Slippery Liquid-infused Porous Surfaces Research Articles

Recent Developments in Slippery Liquid-Infused Porous Surface Coatings for Biomedical Applications.

Slippery liquid-infused porous surface (SLIPS), inspired by the Nepenthes pitcher plant, exhibits excellent performances as it has a smooth surface and extremely low contact angle hysteresis. Biomimetic SLIPS attracts considerable attention from the researchers for different applications in self-cleaning, anti-icing, anticorrosion, antibacteria, antithrombotic, and other fields. Hence, SLIPS has shown promise for applications across both the biomedical and industrial fields. However, the manufacturing of SLIPS with strong bonding ability to different substrates and powerful liquid locking performance remains highly challenging. In this review, a comprehensive overview of research on SLIPS for medical applications is conducted, and the design parameters and common fabrication methods of such surfaces are summarized. The discussion extends to the mechanisms of interaction between microbes, cells, proteins, and the liquid layer, highlighting the typical antifouling applications of SLIPS. Furthermore, it identifies the potential of utilizing the controllable factors provided by SLIPS to develop innovative materials and devices aimed at enhancing human health.

Environmentally friendly SLIPS coating based on flexible sponge: A novel approach to antifouling for ships

To mitigate the attachment of fouling organisms, Slippery Liquid-Infused Porous Surfaces (SLIPS) hold tremendous potential as a green and broad-spectrum antifouling solution, capable of replacing traditional antifouling coatings. However, the complexity of current preparation methods and the limited lifespan of lubricating oils constrain their widespread application in marine antifouling for vessels. In this study, melamine sponge (MS) was used as a substrate, and modifications were made by introducing superhydrophobic silica nanoparticles (SiO2 NPs), a biocompatible adhesive (ethyl cyanoacrylate, ECA), and a highly stretchable polymer (poly-ε-caprolactone, PCL). By combining natural surface microstructures with additional nanomaterials, we successfully obtained a superoleophilic surface, effectively capturing liquid lubricants and maintaining their long-term stability. The sponge substrate possesses distinctive contractility, with the lubricant stored in the grid spontaneously compensating for the loss of surface lubricant, thereby effectively enhancing its durability. This study provides a straightforward fabrication method with reduced manufacturing costs for environmentally friendly marine anti-fouling coatings. The approach demonstrates a prolonged cyclic anti-fouling effect, effectively advancing the development of SLIPS for anti-fouling applications in shallow marine environments.

Evaluation of dropwise condensation from a vertical condenser tube impregnated with semisolid lubricant

AbstractThe quest for augmenting dropwise condensation heat transfer performance has been the driving force behind the exploration of innovative techniques and approaches to fulfill the desired objective. Mostly, earlier research on dropwise condensation was devoted to study condensation from horizontal tubes and plates but, rarely, addressed dropwise condensation from vertical tubes. An interesting topic of current research in dropwise condensation is to explore the application of Slippery Liquid Infused Porous Surfaces (SLIPSs) to improve the condensation performance. The aforesaid facts are the motivation behind the topics of interest in the present study. In this study, we explore the applicability of semisolid lubricant‐impregnated porous surfaces in enhancing dropwise condensation performance of a vertical condenser tube. The experiments conducted over a wide range of subcooling (5°C ≤ ΔT ≤ 65°C) in saturated steam environment showed significant improvement in condensation heat transfer coefficient of a vertical condenser tube impregnated with semisolid lubricants when compared to bare vertical condenser tube. The highest enhancement is found to be 280% at a subcooling of 40°C. Furthermore, these surfaces proficiently sustain dropwise condensation over a period of 72 hours without compromising heat transfer performance. The devised fabrication method is simpler, more cost‐effective, and less time‐consuming than earlier techniques used for creating SLIPSs. Additionally, an approach based on numerical optimization by a stochastic global optimization technique, namely, Genetic Algorithm, is proposed to retrieve the coefficients and the exponent in the mathematical expression of overall resistance, that is being used to compute the tube‐side dropwise convection heat transfer coefficient.

