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Chu F, Hu Z, Feng Y, Lai NC, Wu X, Wang R. Advanced Anti-Icing Strategies and Technologies by Macrostructured Photothermal Storage Superhydrophobic Surfaces. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024; 36:e2402897. [PMID: 38801015 DOI: 10.1002/adma.202402897] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2024] [Revised: 04/23/2024] [Indexed: 05/29/2024]
Abstract
Water is the source of life and civilization, but water icing causes catastrophic damage to human life and diverse industrial processes. Currently, superhydrophobic surfaces (inspired by the lotus effect) aided anti-icing attracts intensive attention due to their energy-free property. Here, recent advances in anti-icing by design and functionalization of superhydrophobic surfaces are reviewed. The mechanisms and advantages of conventional, macrostructured, and photothermal superhydrophobic surfaces are introduced in turn. Conventional superhydrophobic surfaces, as well as macrostructured ones, easily lose the icephobic property under extreme conditions, while photothermal superhydrophobic surfaces strongly rely on solar illumination. To address the above issues, a potentially smart strategy is found by developing macrostructured photothermal storage superhydrophobic (MPSS) surfaces, which integrate the functions of macrostructured superhydrophobic materials, photothermal materials, and phase change materials (PCMs), and are expected to achieve all-day anti-icing in various fields. Finally, the latest achievements in developing MPSS surfaces, showcasing their immense potential, are highlighted. Besides, the perspectives on the future development of MPSS surfaces are provided and the problems that need to be solved in their practical applications are proposed.
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Affiliation(s)
- Fuqiang Chu
- School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing, 100083, China
| | - Zhifeng Hu
- Research Center of Solar Power and Refrigeration, School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China
- Department of Energy and Power Engineering, Tsinghua University, Beijing, 100084, China
| | - Yanhui Feng
- School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing, 100083, China
| | - Nien-Chu Lai
- School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing, 100083, China
| | - Xiaomin Wu
- Department of Energy and Power Engineering, Tsinghua University, Beijing, 100084, China
| | - Ruzhu Wang
- Research Center of Solar Power and Refrigeration, School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China
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Zhou Y, Zhang C, Zhao W, Wang S, Zhu P. Suppression of hollow droplet rebound on super-repellent surfaces. Nat Commun 2023; 14:5386. [PMID: 37666839 PMCID: PMC10477213 DOI: 10.1038/s41467-023-40941-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2023] [Accepted: 08/15/2023] [Indexed: 09/06/2023] Open
Abstract
Droplet rebound is ubiquitous on super-repellent surfaces. Conversion between kinetic and surface energies suggests that rebound suppression is unachievable due to negligible energy dissipation. Here, we present an effective approach to suppressing rebounds by incorporating bubbles into droplets, even in super-repellent states. This suppression arises from the counteractive capillary effects within bubble-encapsulated hollow droplets. The capillary flows induced by the deformed inner-bubble surface counterbalance those driven by the outer-droplet surface, resulting in a reduction of the effective take-off momentum. We propose a double-spring system with reduced effective elasticity for hollow droplets, wherein the competing springs offer distinct behavior from the classical single-spring model employed for single-phase droplets. Through experimental, analytical, and numerical validations, we establish a comprehensive and unified understanding of droplet rebound, by which the behavior of single-phase droplets represents the exceptional case of zero bubble volume and can be encompassed within this overarching framework.
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Affiliation(s)
- Ying Zhou
- Department of Mechanical Engineering, City University of Hong Kong, 999077, Hong Kong, China
| | | | - Wenchang Zhao
- Department of Mechanical Engineering, City University of Hong Kong, 999077, Hong Kong, China
| | - Shiyu Wang
- Department of Mechanical Engineering, City University of Hong Kong, 999077, Hong Kong, China
| | - Pingan Zhu
- Department of Mechanical Engineering, City University of Hong Kong, 999077, Hong Kong, China.
- Shenzhen Research Institute, City University of Hong Kong, 518057, Shenzhen, China.
