Superamphiphobic Surfaces Research Articles

Bioinspired Hierarchical T Structures for Tunable Wettability and Droplet Manipulation by Facile and Scalable Nanoimprinting.

Developing surfaces that effectively repel low-surface-tension liquids with tunable adhesive properties remains a pivotal challenge. Micronano hierarchical re-entrant structures emerge as a promising solution, offering a robust structural defense against liquid penetration, minimizing area fraction, and creating narrow gaps that generate substantial upward Laplace pressure. However, the absence of an efficient, scalable, and tunable construction method has impeded their widespread applications. Here, drawing inspiration from springtail epidermal structures, octopus suckers, and rose petals, we present a scalable manufacturing strategy for artificial micronano hierarchical T-shaped structures. This strategy employs double-transfer UV-curing nanoimprint lithography to form nanostructures on microstructured surfaces, offering high structural tunability. This approach enables precise control over topography, feature size, and arrangement of nano- and microscale sections, resulting in superamphiphobic surfaces that exhibit high contact angles (>150°) and tunable adhesive forces for low-surface-energy liquids. These surfaces can be applied to droplet-based microreactors, programmable droplet-transfer systems, and self-cleaning surfaces suitable for various liquids, particularly those with low surface tension. Remarkably, we have also succeeded in fabricating the hierarchical structures on flexible and transparent substrates. We demonstrate the advantages of this strategy in the fabrication of hierarchical micronanostructures, opening up a wide range of potential applications.

Fabrication of superamphiphobic micro-reentrant structures by inverted electrochemical deposition

Due to excellent oil resistance and shortened liquid-solid contact time, superamphiphobic surfaces have promising application prospects in oil transportation, and petroleum pollution control. Although superamphiphobic surfaces have been constructed on various substrates, there is still a lack of high-efficient methods for fabricating micro-reentrant structures on engineering metal substrates. This paper proposes a new method combining laser processing and inverted electrochemical deposition techniques to achieve high-efficient and large-scale fabrication of superamphiphobic surfaces on copper substrates. Firstly, micropillar array structures are constructed by laser processing, and the structures exhibit excellent superhydrophobicity after low surface energy modification. Then, inverted electrochemical deposition is performed after polishing the top of the array, and local angle of the gas/liquid interface can be controlled by adjusting the distance between the top of the micropillar and the electrolyte level, thus regulating micro-morphology of the roof structure. The influences of electrochemical deposition parameters on characteristics of the micro-reentrant structures are systematically investigated. Finally, superamphiphobic micro-reentrant structures (roof diameter > 190 μm, micropillar spacing <250 μm) with water and oil contact angles exceeding 150° are prepared after lowering the surface energy of the deposited structures. After anti-fouling, blowing, ultrasonic vibration, and tape adhesion tests, the prepared superamphiphobic micro-reentrant structures maintained good water and oil repellency, showing excellent chemical stability and durability. The research may provide a simple, efficient, and low-cost method for high-efficient constructing superamphiphobic surfaces on engineering metal substrates, enriching the fabrication techniques of micro-reentrant structures and facilitating their practical applications.

Rapid fabrication of superamphiphobic surface on AZ91D Mg alloys with re-entrant structures

Developing spray/template-free superamphiphobic surfaces that can resist various kinds of liquids is crucial for academic study and practical demands. In spite of significant evolution, facilely fabricating superamphiphobic surfaces remains a daunting challenge due to the practical dilemma of the time-consuming preparation process and the guarantee of wettability performance. Herein, a facile magnetron-sputtering-assisted chemical deposition technique is advanced to constitute hierarchical dendritic fractal structures on AZ91D Mg alloys that showcase remarkable biomimicry while significantly contributing to superamphiphobicity through extended re-entrant structures. As well as demonstrating promising chemical stability, such surfaces can display exceptional resistance to water and ethylene glycol. The approach employed to create such instrumental superamphiphobic surfaces offers substantial benefits in affordability and efficiency. Remarkably, the entire preparation process only takes 26 min, presenting a novel method for preparing superamphiphobic surfaces.

Superamphiphobic fabrics: design principles, preparation methods, and multifunctional applications

Enabling fabrics to achieve superoleophobicity and superhydrophobicity can greatly improve their application prospects. The superamphiphobic surface based on fabric has attracted widespread attention from researchers and industrial fields due to its unique flexibility and breathability, which are significantly different from other substrates. Herein, we review some important nodes in the development process of superamphiphobic surfaces that chiefly impact superamphiphobic fabrics (SAFs). Meanwhile, the construction mechanism of SAF based on the research progress of low surface energy materials and fabric surfaces was summarized. Finally, we summarize the existing research on SAF, including different preparation methods such as material modification and surface roughness construction, as well as multifunctional applications of SAF achieved by adding other functional materials.

