Underwater Restoration and Retention of Gases on Superhydrophobic Surfaces for Drag Reduction

Lee, Choongyeop; Kim, Chang‐Jin

doi:10.1103/physrevlett.106.014502

Cited by 377 publications

(238 citation statements)

References 24 publications

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“…Developing a geometrical model for stably regenerating underwater superhydrophobicity According to the experimental results, the optimized ZnO/Si HR geometry, including the MP spacing and NR length, was required to completely regenerate the underwater superhydrophobicity. For the bare MPs without ZnO NRs, although gas pockets were stably reformed between MPs with certain structural parameters according to the study of C. Lee et al, 32 it was found that the MP structures were not sufficient for the formation of a continuous gas interlayer, as only 70% of the layer was regenerated. Thus, a modified model of the hierarchical ZnO NR/Si MP structures needed to completely regenerate the underwater superhydrophobicity was developed.…”

Section: Regeneration Of Underwater Superhydrophobicity By Photoelectmentioning

confidence: 99%

“…Then, the gas bubbles gradually grew up the MP sides, almost reaching the top of the MPs. 32 Because the top of the MP was in contact with water, the separately grown gas bubbles could not coalesce to form a continuous gas overlayer (Figure 4c). Thus, the gas bubbles were isolated and remained between the MPs (Figure 4b), partially regenerating the superhydrophobicity.…”

Section: Regeneration Of Underwater Superhydrophobicity By Photoelectmentioning

confidence: 99%

“…26,31 Although several investigations have been performed to understand the mechanism controlling the stability of the underwater non-wetting property, few studies have explored regenerating a stable gas interlayer to restore the underwater superhydrophobicity. 32 Up to now, superhydrophobic surfaces have only been shown to repair or reconstruct themselves via thermal or photochemical post-treatments under atmospheric conditions that restore their surface structures. [33][34][35][36] To regenerate underwater superhydrophobicity, it is essential to develop a method for producing gas and restoring the gas layer on the surface.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Combining the lotus leaf effect with artificial photosynthesis: regeneration of underwater superhydrophobicity of hierarchical ZnO/Si surfaces by solar water splitting

Lee

Yong

2015

NPG Asia Mater

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Fabrication of stable superhydrophobic surfaces in dynamic circumstances is a key issue for practical uses of non-wetting surfaces. However, superhydrophobic surfaces have finite lifetime in underwater conditions due to the diffusion of gas pockets into the water. To overcome this limited lifetime of underwater superhydrophobicity, this study introduces a novel method for regenerating a continuous air interlayer on superhydrophobic ZnO nanorod/Si micropost hierarchical structures (HRs) via the combination of two biomimetic properties of natural leaf: superhydrophobicity from the lotus leaf effect and solar water splitting from photosynthesis. The designed n/p junction in the ZnO/Si HRs allowed for highly stable gas interlayer in water and regeneration of the underwater superhydrophobicity due to the unique ability of the surface to capture and retain a stable gas layer. Furthermore, we developed a model to determine the optimum structural factors of hierarchical ZnO/Si surfaces that aid the formation of an air interlayer to completely regenerate the superhydrophobicity. We also verified that this model satisfactorily predicted the regeneration of underwater superhydrophobicity under various experimental conditions. The regenerative method developed in this work is expected to broaden the range of potential applications involving superhydrophobic surfaces and to create new opportunities for related technologies. NPG Asia Materials (2015) 7, e201; doi:10.1038/am.2015.74; published online 17 July 2015 INTRODUCTIONSuperhydrophobic surfaces that mimic lotus leaves have been extensively studied over the past several decades, and various micro/nanostructures have been developed to create bio-inspired superhydrophobic surfaces. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] In recent years, the non-wetting property of superhydrophobic surfaces submerged in water has attracted much attention because it has potential applications in drag reduction, anti-fouling, anti-corrosion, waterproof devices, microchannels, anti-icing and other non-wetting related applications. [16][17][18][19][20][21][22][23][24][25] Practical applications of non-wetting surfaces, however, have been impeded by the limited stability of their underwater superhydrophobicity. [26][27][28] According to the Cassie-Baxter model, the presence of an air interlayer on the submerged surface causes the non-wetting behavior, and thus, the stability of underwater superhydrophobicity is determined by the lifetime of the air (or gas) interlayer captured by the superhydrophobic surface. 29 However, the gas interlayer is unstable due to diffusion of the gas into the water. 30 According to previous studies, the gas diffusion rates are strongly affected by physical (hydrostatic pressure and micro/nanostructures of the surface) and chemical (surface energy) factors. 26,31