Durable slippery liquid-infused porous surfaces for effective corrosion protection of aluminum alloy in ethylene glycol-water solutions

Aluminum (Al) alloys are extensively utilized in liquid-cooling heat dissipation systems owing to their superior strength-to-weight performance, ease of processing, and high thermal conductivity. However, they are susceptible to corrosion in the cooling medium, such as ethylene glycol-water solutions. This study presents a straightforward and cost-effective method to create a slippery liquid-infused porous surface (SLIPS) designed to effectively prevent corrosion of the 6061 Al alloy in ethylene glycol-water solutions. Micro/nano hierarchical structures were achieved on the SLIPS through plasma electrolytic oxidation and hydrothermal treatment. Following the modification of low-surface-energy materials and the infusion of silicone oil, the SLIPS exhibited an outstanding slippery property, allowing ethylene glycol-water droplets to effortlessly slide down the inclined surface at an angle of 1.1°. Additionally, the SLIPS demonstrated remarkable anti-corrosion performance against ethylene glycol-water solutions, with a minimum corrosion current density (Icorr) of 2.4 × 10−10 A·cm−2. Crucially, long-term immersion test results on corrosion resistance revealed that the SLIPS provided reliable corrosion protection for the 6061 Al alloy, exhibiting an Icorr increased by 4 orders of magnitude compared to a smooth substrate. These findings hold significant potential for advancing the widespread application of SLIPS in liquid-cooling heat dissipation systems.

Sea Anemone-Inspired Slippery Liquid-Infused Porous Surface (SLIPS) with Bionic Cilia for Responsive 4D Antifouling.

The formation process of biofouling is actually a 4D process with both spatial and temporal dimensions. However, most traditional antifouling coatings, including slippery liquid-infused porous surface (SLIPS), are limited to performing antifouling process in the 2D coating plane. Herein, inspired by the defensive behavior of sea anemones' wielding toxic tentacles, a "4D SLIPS" (FSLIPS) is constructed with biomimetic cilia via a magnetic field self-assembly method for antifouling. The bionic cilia move in 3D space driven by an external magnetic field, thereby preventing the attachment of microorganisms. The FSLIPS releases the gaseous antifoulant (nitric oxide) at 1D time in response to light, thereby achieving a controllable biocide effect on microorganisms. The FSLIPS regulates the movement of cilia via the external magnetic field, and controls the release of NO overtime via the light response, so as to adjust the antifouling modes on demand during the day or night. The light/magnetic response mechanism endow the FSLIPS with the ability to adjust the antifouling effect in the 4D dimension of 1D time and 3D space, effectively realizing the intelligence, multi-dimensionality and precision of the antifouling process.

Dual immobilization strategy for slippery surface to achieve durable anti-corrosion and excellent anti-icing

Aluminum alloys always suffer from the deficient corrosion resistance and anti-icing property. Slippery liquid infused porous surfaces (SLIPS) inspired by “Nepenthes” have exhibited great potential in corrosion protection and anti-icing. However, the rapid depletion of the infused lubricants often results in the unsatisfactory long-term protective performances of SLIPS. In this study, a dual immobilization strategy was employed to fabricate a slippery surface with robust lubricant layer. The active lubricants were infused in the nanopores of anodized aluminum oxide (AAO) and grafted on the surface of silanized phytic acid (PA) substrate support simultaneously. Due to the presence of infused and covalently grafted lubricants, the obtained slippery surface possessed excellent and durable water repellency and anticorrosion property. Throughout 21 days of immersion in the 3.5 wt% NaCl solution, the water sliding angle of the slippery surface was lower than 10° and the low frequency impedance of the slippery surface was higher than 2.0 × 106 Ω cm2. Moreover, the slippery surface also possesses self-healing capacities that can automatically seal the scratch and repair the protective performance within 24 h. Furthermore, the cooled water droplet can easily roll away from the slippery surface treated by low temperature freezing. The results suggest that the slippery surfaces prepared using dual immobilization strategy can effectively protect aluminum alloys from corrosion and icing. This study provides a novel insight into the design and construction of SLIPS with excellent durability, which can expand the applications of SLIPS in harsh environments.