A superamphiphobic surface with ordered hexagonal microstructures inspired by springtails

Inspired by springtails, we prepared an ordered hexagonal microscale and nanoparticle composite superamphiphobic surface, which can repel liquids with different surface tensions.

Adjustable oil adhesion on superamphiphobic copper surfaces for controlled oil droplet transport

In this paper, an approach of laser-etched material reduction combined with a chemical method is presented to obtain superamphiphobic copper surfaces with UV resistance, adjustable oil adhesion, and corrosion resistance.

Structure Formation in Supraparticles Composed of Spherical and Elongated Particles.

We studied the evaporation-induced formation of supraparticles from dispersions of elongated colloidal particles using experiments and computer simulations. Aqueous droplets containing a dispersion of ellipsoidal and spherical polystyrene particles were dried on superamphiphobic surfaces at different humidity values that led to varying evaporation rates. Supraparticles made from only ellipsoidal particles showed short-range lateral ordering at the supraparticle surface and random orientations in the interior regardless of the evaporation rate. Particle-based simulations corroborated the experimental observations in the evaporation-limited regime and showed an increase in the local nematic ordering as the diffusion-limited regime was reached. A thin shell of ellipsoids was observed at the surface when supraparticles were made from binary mixtures of ellipsoids and spheres. Image analysis revealed that the supraparticle porosity increased with an increasing aspect ratio of the ellipsoids.

Flexibility and abrasion tolerance of superamphiphobic coatings with rigid core–shell particles

Superamphiphobic coatings maintain surfaces clean even facing severe oil contamination, which is crucial for ensuring the lifespan of materials in highly polluted environments. Achieving excellent wear resistance and flexibility individually on superamphiphobic surfaces is relatively simple, but simultaneously obtaining both properties is challenging and often requires compromises. In this study, we develop an innovative approach inspired by “overcoming firmness by gentleness” to create superamphiphobic composite coatings with flexibility and abrasion tolerance. This innovative strategy combines a soft polyurethane resin with rigid diatomite/aluminum hydroxide (core–shell) particles, resulting in a coating structure resembling karst topography. Depositing aluminum hydroxide enhances the reactivity and content of hydroxyl groups on diatomite particles, simultaneously improving the hardness and 1H,1H,2H,2H-Perfluorodecyltrichlorosilane (FDTS) grafting degree of the core–shell particles. Residual hydroxyl groups on the semi-fluorination core–shell particles chemically bond with the isocyanate groups in the waterborne polyurethane resin, leading to enhanced crosslinking density and improved wear resistance of the coating. The top coating of F-SiO2 particles leads to a reduction in the surface energy of the core–shell coating. The obtained core–shell coating demonstrates excellent oil resistance even after 800 cycles of Taber abrasion under a load of 250 g and 1000 cycles of 360° bending, demonstrating remarkable wear resistance and flexibility simultaneously. This approach provides valuable insights for developing superamphiphobic composite coatings with flexibility and abrasion tolerance and opens new possibilities for their applications in flexible electronics and droplet manipulation.

Superamphiphobic surface with high aperture ratio interconnected pore structures for anti−condensation and repelling hot fluids

Pipeline transportation suffers from high-viscosity crude oil, wax-deposition, and hydrates blockage. Superamphiphobic surfaces with excellent repellency to various liquids have been proposed to solve those problems. However, they may lose superamphiphobicity once their micro-nanostructures were wetted by condensate droplets or hot fluids that require heat to improve liquidity. Here, we report a superamphiphobic P(HFIO)@SiO2@SS with a high aperture ratio pore structures (denoted as the PSSH) to resist water/oil-droplet-condensation and repel hot fluids. Its interconnected high aperture ratio pore structures and ultralow surface energy fluorinated side chains enhance the penetration resistance of droplets to micro-nanostructures and the driving force for condensate droplets to spontaneously roll away from its surface. Besides, it prevents crude oil (25 °C−72 °C) from sticking to its surface (25 °C), as well as molten paraffin droplets (104 °C) from adhering to the surface (104 °C), increasing the flow rate of 4–35 times. In addition, the PSSH reduces adhesive force to hydrates (3.2 °C) and wax (25 °C) by 92.1% and 89.4%, respectively. The PSSH demonstrates the great potential in handling pipeline blockage and improving the transport efficiency of fluids, offering alternative strategy to prepare superamphiphobic surfaces for oil and gas transportation, heat transfer, and other applications.

