A Robust Epoxy Resins @ Stearic Acid-Mg(OH)2 Micronanosheet Superhydrophobic Omnipotent Protective Coating for Real-Life Applications

A comprehensive review on anticorrosive/antifouling superhydrophobic coatings: Fabrication, assessment, applications, challenges and future perspectives

Superhydrophobicity (SHP) is an incredible phenomenon of extreme water repellency of surfaces ubiquitous in nature (E.g. lotus leaves, butterfly wings, taro leaves, mosquito eyes, water-strider legs, etc). Historically, surface exhibiting water contact angle (WCA) > 150° and contact angle hysteresis <10° is considered as SHP. The SHP surfaces garnered considerable attention in recent years due to their applications in anti-corrosion, anti-fouling, self-cleaning, oil-water separation, viscous drag reduction, anti-icing, etc. As corrosion and marine biofouling are global problems, there has been focused efforts in combating these issues using innovative environmentally friendly coatings designs taking cues from natural SHP surfaces. Over the last two decades, though significant progress has been made on the fabrication of various SHP surfaces, the practical adaptation of these surfaces for various applications is hampered, mainly because of the high cost, non-scalability, lack of simplicity, non-adaptability for a wide range of substrates, poor mechanical robustness and chemical inertness. Despite the extensive research, the exact mechanism of corrosion/anti-fouling of such coatings also remains elusive. The current focus of research in recent years has been on the development of facile, eco-friendly, cost-effective, mechanically robust chemically inert, and scalable methods to prepare durable SHP coating on a variety of surfaces. Although there are some general reviews on SHP surfaces, there is no comprehensive review focusing on SHP on metallic and alloy surfaces with corrosion-resistant and antifouling properties. This review is aimed at filling this gap. This review provides a pedagogical description with the necessary background, key concepts, genesis, classical models of superhydrophobicity, rational design of SHP, coatings characterization, testing approaches, mechanisms, and novel fabrication approaches currently being explored for anticorrosion and antifouling, both from a fundamental and practical perspective. The review also provides a summary of important experimental studies with key findings, and detailed descriptions of the evaluation of surface morphologies, chemical properties, mechanical, chemical, corrosion, and antifouling properties. The recent developments in the fabrication of SHP -Cr-Mo steel, Ti, and Al are presented, along with the latest understanding of the mechanism of anticorrosion and antifouling properties of the coating also discussed. In addition, different promising applications of SHP surfaces in diverse disciplines are discussed. The last part of the review highlights the challenges and future directions. The review is an ideal material for researchers practicing in the field of coatings and also serves as an excellent reference for freshers who intend to begin research on this topic.

Bioinspired Hierarchical Multi-Protective Membrane for Extreme Environments via Co-Electrospinning-Electrospray Strategy

Extreme environments can cause severe harm to human health, and even threaten life safety. Lightweight, breathable clothing with multi-protective functions would be of great application value. However, integrating multi-protective functions into nanofibers in a facile way remains a great challenge. Here, a one-step co-electrospinning-electrospray strategy is developed to fabricate a superhydrophobic multi-protective membrane (S-MPM). The water contact angle of S-MPM can reach up to 164.3°. More importantly, S-MPM can resist the skin temperature drop (11.2 °C) or increase (17.2 °C) caused by 0 °C cold or 70 °C hot compared with pure electrospun membrane. In the cold climate (-5 °C), the anti-icing time of the S-MPM is extended by 2.52 times, while the deicing time is only 1.45 s due to the great photothermal effect. In a fire disaster situation, the total heat release and peak heat release rate values of flame retarded S-MPM drop sharply by 24.2% and 69.3%, respectively. The S-MPM will serve as the last line of defense for the human body and has the potential to trigger a revolution in the practical application of next-generation functional clothing.