One step synthesis of durable slippery, oil/water selective, corrosion-resistant silicone coatings with grafted flexible sidechains

Slippery liquid-infused porous surfaces (SLIPSs) based on polymer matrices impregnated with liquid lubricants are multifunctional and provide a wide range of useful properties such as low adhesion of water and other liquids, selectivity, high corrosion resistance, etc. However, these properties vanish quickly due to the gradual depletion of lubricant from the matrix. This issue could be resolved by attaching lubricant molecules to the matrix as flexible, liquid-like sidechains. In the present work, thin silicone films with grafted sidechains are fabricated. The uniform coatings are obtained in “eco-friendly” pressurized (subcritical) CO2 on smooth silicon wafers as well as on rough porous substrates such as carbon aerogels. The possibility of applying films by the traditional dip-coating method is also demonstrated on titanium slides. The coatings demonstrate low sliding angles for water and water/alcohol solution droplets. Coated aerogels preserve high porosity. It is demonstrated that initially hydrophilic aerogels become highly hydrophobic after coating and selectively absorb oil from water/oil mixtures. The tests of obtained coatings on titanium substrates demonstrate a significant increase in corrosion resistance. The proposed technique has a wide range of potential applications where such slippery coatings should be applied on complex rough substrates: from filtration materials production to textile finishing.

When mussel meets lotus leaf and pitcher plant: A combinational biomimetic strategy for Mg-Li corrosion inhibition

Magnesium-lithium alloys hold immense promise as lightweight structural materials due to combination of unique properties. However, their widespread application is hindered by the inherent poor corrosion resistance. This research presents a novel and cost-effective approach to address this obstacle by utilizing metal-phenol networks inspired by mussel as surface modifiers. These networks facilitate the deposition of nanoparticle on magnesium-lithium (Mg-Li) alloys through chemical reactions between phenolic groups and metal ions. The resulting surface is further enhanced by spray-coating a sheet-like biomimetic superhydrophobic surface (SHS) of alkyl-ketone dimer (AKD), subsequently followed by lubricant infusion with dimethylsilicone oil to create a slippery liquid-infused porous surface (SLIPS). Characterization using multiple techniques confirms the chemical composition and morphology of the modified surface, which significantly improves the corrosion resistance of the magnesium-lithium alloy. Importantly, scanning Kelvin probe measurements reveal that SHS and SLIPS enhance the atmospheric corrosion resistance of the material. Further validation in 3.5 wt% NaCl solution demonstrates remarkable effectiveness of SLIPS. During the initial stages of immersion, the impedance magnitude |Z|0.01 Hz for SLIPS reaches a remarkable 3.78 × 107 Ω·cm2, exceeding those of the SHS, TA-LA141, and bare LA141 by 3, 3, and 6 orders of magnitude, respectively. This performance persists even after long-term immersion, with the SLIPS coating still exhibiting an impedance value one order of magnitude higher than the SHS after extended exposure. These results establish the effectiveness of SLIPS as a promising candidate for significantly upgrading the corrosion resistance of Mg-Li alloy, paving the way for their broader utilization in demanding fields.

Facile fabrication of super-slippery and transparent glass with anti-fogging and self-cleaning characteristics

The present work reports a facile and effective approach for developing slippery liquid-infused porous surface (SLIPS) nanoporous glass. Glass was chemically etched using KOH solution followed by silanization and silicone oil coating using vapour deposition at different temperatures. SLIPS glass showed high contact angle ∼ 115⁰ compared to nascent glass (∼40⁰), low hysteresis (<5°). The sample showed sliding angle < 5⁰ against wide range of liquids with surface tension as low as 28 mN/m. The super-slippery behaviour was coupled with uncompromised transparency (>90 %) and enhanced oil retention owing to the presence of nanopores acting as reservoirs. The SLIPS glass maintained slippery nature (SA < 5⁰) during exposure to ultrasonic vibrations, multiple cloth wiping cycles and multiple high-velocity droplet impacts. The slippery glass showed exquisite combination of properties involving anti-fogging, self-cleaning and anti-staining, with widespread applications.

