Slippery Liquid-infused Porous Surfaces Research Articles

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.

Comparison of Superhydrophilic, Liquid-Like, Liquid-Infused, and Superhydrophobic Surfaces in Preventing Catheter-Associated Urinary Tract Infection and Encrustation.

Over the past decade, superhydrophilic zwitterionic surfaces, slippery liquid-infused porous surfaces, covalently attached liquid-like surfaces, and superhydrophobic surfaces have emerged as the most promising strategies to prevent biofouling on biomedical devices. Despite working through different mechanisms, they have demonstrated superior efficacy in preventing the adhesion of biomolecules (e.g., proteins and bacteria) compared with conventional material surfaces. However, their potential in combating catheter-associated urinary tract infection (CAUTI) remains uncertain. In this research, we present the fabrication of these four coatings for urinary catheters and conduct a comparative assessment of their antifouling properties through a stepwise approach. Notably, the superhydrophilic zwitterionic coating demonstrated the highest antifouling activity, reducing 72.3% of fibrinogen deposition and over 75% of bacterial adhesion (Escherichia coli and Staphylococcus aureus) when compared with an uncoated polyvinyl chloride (PVC) surface. The zwitterionic coating also exhibited robust repellence against blood and improved surface lubricity, decreasing the dynamic coefficient of friction from 0.63 to 0.35 as compared with the PVC surface. Despite the fact that the superhydrophilic zwitterionic and hydrophobic liquid-like surfaces showed great promise in retarding crystalline biofilm formation in the presence of Proteus mirabilis, it is worth noting that their long-term antifouling efficacy may be compromised by the proliferation and migration of colonized bacteria as they are unable to kill them or inhibit their swarming. These findings underscore both the potential and limitations of these ultralow fouling materials as urinary catheter coatings for preventing CAUTI.

Durable anti-icing coating with stability based on self-regulating oil storage layer

In recent years, slippery liquid-infused porous surfaces (SLIPSs) have emerged as a potential alternative to superhydrophobic surfaces (SHSs) due to their exceptional anti-icing properties. However, the current challenge lies in the significant lubricant consumption of SLIPSs, which poses a major obstacle to coating durability. In this study, we developed a durable anti-icing coating with stability (DASS), which combines SHSs and SLIPSs. By incorporating high adsorption particles and low cross-linking density rubber into the oil storage layer, the coating achieves an increased oil storage capacity while effectively inhibiting lubricant loss. Additionally, a superhydrophobic layer is introduced on the surface to ensure surface lubrication and prevent lubricant depletion. The three-layer structure enables the coating to maintain a low τice (<20kPa) during 30 icing/deicing cycles, showcasing superior de-icing durability compared to conventional anti-icing coatings. Interestingly, the original anti-icing properties of the coating can be restored through external oil replenishment. Furthermore, this coating exhibits excellent resistance against fouling, mechanical stress, chemical exposure, temperature variations, and weathering effects, making it highly suitable for practical applications in anti-icing coatings.

Micro-nano-engineered slippery liquid-infused porous surface coating with highly sustainable superhydrophobicity and omniphobicity

Omniphobic coatings designed to repel liquid contamination off the surface can be used in various industries such as automotive, constructions, oil-water separation, anti-fouling marine devices, etc. Various methods have been investigated in the past decade to achieve omniphobicity in which majority of them have proven to be either complex, expensive, or impractical for large scale production. This study has employed a simple three-step, micro-nano-structuring fabrication technique to create physico-chemically and thermo-mechanically robust slippery liquid-infused porous surfaces (SLIPS). Polydimethylsiloxane (PDMS) was used as a base resin engineered with chemical bonding to ZnO micro particles and further physical trapping to hydrophobized TiO2 nano particles to create a hierarchy structure able to repel water and create omniphobicity. With very low contact angle hysteresis (CAH) of <1° and a low tilting angle of <5° for various liquid test subjects, the final coating displays excellent hydrophobicity and omniphobicity in spite of going through harsh mechanical tests such as the cross-hatch and scotch tape tests, pressure tests up to 100 N (500 kPa), thermal stability tests by exposure to low and high temperatures (−18 °C to 120 °C), and chemical pH tests from 1 to 13. We believe that the simple and low-cost micro-nano-engineering approach can be easily scaled up and is suitable for a variety of applications for self-cleaning and hydrophobic purposes.