One Pot Self-Assembling Fe@PANI Core-Shell Nanowires for Radar Absorption Application

The one-pot process, which combines the polymerization of polyaniline (i.e., PANI) with subsequent reduction of iron nanowire (i.e., Fe NW) under a magnetic field, was developed to produce Fe@PANI core-shell nanowires. The synthesized nanowires with various PANI additions (0-30 wt.%) were characterized and used as microwave absorbers. Epoxy composites with 10 wt.% absorbers were prepared and examined using the coaxial method to reveal their microwave absorbing performance. Experimental results showed that the Fe NWs with PANI additions (0-30 wt.%) had average diameters ranging from 124.72 to 309.73 nm. As PANI addition increases, the α-Fe phase content and the grain size decrease, while the specific surface area increases. The nanowire-added composites exhibited superior microwave absorption performance with wide effective absorption bandwidths. Among them, Fe@PANI-90/10 exhibits the best overall microwave absorption performance. With a thickness of 2.3 mm, effective absorption bandwidth was the widest and reached 3.73 GHz, ranging from 9.73 to 13.46 GHz. Whereas with a thickness of 5.4 mm, Fe@PANI-90/10 reached the best reflection loss of -31.87 dB at 4.53 GHz.

Preparation, characterization, and energy simulation of ZnTiO3 high near-infrared reflection pigment and its anti-graffiti coating

In the field of cooling materials, ZnTiO₃ (ZT) is still a new member that needs to be further studied. In this paper, pure cubic ZT was synthesized by the sol-gel method, and the effect of calcination temperature on ZT synthesis was investigated. The hydrophobic modification was carried out on ZT to prepare near-infrared reflective thermal insulation functional composite coatings based on silicone resin (SI). Compared with unmodified ZT (U-ZT), the modified ZT (M-ZT) exhibits better dispersion in the SI matrix, contributing to improved solar reflectance and anti-graffiti performance. The EnergyPlus software was used to simulate energy consumption in the air conditioning system. The excellent chemical stability and high NIR reflectance made the synthesized pigments potential candidates for energy-saving coatings. The simulation showed that homeowners could save $10.29 a month by applying an energy-efficient coating consisting of ZT to the walls and roofs of their buildings. Besides, these coatings show potential anti-graffiti application due to the exceptional repellency of coated surfaces against water-based ink, oily red marker, and paint.

Superhydrophobic MXene Coating with Biomimetic Structure for Self-Healing Photothermal Deicing and Photoelectric Detector

Two-dimensional transition metal carbides (Ti₃C₂T_x MXene) have emerged as new candidates for applications in multifunctional devices owing to their outstanding performance. However, these electronic devices are easily disturbed by water, breakage, oxidation during use, and limited energy resources. To solve these problems, herein, inspired by nature, a novel superhydrophobic, healable photothermal deicing and photodetector (SHPP) with a "papillary structure" is successfully fabricated for the first time, by a simple layer-by-layer assembly spraying process with 0D/1D/2D nanomaterials. As a result, the superhydrophobic modified 2D MXene coating (FM coating) on the SHPP sensor exhibits outstanding self-cleaning, long-term durability (>20 days), as well as excellent photothermal deicing performances under near-infrared light. Meanwhile, the unique semiembedded nano-ZnO/1D silver nanowire supports the sensor with desirable photoelectric performance with UV light and a fast response time (∼1 s), and good cycle stability. Moreover, benefiting from the transparent self-healing substrate, the photothermal deicing and photodetector properties can be restored at room temperature. The bioinspired structures and function mechanisms offer SHPP sensors great potential for the utilization of clean light energy, sensing, self-cleaning, anti-icing, and so forth.