Durable bionic honeycomb slippery liquid-infused porous surfaces with anti-icing and water-collecting properties

The slippery liquid-infused porous surfaces with nanostructures have emerged as a high-performance multifunctional surface with super-liquid repellency, low contact angle hysteresis and self-healing. However, the amount of lubricant captured by the nanostructures is extremely low, and such oil-filled functional surfaces are susceptible to lubricant loss depletion. In this research, we developed a honeycomb-inspired multidimensional lubricant-infused surface that has a good ability to lock in lubricant while providing excellent mechanical durability. The honeycomb-shaped hexagonal micropores store lubricant to stabilize the smooth oil layer, while the pine-needle shaped nano-needles in the pores retain the lubricant in the pores, making it more difficult to lose the lubricant and increasing durability. Compared to conventional nanostructured slippery liquid-infused porous surfaces, this surface ensures excellent long-term lubrication performance under extreme conditions such as cooling, high shear and water spray impact. Meanwhile the honeycomb mesh lubricant injected into the surface is able to rapidly coalesce and remove water droplets during condensation due to the presence of coarsening effect, and it also retards the formation of ice. This structure provides a new idea for anti-icing and water collection research

Controllable self‐transport of bouncing droplets on ultraslippery surfaces with wedge‐shaped grooves

AbstractPreventing the accretion of droplets on surfaces is vital and slippery liquid‐infused porous surfaces (SLIPS) have promising application prospects, such as surface self‐cleaning and droplet transportation. In this work, controllable self‐transport of bouncing droplets on ultraslippery surfaces with wedge‐shaped grooves is reported. The impact behaviors of droplets on SLIPS under various impact velocities and diameters are explored, which can be classified as hover, total bounce, partial bounce, Worthington jet, and crush. SLIPS with wedge‐shaped grooves were designed to transport accreted droplets. An energy and transport model is established to explain the impact and self‐transport mechanism, where the Laplace pressure and moving resistance between droplets play a key role. Finally, SLIPS with branched wedge‐shaped grooves were designed for droplet self‐transport and demonstrated advantages. This work provides a general reference for spontaneous motion control of sessile droplets, droplets with initial impacting velocity, or even liquid films.

Solid-like slippery surface for anti-icing and efficient fog collection

Ice accumulation on the surface of aerospace and transportation equipment under extreme weather seriously endangers the safety and efficiency of equipment operation. In recent years, metal corrosion, especially in the marine engineering industry, has become a global concern. The slippery liquid infused porous surface (SLIPS) is a new bionic surface which has caused extensive research in recent years, and has great potential in anti-corrosion and anti-icing. In this study, a multifunctional solid-like lubricated slippery surface (SL-SLIPS) was developed by superhydrophobic modification of the base of copper hydroxide nanoneedles and injection of solid-like lubricant synthesized by embedding oil-stored mesoporous silica nanoparticles on the surface of epoxy resin. At −30 °C, the delayed icing time on the surface of the SL-SLIPS sample was 22.6 times that of the original copper substrate. The ice adhesion was tested on the surface of the sample, and the results showed that the adhesion of the icicle on the SL-SLIPS surface was the smallest, which decreased by 89% compared with the original copper substrate. In addition, SL-SLIPS have excellent corrosion resistance and rapid droplet trapping, nucleation and drop. It has good practical application prospects in corrosion resistance of marine equipment and icing resistance of aerospace and transportation equipment. This study provides new ideas for the design of new slippery surfaces and their application in practical fields, such as anti-corrosion of offshore equipment, anti-icing of equipment in aviation and fog collection engineering in industry.

