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

Strategy for Fabricating Degradable Low-Surface-Energy Cross-Linked Networks with Excellent Anti-Fouling Properties

Marine biofouling negatively impacts marine industries and ship navigation. However, current coatings are based on a single antifouling mechanism, which is insufficient to cope with the complex and ever-changing marine environment. Herein, multifunctional antifouling coatings were developed using a material system containing perfluoropolyether and caprolactone chains. First, an acrylic resin containing perfluoropolyether side chains was synthesized as a liquid-repellent component and then a degradable cross-linked network was constructed by bridging polycaprolactone chains. Surprisingly, polycaprolactone chains not only effectively improved the tensile strength but also provided flexibility to the resin. Thus, the coating exhibited satisfactory mechanical stability and low roughness (4.06 nm) during dynamic polishing. It is worth noting that the cross-linked network with a low surface energy (SE) (22.0 mJ·m-2) effectively inhibited the adhesion of marine fouling organisms. Moreover, the hydrolysis of ester groups promoted the formation of a self-renewing surface, and the synergistic effect of the low SE and degradability of the coating ensured excellent and long-lasting antifouling performance of the coating. The coating reduced the adhesions of Vibrio alginolyticus, Nitzschia sp., and Navicula sp. by 99.99, 84.6, and 91.0%, respectively, compared with their adhesions to a commercially available self-polishing coating (B3000). Thus, the degradable low-SE antifouling coating produced using the proposed strategy can be potentially applied to various maritime industries.

A Fabrication Strategy for Durable Slippery Organic Coating toward Antifouling and Anticorrosion via Digital Light Processing

The slippery liquid-infused porous surfaces (SLIPS) have recently attracted significant interest in marine antifouling and corrosion protection. Nevertheless, the insufficient durability and corrosion resistance of SLIPS considerably affect their application potential. In this work, a preparation strategy for ultradurable slippery organic coating was proposed to combat biofouling and corrosion. Digital light processing (DLP) was first employed to fabricate organic protective coatings with gradient porous structures to improve the stability and durability of the SLIPS. The structure with a smaller pore size in the upper segment relative to the basal area was designed to concurrently enhance the lubricant's storage and retention capabilities. The antifouling experiment demonstrated excellent antifouling performance, with a bacterial colonization of merely 2.08% after immersion in a Pseudomonas aeruginosa solution for 28 days. The antialgae assessment demonstrated that the surface antifouling efficacy of the gradient SLIPS coating was enhanced by 99.75% after a 10-day immersion period. The EIS results indicated that the SLIPS coating with a gradient porous structure exhibited remarkable corrosion resistance, as evidenced by a |Z|0.01 Hz value of 2.93 × 1010 Ω·cm2 after 60 days of immersion. The gradient porous structure effectively resolves the intrinsic dilemma between the storage and depletion of lubricant, which greatly improves the stability and durability of the SLIPS coating. The ultradurable slippery organic coating with facile preparation and controllable structure exhibits exceptional long-term antifouling and anticorrosion properties, thereby making it highly promising for potential application.

Bioinspired Active Dynamic Dust Remover for Multiscale Stardust Repelling of Unmanned Probe Surface

Unmanned probes, mainly powered by solar panels, are effective tools for exploiting space resources to expand the human habitat. However, it remains a great challenge for the unmanned probes to actively repel multiscale dust particles in space. Inspired by the synergistic antifouling mechanism of fly wings and legs, a biomimetic dynamic antifouling surface (BDAS) was prepared based on a combination of self-assembly and template inversion. BDAS consists of flexible and controllable cilia with ultrahigh aspect ratio. Under the control of an external magnetic field, BDAS can perform three modes of dust removal tasks. The synergism of these three modes ensures that BDAS provides superior dust removal against multiscale dust particles in complex environments. Compared to conventional passive dust removal surfaces, the dust removal efficiency is increased by 941%. As proof of concept, BDAS was installed on a lunar probe and achieved effective removal of simulated lunar soil (up to 1158%).