Superamphiphobic interface-enhanced inorganic coating for multi-environments tolerant and zero-energy building radiative cooling

Passive radiative cooling (PRC) is a promising technology to achieve eco-friendly building cooling relying on automatic solar reflection and thermal emission. However, sewage, oil and even dust in actual application often cause irreversible damage of surface optical selectivity required by durable cooling. Herein, ZnAl LDO biomimetic microflowers are fabricated as optically selective substrate following by crosslinking of superamphiphobic (SAP) SiO2 nanoparticles to obtain inorganic SAP-PRC coating. Openly-porous micro-nano-structure from LDO microflowers imparts the coating excellent solar reflectivity (∼97.58% normalized with BaSO4) and thermal emissivity (∼98%) as well as efficient resistance for both water (contact angle >158°/slide angle <5°) and oil (contact angle >151°/slide angle <10°). As the result, the coating achieves about 7℃ of cooling effect under (>1400 W/m2) of solar radiation and ∼5℃ lower than the commercial coating. The superamphiphobic surface help SAP-PRC coating avoid over 7.5℃ increase of temperature under >1500 W/m2 after being immersed by oil pollution. It is estimated that the cooling coating can help achieve ∼26% energy saving in hot areas (Haikou in China) throughout a year also considering warming-energy consumption in winter. The synergistic self-cleaning and optical selectivity strategy will effectively promote the commercialization of building PRC materials and further contribute to energy and environment sustainability.

Experimental and fluid flow simulation studies of laser-electrochemical hybrid manufacturing of micro-nano symbiotic superamphiphobic surfaces.

Micro-nano symbiotic superamphiphobic surfaces can prevent liquids from adhering to metal surfaces and, as a result, improve their corrosion resistance, self-cleaning performance, pollution resistance, and ice resistance. However, the fabrication of stable and controllable micro-nano symbiotic superamphiphobic structures on metal surfaces commonly used in industry remains a significant challenge. In this study, a laser-electrochemical hybrid subtractive-additive manufacturing method was proposed and developed for preparing copper superamphiphobic surfaces. Both experimental and fluid simulation studies were carried out. Utilizing this novel hybrid method, the controllable preparation of superamphiphobic micro-nano symbiotic structures was realized. The experimental results showed that the prepared surfaces had excellent superamphiphobic properties following subsequent modification with low surface energy substances. The contact angles of water droplets and oil droplets on the surface following electrodeposition treatment reached values of 161 ± 4° and 151 ± 4°, respectively, which showed that the prepared surface possessed perfect superamphiphobicity. Both the fabrication method and the test results provided useful insights for the preparation of stable and controllable superamphiphobic structures on metal surfaces in the future.

Directional rebound of compound droplets on asymmetric self-grown tilted mushroom-like micropillars for anti-bacterial and anti-icing applications

Directional liquid bouncing is of great significance for a variety of biological and industrial applications. Although surface engineering through 3D printing or self-assembly enables water droplets to rebound directionally, directional bouncing of compound droplets still poses a challenge due to their low surface tension. Moreover, preparation of superamphiphobic surfaces in an efficient and simple manner to accomplish this mission remains to be studied. Here, a tilted stepped mushroom-like micropillar surface (TSMMs), whose structural morphology can be created and tailored by a facile and direct femtosecond laser-induced asymmetric self-growing strategy, is designed to enable the oblique quasi-pancake bouncing of a low surface tension droplet (γ = 32 mN/m). Oblique quasi-pancake bouncing can not only reduce the droplet contact time (7 ms) but also effectively control the direction of droplet bouncing (the horizontal distance of 2.4 mm). Accompanying mechanistic analysis provides an in-depth understanding of the structure-droplet motion relationship. Finally, we demonstrate the applications of TSMMs in antibacterial and anti-icing scenarios. This work advances the investigation of directed droplet transportation, and paves new avenues in the fields of advanced biomedical and other industrial materials.

Fabrication of superamphiphobic surface with re-entrant structures via self-assembly colloidal template-assisted electrochemical deposition

Superamphiphobic surfaces with re-entrant structures have attracted widespread attention due to their superior water and oil resistance. However, current methods for fabricating superamphiphobic surfaces mostly rely on expensive equipment and cumbersome processes. This paper represents a facile and controlled preparation method for superamphiphobic surfaces with zinc oxide (ZnO) re-entrant structures using self-assembled polystyrene (PS) monolayer colloidal crystals (MCCs) as templates to assist electrochemical deposition of ZnO film. The prepared surface shows contact angles (CAs) larger than 150° and sliding angles smaller than 10° for water, glycerol, ethylene glycol (EG), and olive oil. The morphology and size of the re-entrant structures were modulated by the deposition potential and time, and the mechanism of the influence of the structures on the wetting properties was investigated. This superamphiphobic surface with re-entrant structures can be used as a surface-enhanced Raman spectroscopy (SERS) substrate for molecular detection with a detection limit of 10−10 M for rhodamine (R6G), benefiting from the enrichment effect of the superamphiphobic surface and the Schottky barrier at the Ag/ZnO contact interface. We hope that this preparation method for superamphiphobic surface has broad application prospects in the fields of self-cleaning, anti-icing, anti-fog, corrosion resistance, microfluidics, photocatalysis and fluid drag reduction.