Droplet manipulation on an adjustable closed-open digital microfluidic system utilizing asymmetric EWOD.

The closed-open digital microfluidic (DMF) system offers a versatile and powerful platform for various applications by combining the advantages of both closed and open structures. The current closed-open DMF system faces challenges in scaling up due to electrode structural differences between closed and open regions. Here we developed an adjustable closed-open DMF platform by utilizing the modified slippery liquid-infused porous surfaces (SLIPS) with asymmetric electrowetting on dielectric (AEWOD) as a hydrophobic dielectric layer. The consistent electrode structures of the bottom printed circuit board (PCB) electrode array on both the closed and open regions, and the utilization of a transparent acrylic with floating potential as the top plate allow a low-cost and easily scalable closed-open DMF system to be achieved. The impacts of applied voltage, parallel plate spacing, electrode switching interval, and electrode driving strategies on various droplet manipulations were investigated. The results show that the optimal plate spacings range from 340-510 μm within the closed region. Meanwhile, we also studied the influence of the thickness, geometry, and position of the top plate on the droplet movement at the closed-open boundary. Through force analysis and experimentation, it is found that a thin top plate and a bevel of ∼4° can effectively facilitate the movement of droplets at the boundary. Finally, we successfully achieved protein staining experiments on this platform and developed a customized smartphone application for the accurate detection of protein concentration. This innovative closed-open DMF system provides new possibilities for future applications in real-time biological sample processing and detection.

Earthworm skin inspired rapid secretion of continuous liquid slippery film via nanochannels

The lubricating layer of Slippery Liquid-Infused Porous Surfaces (SLIPS) has certain fluidity and low friction coefficient so that it can serve as a good barrier and protection effect. However, common SLIPS suffer from poor oil-holding capacity that lubricating oil is easy to be washed away and irreparable in practical application. Inspired from self-lubricating earthworm skin, we demonstrate a nanochannels surface covered by silicone-oil-infused polydimethylsiloxane (PDMS), which could form continuous self-complement lubricating layer. The strong capillarity of the confined nanochannels showed self-repairing properties of injected liquid film, which can recover lubricating performance quickly after physical damage for many times, exhibiting high stability. This study provides a simple and reliable way for the preparation of long-term effective antifouling functional interface materials.

Slippery Porous-Liquid-Infused Porous Surface (SPIPS) with On-Demand Responsive Switching between "Defensive" and "Offensive" Antifouling Modes.

Slippery liquid-infused porous surfaces (SLIPS) have received widespread attention in the antifouling field. However, the reduction in antifouling performance caused by lubricant loss limits their application in marine antifouling. Herein, inspired by the skin of a poison dart frog which contains venom glands and mucus, a porous liquid (PL) based on ZIF-8 is prepared as a lubricant and injected into a silicone polyurethane (SPU) matrix to construct a new type of SLIPS for marine antifouling applications: the slippery porous-liquid-infused porous surface (SPIPS). The SPIPS consists of a responsive antifoulant-releasing switch between "defensive" and "offensive" antifouling modes to intelligently enhance the antifouling effect after lubricant loss. The SPIPS can adjust antifouling performance to meet the antifouling requirements under different light conditions. The wastage of antifoulants is reduced, thereby effectively maintaining the durability and service life of SLIPS materials. The SPIPS exhibits efficient lubricant self-replenishment, self-cleaning, anti-protein, anti-bacterial, anti-algal, and self-healing (97.48%) properties. Furthermore, it shows satisfactory 360-day antifouling performance in actual marine fields during boom seasons, demonstrating the longest antifouling lifespan in the field tests of reported SLIPS coatings. Hence, the SPIPS can effectively promote the development of SLIPS for neritic antifouling.