Intelligent antibacterial coatings based on sensitive response and periodic fast drug release for long-term defense against corrosion induced by sulfate-reducing bacteria

Pitting corrosion caused by sulfate-reducing bacteria (SRB) significantly shortens the lifespan of metallic pipelines. Antibacterial coatings containing S2--responsive drug-loaded nanocontainers represent a promising method to mitigate SRB corrosion. However, the challenge of balancing rapid bactericide release with continuous antibacterial effect limits their practical application. In this study, a S2- and pH dual-responsive periodic drug release system was developed based on raspberry-like mesoporous silica intelligent nanocontainers (BAC-RMSNs@Cu-BTA) loaded with bactericide benzalkonium chloride (BAC) and blocked by copper-benzotriazole nano valves (Cu-BTA). When S2- concentration exceeded 0.5 mM or pH fell below 6.3, the intelligent nanocontainers accelerated drug release. Under simultaneous S2- and pH stimulation, the drug release rate was increased by 91 %, compared to isolated S2- stimulation. The sustained release duration exceeded 384 h, which was more than twice that of existing S2--responsive nanocontainers. The reversible dissociation-complexation transition of Cu-BTA nano valves and the adsorption effect of the raspberry structure facilitated an inhibition of drug release after the stimulation disappeared, thereby enabling cyclic drug release and extending the antibacterial duration. The epoxy coating embedded with BAC-RMSNs@Cu-BTA showed excellent repeatable sterilization, long-term antibacterial adhesion and corrosion medium barrier ability in the SRB environment. Based on active intelligent sterilization and passive physical barrier effects, the composite coating's resistance to SRB corrosion in the simulated internal environment of pipelines was 14.6 times that of coating containing BAC-RMSNs. This study aims to provide valuable insights for the design of innovative long-acting antibacterial coatings.

A Bioinspired Antifouling Coating Based on "Host-Guest Interaction" Strategy: Durable Slipperiness and Tunable Transparency

Lubricant-mediated surfaces limit their practical application in transparent antifouling due to the inherent drawbacks of lubricant loss and poor transparency. Liquid-Like Surfaces(LLSs)are expected to solve these problems. Herein, inspired by the skin structure of globefish, some slippery LLSs are prepared with the cyclodextrin-eugenol inclusion complexes as the poison glands and flexible silicone chains as the liquid-like layer. LLSs kill attached organisms by slowly secreting environmentally friendly eugenol through poison glands. Short-term explosive release of the drug is avoided owing to host-guest interactions. In addition, due to low surface energy, the covalently linked flexible silicone chains spontaneously migrate to the surface of the coating, effectively preventing the adhesion of fouling and improving the durability of slippery surfaces, achieving both offense and defense. LLSs exhibit outstanding antifouling, mechanical, and adhesive performance. Interestingly, the transparency of LLSs in seawater and freshwater is quite different. This different behavior is attributed to ion-dipole interactions weakening the hydrogen bonding of water molecules to the polymer network, which provides some insights into tuning the transparency responsiveness of polymers. Furthermore, LLSs-coated lenses achieve a long-lasting transparent application in seawater for 90 days, providing a promising approach for surface antifouling of lenses in marine environments.

Amyloid Proteins Adhesive for Slippery Liquid-Infused Porous Surfaces

Biomimetic slippery liquid-infused porous surfaces (SLIPS) have emerged as a promising solution to solve the limitations of superhydrophobic surfaces, such as inadequate durability in corrosion protection and a propensity for frosting. However, the challenge of ensuring strong, lasting adhesion on diverse materials to enhance the durability of the lubricant layer remains. The research addresses this by leveraging amyloid phase-transitioned lysozyme (PTL) as an adhesive interlayer, conferring stable attachment of SLIPS across a variety of substrates, including metals, inorganics, and polymers. The silica-textured interface robustly secures the lubricant with a notably low sliding angle of 1.15°. PTL-mediated adhesion fortifies the silicone oil attachment to the substrate, ensuring the retention of its repellent efficacy amidst mechanical stressors like ultrasonication, water scrubbing, and centrifugation. The integration of robust adhesion, cross-substrate compatibility, and durability under stress affords the PTL-modified SLIPS exceptional anti-fouling, anti-icing, and anti-corrosion properties, marking it as a leading solution for advanced protective applications.

