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Wong WSY, Naga A, Armstrong T, Karunakaran B, Poulikakos D, Ras RHA. Designing Plastrons for Underwater Bubble Capture: From Model Microstructures to Stochastic Nanostructures. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2024:e2403366. [PMID: 38953394 DOI: 10.1002/advs.202403366] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2024] [Revised: 06/05/2024] [Indexed: 07/04/2024]
Abstract
Bubbles and foams are often removed via chemical defoamers and/or mechanical agitation. Designing surfaces that promote chemical-free and energy-passive bubble capture is desirable for numerous industrial processes, including mineral flotation, wastewater treatment, and electrolysis. When immersed, super-liquid-repellent surfaces form plastrons, which are textured solid topographies with interconnected gas domains. Plastrons exhibit the remarkable ability of capturing bubbles through coalescence. However, the two-step mechanics of plastron-induced bubble coalescence, namely, rupture (initiation and location) and subsequent absorption (propagation and drainage) are not well understood. Here, the influence of 1) topographical feature size and 2) gas fraction on bubble capture dynamics is investigated. Smaller feature sizes accelerate rupture while larger gas fractions markedly improve absorption. Rupture is initiated solely on solid domains and is more probable near the edges of solid features. Yet, rupture time becomes longer as solid fraction increases. This counterintuitive behavior represents unexpected complexities. Upon rupture, the bubble's moving liquid-solid contact line influences its absorption rate and equilibrium state. These findings show the importance of rationally minimizing surface feature sizes and contact line interactions for rapid bubble rupture and absorption. This work provides key design principles for plastron-induced bubble coalescence, inspiring future development of industrially-relevant surfaces for underwater bubble capture.
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Affiliation(s)
- William S Y Wong
- Department of Applied Physics, School of Science, Aalto University, Espoo, FI-02150, Finland
| | - Abhinav Naga
- Department of Physics, Durham University, Durham, DH1 3LE, United Kingdom
- Institute for Multiscale Thermofluids, School of Engineering, University of Edinburgh, Edinburgh, EH9 3FD, United Kingdom
| | - Tobias Armstrong
- Laboratory for Multiphase Thermofluidics and Surface Nanoengineering, Department of Mechanical and Process Engineering, ETH Zurich, Zurich, 8092, Switzerland
| | | | - Dimos Poulikakos
- Laboratory of Thermodynamics in Emerging Technologies, Department of Mechanical and Process Engineering, ETH Zurich, Zurich, 8092, Switzerland
| | - Robin H A Ras
- Department of Applied Physics, School of Science, Aalto University, Espoo, FI-02150, Finland
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2
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Tzitzilis D, Tsekeridis C, Ntakoumis I, Papadopoulos P. Transition of Liquid Drops on Microstructured Hygrophobic Surfaces from the Impaled Wenzel State to the "Fakir" Cassie-Baxter State. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:13422-13427. [PMID: 38825812 DOI: 10.1021/acs.langmuir.4c00618] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2024]
Abstract
Low adhesion of liquids on solid surfaces can be achieved with protrusions that minimize the contact area between the liquid and the solid. The wetting state where an air cushion forms under the drop is known as the Cassie-Baxter state. Surfaces where liquids form macroscopic contact angles above 150° are called superhydrophobic and superhygrophobic, if we refer to water or any liquid, respectively. The Cassie state is desirable for applications, but it is usually unstable compared to the Wenzel state, where the drop is in direct contact with the rough surface. The Cassie-to-Wenzel transition can be triggered by an increase in pressure and vibrations, but the inverse Wenzel-to-Cassie is much more difficult to observe. Here, we examine under what conditions the Wenzel-to-Cassie transition is triggered when the microscopic contact angle changes abruptly. For this, we applied a lubricant of low surface tension around drops that were in the Wenzel state on microstructured surfaces. The increase of the microscopic contact angle lifted the drop from the rough surface, when the pillar height and spacing are large and small, respectively. Numerical calculations for the drop-lubricant interface showed that the surface geometry requirements for the Wenzel-to-Cassie transition are stricter than the ones for the stability of the Cassie state. A surface geometry where the Cassie state is more stable than the Wenzel for a given Laplace pressure of the drop may not always allow the Wenzel-to-Cassie transition to take place. Therefore, the stability of the Cassie state is a necessary but insufficient condition for the inverse transition.
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Affiliation(s)
| | | | - Ioannis Ntakoumis
- Department of Physics, University of Ioannina, 45110 Ioannina, Greece
| | - Periklis Papadopoulos
- Department of Physics, University of Ioannina, 45110 Ioannina, Greece
- University Research Center of Ioannina, Institute of Materials Science and Computing, Ioannina 45110, Greece
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3
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Jia Y, Yang Y, Cai X, Zhang H. Recent Developments in Slippery Liquid-Infused Porous Surface Coatings for Biomedical Applications. ACS Biomater Sci Eng 2024; 10:3655-3672. [PMID: 38743527 DOI: 10.1021/acsbiomaterials.4c00422] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/16/2024]
Abstract
Slippery liquid-infused porous surface (SLIPS), inspired by the Nepenthes pitcher plant, exhibits excellent performances as it has a smooth surface and extremely low contact angle hysteresis. Biomimetic SLIPS attracts considerable attention from the researchers for different applications in self-cleaning, anti-icing, anticorrosion, antibacteria, antithrombotic, and other fields. Hence, SLIPS has shown promise for applications across both the biomedical and industrial fields. However, the manufacturing of SLIPS with strong bonding ability to different substrates and powerful liquid locking performance remains highly challenging. In this review, a comprehensive overview of research on SLIPS for medical applications is conducted, and the design parameters and common fabrication methods of such surfaces are summarized. The discussion extends to the mechanisms of interaction between microbes, cells, proteins, and the liquid layer, highlighting the typical antifouling applications of SLIPS. Furthermore, it identifies the potential of utilizing the controllable factors provided by SLIPS to develop innovative materials and devices aimed at enhancing human health.
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Affiliation(s)
- Yiran Jia
- Joint Diseases Center, Beijing Tsinghua Changgung Hospital, School of Clinical Medicine, Tsinghua University, Beijing 102218, P. R. China
- State Key Laboratory of Tribology in Advanced Equipment, Department of Mechanical Engineering, Tsinghua University, Beijing 100084, P. R. China
| | - Yinuo Yang
- State Key Laboratory of Tribology in Advanced Equipment, Department of Mechanical Engineering, Tsinghua University, Beijing 100084, P. R. China
| | - Xu Cai
- Joint Diseases Center, Beijing Tsinghua Changgung Hospital, School of Clinical Medicine, Tsinghua University, Beijing 102218, P. R. China
| | - Hongyu Zhang
- Joint Diseases Center, Beijing Tsinghua Changgung Hospital, School of Clinical Medicine, Tsinghua University, Beijing 102218, P. R. China
- State Key Laboratory of Tribology in Advanced Equipment, Department of Mechanical Engineering, Tsinghua University, Beijing 100084, P. R. China
- National Center for Translational Medicine (Shanghai) SHU Branch, Shanghai University, Shanghai 200444, P. R. China
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4
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Mai CTK, Halme J, Nurmi HA, da Silva AM, Lorite GS, Martineau D, Narbey S, Mozaffari N, Ras RHA, Hashmi SG, Vuckovac M. Super-Droplet-Repellent Carbon-Based Printable Perovskite Solar Cells. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2024:e2401016. [PMID: 38696594 DOI: 10.1002/advs.202401016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2024] [Revised: 04/01/2024] [Indexed: 05/04/2024]
Abstract
Despite attractive cost-effectiveness, scalability, and superior stability, carbon-based printable perovskite solar cells (CPSCs) still face moisture-induced degradation that limits their lifespan and commercial potential. Here, the moisture-preventing mechanisms of thin nanostructured super-repellent coating (advancing contact angle >167° and contact angle hysteresis 7°) integrated into CPSCs are investigated for different moisture forms (falling water droplets vs water vapor vs condensed water droplets). It is shown that unencapsulated super-repellent CPSCs have superior performance under continuous droplet impact for 12 h (rain falling experiments) compared to unencapsulated pristine (uncoated) CPSCs that degrade within seconds. Contrary to falling water droplets, where super-repellent coating serves as a shield, water vapor is found to physisorb through porous super-repellent coating (room temperature and relative humidity, RH 65% and 85%) that increase the CPSCs performance for 21% during ≈43 d similarly to pristine CPSCs. It is further shown that water condensation forms within or below the super-repellent coating (40 °C and RH 85%), followed by chemisorption and degradation of CPSCs. Because different forms of water have distinct effects on CPSC, it is suggested that future standard tests for repellent CPSCs should include rain falling and condensate formation tests. The findings will thus inspire the development of super-repellent coatings for moisture prevention.
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Affiliation(s)
- Cuc Thi Kim Mai
- Microelectronics Research Unit, Faculty of Information Technology & Electrical Engineering, University of Oulu, Pentti Kaiteran katu 1, Oulu, 90570, Finland
| | - Janne Halme
- Department of Applied Physics, Aalto University School of Science, Konemiehentie 1, Espoo, 02150, Finland
| | - Heikki A Nurmi
- Department of Applied Physics, Aalto University School of Science, Konemiehentie 1, Espoo, 02150, Finland
- Centre of Excellence in Life-Inspired Hybrid Materials (LIBER), Aalto University, Espoo, Finland
| | - Aldeliane M da Silva
- Microelectronics Research Unit, Faculty of Information Technology & Electrical Engineering, University of Oulu, Pentti Kaiteran katu 1, Oulu, 90570, Finland
| | - Gabriela S Lorite
- Microelectronics Research Unit, Faculty of Information Technology & Electrical Engineering, University of Oulu, Pentti Kaiteran katu 1, Oulu, 90570, Finland
| | - David Martineau
- Solaronix SA, Rue de l' Ouriette 129, Aubonne, CH-1170, Switzerland
| | - Stéphanie Narbey
- Solaronix SA, Rue de l' Ouriette 129, Aubonne, CH-1170, Switzerland
| | - Naeimeh Mozaffari
- Department of Materials Science and Engineering, Monash University, Clayton, Victoria, 3800, Australia
| | - Robin H A Ras
- Department of Applied Physics, Aalto University School of Science, Konemiehentie 1, Espoo, 02150, Finland
- Centre of Excellence in Life-Inspired Hybrid Materials (LIBER), Aalto University, Espoo, Finland
| | - Syed Ghufran Hashmi
- Microelectronics Research Unit, Faculty of Information Technology & Electrical Engineering, University of Oulu, Pentti Kaiteran katu 1, Oulu, 90570, Finland
| | - Maja Vuckovac
- Department of Applied Physics, Aalto University School of Science, Konemiehentie 1, Espoo, 02150, Finland
- Centre of Excellence in Life-Inspired Hybrid Materials (LIBER), Aalto University, Espoo, Finland
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5
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Vieira A, Jokinen V, Lepikko S, Ras RHA, Zhou Q. Through-Drop Imaging of Liquid-Solid Interfaces: From Contact Angle Variations Along the Droplet Perimeter to Mapping of Contact Angles Across a Surface. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:9059-9067. [PMID: 38621291 PMCID: PMC11072716 DOI: 10.1021/acs.langmuir.4c00414] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2024] [Revised: 03/28/2024] [Accepted: 03/28/2024] [Indexed: 04/17/2024]
Abstract
When a droplet interacts with a water-repellent surface, its triple-phase contact line typically exhibits varying contact angles, which can vary from point-to-point across the surface. Consequently, measuring the contact angles along the contact line would provide a better representation of the wetting properties of the surface than a single average contact angle. However, an effective method for estimating the local contact angle along the contact line on opaque hydrophobic surfaces is currently lacking. Here we present a method that combines through-drop imaging of the wetting interface during a sliding experiment with Finite Element Modeling of the droplet to estimate contact angle values along the contact line. Using this method, the mean advancing and receding contact angles were measured on four types of hydrophobic samples with contact angles between 99 and 178.9°. The method was further used to produce detailed advancing and receding contact angle maps of surfaces with wetting patterns with an unprecedented resolution of 3 μm.