Tetradecanoate in situ reaction prepares a stable and efficient 3D framework for fog collection

Slippery liquid-infused porous surface (SLIPS) strategy has recently attracted significant attention in the field of foggy water collection. However, the surface on which the lubricant is injected is often unstable, losing control of fog capture and droplet movement. The 3D frame structure combined with the nano-needle-like structure produces a strong oil locking ability to provide more stable Slippery liquid-infused porous surface. In this work, copper myristate flower-like clusters were directly grown on the walls of porous copper foam wires by in situ reactions, resulting in a superhydrophobic skeleton directly, and a 3D skeleton of the injected lubricant was obtained after lubricant injection. The framework also features excellent droplet capture, droplet coalescent growth, and droplet removal, as well as significant anti-ice and anti-fouling properties. This work simplifies the preparation process and it is easy to meet the reaction conditions. The prepared lubricant injected skeleton has excellent atomized collection properties (98.7% higher than the original sample) and has the potential for mass fabrication. It provides a new idea for the efficient and rapid preparation of the liquid infusion fog collection structure.

Robust solid slippery coating for anti-icing and anti-sticking

The slippery liquid-infused porous surface (SLIPS) inspired by the Nepenthes plants has received great attention due to the excellent water-repellency with ultra-low sliding angle. However, the practical application of SLIPS is restricted greatly due to the inevitable loss of lubricant trapped by the micro/nanostructures and the adverse environmental impact of the fluorinated lubricant. Herein, we report a simple and efficient strategy to form a solid slippery coating without loss of lubricant. A commercially available coating with the nominal active constituent of polysilazane (PSZ) was used as the matrix and was slippery with the water sliding angle of approx. 25°. To enhance the water repellency, α, ω- hydroxy silicone oil (HSO) was added into the PSZ solution and the sliding angle of the cured composite coating decreased to approx. 7.0°. The chemical interaction between the Si-H / Si-N bonds of PSZ and the -OH group of HSO produced strong inter-molecular attraction. Acrylic resin was further added to strengthen the overall integrity of the coating and the so-obtained composite coating was durable with no loss of lubricant. Moreover, the curing of PSZ at room temperature was accelerated greatly by HSO from longer than one week to less than one day due to the above-mentioned chemical interactions between the Si-H / Si-N bonds and the -OH group. The solid slippery coating showed promising potential in preventing ice adhesion and anti-sticking to adhesive paper due to its low adhesion properties.

Enhancing corrosion inhibition of zinc with biomimetic slippery liquid-infused porous surfaces (SLIPS): An on-site fabrication strategy

Biomimetic Slippery Liquid-Infused Porous Surfaces (SLIPS) represent a promising solution for protecting metallic materials from the threats of corrosion. However, the practical use of SLIPS coating faces substantial obstacles, primarily stemming from the complexities of surface microstructures and the presence of oil layer. These factors present significant challenges in terms of fabrication, transportation and overall effectiveness of the coating. In response to these challenges, the concept of on-site fabrication is proposed as a promising alternative in this study. Instead of relying on the prefabrication paradigm, this approach involves generating SLIPS right at the location where they will be used. For executing the on-site fabrication, the routes and processes have to be facile and easy to realize. To explore this on-site fabrication strategy, our study involves the reconstruction of zinc through a displacement reaction with tin salt solution, resulting in the creation of a dendritic structure. Subsequently, a straightforward modification using a hydrophobic compound dodecanethiol confers superhydrophobicity to the surface. Introducing a lubricant into superhydrophobic matrix achieves SLIPS coating, which is proved to highly enhance corrosion resistance to the underlying zinc substrate. The corrosion current density of zinc decreases significantly, dropping from the initial 1.92 × 10−4 A/cm2 on bare zinc to a mere 5.65 × 10−7 A/cm2 with SLIPS coated on metal surface. Furthermore, the use of SLIPS provides the metal substrate with increased resistance to icing. By resorting to the facile routes without the requirement of the rigid conditions, this on-site fabrication strategy poses significant promise for practical application of the versatile SLIPS coating.

