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Superhydrophobic Surface

De-Lin Lai, Gang Kong, Xiao-Cong Li, Chun-Shan Che
Superhydrophobic ZnO nanorods coatings with a strong adhesive force to the surface (rose petal effect) or a low sliding angle (lotus leaf effect) were fabricated on the zinc plate by the hydrothermal plus sol-gel method. The corrosion resistance and durability of the superhydrophobic coatings in 5 wt% NaCl solution were investigated. The coating with loose ZnO nanostructure on ZnO nanorods shows a high adhesive force to water with low corrosion resistance, while the coating with a layer of dense nanotubes on nanorods exhibits a low adhesive to water with a high corrosion resistance due to a layer of trapped air among micro/nanostructures, which can delay the penetration of corrosive media...
July 1, 2019: Journal of Nanoscience and Nanotechnology
Sudip Kumar Lahiri, Pengcheng Zhang, Cheng Zhang, Lin Liu
Limited robustness is a serious drawback for superhydrophobic coatings, and degrades the performance of superhydrophobic surfaces in practical applications. Although fluoro-reagents have excellent durability for superhydrophobicity, their use has been restricted due to various health and environmental concerns. In this work, we describe a facile and efficient fabrication strategy for creating robust fluorine-free superhydrophobic composite coatings that are prepared by a simple dip-dry method, in which the H3BO3-incorporated SiO2-alkyl-silane coatings are deposited on woven cotton fabric surfaces followed by polydimethylsiloxane (PDMS) modification...
February 14, 2019: ACS Applied Materials & Interfaces
Sebastian Faas, Uwe Bielke, Rudolf Weber, Thomas Graf
We investigate the approach to scale up the productivity of the laser-based generation of superhydrophobic surfaces by means of increased average laser powers to enhance the surface structuring rates. Polished surfaces (mean roughness depth SRz  = 0.076 μm) of stainless steel AISI 316L were processed with a laser delivering 8 ps long pulses with a constant pulse energy of 1.4 mJ at pulse repetition rates of 100 kHz or 300 kHz corresponding to average laser powers of 140 W or 420 W, respectively...
February 13, 2019: Scientific Reports
Jinlong Lu, Chi-Vinh Ngo, Subhash C Singh, Jianjun Yang, Wei Xin, Zhi Yu, Chunlei Guo
World is facing global issue of water scarcity where two- thirds of the population do not have access to safe drinking water. Water harvesting from ambient has a potential equivalent to around 10% of the fresh water available on the earth's surface, but it requires a special control in surface morphology for efficient water harvesting. Here, we report a novel facile physicochemical hybrid method that combines femtosecond laser structuring with hydrothermal treatment to create a surface with well-arranged hierarchical nanoneedle structures...
February 13, 2019: Langmuir: the ACS Journal of Surfaces and Colloids
Glen McHale, Bethany V Orme, Gary George Wells, Rodrigo Andres Ledesma-Aguilar
A fundamental limitation of liquids on many surfaces is their contact line pinning. This limitation can be overcome by infusing a non-volatile and immiscible liquid or lubricant into texture or roughness created in or applied onto the solid substrate so that the liquid of interest no longer directly contacts the underlying surface. Such slippery liquid infused porous surfaces (SLIPS), also known as lubricant impregnated surfaces, complete remove contact line pinning and contact angle hysteresis. However, although a sessile droplet may rest on such a surface, its contact angle can only be an apparent contact angle because its contact is now with a second liquid and not a solid...
February 13, 2019: Langmuir: the ACS Journal of Surfaces and Colloids
Min Hsiao, Kai-Yu Chen, Chia-Yun Chen
Surface hydrophobicity of silicon with sound durability under mechanical abrasion is highly desirable for practical needs. However, the reported micro-pyramid/nanowires structures suffer from the saturation characteristics of contact angle at around 132 degree, which impede the promotions toward reaching the state of superhydrophobicity. The present study focuses on the realization of two-scale silicon hierarchical structures prepared with the facile, rapid and large-area capable chemical etching methods without the need of lithographic patterning...
February 7, 2019: Scientific Reports
Shaojun Jiang, Yanlei Hu, Hao Wu, Yachao Zhang, Yiyuan Zhang, Yulong Wang, Yinghui Zhang, Wulin Zhu, Jiawen Li, Dong Wu, Jiaru Chu
Smart dynamic regulation structured surfaces, inspired by nature, which can dynamically change their surface topographies under external stimuli for convertible fluidic and optical properties, have recently motivated significant interest for scientific research and industrial applications. However, there is still high demand for the development of multifunctional dynamically transformable surfaces using facile preparation strategies. In this work, a type of Janus high-aspect-ratio magnetically responsive microplates array (HAR-MMA) is readily fabricated by integrating a flexible laser scanning strategy, smart shape-memory-polymer-based soft transfer, and a simple surface treatment...