Fabrication of dual functional marine antifouling coatings by infusing epoxy silicone oil modification of quaternary ammonium

Slippery liquid-infused porous surface (SLIPS) has attracted widespread attention in marine antifouling field, but it lacks the contact-killing ability, which limits its long-term anti-fouling efficiency. Herein, a SLIPS endowed with both resist and contact-killing antimicrobial performances is reported. Firstly, anodic aluminum oxides (AAO) with composite structures of the pores and pyramids were prepared and modified with siloxane. Then, a silicone oil containing quaternary ammonium salt (QAS-SO) groups was synthesized and infused into specially designed AAO, forming a QAS-SLIPS. The surface demonstrated remarkably anti-bacterial performances both Gram-positive Bacillus sp. and Gram-negative V. natriegens, and also maintained essential contact-killing antimicrobial activities from the grafted QAS groups. Biofouling testing suggested excellent antifouling performances of the QAS-SLIPS by declining the adhesion of 90.6 % Phaeodactylum tricornutum and 74.1 % of Chlorella pyrenoidosa. Overall, the antifouling performance of QAS-SLIPS comes primarily from two aspects, including physical isolation and contact-killing. Due to the easy of synthesis and excellent broad-spectrum antifouling effects, the QAS-SO could be potentially used for the development of antifouling coatings or as a lubricant for other devices.

Comparison of Anti-Icing, Antifouling, and Anticorrosion Performances of the Superhydrophobic and Lubricant-Infused Coatings Based on a Hollow-Structured Kapok Fiber.

The superhydrophobic surface and slippery liquid-infused porous surface (SLIPS)/lubricant-infused surface (LIS) have attracted increasing attention owing to their multifunctionality. However, their practical applications face several problems such as complex and inefficient preparation technology, loss of lubricant, and fragile microstructures. Therefore, new strategies for preparing microstructures must be developed for constructing superhydrophobic and lubricant-infused coatings. Herein, a low-cost and high-efficiency method for developing superhydrophobic and lubricant-infused coatings based on in situ grown TiO2 on the surface of a hollow kapok fiber (KF) is reported. The anti-icing, antifouling, and anticorrosion performance of the superhydrophobic and lubricant-infused coatings are compared. The superhydrophobic coating reduces the formation and accumulation of ice. The lubricant-infused coating exhibits an extremely low ice adhesion strength and durable anti-icing properties. The superhydrophobic and lubricant-infused coatings show the outstanding antifouling property of diatom; the superhydrophobic surface exhibits superior stability over LIS without an external force field. The lubricant-infused coating shows excellent corrosion resistance and durability when immersed in a 3.5% NaCl solution. The superhydrophobic coating loses its protection as a result of the corrosion media permeating the metal substrate via the electrolytic cell and coating interface, and the lubricant-infused coating provides lasting corrosion resistance because of the lubricant filling into the interface. Although the superhydrophobic coating is fragile and the lubricant-infused coating will lose lubricant, this simple and convenient approach can be repeated to keep the coatings active. This study provides new inspiration for the fabrication of superhydrophobic surfaces and LIS based on natural products.

Icephobic Coating Based on Novel SLIPS Made of Infused PTFE Fibers for Aerospace Application.

The development of slippery surfaces has been widely investigated due to their excellent icephobic properties. A distinct kind of an ice-repellent structure known as a slippery liquid-infused porous surface (SLIPS) has recently drawn attention due to its simplicity and efficacy as a passive ice-protection method. These surfaces are well known for exhibiting very low ice adhesion values (τice < 20 kPa). In this study, pure Polytetrafluoroethylene (PTFE) fibers were fabricated using the electrospinning process to produce superhydrophobic (SHS) porous coatings on samples of the aeronautical alloy AA6061-T6. Due to the high fluorine-carbon bond strength, PTFE shows high resistance and chemical inertness to almost all corrosive reagents as well as extreme hydrophobicity and high thermal stability. However, these unique properties make PTFE difficult to process. For this reason, to develop PTFE fibers, the electrospinning technique has been used by an PTFE nanoparticles (nP PTFE) dispersion with addition of a very small amount of polyethylene oxide (PEO) followed with a sintering process (380 °C for 10 min) to melt the nP PTFE together and form uniform fibers. Once the porous matrix of PTFE fibers is attached, lubricating oil is added into the micro/nanoscale structure in the SHS in place of air to create a SLIPS. The experimental results show a high-water contact angle (WCA) ≈ 150° and low roll-off angle (αroll-off) ≈ 22° for SHS porous coating and a decrease in the WCA ≈ 100° and a very low αroll-off ≈ 15° for SLIPS coating. On one hand, ice adhesion centrifuge tests were conducted for two types of icing conditions (glaze and rime) accreted in an ice wind tunnel (IWT), as well as static ice at different ice adhesion centrifuge test facilities in order to compare the results for SHS, SLIPs and reference materials. This is considered a preliminary step in standardization efforts where similar performance are obtained. On the other hand, the ice adhesion results show 65 kPa in the case of SHS and 4.2 kPa of SLIPS for static ice and <10 kPa for rime and glace ice. These results imply a significant improvement in this type of coatings due to the combined effect of fibers PTFE and silicon oil lubricant.