Improving antifouling functions of titanium alloys by robust slippery liquid-infused porous surfaces with tailored multiscale structures

The practical applications of delicate micro/nanostructures with extraordinary functions are severely limited by the insufficient mechanical stability. To address this challenge, the incorporation of protective “armor” for fragile micro/nanostructures has emerged as a promising approach to endow mechanical robustness. In this study, we have employed the concept of “armor” by fabricating honeycomb concave cells on surfaces of large-size Ti-6Al-4V (TC4) plates using screen-printed etching, followed by anodic oxidation to establish an array of multiscale structures. A new type of slippery liquid-infused porous surface (TC4-SLIPS) has been further produced by the infusion of lubricants into the exquisite multiscale structures. The results show that the tailored multiscale structures enhance stabilization of the lubricant layer, which can retain surface hydrophobicity (WCAs ∼ 104.8°) even after artificial seawater washout for 30 days. Moreover, the multiscale structures improve resistance to external mechanical abrasion, resulting in the robust hydrophobic nature of the SLIPS. Attractively, TC4-SLIPS can effectively inhibit the adhesion and proliferation of Pseudoalteromonas bacteria, and thereby prevent the formation and proliferation of bacterial biofilms. Therefore, the state-of-the-art TC4-SLIPS with multiscale structures has shown significance for the long-term antifouling of titanium alloys in practical applications.

Blue-ringed Octopus inspired slippery coating with physico-chemical synergistic antifouling properties

Bionic superhydrophobic and slippery liquid-infused porous surfaces (SLIPS) have attracted great interest due to their antifouling properties, while the poor stability, complex preparation of porous structures and rapid loss of lubricants, as well as only possessing physical antifouling capability, have hindered their further application. Herein, inspired by the Blue-ringed Octopus’ defensive equipment of slippery skin and toxin secretion when faced with predators, an antifouling slippery coating containing repellent is easily prepared. The repellent capsaicin physically connected to the slippery networks can be activated to accelerate release in response to the changes in pH caused by bacterial secretions, and the adhesion resistance of the coating is improved by 99 % compared to aluminum plates, both conclusions confirmed by experimental and computational data. The anti-adhesive properties of the slippery surface, combined with the repellent properties of capsaicin provides the coating with excellent synergistic physico-chemical antifouling performance. This is demonstrated by the fact that the surface of the coating remains clear after contamination with proteins, bacteria and diatoms, as well as after 65 days of marine field testing. Additionally, the slippery surface has self-healing and outstanding anticorrosion ability. Therefore, the eco-friendly coating has promising application prospects in marine field for antifouling purposes.

Influence of pH on corrosion resistance of slippery liquid-infused porous surface on magnesium alloy

A slippery liquid-infused porous surface (SLIPS) was developed on the AZ31 Mg alloy to provide corrosion protection. A layered double hydroxide (LDH) was applied to providing accommodation for liquid lubricants. The electrolyte pH was adjusted to obtain the best LDH film for the development of a SLIPS. The surface morphology, surface wettability, and electrochemical behavior of the SLIPS formed at different pH values were investigated. The results indicated that the MgAl-LDH film synthesized at a pH of 10.5 had a maximum thickness of 3.51 μm to accommodate the most silicone oil, with a mass of 0.22 mg/mm2, which provided the best corrosion protection, with the lowest corrosion current density of 3.72×10−9 A/cm2. On the other hand, compared with the superhydrophobic surface, the SLIPS imparted better corrosion resistance for the AZ31 substrate in both electrochemical behavior and long-term immersion test. The improved corrosion resistance of the SLIPS can further accelerate the application of Mg alloys in practice.