February 5, 2019: Advanced Materials
Qianyou Wang, Jimin Han, Yuanyuan Zhang, Zhenzhan Yan, Ever Velasco, Li Yang, Bo Wang, Shuang-Quan Zang
The paradox between safety and detonation performance, along with the intrinsic fragility of primary explosives is the main bottleneck precluding their application in micro-initiation system. To tackle these issues, we fabricate a flexible copper azide film (CA-C film@PF) via employing the metal-organic framework (MOF) film produced by electrospinning technique as the precursor, followed by pyrolysis treatment, in-situ azide reaction and perfluorinated coating procedures. The synergetic effect of MOF and interweaved polymer fiber endows the resultant copper azide film excellent electrostatic stability and remarkable detonation performance...
February 5, 2019: ACS Applied Materials & Interfaces
Ayman M Atta, Mahmood M S Abdullah, Hamad A Al-Lohedan, Nermen H Mohamed
Superhydrophobic nanomaterials are promising in the important pursuit to alleviate the environmental pollution caused by the petroleum crude oil industry, especially to clean-up oil spills. In this work, asphaltenes isolated from crude oil were modified to act as capping agents during the synthesis of hydrophobic silica nanoparticles (HSNPs). The chemical structure, surface morphology, particle size, and surfaces charge of HSNPs were investigated. The contact angles of water droplets on HSNP film surfaces were measured to investigate their wetting properties...
February 2, 2019: Nanomaterials
Samira Shiri, Armela Murrizi, James C Bird
A water drop can bounce upon impacting a superhydrophobic surface. However, on certain superhydrophobic surfaces, a water drop will stick rather than bounce if it is sufficiently hot. Here, we aim to better understand the mechanisms that can lead to this bouncing-sticking transition. Specifically, we model two potential mechanisms in which a superhydrophobic surface could trap a sufficiently hot drop within milliseconds: melting of microtextured wax and condensation of the vapor within the superhydrophobic texture...
November 2, 2018: Micromachines
Mimmi Eriksson, Mikko Tuominen, Mikael Järn, Per Martin Claesson, Viveca Wallqvist, Hans-Jürgen Butt, Doris Vollmer, Michael Kappl, Joachim Schoelkopf, Patrick A C Gane, Hannu Teisala, Agne Swerin
The formation of a bridging gas meniscus via cavitation or nanobubbles is considered the most likely origin of the submicrometer long-range attractive forces measured between hydrophobic surfaces in aqueous solution. However, the dynamics of the formation and evolution of the gas meniscus is still under debate, and in particular in the presence of a thin air layer on a superhydrophobic surface. On superhydrophobic surfaces the range can even exceed 10 µm. Here, we report microscopic images of the formation and growth of a gas meniscus during force measurements between a superhydrophobic surface and a hydrophobic microsphere immersed in water...
February 1, 2019: ACS Nano
Di Sun, Karl F Böhringer
This review focuses on self-cleaning surfaces, from passive bio-inspired surface modification including superhydrophobic, superomniphobic, and superhydrophilic surfaces, to active micro-electro-mechanical systems (MEMS) and digital microfluidic systems. We describe models and designs for nature-inspired self-cleaning schemes as well as novel engineering approaches, and we discuss examples of how MEMS/microfluidic systems integrate with functional surfaces to dislodge dust or undesired liquid residues. Meanwhile, we also examine "waterless" surface cleaning systems including electrodynamic screens and gecko seta-inspired tapes...
January 30, 2019: Micromachines
Cheng Chen, Liu Mingming, Liping Zhang, Yuanyuan Hou, Mengnan Yu, Shaohai Fu
Water-droplet adhesions of the coatings constructed by all-polymer multiscale hierarchical particles (MHPs) were finely adjusted within the range from highly adhesive to self-cleanable. The MHPs were synthesized via thermal-induced polymerization of the reactants absorbed into self-made hollow reactors and in-situ capping of nanocomplexes onto the reactors' shell simultaneously. The dynamic wettability of the prepared MHPs was tuned between water droplet sliding and water droplet adhering by simply controlling the type of the capped nanocomplexes...