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Affiliation(s)
- Arthur Vieira
- Department
of Electrical Engineering and Automation, School of Electrical Engineering, Aalto University, Maarintie 8, 02150 Espoo, Finland
| | - Ville Jokinen
- Department
of Chemistry and Materials Science, School
of Chemical Engineering, Aalto University, Tietotie 3, 02150 Espoo, Finland
| | - Sakari Lepikko
- Department
of Applied Physics, Aalto University, 02150 Espoo, Finland
- Centre
of Excellence in Life-Inspired Hybrid Materials (LIBER), Aalto University, 02150 Espoo, Finland
| | - Robin H. A. Ras
- Department
of Applied Physics, Aalto University, 02150 Espoo, Finland
- Centre
of Excellence in Life-Inspired Hybrid Materials (LIBER), Aalto University, 02150 Espoo, Finland
| | - Quan Zhou
- Department
of Electrical Engineering and Automation, School of Electrical Engineering, Aalto University, Maarintie 8, 02150 Espoo, Finland
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6
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Eriksson M, Claesson PM, Järn M, Wallqvist V, Tuominen M, Kappl M, Teisala H, Vollmer D, Schoelkopf J, Gane PA, Mäkelä JM, Swerin A. Effects of Gas Layer Thickness on Capillary Interactions at Superhydrophobic Surfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:4801-4810. [PMID: 38386540 PMCID: PMC10919075 DOI: 10.1021/acs.langmuir.3c03709] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Revised: 02/12/2024] [Accepted: 02/13/2024] [Indexed: 02/24/2024]
Abstract
Strongly attractive forces act between superhydrophobic surfaces across water due to the formation of a bridging gas capillary. Upon separation, the attraction can range up to tens of micrometers as the gas capillary grows, while gas molecules accumulate in the capillary. We argue that most of these molecules come from the pre-existing gaseous layer found at and within the superhydrophobic coating. In this study, we investigate how the capillary size and the resulting capillary forces are affected by the thickness of the gaseous layer. To this end, we prepared superhydrophobic coatings with different thicknesses by utilizing different numbers of coating cycles of a liquid flame spraying technique. Laser scanning confocal microscopy confirmed an increase in gas layer thickness with an increasing number of coating cycles. Force measurements between such coatings and a hydrophobic colloidal probe revealed attractive forces caused by bridging gas capillaries, and both the capillary size and the range of attraction increased with increasing thickness of the pre-existing gas layer. Hence, our data suggest that the amount of available gas at and in the superhydrophobic coating determines the force range and capillary growth.
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Affiliation(s)
- Mimmi Eriksson
- Materials
and Surface Design, RISE Research Institutes
of Sweden, SE-11486 Stockholm, Sweden
- Department
of Chemistry, Division of Surface and Corrosion Science, KTH Royal Institute of Technology, SE-10044 Stockholm, Sweden
- CR
Colloidal Resource AB, Naturvetarvägen 14, SE-22362 Lund, Sweden
| | - Per M. Claesson
- Department
of Chemistry, Division of Surface and Corrosion Science, KTH Royal Institute of Technology, SE-10044 Stockholm, Sweden
| | - Mikael Järn
- Materials
and Surface Design, RISE Research Institutes
of Sweden, SE-11486 Stockholm, Sweden
| | - Viveca Wallqvist
- Materials
and Surface Design, RISE Research Institutes
of Sweden, SE-11486 Stockholm, Sweden
| | - Mikko Tuominen
- Materials
and Surface Design, RISE Research Institutes
of Sweden, SE-11486 Stockholm, Sweden
- Nordtreat
Oy, Mestarintie 11, FI-01730 Vantaa, Finland
| | - Michael Kappl
- Department
of Physics at Interfaces, Max Planck Institute
for Polymer Research, D-55128 Mainz, Germany
| | - Hannu Teisala
- Department
of Physics at Interfaces, Max Planck Institute
for Polymer Research, D-55128 Mainz, Germany
- Amcor
Flexibles Valkeakoski Oy, Niementie 161, P.O. Box 70, 37601 Valkeakoski, Finland
| | - Doris Vollmer
- Department
of Physics at Interfaces, Max Planck Institute
for Polymer Research, D-55128 Mainz, Germany
| | | | - Patrick A.C. Gane
- School
of Chemical Engineering, Department of Bioproducts and Biosystems, Aalto University, FI-00076 Aalto, Finland
- Faculty of
Technology and Metallurgy, University of
Belgrade, Karnegijeva
4, Belgrade 11000, Serbia
| | - Jyrki M. Mäkelä
- Physics
Unit, Aerosol Physics Laboratory, Tampere
University, Tampere FI-33014, Finland
| | - Agne Swerin
- Department
of Chemistry, Division of Surface and Corrosion Science, KTH Royal Institute of Technology, SE-10044 Stockholm, Sweden
- Department
of Engineering and Chemical Sciences, Karlstad
University, SE-651 88 Karlstad, Sweden
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7
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Huang Y, Wen G, Fan Y, He M, Sun W, Tian X, Huang S. Magnetic-Actuated Jumping of Droplets on Superhydrophobic Grooved Surfaces: A Versatile Strategy for Three-Dimensional Droplet Transportation. ACS NANO 2024; 18:6359-6372. [PMID: 38363638 DOI: 10.1021/acsnano.3c11197] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/17/2024]
Abstract
On-demand droplet transportation is of great significance for numerous applications. Although various strategies have been developed for droplet transportation, out-of-surface three-dimensional (3D) transportation of droplets remains challenging. Here, a versatile droplet transportation strategy based on magnetic-actuated jumping (MAJ) of droplets on superhydrophobic grooved surfaces (SHGSs) is presented, which enables 3D, remote, and precise manipulation of droplets even in enclosed narrow spaces. To trigger MAJ, an electromagnetic field is utilized to deform the droplet on the SHGS with the aid of an attached magnetic particle, thereby the droplet acquires excess surface energy. When the electromagnetic field is quickly removed, the excess surface energy is partly converted into kinetic energy, allowing the droplet to jump atop the surface. Through high-speed imaging and numerical simulation, the working mechanism and size matching effect of MAJ are unveiled. It is found that the MAJ behavior can only be observed if the sizes of the droplets and the superhydrophobic grooves are matched, otherwise unwanted entrapment or pinch-off effects would lead to failure of MAJ. A regime diagram which serves as a guideline to design SHGSs for MAJ is proposed. The droplet transportation capacities of MAJ, including in-surface and out-of-surface directional transportation, climbing stairs, and crossing obstacles, are also demonstrated. With the ability to remotely manipulate droplets in enclosed narrow spaces without using any mechanical moving parts, MAJ can be used to design miniaturized fluidic platforms, which exhibit great potential for applications in bioassays, microfluidics, droplet-based switches, and microreactions.
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Affiliation(s)
- Yusheng Huang
- School of Materials Science and Engineering, State Key Laboratory of Optoelectronic Materials and Technologies, Key Laboratory for Polymeric Composite and Functional Materials of Ministry of Education, Sun Yat-sen University, Guangzhou 510006, China
| | - Guifeng Wen
- School of Materials Science and Engineering, State Key Laboratory of Optoelectronic Materials and Technologies, Key Laboratory for Polymeric Composite and Functional Materials of Ministry of Education, Sun Yat-sen University, Guangzhou 510006, China
| | - Yue Fan
- School of Materials Science and Engineering, State Key Laboratory of Optoelectronic Materials and Technologies, Key Laboratory for Polymeric Composite and Functional Materials of Ministry of Education, Sun Yat-sen University, Guangzhou 510006, China
| | - Maomao He
- State Key Laboratory of Fine Chemicals, Frontiers Science Center for Smart Materials Oriented Chemical Engineering, Dalian University of Technology, Dalian 116024, China
| | - Wen Sun
- State Key Laboratory of Fine Chemicals, Frontiers Science Center for Smart Materials Oriented Chemical Engineering, Dalian University of Technology, Dalian 116024, China
| | - Xuelin Tian
- School of Materials Science and Engineering, State Key Laboratory of Optoelectronic Materials and Technologies, Key Laboratory for Polymeric Composite and Functional Materials of Ministry of Education, Sun Yat-sen University, Guangzhou 510006, China
| | - Shilin Huang
- School of Materials Science and Engineering, State Key Laboratory of Optoelectronic Materials and Technologies, Key Laboratory for Polymeric Composite and Functional Materials of Ministry of Education, Sun Yat-sen University, Guangzhou 510006, China
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8
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Zhang J, Yao Z. Upward Splashing of a Droplet Impacting an Inclined Superhydrophobic Surface. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:2362-2368. [PMID: 38243902 DOI: 10.1021/acs.langmuir.3c03555] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2024]
Abstract
It has long been held that when a droplet impacts obliquely onto a smooth dry surface at normal ambient temperature and pressure, upward splashing can be more easily suppressed than downward splashing. However, in this research, we experimentally find that for a superhydrophobic surface, increasing the wall inclination beforehand suppresses downward splashing and subsequently suppresses upward splashing. The spreading theory for an inclined surface is modified to predict the spreading process on an inclined superhydrophobic wall. Due to the existence of an asymmetric boundary layer between the upward and downward sheet on an inclined wall, the thickness and growth rate of the upward rim are smaller than those of the downward rim; for this reason, the upward side of the spreading sheet splashes more easily on a superhydrophobic wall, considering the theory of a droplet splashing on a flat surface. However, because the upward rim velocity is smaller than the downward rim velocity, the downward lamella splashes more easily than the upward lamella on a smooth surface. We attempt to theoretically describe the interval of the stochastic flow mode (spreading/splashing) that exists in practice for the first time. We also give the phase diagram containing three flow patterns, namely, two-side spreading, upward-only splashing, and two-side splashing, in the parameter space of the Weber number We and the wall inclination angle χ. The theory agrees well with the experimental results.
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Affiliation(s)
- Jinhan Zhang
- School of Engineering Science, University of Chinese Academy of Sciences, Beijing 101408, China
| | - Zhaohui Yao
- School of Engineering Science, University of Chinese Academy of Sciences, Beijing 101408, China
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9
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Wang X, Yan X, Du J, Chen F, Yu F, Tao R, Wang S, Min Q. Dynamic wetting of Newtonian and viscoelastic fluids on microstructured surfaces. J Colloid Interface Sci 2023; 652:2098-2107. [PMID: 37699328 DOI: 10.1016/j.jcis.2023.09.029] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Revised: 08/17/2023] [Accepted: 09/05/2023] [Indexed: 09/14/2023]
Abstract
Hypothesis Although extensive research has been conducted on the dynamic wetting of Newtonian fluids, limited insights have been gained for viscoelastic fluids, particularly on engineered surfaces. We hypothesize that differences in dynamic wetting on microstructured surfaces exist between such fluids, which may be attributed to variations in viscosity and elasticity as well as changes in the microscopic morphology of the moving contact line. Experiments To systematically investigate the wetting differences between Newtonian and viscoelastic fluids on microstructured surfaces, we conducted forced wetting experiments of glycerol-water and carboxymethyl cellulose aqueous solutions on microstructured polytetrafluoroethylene surfaces through a modified Wilhelmy plate method. Findings Results demonstrated an apparent difference in the relationship between the dynamic contact angle and moving velocity with different microstructured surfaces for Newtonian and viscoelastic fluids. The power-law exponent between the capillary number and cubic of the dynamic contact angle increases with the strengthening of shear thinning and elastic effects. In contrast, this exponent is rarely influenced by the scale of microstructured surfaces, particularly in highly viscous regions where viscous force dominates. In addition, viscosity affects the viscous bending and distance that liquid molecules jump at the contact line. These findings have potential applications in coating complex fluids on engineered surfaces.
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Affiliation(s)
- Xiong Wang
- Department of Mechanical Engineering, City University of Hong Kong, Hong Kong 99907, China; Key Laboratory of Advanced Reactor Engineering and Safety of Ministry of Education, Collaborative Innovation Center of Advanced Nuclear Energy Technology, Institute of Nuclear and New Energy Technology, Beijing 100084, China
| | - Xiao Yan
- Department of Mechanical and Aerospace Engineering, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong (SAR) 999077, China.
| | - Jiayu Du
- Key Laboratory of Advanced Reactor Engineering and Safety of Ministry of Education, Collaborative Innovation Center of Advanced Nuclear Energy Technology, Institute of Nuclear and New Energy Technology, Beijing 100084, China
| | - Feipeng Chen
- Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong (SAR) 999077, China
| | - Fanfei Yu
- Department of Mechanical Engineering, City University of Hong Kong, Hong Kong 99907, China
| | - Ran Tao
- Department of Mechanical Engineering, City University of Hong Kong, Hong Kong 99907, China
| | - Steven Wang
- Department of Mechanical Engineering, City University of Hong Kong, Hong Kong 99907, China.
| | - Qi Min
- Key Laboratory of Advanced Reactor Engineering and Safety of Ministry of Education, Collaborative Innovation Center of Advanced Nuclear Energy Technology, Institute of Nuclear and New Energy Technology, Beijing 100084, China.
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10
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Daniel D, Koh XQ. Droplet detachment force and its relation to Young-Dupre adhesion. SOFT MATTER 2023; 19:8434-8439. [PMID: 37877408 DOI: 10.1039/d3sm01178j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/26/2023]
Abstract
Droplets adhere to surfaces due to their surface tension γ and understanding the vertical force Fd required to detach the droplet is key to many technologies (e.g., inkjet printing, optimal paint formulations). Here, we predicted Fd on different surfaces by numerically solving the Young-Laplace equation. Our numerical results are consistent with previously reported results for a wide range of experimental conditions: droplets subjected to surface vs. body forces with |Fd| ranging from nano- to milli-newtons, droplet radii R ranging from tens of microns to several millimetres, and for various surfaces (micro-/nano-structured superhydrophobic vs. lubricated surfaces). Finally, we derive an analytic solution for Fd on highly hydrophobic surfaces and further show that for receding contact angle θr > 140°, the normalized Fd/πR is equivalent to the Young-Dupre work of adhesion γ(1 + cos θr).