A Lionfish-Skin-Inspired Intrinsic Antifouling Coating for Full-Ocean-Depth up to 7730 Meters

As marine equipment advances from shallow to deep-sea environments, the demand for high-performance antifouling materials continues to increase. The lionfish, a species inhabiting both deep-sea and shallow coral reefs, prevents fouling organism adhesion via its smooth, mucus-covered skin, which contains antimicrobial peptides. Inspired by lionfish skin, this work integrates zwitterionic segments with hydration-based fouling-release properties and the furan oxime ester structure with intrinsic antibacterial activity to develop a silicone-based antifouling coating capable of operating from shallow to deep-sea environments. The coating exhibits excellent antifouling properties in shallow-water environments, completely inhibiting protein adhesion and reducing bacterial, algae adhesion by up to 33.23% and 85.23%, respectively. displays superior intrinsic bactericidal activity, achieving a 100% bactericidal rate. Field panel immersion tests confirmed the coating's effectiveness in preventing the adhesion of large shallow-water fouling organisms. After 51 days of immersion at a maximum depth of 7730 meters in the Mariana Trench, no live bacteria are detected on the coating surface, which remained in excellent condition and retained its full bactericidal efficacy. This antifouling coating presents a promising solution for marine equipment across full ocean depths adn expands applications in the marine industry.

An Imine-Functionalized Silicone-Based Epoxy Coating with Stable Adhesion and Controllable Degradation for Enhanced Marine Antifouling and Anticorrosion Properties

Biofouling and corrosion of submerged equipment caused by marine organisms severely restrict the rapid development of the marine industry. Traditional antifouling or anticorrosion coatings typically serve a sole purpose and exhibit limited degradability upon failure, rendering them inadequate for current demands. Herein, a novel imine-functionalized command-degradable bio-based epoxy coating (SAHPEP-DDM) with enhanced integrated antifouling and anticorrosion performances was synthesized utilizing 1,3-bis (3-aminopropyl)-1,1,3,3-tetramethyldisiloxane and syringaldehyde. Compared with commercial epoxy resins (E51-DDM) and polydimethylsiloxanes (PDMS), the SAHPEP-DDM coating exhibits superior antifouling and anticorrosion properties due to the existence of -C=N- and Si-O-Si chain segments in the cross-linking network. The coating achieves resistance rates of 99.59 % and 99.20 % against E. coli and S. aureus, respectively, and shows promising resistance against algae and proteins, as well as excellent corrosion resistance in artificial seawater (with |Z|0.01 Hz and arc radius of about 1011 Ω and exceeding 1010 Ω respectively). The coating also exhibits excellent chemical resistance in organic solvents as well as neutral and alkaline environments. Moreover, its controlled degradation after coating failure can be achieved in acid aqueous solutions through temperature and acidity adjustments, facilitated by the presence of -C=N-. This work presents a novel degradable coating successfully coupled the dual functions of antifouling and anticorrosion coatings, avoiding the employment of intermediate coat, indicating vast potential for application in various marine engineering fields.

Designing a photocatalytic and self-renewed g-C3N4 nanosheet/poly-Schiff base composite coating towards long-term biofouling resistance

Inhibiting the adhesion and growth of marine microorganisms through photocatalysis is a potentially efficient and environmentally friendly antifouling strategy. However, the undesired "shading effect" caused by resin coatings and microbial deposition reduces the utilization of the catalysts and leads to a failure in the antifouling active substance on the coating surface. Here, we successfully developed a composite coating (DPC-x) combining g-C3N4 nanosheet (g-C-NS) photocatalysts with degradable green poly-Schiff base resins, which integrates the dual functions of enhanced dynamic self-renewal and photocatalytic antibacterial activities towards long-term anti-biofouling. The controllable and complete degradability of the poly-Schiff base polymer chains and the self-renewal mechanism of the DPC-x coating exposed the internal g-C-NS, which provided a constant stream of photocatalytic reactive interfaces for 100% utilization and release of the photocatalysts. g-C-NS were homogeneously dispersed in the degradable resin coating, significantly enhancing and adjusting the self-renewal rate of the poly-Schiff base resin coating in visible light. The degradation reaction rate of DPC-0.2 (20 wt% g-C-NS) was 40 times that of DPC, thus improving the capabilities of surface self-renewal and fouling-release. Due to the synergistic antifouling mechanism of the efficient antibacterial properties and the enhanced degradation/self-renewal, the antimicrobial rates of DPC and DPC-0.2 were 94.58% and 99.31% in the dark, and 98.2% and 99.87% in visible light. DPC-x has excellent all-weather antimicrobial efficacy and could offer a new perspective on eco-friendly marine antifouling strategies.