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Steerable directional bouncing and contact time reduction of impacting droplets on superhydrophobic stepped surfaces. J Colloid Interface Sci 2023; 629:1032-1044. [DOI: 10.1016/j.jcis.2022.09.038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2022] [Revised: 08/25/2022] [Accepted: 09/04/2022] [Indexed: 11/19/2022]
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Shu Y, Chu F, Hu Z, Gao J, Wu X, Dong Z, Feng Y. Superhydrophobic Strategy for Nature-Inspired Rotating Microfliers: Enhancing Spreading, Reducing Contact Time, and Weakening Impact Force of Raindrops. ACS APPLIED MATERIALS & INTERFACES 2022; 14:57340-57349. [PMID: 36512411 DOI: 10.1021/acsami.2c16662] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Wind-dispersal of seeds is a remarkable strategy in nature, enlightening the construction of microfliers for environmental monitoring. However, the flight of these microfliers is greatly affected by climatic conditions, especially in rainy days, they suffer serious raindrop impact. Here, a hierarchical superhydrophobic surface is fabricated and a novel strategy is demonstrated that the superhydrophobic coating can enhance spreading while reduce contact time and impact force of raindrops, all of which are beneficial for the rotating microfliers. When the surface rotating speed exceeds a critical value, the effect of centrifugal force becomes considerable so that the droplet spreading is enhanced. The rotating superhydrophobic surface can rotate an impacting droplet by the tangential drag force from the air boundary layer, and the rotation of the droplet generates a negative pressure zone inside it, reducing the contact time by more than 30%. The impact force by the droplet on the rotating superhydrophobic surface also has a remarkable reduction of 53% compared to that on unprocessed hydrophilic surfaces, which helps maintain the flight stability of the microfliers. This work pioneers in revealing the droplet impact effect on rotating microflier surfaces and demonstrates the effectiveness of protecting microfliers with superhydrophobic coatings, which shall guide the manufacture and flight of microfliers in rainy conditions.
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Affiliation(s)
- Yifu Shu
- School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing100083, China
| | - Fuqiang Chu
- School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing100083, China
| | - Zhifeng Hu
- Department of Energy and Power Engineering, Tsinghua University, Beijing100084, China
| | - Jie Gao
- School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing100083, China
| | - Xiaomin Wu
- Department of Energy and Power Engineering, Tsinghua University, Beijing100084, China
| | - Zhichao Dong
- CAS Key Laboratory of Bio-Inspired Materials and Interfacial Sciences, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing100190, China
| | - Yanhui Feng
- School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing100083, China
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Chen C, Zhong H, Liu Z, Wang J, Wang J, Liu G, Li Y, Zhu P. Asymmetric Jetting during the Impact of Liquid Drops on Superhydrophobic Concave Surfaces. MICROMACHINES 2022; 13:1521. [PMID: 36144146 PMCID: PMC9501287 DOI: 10.3390/mi13091521] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/30/2022] [Revised: 09/06/2022] [Accepted: 09/06/2022] [Indexed: 06/16/2023]
Abstract
The impact of liquid drops on superhydrophobic solid surfaces is ubiquitous and of practical importance in many industrial processes. Here, we study the impingement of droplets on superhydrophobic surfaces with a macroscopic dimple structure, during which the droplet exhibits asymmetric jetting. Systematic experimental investigations and numerical simulations provide insight into the dynamics and underlying mechanisms of the observed phenomenon. The observation is a result of the interaction between the spreading droplet and the dimple. An upward internal flow is induced by the dimple, which is then superimposed on the horizontal flow inside the spreading droplet. As such, an inclined jet is issued asymmetrically into the air. This work would be conducive to the development of an open-space microfluidic platform for droplet manipulation and generation.