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Affiliation(s)
- Dan Daniel
- Division of Physical Sciences and Engineering, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia.
| | - Xue Qi Koh
- Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A*STAR), 138634, Singapore
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11
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Jiang Y, Xu Z, Li B, Li J, Guan D. Soft Wetting: Droplet Receding Contact Angles on Soft Superhydrophobic Surfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:15401-15408. [PMID: 37857566 DOI: 10.1021/acs.langmuir.3c02667] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/21/2023]
Abstract
Despite intensive investigations on the droplet receding contact angle on superhydrophobic surfaces, i.e., a key parameter characterizing surface wettability and adhesion, the quantitative correlation between the surface structure mechanical properties (softness) and the droplet receding contact angles remains vague. By systematically varying the geometric dimensions and mechanical properties of soft pillar arrays, we find that the droplet receding contact angles decrease with the decrease in the pillar spring constant. Most surprisingly, the densely packed pillar arrays may result in larger receding contact angles than those on sparsely packed pillars, opposing the understanding of rigid pillar arrays, where the receding contact angles increase with a decrease in the packing density of pillars. This is attributed to the collective effects of capillarity and elasticity, where the energy consumed by the sliding contact line, the energy stored in the distorted liquid-vapor interface, and the energy stored in the deflected pillar contribute to the droplet depinning characteristics. We develop an analytical model to predict the droplet receding contact angles on soft superhydrophobic pillar arrays with knowledge of the material intrinsic receding contact angle, the pillar geometry, and the pillar mechanical properties. The predictions are corroborated by the experimental data measured in this and prior studies.
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Affiliation(s)
- Youhua Jiang
- Department of Mechanical Engineering (Robotics), Guangdong Technion─Israel Institute of Technology, Shantou, Guangdong 515063, China
- Faculty of Mechanical Engineering, Technion─Israel Institute of Technology, Haifa 3200003, Israel
- Guangdong Provincial Key Laboratory of Materials and Technologies for Energy Conversion, Guangdong Technion─Israel Institute of Technology, Shantou, Guangdong 515063, China
| | - Zhijia Xu
- Department of Mechanical Engineering (Robotics), Guangdong Technion─Israel Institute of Technology, Shantou, Guangdong 515063, China
| | - Bin Li
- Department of Mechanical Engineering (Robotics), Guangdong Technion─Israel Institute of Technology, Shantou, Guangdong 515063, China
- Faculty of Mechanical Engineering, Technion─Israel Institute of Technology, Haifa 3200003, Israel
- Guangdong Provincial Key Laboratory of Materials and Technologies for Energy Conversion, Guangdong Technion─Israel Institute of Technology, Shantou, Guangdong 515063, China
| | - Juan Li
- Department of Mechanical Engineering (Robotics), Guangdong Technion─Israel Institute of Technology, Shantou, Guangdong 515063, China
- Faculty of Mechanical Engineering, Technion─Israel Institute of Technology, Haifa 3200003, Israel
| | - Dongshi Guan
- State Key Laboratory of Nonlinear Mechanics, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, China
- School of Engineering Science, University of Chinese Academy of Sciences, Beijing 100049, China
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12
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Li Y, Ma X, Chen Y, Kang X, Yang B. Superhydrophobicity Mechanism and Nanoscale Profiling of PDMS-Modified Kaolinite Nanolayers via Ab Initio-MD Simulation and Atomic Force Microscopy Study. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023. [PMID: 37289639 DOI: 10.1021/acs.langmuir.3c00915] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
This study aimed to investigate the superhydrophobic mechanism of kaolinite particles modified with poly(dimethylsiloxane) (PDMS), which has potential as a superior hydrophobic coating. The study employed a combination of density functional theory (DFT) simulation modeling, characterization of the chemical properties and microstructure, contact angle measurements, and chemical force spectroscopy of atomic force microscopy. The results showed successful PDMS grafting onto the kaolinite surface, resulting in micro- and nanoscale roughness and a contact angle of 165°, indicating a successful superhydrophobic effect. The study also identified the mechanism of the hydrophobic interaction through two-dimensional micro- and nanoscale hydrophobicity images, highlighting the potential of this approach for developing new hydrophobic coatings.
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Affiliation(s)
- Yi Li
- Key Laboratory of Building Safety and Energy Efficiency of the Ministry of Education, Hunan University, Changsha 410082, China
- National Center for International Research Collaboration in Building Safety and Environment, Hunan University, Changsha 410082, China
- College of Civil Engineering, Hunan University, Changsha 410082, China
| | - Xiongying Ma
- Key Laboratory of Building Safety and Energy Efficiency of the Ministry of Education, Hunan University, Changsha 410082, China
- National Center for International Research Collaboration in Building Safety and Environment, Hunan University, Changsha 410082, China
- College of Civil Engineering, Hunan University, Changsha 410082, China
| | - Yongqing Chen
- Key Laboratory of Building Safety and Energy Efficiency of the Ministry of Education, Hunan University, Changsha 410082, China
- National Center for International Research Collaboration in Building Safety and Environment, Hunan University, Changsha 410082, China
- College of Civil Engineering, Hunan University, Changsha 410082, China
| | - Xin Kang
- Key Laboratory of Building Safety and Energy Efficiency of the Ministry of Education, Hunan University, Changsha 410082, China
- National Center for International Research Collaboration in Building Safety and Environment, Hunan University, Changsha 410082, China
- College of Civil Engineering, Hunan University, Changsha 410082, China
| | - Bin Yang
- College of Materials Science and Engineering, Hunan University, Changsha 410082, China
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13
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Wang L, Wang H, Di Y, Dong L, Jin G. Predicting Sliding Angles on Random Pit-Distributed Textures Using Probabilistic Neural Networks. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:6406-6412. [PMID: 37095072 DOI: 10.1021/acs.langmuir.3c00188] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
The three-phase contact line best reflects the sliding ability of droplets on solid surfaces. Most studies on the sliding angle (SA) of superhydrophobic surfaces are limited to regularly arranged microtextured surfaces, lacking definite models and effective methods for a complex surface of a random texture. In this study, random pits with an area ratio of 19% were generated on 1 mm × 1 mm subregions, and the subregions formed arrays on a sample surface of 10 mm × 10 mm to obtain a randomly distributed microtexture surface with no pit overlaps. Although the contact angle (CA) of randomly pitted texture was the same, the SA was different. The SA of surfaces was affected by the pit location. The location of random pits increased the complexity of the three-phase contact line movement. The continuity of the three-phase contact angle (T) can reveal the rolling mechanism of the random pit texture and predict the SA, but the relationship between the T and SA is a relatively poor linear relation (R2 = 74%), and the SA of the random pit texture can only be roughly estimated. The quantized pit coordinates and SA were used as the input and output labels for the PNN model, respectively, and the accuracy of the model convergence was 90.2%.
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Affiliation(s)
- Li Wang
- College of Materials Science and Chemical Engineering, Harbin Engineering University, Harbin 150090, Heilongjiang, China
- Key Laboratory of National Defense Science and Technology for Equipment Remanufacturing Technology, Army Armored Forces Academy, Beijing 100072, China
| | - Haidou Wang
- College of Materials Science and Chemical Engineering, Harbin Engineering University, Harbin 150090, Heilongjiang, China
- National Engineering Research Center for Remanufacturing, Army Armored Forces Academy, Beijing 100072, China
| | - Yuelan Di
- Key Laboratory of National Defense Science and Technology for Equipment Remanufacturing Technology, Army Armored Forces Academy, Beijing 100072, China
| | - Lihong Dong
- Key Laboratory of National Defense Science and Technology for Equipment Remanufacturing Technology, Army Armored Forces Academy, Beijing 100072, China
| | - Guo Jin
- College of Materials Science and Chemical Engineering, Harbin Engineering University, Harbin 150090, Heilongjiang, China
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14
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Yu F, Yang J, Tao R, Tan Y, Wang J, Wang D, Chen L, Wang Z, Deng X. Aerodynamic Super-Repellent Surfaces. RESEARCH (WASHINGTON, D.C.) 2023; 2023:0111. [PMID: 37223699 PMCID: PMC10202376 DOI: 10.34133/research.0111] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Accepted: 03/17/2023] [Indexed: 05/25/2023]
Abstract
Repelling liquid drops from engineering surfaces has attracted great attention in a variety of applications. To achieve efficient liquid shedding, delicate surface textures are often introduced to sustain air pockets at the liquid-solid interface. However, those surfaces are prone to suffer from mechanical failure, which may bring reliability issues and thus limits their applications. Here, inspired by the aerodynamic Leidenfrost effect, we present that impacting drops are directionally repelled from smooth surfaces supplied with an exogenous air layer. Our theoretical analysis reveals that the synchronized nonwetting and oblique bouncing behavior is attributed to the aerodynamic force arising from the air layer. The versatility and practicability of our approach allow for drop repellency without the aid of any surface wettability treatment and also avoid the consideration of mechanical stability issues, which thereby provides a promising candidate for the applications that necessitate liquid shedding, e.g., resolve the problem of tiny raindrop adhesion on the automobile side window during driving.
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Affiliation(s)
- Fanfei Yu
- Institute of Fundamental and Frontier Sciences,
University of Electronic Science and Technology of China, Chengdu 610054, P. R. China
- Department of Mechanical Engineering,
City University of Hong Kong, Kowloon, Hong Kong Special Administrative Region 999077, P. R. China
| | - Jinlong Yang
- Institute of Fundamental and Frontier Sciences,
University of Electronic Science and Technology of China, Chengdu 610054, P. R. China
| | - Ran Tao
- Department of Mechanical Engineering,
City University of Hong Kong, Kowloon, Hong Kong Special Administrative Region 999077, P. R. China
| | - Yao Tan
- Institute of Fundamental and Frontier Sciences,
University of Electronic Science and Technology of China, Chengdu 610054, P. R. China
| | - Jinpei Wang
- Department of Mechanical Engineering,
City University of Hong Kong, Kowloon, Hong Kong Special Administrative Region 999077, P. R. China
| | - Dehui Wang
- Institute of Fundamental and Frontier Sciences,
University of Electronic Science and Technology of China, Chengdu 610054, P. R. China
| | - Longquan Chen
- School of Physics,
University of Electronic Science and Technology of China, Chengdu 610054, P. R. China
| | - Zuankai Wang
- Department of Mechanical Engineering,
Hong Kong Polytechnic University, Kowloon, Hong Kong Special Administrative Region 999077, P. R. China
| | - Xu Deng
- Institute of Fundamental and Frontier Sciences,
University of Electronic Science and Technology of China, Chengdu 610054, P. R. China
- Shenzhen Institute for Advanced Study,
University of Electronic Science and Technology of China, Shenzhen 518110, P. R. China
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15
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Vieira A, Cui W, Jokinen V, Ras RHA, Zhou Q. Through-drop imaging of moving contact lines and contact areas on opaque water-repellent surfaces. SOFT MATTER 2023; 19:2350-2359. [PMID: 36880312 PMCID: PMC10053025 DOI: 10.1039/d2sm01622b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/10/2022] [Accepted: 02/26/2023] [Indexed: 06/18/2023]
Abstract
A myriad of natural surfaces such as plant leaves and insect wings can repel water and remain unwetted inspiring scientists and engineers to develop water-repellent surfaces for various applications. Those natural and artificial water-repellent surfaces are typically opaque, containing micro- and nano-roughness, and their wetting properties are determined by the details at the actual liquid-solid interface. However, a generally applicable way to directly observe moving contact lines on opaque water-repellent surfaces is missing. Here, we show that the advancing and receding contact lines and corresponding contact area on micro- and nano-rough water-repellent surfaces can be readily and reproducibly quantified using a transparent droplet probe. Combined with a conventional optical microscope, we quantify the progression of the apparent contact area and apparent contact line irregularity in different types of superhydrophobic silicon nanograss surfaces. Contact angles near 180° can be determined with an uncertainty as low as 0.2°, that a conventional contact angle goniometer cannot distinguish. We also identify the pinning/depinning sequences of a pillared model surface with excellent repeatability and quantify the progression of the apparent contact interface and contact angle of natural plant leaves with irregular surface topography.
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Affiliation(s)
- Arthur Vieira
- Department of Electrical Engineering and Automation, School of Electrical Engineering, Aalto University, Maarintie 8, 02150 Espoo, Finland.
| | - Wenjuan Cui
- Department of Electrical Engineering and Automation, School of Electrical Engineering, Aalto University, Maarintie 8, 02150 Espoo, Finland.
- School of Chemistry and Chemical Engineering, Lingnan Normal University, Zhanjiang, Guangdong 524048, P. R. China
| | - Ville Jokinen
- Department of Chemistry and Materials Science, School of Chemical Engineering, Aalto University, Tietotie 3, 02150 Espoo, Finland
| | - Robin H A Ras
- Department of Applied Physics, School of Science, Aalto University, P.O. Box 15100, 02150 Espoo, Finland.
- Center of Excellence in Life-Inspired Hybrid Materials (LIBER), Aalto University, P.O. Box 15100, 02150 Espoo, Finland
| | - Quan Zhou
- Department of Electrical Engineering and Automation, School of Electrical Engineering, Aalto University, Maarintie 8, 02150 Espoo, Finland.
