Search

Superspreading surfaces with excellent water transport efficiency are highly desirable for addressing thermal failures through the liquid-vapor phase change of water in electronics thermal management applications. However, the trade-off between capillary pressure and viscous resistance in traditional superspreading surfaces with micro/ nanostructures poses a longstanding challenge in the development of superspreading surfaces with high cooling efficiency in confined spaces. Herein, a heat-treated hierarchical porous enhanced superspreading surface (HTHP) for highly efficient electronic cooling is proposed. Compared with the single porous structures in nanograss, nanosheets, and copper foam, HTHP with hierarchical honeycomb pores effectively resolves the trade-off effect by introducing large vertical through-pores to reduce viscous resistance, and connected small pores to provide sufficient capillary pressure synergistically. HTHP exhibits excellent capillary performance in both horizontal spreading and vertical rising. Despite a thickness of only 0.33 mm, the as-prepared ultrathin vapor chamber (UTVC) fabricated to exploit the superior capillary performance of HTHP achieved effective heat dissipation with outstanding thermal conductivity (12 121 Wm -1 K -1 ), and low thermal resistance (0.1 KW -1 ) at a power of 5 W. This regulation strategy based on hierarchical honeycomb porous structures is expected to promote the development of high-performance superspreading surfaces with a wide range of applications in thermal management., (© 2024 Wiley‐VCH GmbH.)

Surface-initiated iron(0)-mediated controlled radical polymerization (SI-Fe 0 CRP) with low toxicity and excellent biocompatibility is promising for the fabrication of biofunctional polymer coatings. However, the development of Fe(0)-based catalysts remains limited by the lower dissociation activity of the Fe(0) surface in comparison to Cu(0). Here, we found that, by simply polishing the Fe(0) plate surface with sandpaper, the poly(methacryloyloxy)ethyl trimethylammonium chloride brush growth rate has been increased significantly to 3.3 from 0.14 nm min -1 of the pristine Fe(0) plate. The excellent controllability of roughness-mediated SI-Fe 0 CRP can be demonstrated by customizing multicompartment brushes and triblock brushes. Furthermore, we found that the resulting polymer brush coatings exhibit remarkably low water adhesion (0.097 mN) and an outstanding drag reduction rate of 52% in water. This work provides a promising strategy for regulating the grafting rate of polymer brushes via SI-Fe 0 CRP for biocompatible marine drag reduction coatings.

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., (© 2024 Wiley‐VCH GmbH.)

Hydrogels with wet adhesion are promising interfacial adhesive materials; however, their adhesion in water, oil, or organic solvents remains a major challenge. To address this, a pressure-sensitive P(AAm-co-C 18 )/PTA-Fe hydrogel is fabricated, which exhibits robust adhesion to various substrates in both aqueous solutions and oil environments. It is demonstrated that the key to wet adhesion under liquid conditions is the removal of the interfacial liquid, which can be achieved through rational molecular composition regulation. By complexing with hydrophilic polymer networks, phosphotungstic acid (PTA) is introduced into the hydrogel network as a physical cross-linker and anchor point to improve the cohesion strength and drive the migration of polymer chains. The migration and rearrangement of hydrophilic and hydrophobic polymer chains on the hydrogel surface are induced by the electrostatic interactions of Fe 3+ , which create a surface with interfacial water- and oil-removing properties. By co-regulating the hydrophilic and hydrophobic polymer chains, the P(AAm-co-C 18 )/PTA-Fe hydrogel is able to act as a pressure-sensitive adhesive under water and oils with adhesion strength of 92.6 and 90.0 kPa, respectively. It is anticipated that this regulation strategy for polymer chains will promote the development of wet adhesion hydrogels, which can have a wide range of applications., (© 2023 Wiley-VCH GmbH.)

Materials require specific surface structures to achieve the best performance, but achieving an optimal structural design requires a systematic study of how structure affects performance. In this work, we comprehensively and systematically investigated the structure-activity relationship between the nanowire structure and the oil dewetting self-cleaning performance. It is easy for an oil droplet to enter this structure, but it is difficult for it to escape from the gaps between the structures even under the action of water. So, the oil dewetting ability is greatly reduced, showing that this "easy to enter and difficult to exit" mode is very disadvantageous for oil desorption. Moreover, if the structure is dissolved during the test, the oil dewetting ability will be restored. The desorption effect is affected by structural parameters and reaction conditions, which further verifies the negative effect of this structure. In contrast, copper(II) oxide nanowires completely lose their self-cleaning ability due to the enhancement of hydrophobicity and oleophilicity, and the larger-diameter copper(II) oxalate nanorods exhibit a "difficult to enter and difficult to exit" mode, leading to the partial recovery of the oil dewetting performance. This study helps us deeply understand the influence of the surface microstructure on the oil dewetting performance and lay a solid foundation for further appropriate structural design.