Colloidal magnesium hydroxide Nanoflake: One-Step Surfactant-Assisted preparation and Paper-Based relics protection with Long-Term Anti-Acidification and Flame-Retardancy

Enhancing the interfacial dispersion and suspension stability is crucial for magnesium hydroxide (Mg(OH)₂) nanomaterials in the long-term deacidification of paper-based cultural relics. However, because of the low specific surface area and the poor solvent compatibility of as-prepared large-sized Mg(OH)₂, it often tends to agglomerate and settle down during the usage and storage, that is harmful for paper protection due to its unevenly deacidification and nonuniformly distribution on paper cellulose. Herein, we propose a feasible preparation of colloidal Mg(OH)₂ ultrathin nanoflakes with high dispersion stability via a simple one-step surfactant-assisted strategy. The surfactant acts as both a structure-direct agent to confine the growth of Mg(OH)₂ with rich active sites and a surface modifier to enhance its solvent adaptability and dispersion stability, avoiding the common fussy procedure with additional steric stabilizer. Owing to the evenly interaction with free acid species therein and the uniformly distribution on the paper fiber as alkaline reserve, the as-obtained Mg(OH)₂ presents the superior paper protection performance characterized by its safer pH of 7.29 for the original aged paper (pH = 5.03) and the excellent long-term anti-acidification effect with competitive pH of 5.47 after accelerated-aging at 105 °C for 5 months. Furthermore, Mg(OH)₂ nanoflakes with surfactant-modified structure also endue them as an improved flame retardant for multifunctional paper protection. The protection with Mg(OH)₂ has little effect on the paper surface properties and cellulose crystallinity, in line with the principle of least intervention. This work will put forward a feasible way toward colloidal Mg(OH)₂ nanoflakes with excellent paper protection performance, shedding light on the development of emerging protection materials for paper-based cultural relics.

In-situ electrospinning of thymol-loaded polyurethane fibrous membranes for waterproof, breathable, and antibacterial wound dressing application

Skin-like flexible membrane with excellent water resistance and moisture permeability is an urgent need in the wound dressing field to provide comfort and protection for the wound site. Despite efforts that have been made in the development of waterproof and breathable (W&B) membranes, the in-situ electrospinning of W&B membranes suitable for irregular wound surfaces as wound dressings still faces huge challenges. In the current work, a portable electrospinning device with multi-functions, including adjustable perfusion speed for a large range from 0.05 mL/h to 10 mL/h and high voltage up to 11 kV, was designed. The thymol-loaded ethanol-soluble polyurethane (EPU) skin-like W&B nanofibrous membranes with antibacterial activity were fabricated via the custom-designed device. Ultimately, the resultant nanofibrous membranes composed of EPU, fluorinated polyurethane (FPU), and thymol presented uniform structure, robust waterproofness with the hydrostatic pressure of 17.6 cm H₂O, excellent breathability of 3.56 kg m^-2 d^-1, the high tensile stress of 1.83 MPa and tensile strain of 453%, as well as high antibacterial activity. These results demonstrate that the new-type device has potential as a portable electrospinning apparatus for the fabrication of antibacterial membranes directly on the wound surface and puts a new way for the development of portable electrospinning devices.

Anti-greasy and conductive superamphiphobic coating applied to the carbon brushes/conductive rings of hydro-generators

A simple and low-cost method is used to prepare a superamphiphobic coating with excellent anti-greasy and conductivity properties that can be used on the surface of carbon brushes and collector rings.

Effective Harmful Organism Management I: Fabrication of Facile and Robust Superhydrophobic Coating on Fabric

Advances in harmful organism management are highly demanding due to the toxicity of conventional coating approaches. Exploiting biomimetic superhydrophobicity could be a promising alternative on account of its cost-effectiveness and eco-friendliness. Here, we introduce a facile method to fabricate a robust superhydrophobic coating on a fabric substrate. This is achieved by sequentially spraying TiO2-epoxy resin nanocomposite material and fluorocarbon-silane modified SiO2 nanoparticles (FC-silane SiO2 NPs). The superhydrophobicity is attributed to the nanoparticles constituting a micro/nano hierarchical structure and the fluorocarbon of the modified SiO2 NPs lowering the surface energy. The epoxy resin embedded in the coating layer plays an important role in improving the robustness. The robustness of the superhydrophobic surface is demonstrated by measuring the water slide angle of surfaces that are subject to salty water at 500 rpm stirring condition for up to 13 days. This study focuses on ensuring the superhydrophobicity and robustness of the coating surface, which is preliminary work for the practical management of macrofoulers. Based on this work, we will perform practical harmful organism management in seawater as a second research subject.