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16
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Li Y. Theoretical Analysis of Contact Angle Hysteresis of Suspended Drops on Micropillared Superhydrophobic Surfaces. Colloids Surf A Physicochem Eng Asp 2023. [DOI: 10.1016/j.colsurfa.2023.131244] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/11/2023]
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17
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Chu C, Zhao Y, Hao P, Lv C. Wetting state transitions of individual condensed droplets on pillared textured surfaces. SOFT MATTER 2023; 19:670-678. [PMID: 36597934 DOI: 10.1039/d2sm01271e] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
The ability to realize the self-removal of condensed droplets from a surface is of critical importance for science and applications such as water harvesting and thermal engineering. Despite the enormous interest in micro/nanotextured superhydrophobic materials for high-efficiency condensation, a clear picture of the wetting state transition of condensed droplets is missing, particularly, on a single-droplet level of the order of micrometers. Herein, by varying a substantial parameter space of the contact angle and the geometry of the pillared textures, we have quantified the wetting transition of individual droplets during condensation. We found that a droplet is finally either spontaneously removed from the textures due to a Laplace pressure difference or wets the textures; four different wetting state transition modes have been identified numerically and they are classified in a phase diagram. Simple theories have been constructed to correlate the critical conditions of the wetting state transition to the wettability and geometry of the textures, and they were verified experimentally. We found that the self-removal of condensed droplets benefits from the contact angle and the height of the pillars. These findings not only enhance our fundamental understanding of the wetting state transition of condensed droplets but also allow the rational design of micro/nanotextured water-repellent materials for anti-fogging and anti-wetting.
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Affiliation(s)
- Chenlei Chu
- Department of Engineering Mechanics, AML, Tsinghua University, 100084 Beijing, China.
- Beijing Institute of Spacecraft Environment Engineering, 100094 Beijing, China
| | - Yinggang Zhao
- Department of Engineering Mechanics, AML, Tsinghua University, 100084 Beijing, China.
| | - Pengfei Hao
- Department of Engineering Mechanics, AML, Tsinghua University, 100084 Beijing, China.
- Tsinghua University (School of Materials Science and Engineering)-AVIC Aerodynamics Research Institute Joint Research Center for Advanced Materials and Anti-Icing, Tsinghua University, 100084 Beijing, China
| | - Cunjing Lv
- Department of Engineering Mechanics, AML, Tsinghua University, 100084 Beijing, China.
- Center for Nano and Micro Mechanics, Tsinghua University, 100084 Beijing, China
- State Key Laboratory of Tribology in Advanced Equipment (SKLT), Tsinghua University, 100084 Beijing, China
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18
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Garcia-Gonzalez D, Corrales TP, Dacunzi M, Kappl M. Squeezing Drops: Force Measurements of the Cassie-to-Wenzel Transition. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:14666-14672. [PMID: 36410035 DOI: 10.1021/acs.langmuir.2c02095] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Superhydrophobic surfaces have long been the center of attention of many researchers due to their unique liquid repellency and self-cleaning properties. However, these unique properties rely on the stability of the so-called Cassie state, which is a metastable state with air-filled microstructures. This state tends to transit to the stable Wenzel state, where the inside of the microstructures eventually wets. For potential industrial applications, it is therefore critical to maintain the Cassie state. We investigate the Cassie-to-Wenzel transition on superhydrophobic micropillar surfaces by squeezing a water drop between the surface and a transparent superhydrophobic force probe. The probe's transparency allows the use of top-view optics to monitor the area of the drop as it is squeezed against a micropillared surface. The impalement, or Cassie-to-Wenzel transition, is identified as a sharp decrease in force accompanied by an abrupt change in the drop's contact area. We compare the force measured by the sensor with the capillary pressure force calculated from the observed drop shape and find a good agreement between both quantities. We also study the force and pressure at impalement as a function of the pillar's slenderness ratio. Finally, we compare the impalement pressure with three literature predictions and find that our experimental values are consistently lower than the theoretical values. We find that a possible cause of this earlier Cassie-to-Wenzel transition may be the coalescence of the squeezed drop with microdroplets that nucleate around the base of the micropillars.
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Affiliation(s)
- Diana Garcia-Gonzalez
- Physics of Fluids group, Max-Planck Center Twente for Complex Fluid Dynamics, Department of Science and Technology, University of Twente, P.O. Box 217, 7500 AEEnschede, Netherlands
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128Mainz, Germany
| | - Tomas P Corrales
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128Mainz, Germany
- Departamento de Física, Universidad Técnica Federico Santa María, Avenida España 1680, 2390123Valparaíso, Chile
| | - Maria Dacunzi
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128Mainz, Germany
| | - Michael Kappl
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128Mainz, Germany
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19
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He JG, Zhao GL, Dai SJ, Li M, Zou GS, Wang JJ, Liu Y, Yu JQ, Xu LF, Li JQ, Fan LW, Huang M. Fabrication of Metallic Superhydrophobic Surfaces with Tunable Condensate Self-Removal Capability and Excellent Anti-Frosting Performance. NANOMATERIALS (BASEL, SWITZERLAND) 2022; 12:3655. [PMID: 36296847 PMCID: PMC9611512 DOI: 10.3390/nano12203655] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Revised: 10/08/2022] [Accepted: 10/14/2022] [Indexed: 06/16/2023]
Abstract
Laser fabrication of metallic superhydrophobic surfaces (SHSs) for anti-frosting has recently attracted considerable attention. Effective anti-frosting SHSs require the efficient removal of condensed microdroplets through self-propelled droplet jumping, which is strongly influenced by the surface morphology. However, detailed analyses of the condensate self-removal capability of laser-structured surfaces are limited, and guidelines for laser processing parameter control for fabricating rationally structured SHSs for anti-frosting have not yet been established. Herein, a series of nanostructured copper-zinc alloy SHSs are facilely constructed through ultrafast laser processing. The surface morphology can be properly tuned by adjusting the laser processing parameters. The relationship between the surface morphologies and condensate self-removal capability is investigated, and a guideline for laser processing parameterization for fabricating optimal anti-frosting SHSs is established. After 120 min of the frosting test, the optimized surface exhibits less than 70% frost coverage because the remarkably enhanced condensate self-removal capability reduces the water accumulation amount and frost propagation speed (<1 μm/s). Additionally, the material adaptability of the proposed technique is validated by extending this methodology to other metals and metal alloys. This study provides valuable and instructive insights into the design and optimization of metallic anti-frosting SHSs by ultrafast laser processing.
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Affiliation(s)
- Jian-Guo He
- Aerospace Information Research Institute, Chinese Academy of Sciences, Beijing 100094, China
- School of Optoelectronics, University of Chinese Academy of Sciences, Beijing 100049, China
- Key Laboratory of Computational Optical Imaging Technology, Chinese Academy of Sciences, Beijing 100094, China
| | - Guan-Lei Zhao
- State Key Laboratory of Automotive Safety and Energy, School of Vehicle and Mobility, Tsinghua University, Beijing 100084, China
- State Key Laboratory of Tribology, Key Laboratory for Advanced Manufacturing by Materials Processing Technology, Ministry of Education of PR China, Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China
| | - Shou-Jun Dai
- Aerospace Information Research Institute, Chinese Academy of Sciences, Beijing 100094, China
- Key Laboratory of Computational Optical Imaging Technology, Chinese Academy of Sciences, Beijing 100094, China
| | - Ming Li
- State Key Laboratory of Transient Optics and Photonics, Xi’an Institute of Optics and Precision Mechanics of CAS, Xi’an 710119, China
| | - Gui-Sheng Zou
- State Key Laboratory of Tribology, Key Laboratory for Advanced Manufacturing by Materials Processing Technology, Ministry of Education of PR China, Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China
| | - Jian-Jun Wang
- Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Yang Liu
- Aerospace Information Research Institute, Chinese Academy of Sciences, Beijing 100094, China
- Key Laboratory of Computational Optical Imaging Technology, Chinese Academy of Sciences, Beijing 100094, China
| | - Jia-Qi Yu
- Aerospace Information Research Institute, Chinese Academy of Sciences, Beijing 100094, China
- Key Laboratory of Computational Optical Imaging Technology, Chinese Academy of Sciences, Beijing 100094, China
| | - Liang-Fei Xu
- State Key Laboratory of Automotive Safety and Energy, School of Vehicle and Mobility, Tsinghua University, Beijing 100084, China
| | - Jian-Qiu Li
- State Key Laboratory of Automotive Safety and Energy, School of Vehicle and Mobility, Tsinghua University, Beijing 100084, China
| | - Lian-Wen Fan
- Technology and Engineering Center for Space Utilization, Chinese Academy of Sciences, Beijing 100094, China
| | - Min Huang
- Aerospace Information Research Institute, Chinese Academy of Sciences, Beijing 100094, China
- Key Laboratory of Computational Optical Imaging Technology, Chinese Academy of Sciences, Beijing 100094, China
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20
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Xie C, Shi J, Luo Y, Chu G, Li H. Velocity-Dependent Contact Angle and Energy Dissipations of Dynamic Wetting Nanodroplets on Nanopillared Surfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:9822-9832. [PMID: 35921226 DOI: 10.1021/acs.langmuir.2c00906] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Dynamic wetting, described by a dynamic contact angle (DCA), is a fundamental behavior of fluid on surface. With the development of blue energy, the research of droplet nanogenerator is flourishing. There is a growing interest in the dynamic wetting behavior of nanodroplets on surfaces. Molecular dynamics simulations are performed to reveal the influence of the velocity of nanodroplets and the wetting state (Cassie and Wenzel) on the DCA and the energy dissipation on the contact line. The simulation results demonstrate a more complicated scenario of dynamic wetting than the static wetting: The increasing rate of advancing DCA is lower than the decreasing rate of the receding DCA with respect to the nanodroplet velocity. As for the Wenzel state, larger surface roughness increases the dynamic wetting hysteresis, while for Cassie nanodroplets, the larger surface roughness leads to smaller dynamic wetting hysteresis. It is found that a structural force exists on the rough surface. The energy dissipation of the dynamic wetting mainly comes from the motion of the contact line, which is positively correlated to the velocity and can be decomposed to the viscosity and friction dissipations, respectively. The Cassie state causes much lower energy dissipation than the Wenzel state. Furthermore, the quasi-static contact angle is proposed to describe the contact angle on a rough surface. These findings advance the understanding of dynamic wetting behavior and inspire theoretical guidance for the design of novel functional interfaces.
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Affiliation(s)
- Chenxia Xie
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing University of Chemical Technology, Beijing 100029, People's Republic of China
| | - Jie Shi
- Research Center of the Ministry of Education for High Gravity Engineering and Technology, Beijing University of Chemical Technology, Beijing 100029, People's Republic of China
| | - Yong Luo
- Research Center of the Ministry of Education for High Gravity Engineering and Technology, Beijing University of Chemical Technology, Beijing 100029, People's Republic of China
| | - Guangwen Chu
- Research Center of the Ministry of Education for High Gravity Engineering and Technology, Beijing University of Chemical Technology, Beijing 100029, People's Republic of China
| | - Hui Li
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing University of Chemical Technology, Beijing 100029, People's Republic of China
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21
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Zhang J, Li L, Xu P, Lei Y, Song Q, Liu J, Xiong Y, Yang S, Zhang Y, Xue L. Anisotropic Wettability of Bioinspired Surface Characterized by Friction Force. Biomimetics (Basel) 2022; 7:biomimetics7030108. [PMID: 35997428 PMCID: PMC9397054 DOI: 10.3390/biomimetics7030108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Revised: 08/03/2022] [Accepted: 08/04/2022] [Indexed: 11/17/2022] Open
Abstract
Bioinspired surfaces with special wettabilities attract increasing attention due to their extensive applications in many fields. However, the characterizations of surface wettability by contact angle (CA) and sliding angle (SA) have clear drawbacks. Here, by using an array of triangular micropillars (ATM) prepared by soft lithography, the merits of measuring the friction force of a water droplet on ATM over measurements of CA and SA in characterizing the surface wettability are demonstrated. The CA and SA measurements show ignorable differences in the wettabilities of ATM in opposite directions (1.13%) and that with different periodic parameters under the elongation ranging from 0 to 70%. In contrast, the friction measurement reveals a difference of > 10% in opposite directions. Moreover, the friction force shows a strong dependence on the periodic parameters which is regulated by mechanical stretching. Increasing the elongation from 0 to 50% increases the static and kinetic friction force up to 23.0% and 22.9%, respectively. Moreover, the stick-slip pattern during kinetic friction can reveal the periodic features of the measured surface. The friction force measurement is a sensitive technique that could find applications in the characterization of surface wettabilities.
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Affiliation(s)
- Jinhong Zhang
- The Institute of Technological Science, School of Power and Mechanical Engineering, Wuhan University, South Donghu Road 8, Wuhan 430072, China
- Department of Mechanical Engineering, Shanxi Polytechnic College, Taiyuan 030006, China
| | - Lijun Li
- The Institute of Technological Science, School of Power and Mechanical Engineering, Wuhan University, South Donghu Road 8, Wuhan 430072, China
| | - Peng Xu
- The Institute of Technological Science, School of Power and Mechanical Engineering, Wuhan University, South Donghu Road 8, Wuhan 430072, China
| | - Yifeng Lei
- The Institute of Technological Science, School of Power and Mechanical Engineering, Wuhan University, South Donghu Road 8, Wuhan 430072, China
| | - Qianlin Song
- Urology Department, Renmin Hospital of Wuhan University, Zhangzhidong Road 99, Wuhan 430060, China
| | - Junwei Liu
- Urology Department, Renmin Hospital of Wuhan University, Zhangzhidong Road 99, Wuhan 430060, China
| | - Yunhe Xiong
- Urology Department, Renmin Hospital of Wuhan University, Zhangzhidong Road 99, Wuhan 430060, China
| | - Sixing Yang
- Urology Department, Renmin Hospital of Wuhan University, Zhangzhidong Road 99, Wuhan 430060, China
| | - Yurong Zhang
- The Institute of Technological Science, School of Power and Mechanical Engineering, Wuhan University, South Donghu Road 8, Wuhan 430072, China
- Correspondence: (Y.Z.); (L.X.)
| | - Longjian Xue
- The Institute of Technological Science, School of Power and Mechanical Engineering, Wuhan University, South Donghu Road 8, Wuhan 430072, China
- Hubei Yangtze Memory Laboratories, Wuhan 430205, China
- Correspondence: (Y.Z.); (L.X.)
