhydrophobic surfaces have shown great potential in various areas such as self-cleaning, anti-icing, drag reduction and biomedical applications. However, it is still challenging to prepare robust superhydrophobic surfaces for real applications. Here, a facile, low-cost dual-sized particle strategy is proposed to fabricate the robust superhydrophobic composite with an “armoured” micro-/nanostructure. As a proof-of-concept, the intrinsically hard quartz sand microparticles (QS MPs) and the epoxy (EP) adhesive are adopted to construct a firm surface frame (EP@QS) as an “armour” to provide mechanical durability while modified superhydrophobic SiO2 nanoparticles (msSiO2 NPs) are confined within the cavities among the QS MPs, forming a nanostructure to impart liquid repellency. Benefitting from the strong “armour”, the EP@QS@msSiO2 composite can reserve excellent water repellency after different kinds of environmental test such as cycled mechanical abrasion, ultraviolet radiation treatment, outdoor exposure damage, tape-stripping test, acid-base treatment and NaCl salt solution immersion, temperature treatment and knife scratching. Furthermore, the substrate versatility and nanoparticle versatility of our strategy are explored and verified. By virtue of the structural advantages, these EP@QS@msSiO2 composite manifest superior self-cleaning property and efficiently directional oil adsorption ability even after mechanochemical damage. Together with robustness and universality, the design strategy of the robust superhydrophobic composite is expected to extend the application scope in harsh nautical applications.

Mechanically robust and superhydrophobic concrete based on sacrificial template approach

Superhydrophobic (SH) concrete with low adhesion, self-cleaning, and corrosion resistance has the potential to significantly meet the challenges of injury and fatality under various external conditions such as irradiation, chemical corrosion, and biological contamination. However, the traditional process to realize the superhydrophobicity normally brings the concern of compressive strength loss. Herein, we introduced a facile approach to fabricate the superhydrophobic concrete with mechanical robustness based on the sacrificial template strategy. The concrete exhibits prominent water-repellency and admirable compressive strength simultaneously. The superhydrophobicity was well maintained after cyclic robustness evaluations, including sandpaper abrasion, knife scratch, water impacting, corrosive solution immersion, and UV radiation. The superhydrophobic concrete also exhibits broad-spectrum self-cleaning capability, such as easy removal of common dust, bacteria detachment, and resistance of ice formations. We believe that the SH concrete can potentially address the mechanical robustness and long-term water repellency towards the real applications in the future.

Superhydrophobic ultra-high molecular weight polyethylene porous material with self-cleaning ability, long-term stability, and high durability

Superhydrophobic self-cleaning of polymer materials is realized based on the formation of micro-nano morphology structures on the surface of the materials usually. However, such surface has poor resistance to mechanical damage and easily wears, and the widespread application is limited. In this work, a superhydrophobic porous material with a self-cleaning function, long-term stability, high durability, and high resistance to mechanical damage was developed based on supercritical fluid micro-foaming and the construction of complex hierarchical micro-nanosized structures in the later stage. The surface of porous sample presents a complex micro-nanosized hierarchical structures with a scale progressive ridge-groove, which increased the water contact angle from 110° to a superhydrophobic contact angle of 156°, decreased the sliding angle to 3.5°, and presented an obvious water repellency. Using the water repellency, self-cleaning function of the porous sample was realized. More importantly, the porous material exhibits superior superhydrophobic stability under long-term strong mechanical damage such as ultrasound, knife scratching, repeated bending, and wire ball scraping, and maintains excellent stability in strong acid/alkali, high and low temperature extreme environments. A stable superhydrophobic high-performance porous material with a self-cleaning function was prepared, and the application of ultra-high molecular weight polyethylene (UHMWPE) porous materials in superhydrophobic field was expanded and spread widely, which provides a certain insight for the preparation of superhydrophobic porous materials with superior durability and strong mechanical damage resistance.

Universal and Stable Slippery Coatings: Chemical Combination Induced Adhesive-Lubricant Cooperation.