Superamphiphobic ridge-like surfaces produced by a layer-by-layer self-assembly under electrophoretic deposition of fluorinated nanoparticles for comprehensive protection

Superamphiphobic surfaces possess a great repellency for both polar and nonpolar liquids, and have attracted tremendous interest from academic research and practical applications owing to their potential for self-cleaning and anti-fouling. However, the existing technologies for the preparation of superamphiphobic surfaces, including spraying, dip-coating, etching, and chemical vapor deposition, are difficult to deal with the surface treatment of irregularly shaped components. And the relatively complicated and time-consuming processes drastically limit the large-scale production and industrialization. Herein, electrophoretic deposition (EPD) is highlighted for the fast modification of metal sheets by embedding silica nanoparticles in an epoxy matrix to prepare highly stable coatings. Firstly, the epoxy resin and silica nanoparticles are deposited under an applied electrical field to form a thin polymer layer for pre-roughening. Next, the functionalized nanoparticles are uniformly dispersed on the polymer layers to generate the superamphiphobic surfaces with a ridge-like structure through the layer-by-layer self-assembly under EPD conditions. The as-prepared superamphiphobic surfaces exhibit super liquid-repellency to various low-surface-tension liquids and considerable anti-condensation performance. Moreover, they are durable against comprehensive chemical contamination, such as oil immersion, and acid/alkali erosion, and resist corrosion after immersion in a 3.5 wt% NaCl solution for more than 70 days. These findings demonstrate a new strategy of using EPD to fabricate durable superamphiphobic coatings for comprehensive protection of metal surfaces to endure harsh chemical environments in operation.

Microwave‐Assisted Fabrication of Superamphiphobic Surfaces on Aluminum Substrates

The field of superamphiphobic surface fabrication has evolved rapidly in the last decade; however, research on important issues such as sustainability and green chemistry procedures is still scarce. Herein, a simple method of microwave irradiation (MW) to minimize energy consumption during the preparation of superamphiphobic aluminum (Al) surfaces is reported. Al substrates are first etched in diluted HCl solutions to generate a microstructure and then irradiated in a commercial microwave unit for several time intervals, temperatures, and pressures. The surfaces are then coated with different compounds, and the wettability is tested with high and very‐low surface tension liquids. Optical profilometry and scanning electron microscopy images show that the density of hierarchical micro‐nanostructures increases with MW time, temperature, and pressure. At 170 °C and 7.9 bar, the surfaces present a high density of structures and re‐entrant topographies. The obtained coatings display excellent repellence to liquids with surface tensions as low as 27.5 mN m−1. X‐ray photoelectron spectroscopy data show the importance of efficient surface functionalization for the production of superamphiphobicity in Al substrates. The results show that MW irradiation of Al substrates can be a green and efficient method for fabricating superamphiphobic surfaces.

Effects of liquid surface tension on gas capillaries and capillary forces at superamphiphobic surfaces

The formation of a bridging gas capillary between superhydrophobic surfaces in water gives rise to strongly attractive interactions ranging up to several micrometers on separation. However, most liquids used in materials research are oil-based or contain surfactants. Superamphiphobic surfaces repel both water and low-surface-tension liquids. To control the interactions between a superamphiphobic surface and a particle, it needs to be resolved whether and how gas capillaries form in non-polar and low-surface-tension liquids. Such insight will aid advanced functional materials development. Here, we combine laser scanning confocal imaging and colloidal probe atomic force microscopy to elucidate the interaction between a superamphiphobic surface and a hydrophobic microparticle in three liquids with different surface tensions: water (73 mN m−1), ethylene glycol (48 mN m−1) and hexadecane (27 mN m−1). We show that bridging gas capillaries are formed in all three liquids. Force-distance curves between the superamphiphobic surface and the particle reveal strong attractive interactions, where the range and magnitude decrease with liquid surface tension. Comparison of free energy calculations based on the capillary menisci shapes and the force measurements suggest that under our dynamic measurements the gas pressure in the capillary is slightly below ambient.