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22
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Song S, Wang Y, Wang J, Mei S, Jiang Y, Li C, Pan M. Fabrication of All-Polymeric Hierarchical Colloidal Particles with Tunable Wettability by In Situ Capping Raspberry-Like Precursors. Ind Eng Chem Res 2022. [DOI: 10.1021/acs.iecr.2c00630] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Shaofeng Song
- Hebei Key Laboratory of Functional Polymers, School of Chemical Engineering and Technology, Hebei University of Technology, Tianjin 300130, P. R. China
| | - Yajiao Wang
- Hebei Key Laboratory of Functional Polymers, School of Chemical Engineering and Technology, Hebei University of Technology, Tianjin 300130, P. R. China
| | - Juan Wang
- Hebei Key Laboratory of Functional Polymers, School of Chemical Engineering and Technology, Hebei University of Technology, Tianjin 300130, P. R. China
| | - Shuxing Mei
- Hebei Key Laboratory of Functional Polymers, School of Chemical Engineering and Technology, Hebei University of Technology, Tianjin 300130, P. R. China
| | - Yuan Jiang
- Hebei Key Laboratory of Functional Polymers, School of Chemical Engineering and Technology, Hebei University of Technology, Tianjin 300130, P. R. China
| | - Chao Li
- Hebei Key Laboratory of Functional Polymers, School of Chemical Engineering and Technology, Hebei University of Technology, Tianjin 300130, P. R. China
| | - Mingwang Pan
- Hebei Key Laboratory of Functional Polymers, School of Chemical Engineering and Technology, Hebei University of Technology, Tianjin 300130, P. R. China
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23
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Lou J, Shi S, Ma C, Zhou X, Huang D, Zheng Q, Lv C. Polygonal non-wetting droplets on microtextured surfaces. Nat Commun 2022; 13:2685. [PMID: 35562518 PMCID: PMC9106735 DOI: 10.1038/s41467-022-30399-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2021] [Accepted: 04/25/2022] [Indexed: 11/09/2022] Open
Abstract
Understanding the interactions between liquids and solids is important for many areas of science and technology. Microtextured surfaces have been extensively studied in microfluidics, DNA technologies, and micro-manufacturing. For these applications, the ability to precisely control the shape, size and location of the liquid via textured surfaces is of particular importance for the design of fluidic-based systems. However, this has been passively realized in the wetting state thanks to the pinning of the contact line, leaving the non-wetting counterpart challenging due to the low liquid affinity. In this work, confinement is imposed on droplets located on well-designed shapes and arrangements of microtextured surfaces. An active way to shape non-wetting water and liquid metal droplets into various polygons ranging from triangles, squares, rectangles, to hexagons is developed. The results suggest that energy barriers in different directions account for the movement of the contact lines and the formation of polygonal shapes. By characterizing the curvature of the liquid-vapour meniscus, the morphology of the droplet is correlated to its volume, thickness, and contact angle. The developed liquid-based patterning strategy under active regulation with low adhesion looks promising for low-cost micromanufacturing technology, DNA microarrays, and digital lab-on-a-chip. Exploring the interactions between liquids and solids is critical for improving control over fluidic systems. Here, authors develop an active way to tailor various polygonal shapes of non-wetting droplet on microtextured surfaces, resulting from the anisotropic energy barriers of the contact line.
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Affiliation(s)
- Jing Lou
- Department of Engineering Mechanics and Center for Nano and Micro Mechanics, AML, Tsinghua University, Beijing, 100084, China
| | - Songlin Shi
- Department of Engineering Mechanics and Center for Nano and Micro Mechanics, AML, Tsinghua University, Beijing, 100084, China
| | - Chen Ma
- Department of Engineering Mechanics and Center for Nano and Micro Mechanics, AML, Tsinghua University, Beijing, 100084, China
| | - Xiaohuan Zhou
- Department of Engineering Mechanics and Center for Nano and Micro Mechanics, AML, Tsinghua University, Beijing, 100084, China
| | - Dong Huang
- National Key Laboratory of Science and Technology on Micro/Nano Fabrication, Institute of Microelectronics, Peking University, Beijing, 100871, China
| | - Quanshui Zheng
- Department of Engineering Mechanics and Center for Nano and Micro Mechanics, AML, Tsinghua University, Beijing, 100084, China
| | - Cunjing Lv
- Department of Engineering Mechanics and Center for Nano and Micro Mechanics, AML, Tsinghua University, Beijing, 100084, China.
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Su H, Liu Y, Gao Y, Fu C, Li C, Qin R, Liang L, Yang P. Amyloid-Like Protein Aggregation Toward Pesticide Reduction. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2022; 9:e2105106. [PMID: 35257513 PMCID: PMC9069373 DOI: 10.1002/advs.202105106] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Revised: 01/24/2022] [Indexed: 05/19/2023]
Abstract
Pesticide overuse is a major global problem and the cause of this problem is noticeable pesticide loss from undesired bouncing of sprayed pesticide droplets and rain erosion. This further becomes a primary source of soil and groundwater pollution. Herein, the authors report a method that can enhance pesticide droplet deposition and adhesion on superhydrophobic plant leave surfaces by amyloid-like aggregation of bovine serum albumin (BSA). Through the reduction of the disulfide bond of BSA by tris(2-carboxyethyl) phosphine hydrochloride (TCEP), the amyloid-like phase transition of BSA is triggered that rapidly affords abundant phase-transitioned BSA (PTB) oligomers to facilitate the invasion of the PTB droplet into the nanostructures on a leaf surface. Such easy penetration is further followed by a robust amyloid-mediated interfacial adhesion of PTB on leaf surface. As a result, after mixing with pesticides, the PTB system exhibits a remarkable pesticide adhesion capacity that is more than 10 times higher than conventional fixation of commercial pesticides. The practical farmland experiments show that the use of PTB aggregation could reduce the use of pesticides by 70-90% while ensuring yield. This work demonstrates that current pesticide dosage in actual agriculture production may be largely reduced by utilizing eco-friendly amyloid-like protein aggregation.
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Affiliation(s)
- Hao Su
- Key Laboratory of Applied Surface and Colloid ChemistryMinistry of EducationSchool of Chemistry and Chemical EngineeringShaanxi Normal UniversityXi'an710119China
| | - Yongchun Liu
- Key Laboratory of Applied Surface and Colloid ChemistryMinistry of EducationSchool of Chemistry and Chemical EngineeringShaanxi Normal UniversityXi'an710119China
| | - Yingtao Gao
- Key Laboratory of Applied Surface and Colloid ChemistryMinistry of EducationSchool of Chemistry and Chemical EngineeringShaanxi Normal UniversityXi'an710119China
| | - Chengyu Fu
- Key Laboratory of Applied Surface and Colloid ChemistryMinistry of EducationSchool of Chemistry and Chemical EngineeringShaanxi Normal UniversityXi'an710119China
| | - Chen Li
- School of Chemistry and Chemical EngineeringHenan Institute of Science and TechnologyEastern HuaLan AvenueXinxiangHenan453003China
| | - Rongrong Qin
- Key Laboratory of Applied Surface and Colloid ChemistryMinistry of EducationSchool of Chemistry and Chemical EngineeringShaanxi Normal UniversityXi'an710119China
| | - Lei Liang
- School of Chemistry and Chemical EngineeringHenan Institute of Science and TechnologyEastern HuaLan AvenueXinxiangHenan453003China
| | - Peng Yang
- Key Laboratory of Applied Surface and Colloid ChemistryMinistry of EducationSchool of Chemistry and Chemical EngineeringShaanxi Normal UniversityXi'an710119China
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25
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McHale G, Gao N, Wells GG, Barrio-Zhang H, Ledesma-Aguilar R. Friction Coefficients for Droplets on Solids: The Liquid-Solid Amontons' Laws. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:4425-4433. [PMID: 35353534 PMCID: PMC9009185 DOI: 10.1021/acs.langmuir.2c00178] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
The empirical laws of dry friction between two solid bodies date back to the work of Amontons in 1699 and are pre-dated by the work of Leonardo da Vinci. Fundamental to those laws are the concepts of static and kinetic coefficients of friction relating the pinning and sliding friction forces along a surface to the normal load force. For liquids on solid surfaces, contact lines also experience pinning and the language of friction is used when droplets are in motion. However, it is only recently that the concept of coefficients of friction has been defined in this context and that droplet friction has been discussed as having a static and a kinetic regime. Here, we use surface free energy considerations to show that the frictional force per unit length of a contact line is directly proportional to the normal component of the surface tension force. We define coefficients of friction for both contact lines and droplets and provide a droplet analogy of Amontons' first and second laws but with the normal load force of a solid replaced by the normal surface tension force of a liquid. In the static regime, the coefficient of static friction, defined by the maximum pinning force of a droplet, is proportional to the contact angle hysteresis, whereas in the kinetic regime, the coefficient of kinetic friction is proportional to the difference in dynamic advancing and receding contact angles. We show the consistency between the droplet form of Amontons' first and second laws and an equation derived by Furmidge. We use these liquid-solid Amontons' laws to describe literature data and report friction coefficients for various liquid-solid systems. The conceptual framework reported here should provide insight into the design of superhydrophobic, slippery liquid-infused porous surfaces (SLIPS) and other surfaces designed to control droplet motion.
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Affiliation(s)
- Glen McHale
- Institute
for Multiscale Thermofluids, School of Engineering, The University of Edinburgh, Edinburgh EH9 3FB, U.K.
| | - Nan Gao
- Department
of Mechanical Engineering, University of
Birmingham, Birmingham B15 2TT, U.K.
| | - Gary G. Wells
- Institute
for Multiscale Thermofluids, School of Engineering, The University of Edinburgh, Edinburgh EH9 3FB, U.K.
| | - Hernán Barrio-Zhang
- Institute
for Multiscale Thermofluids, School of Engineering, The University of Edinburgh, Edinburgh EH9 3FB, U.K.
| | - Rodrigo Ledesma-Aguilar
- Institute
for Multiscale Thermofluids, School of Engineering, The University of Edinburgh, Edinburgh EH9 3FB, U.K.
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Butt HJ, Liu J, Koynov K, Straub B, Hinduja C, Roismann I, Berger R, Li X, Vollmer D, Steffen W, Kappl M. Contact angle hysteresis. Curr Opin Colloid Interface Sci 2022. [DOI: 10.1016/j.cocis.2022.101574] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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27
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Du Q, Zhou P, Pan Y, Qu X, Liu L, Yu H, Hou J. Influence of hydrophobicity and roughness on the wetting and flow resistance of water droplets on solid surface: A many-body dissipative particle dynamics study. Chem Eng Sci 2022. [DOI: 10.1016/j.ces.2021.117327] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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28
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Varol HS, Seeger S. Fluorescent Staining of Silicone Micro- and Nanopatterns for Their Optical Imaging. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:231-243. [PMID: 34932361 DOI: 10.1021/acs.langmuir.1c02436] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Performance of engineered surfaces can be enhanced by making them hydrophobic or superhydrophobic via coating them with low-surface-energy micro- and nanopatterns. However, the wetting phenomena of particularly irregular shape and spacing (super)hydrophobic patterns such as polysiloxane coatings are not yet fully understood from a microscopic perspective. Here, we show a new method to collect 3D confocal images from irregular polysiloxane micro- and nanorods from a single rod resolution to discuss their wetting response over long liquid/solid interaction times and quantify the length and diameter of these rods. To collect such 3D confocal images, fluorescent dye containing water droplets were left on our superhydrophobic and hydrophobic polysiloxane coated surfaces. Then their liquid/solid interfaces were imaged at different staining scenarios: (i) using different fluorescent dyes, (ii) when the droplets were in contact with surfaces, or (iii) after the droplets were taken away from the surface at the end of staining. Using such staining strategies, we could resolve the micro- and nanorods from root to top and determine their length and diameter, which were then found to be in good agreement with those obtained from their electron microscopy images. 3D confocal images in this paper, for the first time, present the long-time existence of more than one wetting state under the same droplet in contact with surfaces, as well as external and internal three-phase contact lines shifting and pinning. In the end, these findings were used to explain the time-dependent wetting kinetics of our surfaces. We believe that the proposed imaging strategy here will, in the future, be used to study many other irregular patterned (super)antiwetting surfaces to describe their wetting theory, which is today impossible due to the complicated surface geometry of these irregular patterns.