Green Fabrication of a Multifunctional Sponge as an Absorbent for Highly Efficient and Ultrafast Oil-Water Separation

Oil leakage results in serious environmental pollution and severe waste of resources, which makes the development of low-cost, environmentally friendly, high-capacity, and durable oil absorbents an urgent task. In this paper, superhydrophobic coatings of activated carbon (AC)-TiO₂-PDMS@PDMS were developed without using any fluorine-containing reagents. The TiO₂ particles were grown on the AC surface to form AC-TiO₂ powders. The hydrophilic AC-TiO₂ powders were further grafted with polydimethylsiloxane (PDMS) molecules (AC-TiO₂-PDMS) to achieve superhydrophobicity through covalent reaction between PDMS and TiO₂ under UV light. The AC-TiO₂-PDMS powder was mixed with a PDMS polymer to form a superhydrophobic coating solution, which made the commercial sponge obtain durable superhydrophobicity. It showed high liquid repellency and antifouling ability toward various liquids and drinks. Taking advantage of the large surface area and high absorption capacity of AC, the coated sponge showed superior high absorption capacity (up to 100-158 g/g) toward various oils and organic solvents with a high absorption speed. Besides, the sponge showed high reusability that could be repeatedly used to absorb various oils and organic solvents. Moreover, the sponge also presented photocatalytic capability, which could repeatedly photodegrade the oil contaminants without influencing the superhydrophobicity, therefore largely increasing the recyclability and lifetime of the sponge. It also could separate immiscible oil-water mixtures with high efficiency and continuously remove oils from water. It was chemically stable and mechanically durable and could resist various harsh conditions without losing its superhydrophobicity. This study developed a facile, cost-effective, and environmentally friendly method to fabricate very promising absorbents for large-scale oil and solvent cleanups and recovery.

Underwater writable and heat-insulated paper with robust fluorine-free superhydrophobic coatings

Since its invention invented in China, paper has been widely used in the world for quite a long time. However, some intrinsic defects servely hinder its application in some extreme conditions, such as underwater or in fire. Herein, a bio-inspired durable paper with robust fluorine-free coatings was fabricated via a two-step spray-deposition technique. It not only consisted of modified SiO₂ microspheres and nanoparticles, but also contained an epoxy resin, endowing the paper with multifunctional properties. First, this bio-inspired functional paper showed excellent superhydrophobic and self-cleaning properties with a high static water contact angle (WCA) of 162.7 ± 0.5° and a low sliding angle (SA) of 5.7 ± 0.6°. Moreover, it possessed unusual repellent properties toward multiple aqueous-based liquids and heat-insulated properties. Second, this paper could be used for writing underwater and maintained satisfactory superhydrophobic performance for a long time with a WCA of 153.3 ± 1.8°. Besides, its high mechanical robustness was also experimentally confirmed in harsh working conditions, such as strong acid/alkali, boiling water, abrasion, bending, and folding. Compared with conventional paper, it is anticipated that this bio-inspired functional paper would be really competitive and demonstrate great potential in the field of underwater and fire-proof applications.

Robust, transparent, superhydrophobic coatings using novel hydrophobic/hydrophilic dual-sized silica particles

HYPOTHESIS

The superhydrophobic lotus leaf has dual-scale surface structures, that is, nano-bumps on micro-mountains. Large hydrophilic particles, due to its high surface energy and weight, have high affility to substrates and tend to precipitate at the bottom of coating films. Small hydrophobic particles, due to its low surface energy and weight, tends to sit on the top of coating films and form porous structures. To mimic the lotus leaf surface, it may be possible to develop dual-sized particle films, in which small particles are decorated on large particles.