Coarsening droplets for frosting delay on hydrophilic slippery liquid‐infused porous surfaces

AbstractFrosting occurs due to the freezing of condensed water droplets on a supercooled surface. The nucleated frost propagates through interdroplet bridges and covers the entire surface, resulting from the deposition of highly supersaturated vapor surrounding tiny droplets. While inhibition of the formation of frost bridges is not possible, the propagation of frost can be delayed by effectively removing tiny droplets. Passive technologies, such as superhydrophobic surfaces (SHS) and hydrophobic slippery liquid‐infused porous surfaces (SLIPS), rely on static growth and direct contact with densely distributed droplets. However, use of these approaches in delaying frost propagation involves challenges, as the interdroplet distance remains small. Here, we report a new approach of spontaneous droplet movement on hydrophilic SLIPS to delay the formation of interdroplet frost bridges. Surface tension forces generated by the hydrophilic oil meniscus of a large water droplet efficiently pull neighboring droplets with a diameter of less than 20 μm from all directions. This causes a dynamic separation between water droplets and an adjacent frozen droplet. Such a process delays the formation and propagation of interdroplet frost bridges. Consequently, there is significant delay in frosting on hydrophilic SLIPS compared to those on SHS and hydrophobic SLIPS.

Superwettable surfaces and factors impacting microbial adherence in microbiologically-influenced corrosion: a review.

Microbiologically-influenced corrosion (MIC) is a common operational hazard to many industrial processes. The focus of this review lies on microbial corrosion in the maritime industry. Microbial metal attachment and colonization are the critical steps in MIC initiation. We have outlined the crucial factors influencing corrosion caused by microorganism sulfate-reducing bacteria (SRB), where its adherence on the metal surface leads to Direct Electron Transfer (DET)-MIC. This review thus aims to summarize the recent progress and the lacunae in mitigation of MIC. We further highlight the susceptibility of stainless steel grades to SRB pitting corrosion and have included recent developments in understanding the quorum sensing mechanisms in SRB, which governs the proliferation process of the microbial community. There is a paucity of literature on the utilization of anti-quorum sensing molecules against SRB, indicating that the area of study is in its nascent stage of development. Furthermore, microbial adherence to metal is significantly impacted by surface chemistry and topography. Thus, we have reviewed the application of super wettable surfaces such as superhydrophobic, superhydrophilic, and slippery liquid-infused porous surfaces as "anti-corrosion coatings" in preventing adhesion of SRB, providing a potential avenue for the development of practical and feasible solutions in the prevention of MIC. The emerging field of super wettable surfaces holds significant potential for advancing efficient and practical MIC prevention techniques.

The impact, freezing, and melting processes of a supercooled water droplet onto a cold slippery liquid-infused porous surface

In the present study, we report for the first time the observations of the impact, freezing, and melting processes of a supercooled water droplet onto a cold slippery liquid-infused porous surface (SLIPS). A parameter study of the droplet supercooling degree and the SLIPS temperature was carefully performed. Moreover, the impact process of a water droplet onto the SLIPS under the room temperature conditions was also measured for comparisons. The results showed that the impact kinematics of a water droplet on a SLIPS under the room temperature conditions was significantly different from those of the supercooled water droplet impinging onto a cold SLIPS. Under the same water droplet temperature conditions, the spreading factors rapidly increased to their maximum values at a similar rate, regardless of the change of the SLIPS temperature. Besides, under the same SLIPS temperature conditions, the maximum spreading factor of the water droplet at room temperature was significantly greater than those of the supercooled water droplet cases. When the temperatures of the water droplet and SLIPS were relatively high, freezing process started after the recoiling process had already finished for a certain period of time. However, when the temperatures of the water droplet and SLIPS were relatively low, freezing process could happen during the supercooled water droplet recoiling process. In addition, under the same water droplet temperature conditions, the decrease of the SLIPS temperature could result in the increase of the average energy dissipation rate of the water droplet.

