Lube-Tech PUBLISHED BY LUBE: THE EUROPEAN LUBRICANTS INDUSTRY MAGAZINE
adoption of less harmful compounds, mostly being copper and zinc in anti-fouling paints and biocides, which, although effective, continue to pose ecological risk and require frequent reapplication, usually 6 to 12 months, making them costly and unsustainable in the long term [13,17].
In response, current anti-fouling strategies are focused on nontoxic, biodegradable, and biologically inspired solutions. Advancements in surface-engineering combined with biolubricants, nanoparticle-infused coating, and stimuli-responsive materials, are paving the way for anti-fouling systems that are both environmentally friendly and economically viable.
Slippery liquid infused porous surfaces To combat the issues of biofouling, a slippery liquid- infused porous surface (SLIPS) was created by Aizenberg’s group [18] in 2011 at Wyss Institute for Biologically Inspired Engineering of Harvard University, embedding a liquid, usually a lubricant, into the substrate, enhancing anti-fouling properties and corrosion resistance [18]. This idea was inspired by Nepenthes pitcher plants, which trap prey with an infused slippery liquid on their microstructure surface. SLIPS technology can replicate this mechanism by locking lubricants in engineered surface textures to create a smooth, non-adhesive interface [18].
SLIPSs are composed of two key components: a substrate with appropriate surface energy and roughness, and a lubricating liquid held by capillary forces. The lubricant layer forms a slippery, dynamic barrier that effectively resists the adhesion of various marine organisms, from microorganisms such as algae to larger biofoulers like mussels [19].
The surface morphology of the substrate is critical to SLIPS performance. By introducing micro- or nanostructures, these surfaces can better retain the lubricants, minimising lubricant loss under shear stress, and enhancing anti-fouling efficacy [18]. Techniques
36 LUBE MAGAZINE NO.189 OCTOBER 2025
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such as lithography and etching are commonly used to fabricate structured surfaces, including nanopillars and nanosheets [20]. One-dimensional (1D) nanostructured materials can provide promising and supreme superhydrophobic self-cleaning surfaces because of their extremely high surface area and unparalleled morphology. Thus, the incorporation of 1D nanomaterial in non-toxic fouling release coatings is a strategic goal for fouling prevention.
Another equally important factor is the compatibility between the lubricant and the substrate [21]; the lubricant must also be chemically and physically stable within the surface of the substrate to achieve long-lasting, effective performance via high surface wettability, hydrophobicity, roughness and free energy [22, 23]. Common lubricants that are used are silicone oils, polydimethylsiloxane (PDMS), perfluoropolyether oils, long-chain alkanes, or paraffins. These selected lubricants have desirable properties such as thermal stability, long-lasting, low surface energy, and durability in marine environments [19]. This notion was confirmed after Selim et al. [22] synthesised a PDMS/SiO2-ZnO nanocomposite as a low cost nanofiller and discovered that it featured a stable, well-dispersed, uniform particle morphology. The nanofiller showed high potential for fouling release self-cleaning via a physical repelling mechanism, indicating the success of this nanocomposite as an efficient and environment-friendly self-cleaning coating of ship hulls and other marine applications.
Overall, SLIPSs represent an innovative and promising technology that continue to attract significant research interest. With the integration of rising nanotechnologies and biolubricants, SLIPS holds even greater potential to serve as a sustainable, eco-friendly alternative in marine applications, delivering effective anti-fouling performance while minimising environmental impact, and enhancing the applicability of marine lubricants in tandem with growing environmental regulatory demands.
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