EXPERIMENTS

A one-step spin coating of a mixture of dual-sized silica particles (55/200 nm) was used. Epoxy resin was added to improve the adhesion of particle films. The single-sized and dual-sized particle films were compared. The mechanical robustness of particle films was tested by tape peeling and droplet impact.

FINDINGS

The novel combination of hydrophobic silica (55 nm) and hydrophilic silica (200 nm) is essential in creating the hierarchical structures. By combining the strong adhesion of hydrophilic silica (bottom of coating film) to polymer substrates and porous structures of hydrophobic silica (top of coating film), we first time report a one-step and versatile approach to create uniform, transparent, robust, and superhydrophobic surface.

Bioinspired Smart Liquid Directional Transport Control

Developments in bioinspired superwetting materials have triggered technological revolutions in many disciplines. One representative area is liquid directional transport dominated by interface properties, which has experienced rapid progress recently. To improve the controllability, scientists try to use the external field, such as light, electricity, thermal, and so on, to assist or achieve controllable smart, responsive liquid directional transport. However, there are still some intractable problems and challenges behind prosperity. Here, we summarize the relevant basic theory of surface wettability and the processes of the development of bioinspired superwetting materials. We discuss the different essential mechanisms of liquid directional transport. Furthermore, smart external field-controlled fluid directional transport is the primary focus of this feature article. We briefly put forward our views on some outstanding problems, existing challenges, and trends in this field.

Wear-resistant and robust superamphiphobic coatings with hierarchical TiO2/SiO2 composite particles and inorganic adhesives

Superamphiphobic coatings, which could repel liquids with a surface tension as low as 21.6 mN m⁻¹ (n-octane), were prepared using a spray-coating method based on a flower-like hierarchical structure and highly fluorinated TiO₂/SiO₂ composite particles.

The elaboration of multifunctional hollow core–shell Fe3O4@PDA@TiO2 architecture with dual magnetic- and photo-responsive performance

Fe₃O₄@PDA@TiO₂ microspheres with a core–shell structure can be applied to magnetic recycling and photocatalytic degradation.

Facile preparation of a superamphiphobic fabric coating with hierarchical TiO2 particles

A functional superamphiphobic fabric coating with hierarchical TiO₂ composite particles and inorganic adhesives displays excellent mechanical robustness, good chemical stability and self-healing property by a simple spraying method.

A facile approach to achieve multifunctional polyethylene terephthalate fabrics with durable superhydrophobicity, photocatalysis and self-quenched flame retardance

Multifunctional PET fabrics were fabricated through combing layer-by-layer and spray coating methods.

Robust and nanoparticle-free superhydrophobic cotton fabric fabricated from all biological resources for oil/water separation

Traditional superhydrophobic cotton fabrics (SCFs) for oil/water separation were usually fabricated by surface coating with inorganic nanoparticles combined with nonrenewable and nonbiodegradable or even toxic fossil-based chemicals, which would lead to secondary environmental pollution after their lifetime. In this study, we report robust, nanoparticle-free, fluorine-free SFC, which was prepared by acid etching followed by surface coating with epoxidized soybean oil resin (CESO) and subsequent modification with stearic acid (STA). No toxic compound and no nanoparticle were included within the SCF and all the raw materials including cotton fabric, CESO and STA are biodegradable and derived from biological resources. The SCF showed excellent mechanical stability and chemical/environmental resistances. The superhydrophobicity of the SFC survived from mechanical abrasion, tape peeling, ultrasonication, solvent erosion and low/high temperature exposure. The SCF also exhibited good acid/alkali resistance with contact angle over 150° toward different pH water droplets. Moreover, the SCF could efficiently separate oil/water mixtures with efficiency above 97.9% and the superhydrophobicity remained after reusing for at least 10 times. The fully biological-derived SCF with excellent mechanical and chemical resistances exhibit great potential for separation of oil/water mixtures.

