A robust paintlike repellent coating: Superhydrophobic materials often depend on a particular surface patterning or an applied coating. However, these surfaces can be damaged by wear or fouled by oily materials. Lu et al. devised a suspension of coated titanium dioxide nanoparticles that can be spray-painted or dipcoated onto a range of hard and soft surfaces, including paper, cloth, and glass. The coatings resisted rubbing, scratching, and surface contamination. Science , this issue p. 1132

Liquid-repellent surfaces, such as superhydrophobic surfaces, superoleophobic surfaces, and slippery liquid-infused surfaces, have drawn keen research interest from the communities engaged in chemical synthesis, interfacial chemistry, surface engineering, bionic manufacturing and micro-nano machining. This is due to their great potential applications in liquid-proofing, self-cleaning, chemical resistance, anti-icing, water/oil remediation, biomedicine, etc. However, poor robustness and durability that notably hinders the real-world applications of such surfaces remains their Achilles heel. The past few years have witnessed rapidly increasing publications that address the robustness and durability of liquid-repellent surfaces, and many breakthroughs have been achieved. This review provides an overview of the recent progress made towards robust and durable liquid-repellent surfaces. First, we discuss the wetting of solid surface and its generally-adopted characterisation methods, and introduce typical liquid-repellent surfaces. Second, we focus on various evaluation methods of the robustness and durability of liquid-repellent surfaces. Third, the recent advances in design and fabrication of robust and durable liquid-repellent surfaces are reviewed in detail. Fourth, we present the applications where these surfaces have been employed in fields like chemistry, engineering, biology and in daily life. Finally, we discuss the possible research perspectives in robust and durable liquid-repellent surfaces. By presenting such state-of-the-art of this significant and fast-developing area, we believe that this review will inspire multidisciplinary scientific communities and industrial circles to develop novel liquid-repellent surfaces that can meet the requirements of various real-world applications.

A novel filtration system has been developed for the separation of water and hydrophobic solvents. Copper meshes of various pore diameter (297, 251, 178 and 152 μm) were coated with extremely rough silicone elastomer films. Depositions of this polymer were carried out by aerosol assisted chemical vapour deposition. The polymer coating rendered all meshes superhydrophobic, with static water contact angles of 152–167° depending on mesh diameter. The meshes were found to be exceptionally efficient in separating organic solvents (hexane, petroleum ether and toluene) from water. The dual-layered filtration system developed focuses on directing the transport of oil away from water with the highest efficiency. The device provides a scalable solution to many challenges, including microanalysis, filtration and chemical processing.

Superhydrophobic materials have been widely reported throughout the scientific literature. Their properties originate from a highly rough morphology and inherently water repellent surface chemistry. Despite promising an array of functionalities, these materials have seen limited commercial development. This could be attributed to many factors, like material compatibility, low physical resilience, scaling-up complications, etc. In applications where persistent water contact is required, another limitation arises as a major concern, which is the stability of the air layer trapped at the surface when submerged or impacted by water. This review is aimed at examining the diverse array of research focused on monitoring/improving air layer stability, and highlighting the most successful approaches. The reported complexity of monitoring and enhancing air layer stability, in conjunction with the variety of approaches adopted, results in an assortment of suggested routes to achieving success. The review is addressing the challenge of finding a balance between maximising water repulsion and incorporating structures that protect air pockets from removal, along with challenges related to the variant approaches to testing air-layer stability across the research field, and the gap between the achieved progress and the required performance in real-life applications.