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Affiliation(s)
- Chengmin Chen
- Energy Institute, Qilu University of Technology (Shandong Academy of Sciences), Jinan 250100, China
- School of Energy and Power Engineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan 250100, China
- Jinan Key Laboratory of High-Performance Industrial Software, Jinan Institute of Supercomputing Technology, Jinan 250100, China
| | - Hongjun Zhong
- Jinan Key Laboratory of High-Performance Industrial Software, Jinan Institute of Supercomputing Technology, Jinan 250100, China
| | - Zhe Liu
- School of Energy and Power Engineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan 250100, China
| | - Jianchun Wang
- Energy Institute, Qilu University of Technology (Shandong Academy of Sciences), Jinan 250100, China
- School of Energy and Power Engineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan 250100, China
| | - Jianmei Wang
- Energy Institute, Qilu University of Technology (Shandong Academy of Sciences), Jinan 250100, China
- School of Energy and Power Engineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan 250100, China
| | - Guangxia Liu
- Energy Institute, Qilu University of Technology (Shandong Academy of Sciences), Jinan 250100, China
- School of Energy and Power Engineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan 250100, China
| | - Yan Li
- Energy Institute, Qilu University of Technology (Shandong Academy of Sciences), Jinan 250100, China
- School of Energy and Power Engineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan 250100, China
| | - Pingan Zhu
- Department of Mechanical Engineering, City University of Hong Kong, Hong Kong 999077, China
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Han X, Li J, Tang X, Li W, Zhao H, Yang L, Wang L. Droplet Bouncing: Fundamentals, Regulations, and Applications. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2022; 18:e2200277. [PMID: 35306734 DOI: 10.1002/smll.202200277] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Revised: 02/13/2022] [Indexed: 06/14/2023]
Abstract
Droplet impact is a ubiquitous phenomenon in nature, daily life, and industrial processes. It is thus crucial to tune the impact outcomes for various applications. As a special outcome of droplet impact, the bouncing of droplets keeps the form of the droplets after the impact and minimizes the energy loss during the impact, being beneficial in many applications. A unified understanding of droplet bouncing is in high demand for effective development of new techniques to serve applications. This review shows the fundamentals, regulations, and applications of millimeter-sized droplet bouncing on solid surfaces and same/miscible liquids (liquid pool and another droplet). Regulation methods and current applications are summarized, and potential directions are proposed.
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Affiliation(s)
- Xing Han
- Department of Mechanical Engineering, The University of Hong Kong, Hong Kong, 999077, Hong Kong
| | - Jiaqian Li
- Department of Mechanical Engineering, The University of Hong Kong, Hong Kong, 999077, Hong Kong
| | - Xin Tang
- Department of Mechanical Engineering, The University of Hong Kong, Hong Kong, 999077, Hong Kong
| | - Wei Li
- Department of Mechanical Engineering, The University of Hong Kong, Hong Kong, 999077, Hong Kong
| | - Haibo Zhao
- Department of Mechanical Engineering, The University of Hong Kong, Hong Kong, 999077, Hong Kong
- Department of Mechanics and Aerospace Engineering, Southern University of Science and Technology, Shenzhen, Guangdong, 518055, China
| | - Ling Yang
- Department of Mechanical Engineering, The University of Hong Kong, Hong Kong, 999077, Hong Kong
| | - Liqiu Wang
- Department of Mechanical Engineering, The University of Hong Kong, Hong Kong, 999077, Hong Kong
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Hu Z, Chu F, Lin Y, Wu X. Contact Time of Droplet Impact on Inclined Ridged Superhydrophobic Surfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:1540-1549. [PMID: 35072484 DOI: 10.1021/acs.langmuir.1c03001] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Superhydrophobic surfaces decorated with macrostructures have attracted extensive attention due to their excellent performance of reducing the contact time of impacting droplets. In many practical applications, the surface is not perpendicular to the droplet impact direction, but the impacting dynamics in such scenarios still remain mysterious. Here, we experimentally investigate the dynamics of droplet impact on inclined ridged superhydrophobic surfaces and reveal the effect of Wen (the normal Weber number) and α (the inclination angle) on the contact time τ. As Wen increases, τ first decreases rapidly until a platform is reached; if Wen continues to increase, τ further reduces to a lower platform, indicating a three-stage variation of τ in low, middle, and high Wen regions. In the middle and high Wen regions, the contact time is reduced by 30 and 50%, respectively, and is dominated by droplet spreading/retraction in the tangential and lateral directions, respectively. A quantitative analysis demonstrates that τ in the middle and high Wen regions is independent of Wen and α, while the range of middle and high Wen regions is related to α. When α < 30°, increasing α narrows the middle Wen region and enlarges the high Wen region; when α ≥ 30°, the two Wen regions remain unchanged. In addition, droplet sliding is hindered by the friction and is affected by the droplet morphology in the high Wen region. Overall, the synergistic effect of the surface inclination and macrostructures effectively promotes the detachment of impacting droplets on superhydrophobic surfaces, which provides guidance for applications of superhydrophobic surfaces.