Liquid lubricant of low affinity makes slippery coatings widely used in lubricating, anti-biofouling, anti-icing, fluid guiding, and drag reduction. Two critical challenges, however, remain in the practical application of slippery coatings consisting of liquid lubricants: (1) universality regardless of roughness and chemical composition of substrates, (2) stability of surface lubricity against evaporation. Herein, a chemical method is reported to create a universal and stable slippery lubricant-adhesive cooperated coating (SLACC) through acid catalyzed dehydration reaction between the phenolic hydroxyl of polydopamine (PDA), with universal (for challenge-1) and strong (for challenge-2) adhesion properties, and liquid-like polydimethylsiloxane (PDMS), with lubricant properties. Through overlying PDMS on PDA, a spatial gradient interpenetration of chemical combined PDA and PDMS leaving lubricant PDMS at the outermost of coating is achieved. This structure contributes to the following performances of SLACC: nearly universality suitable for 100 different abiotic or biotic substrates and stability sustainable for long-term usages, UV radiating, refrigerating, hot air drying, freeze drying, knife scratch and abrasion. This proposed strategy is envisioned anti-fouling from plane to tube and exhibits drag reduction in confined space.

A rapid two-step method for fabrication of superhydrophobic-superoleophobic nickel/copper alloy coating with self-cleaning and anticorrosion properties

In this study, the nickel/copper (Ni/Cu) alloy coating with layered micro/nanostructures was prepared on a brass substrate by the controlled generation of particles during the electrochemical co-deposition of nickel and copper ions. Subsequently, the surface of Ni/Cu alloy (NCA) coating was modified by 1 H,1 H,2 H,2 H-perfluorodecyltrimethoxysilane (PFDS), so that the prepared PFDS/NCA composite (PNCA) coating had excellent super-amphiphobicity. The structures and properties of PNCA coating evaluated and described used a range of methods. The wettability tests shown that the water and oil contact angles of the optimal coating sample with current density of 0.08 A/cm2 are 163 ± 1.3° and 155 ± 1.5°, respectively, and the sliding angle (SA) is no longer than 10°, indicating the high degree of super-amphiphobicity. Gratifyingly, the optimal PNCA coating exhibited good mechanical and chemical stabilities after knife scratching, tape peeling, sandpaper wear and chemical corrosion. The self-cleaning test shows that PNCA coatings have also outstanding self-cleaning ability, and the contaminants spread on their surfaces can be easily carried away by sealed droplets within 20 s. In addition, the corrosion resistances of PNCA coatings are greatly improved to compare with NCA coating, especially the corrosion rate of the optimal sample coating is the lowest, and the corrosion protection efficiency reaches to 91.73 %. Therefore, the conclusion can be depicted that the super-amphiphobic PNCA composite coatings prepared by electrochemical co-deposition combined with modification of low surface energy materials have a wide range of industrial prospects for applications in the fields of oil, fouling and corrosion resistances.

Facile Fabrication of Fluorine-Free, Anti-Icing, and Multifunctional Superhydrophobic Surface on Wood Substrates.

Building superhydrophobic protective layers on the wood substrates is promising in terms of endowing them with multiple functions, including water-repellent, self-cleaning, anti-icing functions. In this study, multifunctional superhydrophobic wood was successfully fabricated by introducing SiO2 sol and superhydrophobic powder (PMHOS). The SiO2 sol was prepared using tetraethoxysilane as a precursor and ethanol was used as the dispersant. The PMHOS was synthesized using poly(methylhydrogen)siloxane (PMHS) and ethanol. As a result, the obtained superhydrophobic wood had a water contact angle (WCA) of 156° and a sliding angle (SA) of 6° at room temperature. The obtained superhydrophobic wood exhibited excellent repellency toward common liquid (milk, soy sauce, juice, and coffee). The superhydrophobic layer on the wood surface also exhibited good durability after a series of mechanical damages, including finger wiping, tape peeling, knife scratching, and sandpaper abrasion. In addition, the obtained superhydrophobic wood showed excellent anti-icing properties.

Aqueous construction of raspberry-like ZIF-8 hierarchical structures with enhanced superhydrophobic performance.

Materials with super-wetting ability have attracted wide attention from both academia and industry due to their great potential applications. A straightforward and versatile route was proposed for the large-scale synthesis of a monodisperse raspberry-like metal-organic framework (ZIF-8) using zinc nitrate as a zinc source and dimethylimidazole as an organic ligand in aqueous solution. After hydrophobic treatment with hexadecyltrimethoxysilane, the ethanolic suspension of three-dimensional raspberry-like ZIF-8 showed excellent superhydrophobic properties. Furthermore, commercial adhesives were used to blend with the suspension to improve the bonding strength to different substrates. These surfaces retained their water resistance after 50 finger-wipe cycles, 40 sandpaper abrasions and knife scratches. Moreover, the prepared hydrophobic surface can withstand the impact of water flow for 10 minutes. The formulations developed can be used for superhydrophobic coating applications on different substrate surfaces such as aluminum foil, glass, paper and cotton.