Droplet Self-Propulsion on Slippery Liquid-Infused Surfaces with Dual-Lubricant Wedge-Shaped Wettability Patterns.

Young's equation is fundamental to the concept of the wettability of a solid surface. It defines the contact angle for a droplet on a solid surface through a local equilibrium at the three-phase contact line. Recently, the concept of a liquid Young's law contact angle has been developed to describe the wettability of slippery liquid-infused porous surfaces (SLIPS) by droplets of an immiscible liquid. In this work, we present a new method to fabricate biphilic SLIP surfaces and show how the wettability of the composite SLIPS can be exploited with a macroscopic wedge-shaped pattern of two distinct lubricant liquids. In particular, we report the development of composite liquid surfaces on silicon substrates based on lithographically patterning a Teflon AF1600 coating and a superhydrophobic coating (Glaco Mirror Coat Zero), where the latter selectively dewets from the former. This creates a patterned base surface with preferential wetting to matched liquids: the fluoropolymer PTFE with a perfluorinated oil Krytox and the hydrophobic silica-based GLACO with olive oil (or other mineral oils or silicone oil). This allows us to successively imbibe our patterned solid substrates with two distinct oils and produce a composite liquid lubricant surface with the oils segregated as thin films into separate domains defined by the patterning. We illustrate that macroscopic wedge-shaped patterned SLIP surfaces enable low-friction droplet self-propulsion. Finally, we formulate an analytical model that captures the dependence of the droplet motion as a function of the wettability of the two liquid lubricant domains and the opening angle of the wedge. This allows us to derive scaling relationships between various physical and geometrical parameters. This work introduces a new approach to creating patterned liquid lubricant surfaces, demonstrates long-distance droplet self-propulsion on such surfaces, and sheds light on the interactions between liquid droplets and liquid surfaces.

Innovative Solid Slippery Coating: Uniting Mechanical Durability, Optical Transparency, Anti-Icing, and Anti-Graffiti Traits.

Slippery coatings, such as the slippery liquid-infused porous surface (SLIPS), have gained significant attention for their potential applications in anti-icing and anti-fouling. However, they lack durability when subjected to mechanical impact. In this study, we have developed a robust slippery coating by blending polyurethane acrylate (PUA) with methyltriethoxysilane (MTES) and perfluoropolyether (PFPE) in the solvent of butyl acetate. The resulting mixture is homogeneous and allows for uniform coating on various substrates using a drop coating process followed by drying at 160 °C for 3 h. The cured coating exhibits excellent water repellency (contact angle of ~108° and sliding angle of ~8°), high transparency (average visible transmittance of ~90%), exceptional adherence to the substrate (5B rating according to ASTMD 3359), and remarkable hardness (4H on the pencil hardness scale). Moreover, the coating is quite flexible and can be folded without affecting its wettability. The robustness of the coating is evident in its ability to maintain a sliding angle below 25° even when subjected to abrasion, water jetting, high temperature, and UV irradiation. Due to its excellent nonwetting properties, the coating can be employed in anti-icing, anti-graffiti, and anti-sticking applications. It effectively reduces ice adhesion on aluminum substrates from approximately 217 kPa to 12 kPa. Even after 20 cycles of icing and de-icing, there is only a slight increase in ice adhesion, stabilizing at 40 kPa. The coating can resist graffiti for up to 400 cycles of writing with an oily marker pen and erasing with a tissue. Additionally, the coating allows for easy removal of 3M tape thereon without leaving any residue.