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Affiliation(s)
- Zhifeng Hu
- Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Energy and Power Engineering, Tsinghua University, Beijing 100084, China
| | - Fuqiang Chu
- School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing 100083, China
| | - Yukai Lin
- Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Energy and Power Engineering, Tsinghua University, Beijing 100084, China
| | - Xiaomin Wu
- Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Energy and Power Engineering, Tsinghua University, Beijing 100084, China
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Zhu P, Wang L. Microfluidics-Enabled Soft Manufacture of Materials with Tailorable Wettability. Chem Rev 2021; 122:7010-7060. [PMID: 34918913 DOI: 10.1021/acs.chemrev.1c00530] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Microfluidics and wettability are interrelated and mutually reinforcing fields, experiencing synergistic growth. Surface wettability is paramount in regulating microfluidic flows for processing and manipulating fluids at the microscale. Microfluidics, in turn, has emerged as a versatile platform for tailoring the wettability of materials. We present a critical review on the microfluidics-enabled soft manufacture (MESM) of materials with well-controlled wettability and their multidisciplinary applications. Microfluidics provides a variety of liquid templates for engineering materials with exquisite composition and morphology, laying the foundation for precisely controlling the wettability. Depending on the degree of ordering, liquid templates are divided into individual droplets, one-dimensional (1D) arrays, and two-dimensional (2D) or three-dimensional (3D) assemblies for the modular fabrication of microparticles, microfibers, and monolithic porous materials, respectively. Future exploration of MESM will enrich the diversity of chemical composition and physical structure for wettability control and thus markedly broaden the application horizons across engineering, physics, chemistry, biology, and medicine. This review aims to systematize this emerging yet robust technology, with the hope of aiding the realization of its full potential.
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Affiliation(s)
- Pingan Zhu
- Department of Mechanical Engineering, City University of Hong Kong, Hong Kong, China
| | - Liqiu Wang
- Department of Mechanical Engineering, The University of Hong Kong, Hong Kong, China
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Yu Z, Kadir M, Liu Y, Huang J. Droplet-capturing coatings on environmental surfaces based on cosmetic ingredients. Chem 2021. [DOI: 10.1016/j.chempr.2021.05.017] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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Zhu P, Wang Y, Chu H, Wang L. Superhydrophobicity preventing surface contamination as a novel strategy against COVID-19. J Colloid Interface Sci 2021; 600:613-619. [PMID: 34034121 PMCID: PMC8110320 DOI: 10.1016/j.jcis.2021.05.031] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Revised: 04/12/2021] [Accepted: 05/06/2021] [Indexed: 01/01/2023]
Abstract
Surface contact with virus is ubiquitous in the transmission pathways of respiratory diseases such as Coronavirus Disease 2019 (COVID-19), by which contaminated surfaces are infectious fomites intensifying the transmission of the disease. To date, the influence of surface wettability on fomite formation remains elusive. Here, we report that superhydrophobicity prevents the attachment of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on surfaces by repelling virus-laden droplets. Compared to bare surfaces, superhydrophobic (SHPB) surfaces exhibit a significant reduction in SARS-CoV-2 attachment of up to 99.99995%. We identify the vital importance of solid-liquid adhesion in dominating viral attachment, where the viral activity (N) is proportional to the cube of solid-liquid adhesion (A), N ∝ A3. Our results predict that a surface would be practically free of SARS-CoV-2 deposition when solid-liquid adhesion is ≤1 mN. Engineering surfaces with superhydrophobicity would open an avenue for developing a general approach to preventing fomite formation against the COVID-19 pandemic and future ones.
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Affiliation(s)
- Pingan Zhu
- Department of Mechanical Engineering, City University of Hong Kong, Hong Kong, China; Department of Mechanical Engineering, the University of Hong Kong, Hong Kong, China; HKU-Zhejiang Institute of Research and Innovation (HKU-ZIRI), 311300 Hangzhou, China
| | - Yixin Wang
- Department of Microbiology, Li Ka Shing Faculty of Medicine, the University of Hong Kong, Hong Kong, China
| | - Hin Chu
- Department of Microbiology, Li Ka Shing Faculty of Medicine, the University of Hong Kong, Hong Kong, China.
| | - Liqiu Wang
- Department of Mechanical Engineering, the University of Hong Kong, Hong Kong, China; HKU-Zhejiang Institute of Research and Innovation (HKU-ZIRI), 311300 Hangzhou, China.
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