Hypothesis: Transparent superhydrophilic coatings are very promising in various scenarios. Appropriate fabrication of colloid coatings with superhydrophilicity both in air and under oil would enlarge their application potential in anti-oil fouling and facilitate anti-fogging of transparent surfaces., Experiments: The Barite colloid was obtained from a one-step precipitation method and was transferred onto glasses to prepare transparent coatings with different thicknesses simply by dip-coating. Then, the impact of thickness on wettability and property was studied through the investigation of wettability in various phase, anti-crude oil fouling performance and anti-fogging ability., Findings: Similar surface morphology and roughness of these coatings were achieved and all the coated surfaces showed ultra-hydrophilicity both in air and under oil. Moreover, the hydrophilicity in air and under oil was found to deteriorate with the decrease of coatings' thickness and dual superhydrophilicity could be achieved on thick coatings. More importantly, excellent anti-crude oil fouling property and durable anti-fogging ability were realized on these transparent coatings with dual superhydrophilicity., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier Inc. All rights reserved.)

A photocatalytic membrane with significant degradation and antifouling performance has become an important part in wastewater treatment. However, the low catalyst loading on the polymer membrane limits its performance improvement. Herein, we fabricated poly(vinylidene fluoride) (PVDF) and poly(acrylic acid) (PAA) blend membranes with a rough surface via a vapor-induced phase separation (VIPS) process. Then Fe 3+ was cross-linked with the carboxyl groups on the membrane surface and further in situ mineralized into β-FeOOH nanorods. The resultant membranes exhibit not only hydrophilicity and underwater superoleophobicity but also favorable separation efficiency and high water flux in oil-in-water emulsions separation. Under visible light irradiation, the membrane can degrade methylene blue (MB) to 95.2% in 180 min. More importantly, the membrane has a significant photocatalytic self-cleaning ability for crude oil with a flux recovery ratio ( FRR ) as high as 94.1%. This work brings a new strategy to fabricate the rough and porous surface for high loading of the hydrophilic photo-Fenton catalyst, improving the oil/water emulsion separation and antifouling performance of the membranes.

Viscous oil adherence onto solid surfaces is ubiquitous and has caused intractable fouling problems, impairing the function of solid surfaces in various areas such as optics and separation membranes. Materials with superhydrophilicity and underwater superoleophobicity are very effective in elimination of oil fouling. However, most of them cannot dewet viscous oils and may malfunction without prehydration treatment. Herein, we report a facile and environmental strategy to prepare barium sulfate (BaSO 4 ) nanocoating to dewet viscous oils on dry surfaces. Abundant surface polar groups (surface hydroxyl) on BaSO 4 nanocoating enhance both hydrophilicity after oil fouling (underoil water contact angle <10°) and underwater superoleophobicity (underwater-oil contact angle >155°) and then facilitate oil dewetting ability. Different oils with viscosity up to 900 mPa·s can be easily eliminated after immersion into water. The results and force analysis also demonstrate that small surface roughness and ultrahydrophilicity under oil are beneficial to achieve oil dewetting property on dry surfaces. Furthermore, BaSO 4 nanocoating displays excellent mechanical, thermal and chemical stability and can maintain oil repellency through various harsh conditions. Outstanding antioil fouling ability also enables the fabric coated by BaSO 4 nanocoating to separate crude oil/water with flux higher than 28 000 Lm 2- h -1 and separation efficiency larger than 99.9% and maintain effective separation performance even after 100 times of separation. Thus, the robust superhydrophilic BaSO 4 nanocoating is potential in oil dewetting and waste oil remediation.

Based on the superhydrophilicity of titanium dioxide (TiO 2 ) after ultraviolet irradiation, it has a high potential in the application of antifogging. However, a durable superhydrophilic state and a broader photoresponse range are necessary. Considering the enhancement of the photoresponse of TiO 2 , doping is an effective method to prolong the superhydrophilic state. In this paper, a Fe 3+ doped TiO 2 film with long-lasting superhydrophilicity and antifogging is prepared by sol-gel method. The experiment and density-functional theory (DFT) calculations are performed to investigate the antifogging performance and the underlying microscopic mechanism of Fe 3+ doped TiO 2 . Antifogging tests demonstrate that 1.0 mol % Fe 3+ doping leads to durable antifogging performance which lasts 60 days. The DFT calculations reveal that the Fe 3+ doping can both increase the photolysis ability of TiO 2 under sunlight exposure and enhance the stability of the hydroxyl adsorbate on TiO 2 surface, which are the main reasons for a long-lasting superhydrophilicity of TiO 2 after sunlight exposure.

With the development of research on superwettability materials, superhydrophobic and superoleophilic materials show superior separation ability in oil-water separation due to their excellent oil-water selectivity. However, due to the super wetting ability of the oil to the material, it is difficult to clean and reuse after adsorbing the oil spill. Therefore, how to realize the complete regeneration of superhydrophobic and superoleophilic materials is still a worldwide problem. In this paper, the controlled adsorption-desorption process of oil and the complete regeneration of materials are realized by pH induced superwettability transformation. We fabricate a pH-responsive oil-water separation sponge by a method of simply impregnating the carboxyl and alkyl group modified SiO 2 nanoparticles on the surface of melamine sponge (MS) skeleton, which can change the wettability from superhydrophobicity and superhydrophilicity through protonation and deprotonation in different pH solutions. The experiment results indicate that the sponge is superhydrophobic and superoleophilic in acid and neutral solution, and can adsorb oil in water. While in basic solution, it becomes superhydrophilic and underwater superoleophobic, which can release the adsorbed oil. With the help of a vacuum pump, we can use this wettability transition to achieve a continuous oil adsorption and desorption process. These findings offer a new preparation method of regenerative 3D adsorption materials like MS in oil-water separation., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Inc. All rights reserved.)