Tuning contact line dynamics on slippery silicone oil grafted surfaces for sessile droplet evaporation

Controlling the dynamics of droplet evaporation is critical to numerous fundamental and industrial applications. The three main modes of evaporation so far reported on smooth surfaces are the constant contact radius (CCR), constant contact angle (CCA), and mixed mode. Previously reported methods for controlling droplet evaporation include chemical or physical modifications of the surfaces via surface coating. These often require complex multiple stage processing, which eventually enables similar droplet-surface interactions. By leveraging the change in the physicochemical properties of the outermost surface by different silicone oil grafting fabrication parameters, the evaporation dynamics and the duration of the different evaporation modes can be controlled. After grafting one layer of oil, the intrinsic hydrophilic silicon surface (contact angle (CA) ≈ 60°) is transformed into a hydrophobic surface (CA ≈ 108°) with low contact angle hysteresis (CAH). The CAH can be tuned between 1° and 20° depending on the fabrication parameters such as oil viscosity, volume, deposition method as well as the number of layers, which in turn control the duration of the different evaporation modes. In addition, the occurrence and strength of stick–slip behaviour during evaporation can be additionally controlled by the silicone oil grafting procedure adopted. These findings provide guidelines for controlling the droplet-surface interactions by either minimizing or maximising contact line initial pinning, stick–slip and/or constant contact angle modes of evaporation. We conclude that the simple and scalable silicone oil grafted coatings reported here provide similar functionalities to slippery liquid infused porous surfaces (SLIPSs), quasi-liquid surfaces (QLS), and/or slippery omniphobic covalently attached liquid (SOCAL) surfaces, by empowering pinning-free surfaces, and have great potential for use in self-cleaning surfaces or uniform particle deposition.

A mechanically durable slippery liquid-infused porous surface based on distinctive ‘jaboticaba-like’ TiO2/sepiolite nanocomposites with superior hot water repellency and anti-corrosion for protecting various substrates

Slippery liquid infused porous surfaces (SLIPS) are widely utilized due to their omniphobicity and distinctive slippery properties. Fragile mechanical properties and unstable lubricant layer of SLIPS have a substantial impact on its long-term application performance. Herein, a pre-oil-infused mechanically robust organic/inorganic composite superhydrophobic surface (SC) for SLIPS with hierarchical roughness was obtained by in-situ growing a significant amount TiO2 nanospheres on the surface of sepiolite (SEP) fiber structures via hydrogen bonding, Ti-O-Si covalent bonding, and electrostatic power, resulting in a unique bionic “jaboticaba-like” structure on SC. Through hydrogen bonding, the hydroxyl groups on the TiO2 surface can also interact with the cross-linked polymer PVDF-HFP (polyethylene fluoride hexafluoropropylene). In the presence of multiple interactions, SC could resist 300 cycles of a rigorous Taber rubbing test with a 500 g weight and yet retain superhydrophobicity. The prepared SLIPS have exceptional hot water (boiling water) resistance, strong shear stability (8000 rpm/min), and water jetting resistance (40 kPa). Corrosion current density of SLIPS and SC was decreased by roughly 4 orders of magnitude and 3 orders of magnitude, respectively, after exposure to 3.5 wt% NaCl solution as compared to bare aluminum substrate. SLIPS have higher long-term corrosion resistance compared to SC. Owing to the “jaboticaba-like” hierarchical structure, SLIPS have great oil-locking capabilities, as well as good mechanical stability and long-term corrosion resistance. This article offers recommendations for developing tough SLIPS for future engineering applications.