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Affiliation(s)
- H Samet Varol
- Department of Chemistry, Universität Zürich, Zürich, CH 8057, Switzerland
- Ernst-Berl Institut für Technische und Makromolekulare Chemie, Technische Universität Darmstadt, Alarich-Weiss-Str. 12, Darmstadt, D-64287, Germany
| | - Stefan Seeger
- Department of Chemistry, Universität Zürich, Zürich, CH 8057, Switzerland
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29
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Hydrodynamic collisions involving bubbles and mineral particles. CAN J CHEM ENG 2021. [DOI: 10.1002/cjce.24347] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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30
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Feldmann D, Pinchasik BE. How Droplets Move on Surfaces with Directional Chemical Heterogeneities. J Phys Chem Lett 2021; 12:11703-11709. [PMID: 34846895 DOI: 10.1021/acs.jpclett.1c03423] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The nature of adhesion of droplets to surfaces is a long pending scientific question. With the evolution of complex surfaces, quantification and prediction of these adhesion forces become intricate. Nevertheless, understanding these forces is highly relevant for explaining liquid transport in nature and establishing design guidelines for manmade interfaces. Here, it is shown that adhesion of droplets is highly sensitive to the direction of chemical heterogeneities, both in the static and dynamic regimes. This dependency is quantified by bending beam and droplet roll-off experiments. The shape of the fluid contact line on the microscale elucidates the origin of the direction-dependent adhesion. Namely, the droplet receding part pins to a higher number of patches when moving toward to the apex in comparison to the opposite direction. These findings improve the understanding of droplet adhesion to surfaces with chemical heterogeneities and directional transport phenomena.
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Affiliation(s)
- David Feldmann
- School of Mechanical Engineering, Faculty of Engineering, Tel-Aviv University, 6997801 Tel-Aviv, Israel
| | - Bat-El Pinchasik
- School of Mechanical Engineering, Faculty of Engineering, Tel-Aviv University, 6997801 Tel-Aviv, Israel
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31
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Qiu J, Chen S, Di Y, Wang H, Lan L, Wang L. Prediction of Droplet Sliding on the Continuity of the Three-Phase Contact Line. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:13038-13045. [PMID: 34702036 DOI: 10.1021/acs.langmuir.1c02102] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Many animals and plants have evolved wonderful hydrophobic abilities to adapt to the complex climate environment. The microstructure design of a superhydrophobic surface focuses on bionics and will be restricted by processing technology. Although certain functions can be achieved, there is a lack of unified conclusion on the wetting mechanism and a few quantitative analyses of the continuity of the three-phase contact line. Therefore, the relationship between the surface microstructure of the lattice pattern and the critical sliding angle of the water droplet in the Cassie state was investigated in this paper, and we proposed a method to quantitatively analyze the continuity of the three-phase contact line by a dimensionless length f. The results showed that the three-phase contact line was an important factor to determine the sliding performance of the droplet. The upward traction force generated by the surface tension through the force analysis on the three-phase contact line can enhance the sliding ability of the droplet on the solid surface. There was a good negative linear correlation between the critical sliding angle and dimensionless length, which provided a guiding basis for the optimal design of superhydrophobic surfaces.
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Affiliation(s)
- Junhong Qiu
- College of Mechanical and Electrical Engineering, Jiangxi University of Science and Technology, Ganzhou 341000, China
| | - Shuang Chen
- College of Mechanical and Electrical Engineering, Jiangxi University of Science and Technology, Ganzhou 341000, China
| | - Yuelan Di
- National Key Laboratory for Remanufacturing, Army Academy of Armored Forces, Beijing 100072, China
| | - Haidou Wang
- National Engineering Research Center for Remanufacturing, Army Academy of Armored Forces, Beijing 100072, China
| | - Ling Lan
- National Key Laboratory for Remanufacturing, Army Academy of Armored Forces, Beijing 100072, China
| | - Li Wang
- National Key Laboratory for Remanufacturing, Army Academy of Armored Forces, Beijing 100072, China
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32
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Xu H, Zhang L, Wang L, Lu Y, Feng H. A Robust Superhydrophobic/Conductive Composite Coating with Excellent Anticorrosive Performance. ChemistrySelect 2021. [DOI: 10.1002/slct.202101043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Haidong Xu
- College of Petrochemical Technology Lanzhou University of Technology Lanzhou 730050 China
| | - Liang Zhang
- College of Petrochemical Technology Lanzhou University of Technology Lanzhou 730050 China
| | - Luyao Wang
- College of Petrochemical Technology Lanzhou University of Technology Lanzhou 730050 China
| | - Yong Lu
- College of Petrochemical Technology Lanzhou University of Technology Lanzhou 730050 China
| | - Huixia Feng
- College of Petrochemical Technology Lanzhou University of Technology Lanzhou 730050 China
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33
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Yada S, Allais B, van der Wijngaart W, Lundell F, Amberg G, Bagheri S. Droplet Impact on Surfaces with Asymmetric Microscopic Features. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:10849-10858. [PMID: 34469168 PMCID: PMC8447403 DOI: 10.1021/acs.langmuir.1c01813] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
The impact of liquid drops on a rigid surface is central in cleaning, cooling, and coating processes in both nature and industrial applications. However, it is not clear how details of pores, roughness, and texture on the solid surface influence the initial stages of the impact dynamics. Here, we experimentally study drops impacting at low velocities onto surfaces textured with asymmetric (tilted) ridges. We found that the difference between impact velocity and the capillary speed on a solid surface is a key factor of spreading asymmetry, where the capillary speed is determined by the friction at a moving three-phase contact line. The line-friction capillary number Caf = μfV0/σ (where μf,V0, and σ are the line friction, impact velocity, and surface tension, respectively) is defined as a measure of the importance of the topology of surface textures for the dynamics of droplet impact. We show that when Caf ≪ 1, the droplet impact is asymmetric; the contact line speed in the direction against the inclination of the ridges is set by line friction, whereas in the direction with inclination, the contact line is pinned at acute corners of the ridges. When Caf ≫ 1, the geometric details of nonsmooth surfaces play little role.
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Affiliation(s)
- Susumu Yada
- Department
of Engineering Mechanics, Royal Institute
of Technology, 100 44 Stockholm, Sweden
| | | | | | - Fredrik Lundell
- Department
of Engineering Mechanics, Royal Institute
of Technology, 100 44 Stockholm, Sweden
| | - Gustav Amberg
- Department
of Engineering Mechanics, Royal Institute
of Technology, 100 44 Stockholm, Sweden
- Södertörn
University, 141 89 Stockholm, Sweden
| | - Shervin Bagheri
- Department
of Engineering Mechanics, Royal Institute
of Technology, 100 44 Stockholm, Sweden
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34
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Super liquid repellent surfaces for anti-foaming and froth management. Nat Commun 2021; 12:5358. [PMID: 34504098 PMCID: PMC8429590 DOI: 10.1038/s41467-021-25556-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Accepted: 08/18/2021] [Indexed: 11/23/2022] Open
Abstract
Wet and dry foams are prevalent in many industries, ranging from the food processing and commercial cosmetic sectors to industries such as chemical and oil-refining. Uncontrolled foaming results in product losses, equipment downtime or damage and cleanup costs. To speed up defoaming or enable anti-foaming, liquid oil or hydrophobic particles are usually added. However, such additives may need to be later separated and removed for environmental reasons and product quality. Here, we show that passive defoaming or active anti-foaming is possible simply by the interaction of foam with chemically or morphologically modified surfaces, of which the superamphiphobic variant exhibits superior performance. They significantly improve retraction of highly stable wet foams and prevention of growing dry foams, as quantified for beer and aqueous soap solution as model systems. Microscopic imaging reveals that amphiphobic nano-protrusions directly destabilize contacting foam bubbles, which can favorably vent through air gaps warranted by a Cassie wetting state. This mode of interfacial destabilization offers untapped potential for developing efficient, low-power and sustainable foam and froth management. Wong et al. demonstrate the efficacy of super-amphiphobic surfaces for in situ defoaming and inhibition of foam growth while handling aqueous solutions. Without the use of chemical additives, their passive approach suggests a facile alternative route to froth management in industrial processes.
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35
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Li S, Sng A, Daniel D, Lau HC, Torsæter O, Stubbs LP. Visualizing and Quantifying Wettability Alteration by Silica Nanofluids. ACS APPLIED MATERIALS & INTERFACES 2021; 13:41182-41189. [PMID: 34424661 DOI: 10.1021/acsami.1c08445] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
An aqueous suspension of silica nanoparticles or nanofluid can alter the wettability of surfaces, specifically by making them hydrophilic and oil-repellent under water. Wettability alteration by nanofluids has important technological applications, including for enhanced oil recovery and heat transfer processes. A common way to characterize the wettability alteration is by measuring the contact angles of an oil droplet with and without nanoparticles. While easy to perform, contact angle measurements do not fully capture the wettability changes to the surface. Here, we employed several complementary techniques, such as cryo-scanning electron microscopy, confocal fluorescence and reflection interference contrast microscopy, and droplet probe atomic force microscopy (AFM), to visualize and quantify the wettability alterations by fumed silica nanoparticles. We found that nanoparticles adsorbed onto glass surfaces to form a porous layer with hierarchical micro- and nanostructures. The porous layer can trap a thin water film, which reduces contact between the oil droplet and the solid substrate. As a result, even a small addition of nanoparticles (0.1 wt %) lowers the adhesion force for a 20 μm sized oil droplet by more than 400 times from 210 ± 10 to 0.5 ± 0.3 nN as measured by using droplet probe AFM. Finally, we show that silica nanofluids can improve oil recovery rates by 8% in a micromodel with glass channels that resemble a physical rock network.
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Affiliation(s)
- Shidong Li
- Institute of Chemical and Engineering Sciences (ICES), Agency for Science, Technology and Research (A*STAR), 1, Pesek Road, Jurong Island, Singapore 627833
| | - Anqi Sng
- Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, Innovis, Singapore 138634
| | - Dan Daniel
- Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, Innovis, Singapore 138634
| | - Hon Chung Lau
- Department of Civil and Environmental Engineering, National University of Singapore, 1 Engineering Drive 2, Singapore 117576
| | - Ole Torsæter
- PoreLab - Norwegian Center of Excellence, S. P. Andersens vei 15b, Trondheim, Norway 7031
- Department of Geoscience and Petroleum, Norwegian University of Science and Technology (NTNU), S.P. Andersens veg 15a, Trondheim, Norway 7031
| | - Ludger P Stubbs
- Institute of Chemical and Engineering Sciences (ICES), Agency for Science, Technology and Research (A*STAR), 1, Pesek Road, Jurong Island, Singapore 627833
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36
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Liu G, Wong WSY, Kraft M, Ager JW, Vollmer D, Xu R. Wetting-regulated gas-involving (photo)electrocatalysis: biomimetics in energy conversion. Chem Soc Rev 2021; 50:10674-10699. [PMID: 34369513 DOI: 10.1039/d1cs00258a] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
(Photo)electrolysis of water or gases with water to species serving as industrial feedstocks and energy carriers, such as hydrogen, ammonia, ethylene, propanol, etc., has drawn tremendous attention. Moreover, these processes can often be driven by renewable energy under ambient conditions as a sustainable alternative to traditional high-temperature and high-pressure synthesis methods. In addition to the extensive studies on catalyst development, increasing attention has been paid to the regulation of gas transport/diffusion behaviors during gas-involving (photo)electrocatalytic reactions towards the goal of creating industrially viable catalytic systems with high reaction rates, excellent long-term stabilities and near-unity selectivities. Biomimetic surfaces and systems with special wetting capabilities and structural advantages can shed light on the future design of (photo)electrodes and address long-standing challenges. This article is dedicated to bridging the fields of wetting and catalysis by reviewing the cutting-edge design methodologies of both gas-evolving and gas-consuming (photo)electrocatalytic systems. We first introduce the fundamentals of various in-air/underwater wetting states and their corresponding bioinspired structural properties. The relationship amongst the bubble transport behavior, wettability, and porosity/tortuosity is also discussed. Next, the latest implementations of wetting-related design principles for gas-evolving reactions (i.e. the hydrogen evolution reaction and oxygen evolution reaction) and gas-consuming reactions (i.e. the oxygen reduction reaction and CO2 reduction reaction) are summarized. For photoelectrode designs, additional factors are taken into account, such as light absorption and the separation, transport and recombination of photoinduced electrons and holes. The influences of wettability and 3D structuring of (photo)electrodes on the catalytic activity, stability and selectivity are analyzed to reveal the underlying mechanisms. Finally, remaining questions and related future perspectives are outlined.