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Section: Regeneration Of Underwater Superhydrophobicity By Photoelectmentioning

confidence: 99%

Section: Regeneration Of Underwater Superhydrophobicity By Photoelectmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Combining the lotus leaf effect with artificial photosynthesis: regeneration of underwater superhydrophobicity of hierarchical ZnO/Si surfaces by solar water splitting

Lee

Yong

2015

NPG Asia Mater

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“…b-1 Pressurizing the gas layer using an external tank (Carlborg et al 2008); b-2 Replenishing the gas when it is lost from SHPo surface. The combination of two-tier structures (microstructures on the nanostructured bottom) and selflimiting gas generation by electrolysis prevented the wetting even under a very high liquid pressure (7 atm) (Lee and Kim 2011b) …”

Section: Toward Robust Plastron: Passive Approachmentioning

confidence: 99%

Superhydrophobic drag reduction in laminar flows: a critical review

2016

Self Cite

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“…To prove the sustainability of this surface, Wong et al [105] compared its capability against best in the market synthetic liquid-repellent surfaces by testing with simple and complex liquids such as water, hydrocarbons, crude oils, and blood. This bio-mimicked surface was able to outperform its counterparts [107][108][109] in all scenarios by being able to perform at high pressures, resist ice adhesion, and maintain a low hysteresis angle. It is also shown that geometry of the substrate has minimal effect on the performance of the lubricated layer.…”

Section: Efficient Slippery and Self-healing Coating From Pitcher Plantmentioning

confidence: 99%

Advances in Bio-inspired Tribology for Engineering Applications

Siddaiah

Menezes

2016

J Bio Tribo Corros

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Bio-inspired tribology is an interdisciplinary field of science where scientists and engineers seek to investigate and incorporate tribological properties encountered in biological beings into engineering applications. In this paper, bio-inspired tribological research that are speculated to have a huge impact on tribological applications have been reviewed. These research involve (1) investigations related to replication of lubricin found in synovial fluids of mammalian joints which have super-low friction values that can be utilized in IC engines, (2) surface replication concerning to superhydrophobic properties of gecko skin which is seen to have anti-wetting and selfcleaning properties, (3) friction-reducing shark skin through specialized nanoparticle coatings that is seen to give a different perspective on surface texturing, (4) new techniques, such as soft lithography to replicate surfaces of lotus leaf and air lubrication phenomenon inspired by emperor penguins that is being applied to propel boats, ships, and torpedoes faster by reducing skin friction underwater. Further, an investigation in self-healing materials inspired from pitcher plant that has led to the innovation of self-healing and slippery liquid-infused porous surfaces has been discussed. These research works reviewed not only provide a deep insight into the current advances in bio-inspired tribology but also helps understand the plausibility of the research applications in the future and the practicality of innovations possible.

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Underwater Restoration and Retention of Gases on Superhydrophobic Surfaces for Drag Reduction

Cited by 377 publications

References 24 publications

Combining the lotus leaf effect with artificial photosynthesis: regeneration of underwater superhydrophobicity of hierarchical ZnO/Si surfaces by solar water splitting

Combining the lotus leaf effect with artificial photosynthesis: regeneration of underwater superhydrophobicity of hierarchical ZnO/Si surfaces by solar water splitting

Superhydrophobic drag reduction in laminar flows: a critical review

Advances in Bio-inspired Tribology for Engineering Applications

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