Bioinspired Slippery Surfaces for Liquid Manipulation from Tiny Droplet to Bulk Fluid

Slippery surfaces, which originate in nature with special wettability, have attracted considerable attention in both fundamental research and practical applications in a variety of fields due to their unique characteristics of superlow liquid friction and adhesion. Although research on bioinspired slippery surfaces is still in its infancy, it is a rapidly growing and enormously promising field. Herein, a systematic review of recent progress in bioinspired slippery surfaces, beginning with a brief introduction of several typical creatures with slippery property in nature, is presented. Subsequently,this review gives a detailed discussion on the basic concepts of the wetting, friction, and drag from micro- and macro-aspects and focuses on the underlying slippery mechanism. Next, the state-of-the-art developments in three categories of slippery surfaces of air-trapped, liquid-infused, and liquid-like slippery surfaces, including materials, design principles, and preparation methods, are summarized and the emerging applications are highlighted. Finally, the current challenges and future prospects of various slippery surfaces are addressed.

NIR-Driven Self-Healing Phase-Change Solid Slippery Surface with Stability and Promising Antifouling and Anticorrosion Properties

Slippery liquid-infused porous surfaces (SLIPSs) have great potential to replace traditional antifouling coatings due to their efficient, green, and broad-spectrum antifouling performance. However, the lubricant dissipation problem of SLIPS severely restricts its further development and application, and the robust SLIPS continues to be extremely challenging. Here, a composite phase-change lubricant layer consisting of paraffin, silicone oil, and MXene is designed to readily construct a stable and NIR-responsive self-healing phase-change solid slippery surface (PCSSS). Collective results showed that PCSSS could rapidly achieve phase-change transformation and complete self-healing under NIR irradiation and keep stable after high-speed water flushing, centrifugation, and ultrasonic treatment. The antifouling performance of PCSSS evaluated by protein, bacteria, and algae antiadhesion tests demonstrated the adhesion inhibition rate was as high as 99.99%. Moreover, the EIS and potentiodynamic polarization experiments indicated that PCSSS had stable and exceptional corrosion resistance (|Z|0.01Hz = 3.87 × 108 Ω·cm2) and could effectively inhibit microbiologically influenced corrosion. The 90 day actual marine test reveals that PCSSS has remarkable antifouling performance. Therefore, PCSSS presents a novel, facile, and effective strategy to construct a slippery surface with the prospect of facilitating its application in marine antifouling and corrosion protection.

Biomimetic Slippery Surface with Exclusive Liquid-Repellent and Self-Cleaning Properties for Antifouling

The nature always offers amazing inspiration, where it is highly desirable to endow coatings on marine equipment with powerful functions. An excellent example is slippery zone of Nepenthes pitcher, which possesses novel liquid-repellent and self-cleaning performance. Therefore, this study presents an efficient fabrication method to prepare a novel coating. The coatings were fabricated by designing biomimetic textures extracted from the lunate bodies of slippery zone on polydimethylsiloxane (PDMS) and then grafting Dictyophora indusiata polysaccharide (DIP) modifier. The as-prepared slippery coatings exhibited outstanding antifouling properties against kinds of daily life pollutants such as Chlorella and coffee. This synergistic strategy was proposed combined with environmentally friendly modifier grafting and heterogeneous microstructure on the surface to broaden new probabilities for manufacturing slippery coatings with incredible protective functionality.

Room-temperature endogenous lubricant-infused slippery surfaces by evaporation induced phase separation

We present a novel approach to fabricate endogenous slippery lubricant-infused porous surfaces (eSLIPS) at room temperature using an evaporation-induced phase separation process. The ternary coating system, comprising ethylene-propylene copolymer, caprylyl methicone, and n-hexane, forms a porous structure in situ infiltrated with lubricant, resulting in surfaces with remarkable anti-fouling and anti-icing properties.