Durable Epoxy@ZnO Coating for Improvement of Hydrophobicity and Color Stability of Wood

The hydrophobicity and color stability of wood are important properties that can be easily changed when wood is used as a raw material for outdoor products, reducing the service life of wood. Herein, an epoxy@ZnO coating was applied by a two-step simple spray coating method to improve the hydrophobicity and color stability of Styrax tonkinensis wood. The hydrophobicity, robustness of coating, as well as the color stability of uncoated wood samples and epoxy@ZnO coated wood samples were evaluated. The microstructure morphology and crystal structures of the coating were also characterized by a field-emission scanning electron microscope (FESEM) and X-ray diffraction (XRD) analysis, respectively. Results showed that the obtained epoxy@ZnO coating was not only superhydrophobic with an average water contact angle of 154.1°, but also maintained superhydrophobicity with an average water contact angle of 149.6° after five water jetting tests. The color stability of the coated wood samples was improved by around 50% compared to that of uncoated wood samples. Additionally, a continuous epoxy@ZnO coating with hierarchical micro/nanoscale structures constructed by the wurtzite hexagonal structure of ZnO micro/nanoparticles on wood surfaces was confirmed.

Bio-inspired robust superhydrophobic-superoleophilic polyphenylene sulfide membrane for efficient oil/water separation under highly acidic or alkaline conditions

The separation of water-in-oil emulsions in harsh environment (strong acid/alkali) is a challenging subject. In this study, we prepared a superhydrophobic-superoleophilic polyphenylene sulfide (PPS) membrane by the mixture of hydrophobic SiO₂ nanoparticles, diphenyl ketone (DPK), benzoin (BZ) and PPS via thermally induced phase separation (TIPS) technology. This superhydrophobic membrane displayed a lotus leaf-like micro-nano structure, and it could be used for oil/water separation in strong acidic or alkaline environment. The hydrophobic SiO₂ nanoparticles played a key role in the membrane structure evolution and its performance. When SiO₂ content was 4 wt%, the pure water contact angle of the prepared superhydrophobic-superoleophilic membrane reached 156.9° and the oil contact angle achieved 0°. The fluxes of water-in-oil emulsions (kerosene, toluene and chloroform) reached 1926, 3150 and 3416 L/(m²·h), respectively. However, the fluxes of their surfactant-stabilized water-in-oil emulsions declined to 531, 685 and 724 L/(m²·h), respectively, due to the great stability of surfactant-stabilized emulsions. Most importantly, all the water rejection rates exceeded 99.9% when the PPS membranes modified with 4 wt% hydrophobic SiO₂ nanoparticles. In addition, the PPS-SiO₂ hybrid membranes exhibited excellent self-cleaning antifouling performance, cycling performance and superior acid/alkali resistance.

Performance Investigation on Different Designs of Superhydrophobic Surface Texture for Composite Insulator

To investigate the superhydrophobic properties of different surface textures, nine designs of textures with micro-nanostructures were produced successfully using the laser engraving technique on the surfaces of composite insulator umbrella skirt samples made of silicon rubber. The optimal parameters of the texture designs to give rise to the best hydrophobicity were determined. The surface morphology, abrasion resistance, corrosion resistance, self-cleaning and antifouling property of the different textured surfaces as well as water droplets rolling on the textured surfaces were studied experimentally using a contact angle meter, scanning electron microscope, three-dimensional topography meter and high-speed camera system. It was found that the diamond column design with optimal parameters has the best superhydrophobicity and overall performance. The most remarkable advantage of the optimal diamond column design is its robustness and long-term superhydrophobicity after repeated de-icing in harsh conditions. The reported work is an important step towards achieving superhydrophobic surface without coating for outdoor composite insulator in practical applications.