January 30, 2019: ACS Applied Materials & Interfaces
Jiale Yong, Subhash C Singh, Zhibing Zhan, Feng Chen, Chunlei Guo
In this paper, the reversible switching between underwater (super-) aerophilicity and superaerophobicity was achieved on various femtosecond (fs) laser-induced superhydrophobic surfaces. A range of materials including Al, stainless steel, Cu, Ni, Si, polytetrafluoroethylene (PTFE), and polydimethylsiloxane (PDMS) were first transformed to superhydrophobic after the formation of surface microstructures through fs laser treatment. These surfaces showed (super-) aerophilicity when immersed in water. In contrast, if the surface was pre-wetted with ethanol and then dipped into water, the surfaces showed superaerophobicity in water...
January 30, 2019: ACS Applied Materials & Interfaces
Christopher Walker, Efstratios Mitridis, Thomas Kreiner, Hadi Eghlidi, Thomas M Schutzius, Dimos Poulikakos
Surface fogging is a common phenomenon that can have significant and detrimental effects on surface transparency and visibility. It affects the performance in a wide range of applications including windows, windshields, electronic displays, cameras, mirrors, and eyewear. A host of ongoing research is aimed at combating this problem by understanding and developing stable and effective anti-fogging coatings that are capable of handling a wide range of environmental challenges "passively" without consumption of electrical energy...
January 28, 2019: Nano Letters
Ludmila B Boinovich, Valery V Kaminsky, Alexandr G Domantovsky, Kirill A Emelyanenko, Andrey V Aleshkin, Eldar R Zulkarneev, Irina A Kiseleva, Alexandre M Emelyanenko
A method based on nanosecond laser processing was used to design superhydrophilic and superhydrophobic copper substrates. Three different protocols were used to analyze the evolution of bactericidal activity of the copper substrates with different wettability. Scanning electron microscopy was used to study the variation of cell morphology after attachment to superhydrophilic and superhydrophobic surfaces. The dispersions of Escherichia coli K12 C600 and Klebsiella pneumoniae 811 in Luria Bertani broth contacted with the superhydrophilic copper surface showed enhanced bacterial inactivation, associated with toxic action of both hierarchically textured copper surface and high content of Cu(2+) ions in the dispersion medium...
January 28, 2019: Langmuir: the ACS Journal of Surfaces and Colloids
Jinlong Song, Yuxiang Li, Wei Xu, Hong Liu, Yao Lu
Reinforced concrete is widely used in civil engineering due to its outstanding mechanical properties and low cost. However, icing and corrosion on concrete-based facilities such as roads, dams, and bridges often cause safety issues. Superhydrophobic surface with completely water-repellent properties that are inspired by the lotus leaf in nature, has great potential to solve this problem, however, most state-of-the-art and commercial superhydrophobic coatings are expensive and weak in mechanical robustness for large-scale application on concrete...
January 6, 2019: Journal of Colloid and Interface Science
Chengchun Zhang, Yihua Zheng, Zhengyang Wu, Jing Wang, Chun Shen, Yan Liu, Luquan Ren
HYPOTHESIS: Flying in the rain presents a greater challenge for smaller animals such as kingfishers, compared with aircraft in the same situation. Regardless, kingfishers have developed advanced water repellency as reflected in the hydrophobicity and elasticity of their feathers. Therefore, it is possible to confirm that the elastic superhydrophobic surface can enhance the water repellency of the surface by experimental and theoretical analysis. EXPERIMENTS: A simplified device simulating droplet impact on a kingfisher feather was configured for comparison...
January 18, 2019: Journal of Colloid and Interface Science
Zhiwei Huang, Robert S Gurney, Yalun Wang, Wenjiao Han, Tao Wang, Dan Liu
Durability under UV illumination remains as a big challenge of TiO2-based superhydrophobic coatings, with the photocatalytic effect causing degradation of low surface energy material over time resulting in surfaces losing their hydrophobicity. We report surfaces made from tolylene-2, 4-diisocyanate (TDI)/TiO2 hybrid networks that demonstrate superhydrophobicity and superior UV-durability. Structural and morphological studies reveal that the TDI/TiO2 hybrid networks are composed of TiO2 nanoparticles interconnected with TDI bridges, and then encapsulated by a TDI layer...
January 25, 2019: ACS Applied Materials & Interfaces
Zhipeng Duan, Hao Ma, Boshu He, Liangbin Su, Xin Zhang
The entrance region constitutes a considerable fraction of the channel length in miniaturized devices. Laminar slip flow in microchannel plate fin heat sinks under hydrodynamically developing conditions is investigated semi-analytically and numerically in this paper. The semi-analytical model for the pressure drop of microchannel plate fin heat sinks is obtained by solving the momentum equation with the first-order velocity slip boundary conditions at the channel walls. The simple pressure drop model utilizes fundamental solutions from fluid dynamics to predict its constitutive components...
January 24, 2019: Micromachines
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