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Affiliation(s)
- Guanyu Liu
- School of Chemical & Biomedical Engineering, Nanyang Technological University, 62 Nanyang Drive, 637459 Singapore. and Cambridge Centre for Advanced Research and Education in Singapore (CARES), CREATE Tower, 1 Create Way, 138602 Singapore
| | - William S Y Wong
- Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128, Mainz, Germany
| | - Markus Kraft
- Cambridge Centre for Advanced Research and Education in Singapore (CARES), CREATE Tower, 1 Create Way, 138602 Singapore and Department of Chemical Engineering and Biotechnology, University of Cambridge, West Cambridge Site, Philippa Fawcett Drive, Cambridge CB3 0AS, UK
| | - Joel W Ager
- Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA and Berkeley Educational Alliance for Research in Singapore (BEARS), CREATE Tower, 1 Create Way, 138602 Singapore
| | - Doris Vollmer
- Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128, Mainz, Germany
| | - Rong Xu
- School of Chemical & Biomedical Engineering, Nanyang Technological University, 62 Nanyang Drive, 637459 Singapore. and Cambridge Centre for Advanced Research and Education in Singapore (CARES), CREATE Tower, 1 Create Way, 138602 Singapore
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37
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Lu Y, Zhu Y, Yang F, Xu Z, Liu Q. Advanced Switchable Molecules and Materials for Oil Recovery and Oily Waste Cleanup. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2021; 8:e2004082. [PMID: 34047073 PMCID: PMC8336505 DOI: 10.1002/advs.202004082] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2020] [Revised: 01/19/2021] [Indexed: 05/07/2023]
Abstract
Advanced switchable molecules and materials have shown great potential in numerous applications. These novel materials can express different states of physicochemical properties as controlled by a designated stimulus, such that the processing condition can always be maintained in an optimized manner for improved efficiency and sustainability throughout the whole process. Herein, the recent advances in switchable molecules/materials in oil recovery and oily waste cleanup are reviewed. Oil recovery and oily waste cleanup are of critical importance to the industry and environment. Switchable materials can be designed with various types of switchable properties, including i) switchable interfacial activity, ii) switchable viscosity, iii) switchable solvent, and iv) switchable wettability. The materials can then be deployed into the most suitable applications according to the process requirements. An in-depth discussion about the fundamental basis of the design considerations is provided for each type of switchable material, followed by details about their performances and challenges in the applications. Finally, an outlook for the development of next-generation switchable molecules/materials is discussed.
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Affiliation(s)
- Yi Lu
- Department of Chemical and Materials EngineeringUniversity of AlbertaEdmontonAlbertaT6G 1H9Canada
| | - Yeling Zhu
- Department of Chemical and Materials EngineeringUniversity of AlbertaEdmontonAlbertaT6G 1H9Canada
| | - Fan Yang
- College of New Materials and New EnergiesShenzhen Technology UniversityShenzhen518118P. R. China
| | - Zhenghe Xu
- Department of Chemical and Materials EngineeringUniversity of AlbertaEdmontonAlbertaT6G 1H9Canada
- Department of Materials Science and EngineeringSouthern University of Science and TechnologyShenzhen518055P. R. China
| | - Qingxia Liu
- Department of Chemical and Materials EngineeringUniversity of AlbertaEdmontonAlbertaT6G 1H9Canada
- College of New Materials and New EnergiesShenzhen Technology UniversityShenzhen518118P. R. China
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Díaz D, Nickel O, Moraga N, Catalán RE, Retamal MJ, Zelada H, Cisternas M, Meißner R, Huber P, Corrales TP, Volkmann UG. How water wets and self-hydrophilizes nanopatterns of physisorbed hydrocarbons. J Colloid Interface Sci 2021; 606:57-66. [PMID: 34388573 DOI: 10.1016/j.jcis.2021.07.121] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2021] [Revised: 07/22/2021] [Accepted: 07/23/2021] [Indexed: 11/26/2022]
Abstract
HYPOTHESIS Weakly bound, physisorbed hydrocarbons could in principle provide a similar water-repellency as obtained by chemisorption of strongly bound hydrophobic molecules at surfaces. EXPERIMENTS Here we present experiments and computer simulations on the wetting behaviour of water on molecularly thin, self-assembled alkane carpets of dotriacontane (n-C32H66 or C32) physisorbed on the hydrophilic native oxide layer of silicon surfaces during dip-coating from a binary alkane solution. By changing the dip-coating velocity we control the initial C32 surface coverage and achieve distinct film morphologies, encompassing homogeneous coatings with self-organised nanopatterns that range from dendritic nano-islands to stripes. FINDINGS These patterns exhibit a good water wettability even though the carpets are initially prepared with a high coverage of hydrophobic alkane molecules. Using in-liquid atomic force microscopy, along with molecular dynamics simulations, we trace this to a rearrangement of the alkane layers upon contact with water. This restructuring is correlated to the morphology of the C32 coatings, i.e. their fractal dimension. Water molecules displace to a large extent the first adsorbed alkane monolayer and thereby reduce the hydrophobic C32 surface coverage. Thus, our experiments evidence that water molecules can very effectively hydrophilize initially hydrophobic surfaces that consist of weakly bound hydrocarbon carpets.
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Affiliation(s)
- Diego Díaz
- Instituto de Física, Pontificia Universidad Católica de Chile, Santiago 7820436, Chile; Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz, Germany
| | - Ole Nickel
- Hamburg University of Technology, Institute of Polymers and Composites, 21073 Hamburg, Germany
| | - Nicolás Moraga
- Instituto de Física, Pontificia Universidad Católica de Chile, Santiago 7820436, Chile
| | - Rodrigo E Catalán
- Instituto de Física, Pontificia Universidad Católica de Chile, Santiago 7820436, Chile
| | - María José Retamal
- Instituto de Física, Pontificia Universidad Católica de Chile, Santiago 7820436, Chile
| | - Hugo Zelada
- Instituto de Física, Pontificia Universidad Católica de Chile, Santiago 7820436, Chile
| | - Marcelo Cisternas
- Instituto de Física, Pontificia Universidad Católica de Chile, Santiago 7820436, Chile
| | - Robert Meißner
- Hamburg University of Technology, Institute of Polymers and Composites, 21073 Hamburg, Germany; Helmholtz-Zentrum Hereon, Institute of Surface Science, 21494 Geesthacht, Germany
| | - Patrick Huber
- Hamburg University of Technology, Institute for Materials and X-Ray Physics, 21073 Hamburg, Germany; Deutsches Elektronen-Synchrotron DESY, Centre for X-Ray and Nano Science CXNS, 22603 Hamburg, Germany; University of Hamburg, Centre for Hybrid Nanostructures CHyN, 22607 Hamburg, Germany.
| | - Tomas P Corrales
- Departamento de Física, Universidad Técnica Federico Santa María, Valparaiso 2390123, Chile.
| | - Ulrich G Volkmann
- Instituto de Física, Pontificia Universidad Católica de Chile, Santiago 7820436, Chile; Centro de Investigación en Nanotecnología y Materiales Avanzados (CIEN-UC), Pontificia Universidad Católica de Chile, Santiago 7820436, Chile.
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39
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Lin HP, Chen LJ. Direct observation of wetting behavior of water drops on single micro-scale roughness surfaces of rose petal effect. J Colloid Interface Sci 2021; 603:539-549. [PMID: 34216950 DOI: 10.1016/j.jcis.2021.06.132] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Revised: 06/21/2021] [Accepted: 06/22/2021] [Indexed: 01/28/2023]
Abstract
HYPOTHESIS It has been verified that a surface of single micro-scale structures with certain roughness could exhibit petal effect. That is, water drops with a contact angle larger than 150° would pin on the petal effect surface. It is conjectured that the water drop could pin on the single micro-scale roughness petal effect surface by totally infiltrating into spaces (or grooves) between micro-pillars. EXPERIMENTS An inverted optical microscopy system is synchronically applied in the process of advancing/receding contact angle (ACA/RCA) measurements to directly observe the wetting behavior of water droplets on hydrophobic patterned surfaces with regular arrays of square micro-pillars. FINDINGS A sequence of wetting behavior evolution, Wenzel → petal → pseudo-lotus → lotus, is observed on the hydrophobic patterned surfaces along with increasing surface roughness. It is interesting to observe a Cassie-Wenzel transition for water drops on a petal substrate during the ACA measurement (embedded needle method), leading to two ACAs, one before (in Cassie state) and one after the transition (in Wenzel state). Thus, the petal substrates have large contact angle hysteresis (CAH) (with both ACA and RCA in Wenzel state) to pin the water drop in Wenzel state. A Cassie-Wenzel transition is consistently observed during the evaporation process of water drops on pseudo-lotus substrates, leading to two RCAs: one in Cassie state and one in Wenzel state. The pseudo-lotus substrates have CAH (with both ACA and RCA in Cassie state) small enough to make water drops easily slide off.
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Affiliation(s)
- Hui-Ping Lin
- Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan
| | - Li-Jen Chen
- Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan.
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40
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D'Acunzi M, Sharifi-Aghili A, Hegner KI, Vollmer D. Super liquid repellent coatings against the everyday life wear: Heating, freezing, scratching. iScience 2021; 24:102460. [PMID: 34027319 DOI: 10.1016/j.isci.2021.102460] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Revised: 03/22/2021] [Accepted: 04/20/2021] [Indexed: 12/01/2022] Open
Abstract
Super liquid repellent coatings are among the most promising candidates for self-cleaning surfaces for indoor and outdoor applications. However, the characteristic nano- and micro-scale protrusions can easily be damaged. Improving the durability of these coatings belongs to the most important challenges to increase the coating's application potential. Here, we show that commercial polyester fabrics coated with silicone nanofilaments maintain their self-cleaning properties throughout repeated freezing-unfreezing cycles, ironing, and mechanical stress. The coating improves the heat resistance of the fabric. The surface keeps its water repellency until the fabric is almost destroyed by scratching with sandpaper or a metal sponge. The excellent performance results from the synergetic effects of i) the interwoven structure of the fabric and ii) the intrinsic hydrophobic and flexible nature of the fabric and of the nanofilaments coating. The combination of these factors generates a product which overcomes the most claimed drawbacks of super liquid repellent coatings.
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Affiliation(s)
- Maria D'Acunzi
- Max Planck Institute for Polymer Research, Department of Physics at Interfaces, Ackermannweg 10, 55128 Mainz, Germany
| | - Azadeh Sharifi-Aghili
- Max Planck Institute for Polymer Research, Department of Physics at Interfaces, Ackermannweg 10, 55128 Mainz, Germany
| | - Katharina Irene Hegner
- Max Planck Institute for Polymer Research, Department of Physics at Interfaces, Ackermannweg 10, 55128 Mainz, Germany
| | - Doris Vollmer
- Max Planck Institute for Polymer Research, Department of Physics at Interfaces, Ackermannweg 10, 55128 Mainz, Germany
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41
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Xu H, Ye Q, Chen N, Feng H, Qiu J. Designing and Exploring a Brand-new Strong Superhydrophobic-Conductive Polyaniline-Polysiloxane Composite Anti-corrosion Coating. CHEM LETT 2021. [DOI: 10.1246/cl.200724] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Haidong Xu
- School of Petrochemical Engineering, Lanzhou University of Technology, Lanzhou 730050, P. R. China
| | - Qinqin Ye
- School of Petrochemical Engineering, Lanzhou University of Technology, Lanzhou 730050, P. R. China
| | - Nali Chen
- School of Petrochemical Engineering, Lanzhou University of Technology, Lanzhou 730050, P. R. China
| | - Huixia Feng
- School of Petrochemical Engineering, Lanzhou University of Technology, Lanzhou 730050, P. R. China
| | - Jianhui Qiu
- Faculty of Systems Science and Technology, Akita Prefectural University, Yurihonjo, Akita 015-0055, Japan
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42
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Zhu Z, Yu Z, Yun FF, Pan D, Tian Y, Jiang L, Wang X. Crystal face dependent intrinsic wettability of metal oxide surfaces. Natl Sci Rev 2021; 8:nwaa166. [PMID: 34691554 PMCID: PMC8288373 DOI: 10.1093/nsr/nwaa166] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Revised: 07/06/2020] [Accepted: 07/12/2020] [Indexed: 01/10/2023] Open
Abstract
Knowledge of intrinsic wettability at solid/liquid interfaces at the molecular level perspective is significant in understanding crucial progress in some fields, such as electrochemistry, molecular biology and earth science. It is generally believed that surface wettability is determined by the surface chemical component and surface topography. However, when taking molecular structures and interactions into consideration, many intriguing phenomena would enrich or even redress our understanding of surface wettability. From the perspective of interfacial water molecule structures, here, we discovered that the intrinsic wettability of crystal metal oxide is not only dependent on the chemical components but also critically dependent on the crystal faces. For example, the [Formula: see text] crystal face of α-Al2O3 is intrinsically hydrophobic with a water contact angle near 90°, while another three crystal faces are intrinsically hydrophilic with water contact angles <65°. Based on surface energy analysis, it is found that the total surface energy, polar component and Lewis base portion of the hydrophobic crystal face are all smaller than the other three hydrophilic crystal faces indicating that they have different surface states. DFT simulation further revealed that the adsorbed interfacial water molecules on each crystal face hold various orientations. Herein, the third crucial factor for surface wettability from the perspective of the molecular level is presented, that is the orientations of adsorbed interfacial water molecules apart from the macro-level chemical component and surface topography. This study may serve as a source of inspiration for improving wetting theoretical models and designing controllable wettability at the molecular/atomic level.