Photocatalytically Stable Superhydrophobic and Translucent Coatings Generated from PDMS-Grafted-SiO2/TiO2@PDMS with Multiple Applications

In this paper, we present a highly efficient, cost-effective, and widely applicable functionalized SiO₂/TiO₂-polymer based coating to fabricate a translucent, fluorine-free, chemically stable, photocatalytic active, self-healable superhydrophobic coating, which consisted of two mixed functionalized particles (MFP) and polydimethylsiloxane (PDMS) in a proper ratio. Both SiO₂ and TiO₂ powders were functionalized with PDMS brushes to achieve superhydrophobicity. To maximally optimize its properties, including superhydrophobicity, transparency, and photocatalytic activity, the ratios between MFP with PDMS were carefully studied and optimized. Glass slides coated with this mixed coating (MC) showed translucence with a transparency of 75%. It also presented superior photocatalytic activity and strong UV resistance that could repeatedly degrade organic oil pollutants as many as 50 times, while still maintaining superhydrophobicity even upon exposure to UV light with a high intensity of 80 mW/cm² for as long as 36 h. When low-surface-tension oils such as dodecane wetted the MC surface, it showed excellent slippery performance and could quickly repel strong acid/alkali/hot water and even very corrosive liquids such as aqua regia. MC achieved extremely stable underoil superhydrophobicity (toward liquids including water, strong acid and base, hot water, etc.) and self-cleaning properties, not only in oils at room temperature but also in a scalded oil environment. Moreover, MC showed self-healable performance after recycled plasma treatment. The stainless steel mesh coated with MC was also used to highly efficiently separate oil-water mixtures. Moreover, harsher liquids including strong acid/alkali solutions/hot water/ice water-oil mixtures could also be successfully separated by the coated mesh. This coating was believed to largely broaden both indoor and outdoor applications for superhydrophobic surfaces.

Polysulfide microspheres with chemical modification for generation of interfaces with macroscopic colour variation and biomimetic superhydrophobicity

Both superwettability and structural colours have attracted considerable attention in recent years. In addition, the combination of structural colours and superwettability could endow materials with broader application prospects. The combination provides a new strategy to design novel functional materials, and there are many studies pertaining to these materials that have been reported in recent years. Herein, a polysulfide (PSF) superhydrophobic coating was synthesized successfully. The PSF superhydrophobic coating possesses excellent superhydrophobicity, oleophobicity for diesel and macroscopic structural colour variation when wetted. The colour is changed when the coating is wetted and it returns to its original colour after drying. In addition, the surface presents better reusability and thermostability which satisfies various daily needs. The PSF superhydrophobic coating can be considered as an excellent candidate for designing wetting responsive materials, and it has enormous application potential in the fields of detection, sensing, anti-counterfeiting and security. For the first time, we present a novel and low-cost strategy to fabricate materials with both superhydrophobicity and structural colour, offering significant insights into the practical application of these functional materials.

A different wettable Janus material with universal floatability for anti-turnover and lossless transportation of crude oil

Flower-like TiO₂ particles were prepared to endow diverse materials with the ability of steady floatability and anti-turnover on different liquids. This strategy was applied in the design of a promising way for lossless transportation of crude oil via sea.

Molding processed multi-layered and multi-functional nanocomposites with high structural ability, electrical conductivity and durable superhydrophobicity

Bioinspired superhydrophobic surfaces are mainly attributed to nano/micro textures and low surface energy materials, and have exciting potential for use in fields such as self-cleaning, water-proofing, anti-icing, anti-fouling, and so forth. However, the natural weakness of such delicate hierarchical surface structures pose great challenges to using artificial superhydrophobic surfaces under harsh mechanical conditions. Completely transforming multi-layered composite materials with good structural ability into superhydrophobic surfaces would greatly extend their durability under continuous mechanical abrasion. Endowing these composites with electrical conductivity could further expand their scope of application, especially in anti-static environments. Here we employ a facile molding process to fabricate a new type of multi-layered and multi-functional nanocomposite (MMNC), with a tensile strength up to ∼226.4 MPa, a modulus of up to ∼24.8 GPa, a surface electric conductivity of ∼1.2 S cm-1, a water contact angle of ∼155.4° and a water sliding angle of ∼2.0°. These multi-layered and multi-functional nanocomposites (MMNCs) demonstrate robust water-repellency under harsh mechanical abrasion (tested using a high tack sticky tape peel, cyclic sand paper abrasion and even file abrasion) and strong chemical corrosion (tested by using hydrochloric acid, sulfuric acid and sodium hydroxide solutions). Additionally, our MMNCs are highly resistant to water impalement (tested by turbulent water jet impact with a velocity of up to ∼29.5 m s-1 and a corresponding Weber number of ∼32 000). The robustness of the superhydrophobicity is multifaceted, and owing to the excellent structural performance and conductivity, these MMNCs could find potential uses in vehicles, containers, wind blades, infrastructures, electronics and so forth, which usually experience comprehensively harsh conditions such as rainfall, abrasion, static electricity, high loads and so forth.