Multifunctional slippery photothermal coating

Slippery liquid-infused porous surface (SLIPS) has shown significant application values in various areas and has been commonly obtained by injecting the water-immiscible lubricant into a low-surface-energy modified micro/nano-structured surface. Constrained by the availability of desirable structured substrates or simple preparation schemes, the exploration of SLIPS with multifunctionality and universality that is facile to fabricate and robust in realistic applications remains challenging. Herein, we propose a one-step, fluoride-free and unconventional protocol based on a one-pot reaction of polysilazane (PSZ), silicone oils and multiwalled carbon nanotubes (MWCNT), which creates not only the favorable micro/nano-scale physical structures and surface chemistry for the excellent slippery property (sliding angle < 3°) and robust lubricant retention, but also the superior photothermal responsiveness for the potential multifunctional applications. It has been demonstrated that the proposed multifunctional slippery photothermal coating (MSPC) displayed outstanding potential in corrosion resistance, droplet manipulation and anti/de-icing. We envision that the proposed strategy could be realized in the real-life applications.

Cinnamaldehyde grafted porous Aerogel-Organ gel liquid infused surface for achieving difunctional long-term dynamic antifouling

Marine biofouling caused a number of questions about energy consumption and safety. While there were still some challenges in developing an environmentally friendly, non-toxic and long-term antifouling slippery liquid-infused porous surface (SLIPS). Here, we proposed a difunctional antifouling strategy via constructing porous polydimethylsiloxane (PDMS) surface with a layer of aerogel by sol-gel method and grafted cinnamaldehyde chemically. The improvement in structure enhanced the liquid storage stability of coating, which in turn increases its anti-bioadhesive ability. In addition, the grafted cinnamaldehyde could also be used to act as a chemical antibacterial and is intelligently released in the face of harsh fouling environments, which played a key role in prolonging the antibacterial lifespan of the coating. After the 120-hour anti-bacteria experiment and the 25-day anti-algae experiment, the anti-Escherichia coli (anti-E. coli) rate and the anti-algae rate of the coating reached 99.6% and 99.9%, respectively, which was attributed to the excellent long-term antifouling properties of the coating. The combination of physical and chemical antifouling property made the coating achieve long-term fouling prevention for marine engineering equipment.

Oil sands in glacial till as a driver of fast flow and instability in the former Laurentide Ice Sheet: Alberta, Canada

AbstractReconstructions of the southwestern Laurentide Ice Sheet (LIS) from geomorphology have revealed complex cross‐cutting ice streams, indicative of surging and flow switching. This flow pattern and behaviour is distinct from the rest of the ice sheet where ice streams flowed radially to the ice sheet margin. Many ice streams in the southwestern sector originate around the Alberta Oil Sands (AOS). Previous reports have detected oil sands material in surficial and glacial sediments south of the AOS, demonstrating potential glacial mobilisation of the oil sands. In this study, we use geochemical fingerprinting to systematically investigate surficial sediments from the former Central Alberta Ice Stream (CAIS) flow track. We compare the geochemical signatures of 82 sediments from within and outside the CAIS limits with those of the AOS (from mines and natural exposures), using gas chromatography–mass spectrometry oil–oil correlation techniques. Our results provide geochemical evidence of glacial erosion and long‐distance mobilisation of AOS producing contamination signatures in sediments throughout the CAIS flow track. The strength of the AOS signature is particularly strong in sediments along the terminating margins, to the east of Calgary and in the Cooking Lake area to the southeast of Edmonton. These results inform theoretical models of enhanced slipperiness, inspired by slippery liquid infused porous surfaces (SLIPS), whereby oil lubrication of the basal sediment influences the degree of sliding and basal deformation in the ice stream. We hypothesise that naturally occurring hydrocarbons at the basal interface exerted control on the location of the onset zone of the CAIS and surrounding ice streams in Alberta. The enhanced slipperiness caused by oil contamination may also explain ice streaming and surging in other ice sheets, such as the Barents Sea Ice Sheet, where hydrocarbons are known to have been driven to the sedimentary interface during glaciation.