Study of drop mobility over a surface having electric charge gradient

Though different methodologies like thermal and magnetic fields have been tried to control a droplet's mobility in biochemical and medical applications, charge imprinted super-amphiphobic surface is the recent and promising development in which droplets can be transported through any predefined path over the surface. Such surfaces are electrified by impacting water droplets from varying release heights through triboelectrification. Impacting droplets on pillared surface dynamics of the same have been analyzed to understand the nature of electrostatic charge distribution generated. Further to this, droplet actuation on such surfaces with surface charge gradient has been simulated. Charge separation inside the liquid droplet and charge accumulation near the interface has been visualized to understand the phenomenon. Asymmetry in droplet shape and charge distribution has been analyzed as the reason behind the droplet actuation. The effect of different charge density gradients and surface wettability over droplet mobility has also been studied.

Fluoropolymer: A Review on Its Emulsion Preparation and Wettability to Solid-Liquid Interface.

In the preparation of a superamphiphobic surface, the most basic method is to reduce the surface free energy of the interface. The C-F bond has a very low surface free energy, which can significantly change the wettability of the solid-liquid interface and make it a hydrophobic or oleophobic, or even superamphiphobic surface. Based on the analysis of a large number of research articles, the preparation and application progress in fluoropolymer emulsion were summarized. After that, some corresponding thoughts were put forward combined with our professional characteristics. According to recent research, the status of the fluoropolymer emulsion preparation system was analyzed. In addition, all related aspects of fluoropolymer emulsion were systematically classified in varying degrees. Furthermore, the interaction between fluoropolymer structure and properties, especially the interaction with nanomaterials, was also explored. The aim of this review is to try to attract more scholars' attention to fluorocarbon interfacial materials. It is expected that it will make a certain theoretical and practical significance in the preparation and application of fluoropolymer.

A strategy for fabricating multi-level micro-nano superamphiphobic surfaces by laser-electrochemistry subtractive-additive hybrid manufacturing method

To achieve superamphiphobic properties on the surface of copper, a novel strategy for fabricating multi-level micro-nano superamphiphobic membranes by laser-electrochemistry subtractive-additive manufacturing method is explored. To test the properties of the metal surface prepared by this method, a variety of testing experiments are carried out. The experiment results shows that the contact angle (CA) of water and oil droplets are 161° ± 4° and 151° ± 4°, while those rolling CAs are 2° and 10°, which shows that the prepared surface had excellent superamphiphobic properties. Through the wettability test at different temperatures, the surface hydrophobicity of the prepared samples at low temperature 5 °C is worse than that at a room temperature 25 °C. According to droplet bounce test, the water drops experiences two complete bouncing processes on the surface of the prepared samples when the laser scanning interval is equal to the laser spot diameter, which indicates that the stable Cassie state is related to the multi-level micro-nano structures. In addition, the superamphiphobic surfaces fabricated in this paper have perfect functionality and stability, which provides a novel method for the potential application in the automotive, aerospace, and shipbuilding industries.

Multifunctional Superamphiphobic Cotton Fabrics with Highly Efficient Flame Retardancy, Self-Cleaning, and Electromagnetic Interference Shielding

Here, a facile method is reported to prepare multifunctional cotton fabrics with high flame retardancy, high electrical conductivity, superamphiphobicity, and high electromagnetic shielding. The cotton fabric surface was first modified with phytic acid (PA), which promoted dehydration and carbonization of cellulose to increase flame retardancy in the process of pyrolysis. Tannic acid (TA) and 3-aminopropyltriethoxysilane (APTES) coating with nanospheres as interlayers created hierarchical roughness that facilitated the construction of superamphiphobic surfaces and provided adhesion sites for silver nanoparticles. In addition, the TA-APTES coating improved flame retardancy because the APTES-containing silicon could form silicon carbon layers to isolate heat and oxygen. Subsequently, the surface energy of the composite cotton fabric was reduced by fluorine-containing molecules. The prepared composite cotton fabric exhibited excellent superamphiphobicity with contact angles of 160.3 and 152° for water and olive oil, respectively. The conductivity and EMI shielding efficiency of the prepared composite cotton fabric reached 629.93 S/cm and 76 dB, respectively. Importantly, the composite cotton fabric maintained a relatively stable EMI shielding efficiency even after cyclic bending and abrasion tests. Moreover, the composite cotton fabric possessed a high limiting oxygen index (LOI) of 45.3% and self-extinguishing properties with the peak heat release rate (PHHR) and total heat release (THR) reduced by 73 and 67%, respectively, than the pure cotton fabric, indicating the outstanding flame retardancy.