Bioinspired Designs of Superhydrophobic and Superhydrophilic Materials

Bioinspired designs of superhydrophobic and superhydrophilic materials have been an important and fascinating area of research in recent years for their extensive potential application prospects from industry to our daily life. Despite extensive progress, existing research achievements are far from real applications. From biomimetic performance to service life, the related research has faced serious problems at present. A timely outlook is therefore necessary to summarize the existing research, to discuss the challenges faced, and to propose constructive advice for the ongoing scientific trend. Here, we comb the process of development of bioinspired superhydrophobic and superhydrophilic materials at first. Then, we also describe how to design artificial superhydrophobic and superhydrophilic materials. Furthermore, current challenges faced by bioinspired designs of superhydrophobic and superhydrophilic materials are pointed out, separately, and the possible solutions are discussed. Emerging applications in this field are also briefly considered. Finally, the development trend within this field is highlighted to lead future research.

Facile Fabrication of a PDMS@Stearic Acid-Kaolin Coating on Lignocellulose Composites with Superhydrophobicity and Flame Retardancy

The disadvantages such as swelling after absorbing water and flammability restrict the widespread applications of lignocellulose composites (LC). Herein, a facile and effective method to fabricate superhydrophobic surfaces with flame retardancy on LC has been investigated by coating polydimethylsiloxane (PDMS) and stearic acid (STA) modified kaolin (KL) particles. The as-prepared coatings on the LC exhibited a good repellency to water (a contact angle = 156°). Owing to the excellent flame retardancy of kaolin particles, the LC coated with PDMS@STA-KL displayed a good flame retardancy during limiting oxygen index and cone calorimeter tests. After the coating treatment, the limiting oxygen index value of the LC increased to 41.0. Cone calorimetry results indicated that the ignition time of the LC coated with PDMS@STA-KL increased by 40 s compared with that of uncoated LC. Moreover, the peak heat release rate (PHRR) and the total heat release (THR) of LC coated with PDMS@STA-KL reduced by 18.7% and 19.2% compared with those of uncoated LC, respectively. This LC coating with improved water repellency and flame retardancy can be considered as a potential alternative to protect the lignocellulose composite.

Janus Gradient Meshes for Continuous Separation and Collection of Flowing Oils under Water

Gradient meshes with Janus wettabilities are fabricated to stably separate and collect spilled oils from a range of flowing oily wastewater. Here, we demonstrate an overflow with separation methodology, which combines selective oil overflow and membrane separation, to separate low content oils from dynamic flowing oil-water mixtures by a curved gradient mesh that covered on a solid edge. The microscaled air-oil-water-solid four-phase wetting state during the oil-water separation process is visualized and demonstrated. The fundamental understanding of this overflow with separation system and the superior gradient mesh materials would enable us to construct a wide variety of separation devices out of traditional designs and advance related applications, such as wastewater treatment and fuel purification.

Biomimetic multi-functional superhydrophobic stainless steel and copper meshes for water environment applications

The robust, multi-functional superhydrophobic metal meshes were fabricated by the one-step solution immersion method for water environment applications.