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Affiliation(s)
- Zhongpeng Zhu
- Key Laboratory of Bio-inspired Materials and Interfacial Science, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, China
- Key Laboratory of Bio-inspired Smart Interfacial Science and Technology of Ministry of Education, School of Chemistry, Beihang University, Beijing 100191, China
| | - Zhenwei Yu
- Institute for Superconducting and Electronic Materials, Australian Institute for Innovative Materials, University of Wollongong, Wollongong, NSW 2500, Australia
- Key Laboratory of Bio-inspired Smart Interfacial Science and Technology of Ministry of Education, School of Chemistry, Beihang University, Beijing 100191, China
| | - Frank F Yun
- Institute for Superconducting and Electronic Materials, Australian Institute for Innovative Materials, University of Wollongong, Wollongong, NSW 2500, Australia
| | - Deng Pan
- Jinan Yian Biology Institute, Shandong Yian Biological Engineering Co. Ltd., Jinan 250100, China
| | - Ye Tian
- Key Laboratory of Bio-inspired Materials and Interfacial Science, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Lei Jiang
- Key Laboratory of Bio-inspired Materials and Interfacial Science, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, China
- Key Laboratory of Bio-inspired Smart Interfacial Science and Technology of Ministry of Education, School of Chemistry, Beihang University, Beijing 100191, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xiaolin Wang
- Institute for Superconducting and Electronic Materials, Australian Institute for Innovative Materials, University of Wollongong, Wollongong, NSW 2500, Australia
- ARC Centre of Excellence for Future Low-Energy Electronics Technologies (FLEET), University of Wollongong, North Wollongong, NSW 2522, Australia
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43
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Abstract
A gravity-driven droplet will rapidly flow down an inclined substrate, resisted only by stresses inside the liquid. If the substrate is compliant, with an elastic modulus G < 100 kPa, the droplet will markedly slow as a consequence of viscoelastic braking. This phenomenon arises due to deformations of the solid at the moving contact line, enhancing dissipation in the solid phase. Here, we pattern compliant surfaces with textures and probe their interaction with droplets. We show that the superhydrophobic Cassie state, where a droplet is supported atop air-immersed textures, is preserved on soft textured substrates. Confocal microscopy reveals that every texture in contact with the liquid is deformed by capillary stresses. This deformation is coupled to liquid pinning induced by the orientation of contact lines atop soft textures. Thus, compared to flat substrates, greater forcing is required for the onset of drop motion when the soft solid is textured. Surprisingly, droplet velocities down inclined soft or hard textured substrates are indistinguishable; the textures thus suppress viscoelastic braking despite substantial fluid-solid contact. High-speed microscopy shows that contact line velocities atop the pillars vastly exceed those associated with viscoelastic braking. This velocity regime involves less deformation, thus less dissipation, in the solid phase. Such rapid motions are only possible because the textures introduce a new scale and contact-line geometry. The contact-line orientation atop soft pillars induces significant deflections of the pillars on the receding edge of the droplet; calculations confirm that this does not slow down the droplet.
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44
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Kim D, Ryu S. How and When the Cassie-Baxter Droplet Starts to Slide on Textured Surfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:14031-14038. [PMID: 33175546 DOI: 10.1021/acs.langmuir.0c02614] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
A theoretical analysis of the sliding of a Cassie-Baxter droplet on a microstructured surface is conducted. The conventional theory based on the force balance has been frequently used to predict the sliding condition of the droplet; however, the sliding condition cannot be precisely determined because the theory requires the available ranges of the contact angles at the rear and front ends of the droplet. In this study, by calculating the droplet shape and examining the stability of a droplet at every possible pinning point, we propose a new theoretical model that can predict the sliding condition of a two-dimensional (2D) Cassie-Baxter droplet without any a priori measurement but using only the surface information. With the proposed theory, we answer two open questions in sliding research: (i) whether the sliding initiates with front end slip or rear end slip and (ii) whether the advancing and receding contact angles measured on the horizontal surface are comparable with the front and rear contact angles of the droplet at the onset of sliding. Additionally, a new droplet translation motion mechanism promoted by a cycle of condensation and evaporation is suggested, which can be further utilized for precise droplet transportation. Finally, the theoretical results are validated against the 2D line-tension-based front-tracking method (LTM), which can seamlessly capture the attachment and detachment between the droplet and the textured surface.
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Affiliation(s)
- Donggyu Kim
- Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
| | - Seunghwa Ryu
- Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
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45
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Durability of Superamphiphobic Polyester Fabrics in Simulated Aerodynamic Icing Conditions. COATINGS 2020. [DOI: 10.3390/coatings10111058] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Fabrics treated to repel water, superhydrophobic, and water and oil, superamphiphobic, have numerous industrial and consumer-level benefits. However, the liquid repellency decreases in the course of time. This is largely due to chemical or physical changes of the coating due to prolonged exposure to relatively harsh environments. To develop more durable fabric treatments for specific applications, it is necessary to measure the extent to which the treated fabrics retain their low-wettability after being subjected to controlled aggressive environmental conditions. In this study, plain weave fabrics made from polyester filaments and coated with silicone nanofilaments in-solution were exposed to aerodynamic icing conditions. The coated fabrics showed superhydrophobic behavior, or superamphiphobic for those that were fluorinated. The wettability of the fabrics was progressively evaluated by contact angle and roll-off-angle measurements. The coated fabrics were able to maintain their low-wettability characteristics after exposure to water droplet clouds at airspeeds up to 120 m/s, despite damage to the silicone nanofilaments, visible through scanning electron microscopy.
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46
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Sadullah MS, Panter JR, Kusumaatmaja H. Factors controlling the pinning force of liquid droplets on liquid infused surfaces. SOFT MATTER 2020; 16:8114-8121. [PMID: 32734997 DOI: 10.1039/d0sm00766h] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Liquid infused surfaces with partially wetting lubricants have recently been exploited for numerous intriguing applications, such as for droplet manipulation, droplet collection and spontaneous motion. When partially wetting lubricants are used, the pinning force is a key factor that can strongly affect droplet mobility. Here, we derive an analytical prediction for contact angle hysteresis in the limit where the meniscus size is much smaller than the droplet, and numerically study how it is controlled by the solid fraction, the lubricant wetting angles, and the various fluid surface tensions. We further relate the contact angle hysteresis and the pinning force experienced by a droplet on a liquid infused surface, and our predictions for the critical sliding angles are consistent with existing experimental observations. Finally, we discuss why a droplet on a liquid infused surface with partially wetting lubricants typically experiences stronger pinning compared to a droplet on a classical superhydrophobic surface.
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Affiliation(s)
| | - Jack R Panter
- Department of Physics, Durham University, Durham, DH1 3LE, UK.
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47
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Daniel D, Florida Y, Lay CL, Koh XQ, Sng A, Tomczak N. Quantifying Surface Wetting Properties Using Droplet Probe Atomic Force Microscopy. ACS APPLIED MATERIALS & INTERFACES 2020; 12:42386-42392. [PMID: 32799518 DOI: 10.1021/acsami.0c12123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The functional properties of a surface, such as its anti-fogging or anti-fouling performance, are influenced by its wettability. To quantify surface wettability, the most common approach is to measure the contact angles of a liquid droplet on the surface. While well established and relatively easy to perform, contact angle measurements were developed to describe macroscopic wetting properties and are difficult to perform for submillimetric droplets. Moreover, they cannot spatially resolve surface heterogeneities that can contribute to surface fouling. To address these shortcomings, we report on using an atomic force microscopy technique to quantitatively measure the interaction forces between a microdroplet and a surface with piconewton force resolution. We show how our technique can be used to spatially map topographical and chemical heterogeneities with micron resolution.
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Affiliation(s)
- Dan Daniel
- Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), 2 Fusionopolis Way, Innovis, 138634 Singapore
| | - Yunita Florida
- Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), 2 Fusionopolis Way, Innovis, 138634 Singapore
| | - Chee Leng Lay
- Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), 2 Fusionopolis Way, Innovis, 138634 Singapore
| | - Xue Qi Koh
- Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), 2 Fusionopolis Way, Innovis, 138634 Singapore
| | - Anqi Sng
- Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), 2 Fusionopolis Way, Innovis, 138634 Singapore
| | - Nikodem Tomczak
- Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), 2 Fusionopolis Way, Innovis, 138634 Singapore
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48
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Li Q, Li L, Shi K, Yang B, Wang X, Shi Z, Tan D, Meng F, Liu Q, Hu S, Lei Y, Liu S, Xue L. Reversible Structure Engineering of Bioinspired Anisotropic Surface for Droplet Recognition and Transportation. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2020; 7:2001650. [PMID: 32999850 PMCID: PMC7509748 DOI: 10.1002/advs.202001650] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Revised: 06/05/2020] [Indexed: 05/22/2023]
Abstract
Surfaces with tunable liquid adhesion have aroused great attention in past years. However, it remains challenging to endow a surface with the capability of droplet recognition and transportation. Here, a bioinspired surface, termed as TMAS, is presented that is inspired by isotropic lotus leaves and anisotropic butterfly wings. The surface is prepared by simply growing a triangular micropillar array on the pre-stretched thin poly(dimethylsiloxane) (PDMS) film. The regulation of mechanical stress in the PDMS film allows the fine tuning of structural parameters of the micropillar array reversibly, which results in the instantaneous, in situ switching between isotropic and various degrees of anisotropic droplet adhesions, and between strong adhesion and directional sliding of water droplets. TMAS can thus be used for robust droplet transportation and recognition of acids, bases, and their pH strengths. The results here could inspire the design of robust sensor techniques.
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Affiliation(s)
- Qian Li
- School of Power and Mechanical Engineering, The Institute of Technological ScienceWuhan UniversitySouth Donghu Road 8Wuhan430072China
| | - Lijun Li
- School of Power and Mechanical Engineering, The Institute of Technological ScienceWuhan UniversitySouth Donghu Road 8Wuhan430072China
| | - Kui Shi
- School of Power and Mechanical Engineering, The Institute of Technological ScienceWuhan UniversitySouth Donghu Road 8Wuhan430072China
| | - Baisong Yang
- School of Power and Mechanical Engineering, The Institute of Technological ScienceWuhan UniversitySouth Donghu Road 8Wuhan430072China
| | - Xin Wang
- School of Power and Mechanical Engineering, The Institute of Technological ScienceWuhan UniversitySouth Donghu Road 8Wuhan430072China
| | - Zhekun Shi
- School of Power and Mechanical Engineering, The Institute of Technological ScienceWuhan UniversitySouth Donghu Road 8Wuhan430072China
| | - Di Tan
- School of Power and Mechanical Engineering, The Institute of Technological ScienceWuhan UniversitySouth Donghu Road 8Wuhan430072China
| | - Fandong Meng
- School of Power and Mechanical Engineering, The Institute of Technological ScienceWuhan UniversitySouth Donghu Road 8Wuhan430072China
| | - Quan Liu
- School of Power and Mechanical Engineering, The Institute of Technological ScienceWuhan UniversitySouth Donghu Road 8Wuhan430072China
| | - Shiqi Hu
- School of Power and Mechanical Engineering, The Institute of Technological ScienceWuhan UniversitySouth Donghu Road 8Wuhan430072China
| | - Yifeng Lei
- School of Power and Mechanical Engineering, The Institute of Technological ScienceWuhan UniversitySouth Donghu Road 8Wuhan430072China
| | - Sheng Liu
- School of Power and Mechanical Engineering, The Institute of Technological ScienceWuhan UniversitySouth Donghu Road 8Wuhan430072China
| | - Longjian Xue
- School of Power and Mechanical Engineering, The Institute of Technological ScienceWuhan UniversitySouth Donghu Road 8Wuhan430072China
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49
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Ramírez-Soto O, Sanjay V, Lohse D, Pham JT, Vollmer D. Lifting a sessile oil drop from a superamphiphobic surface with an impacting one. SCIENCE ADVANCES 2020; 6:eaba4330. [PMID: 32875104 PMCID: PMC7438093 DOI: 10.1126/sciadv.aba4330] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Accepted: 07/09/2020] [Indexed: 05/25/2023]
Abstract
Colliding drops are encountered in everyday technologies and natural processes, from combustion engines and commodity sprays to raindrops and cloud formation. The outcome of a collision depends on many factors, including the impact velocity and the degree of alignment, and intrinsic properties like surface tension. Yet, little is known on binary impact dynamics of low-surface-tension drops on a low-wetting surface. We investigate the dynamics of an oil drop impacting an identical sessile drop sitting on a superamphiphobic surface. We observe five rebound scenarios, four of which do not involve coalescence. We describe two previously unexplored cases for sessile drop liftoff, resulting from drop-on-drop impact. Numerical simulations quantitatively reproduce the rebound scenarios and enable quantification of velocity profiles, energy transfer, and viscous dissipation. Our results illustrate how varying the offset from head-on alignment and the impact velocity results in controllable rebound dynamics for oil drop collisions on superamphiphobic surfaces.
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Affiliation(s)
- Olinka Ramírez-Soto
- Max Planck Institute for Polymer Research, Mainz, Germany
- Physics of Fluids Group, Max Planck Center for Complex Fluid Dynamics, Mesa+ Institute, and J.M. Burgers Center for Fluid Dynamics, University of Twente, Enschede, Netherlands
- Max Planck Institute for Dynamics and Self-Organization, 37077 Göttingen, Germany
| | - Vatsal Sanjay
- Physics of Fluids Group, Max Planck Center for Complex Fluid Dynamics, Mesa+ Institute, and J.M. Burgers Center for Fluid Dynamics, University of Twente, Enschede, Netherlands
| | - Detlef Lohse
- Physics of Fluids Group, Max Planck Center for Complex Fluid Dynamics, Mesa+ Institute, and J.M. Burgers Center for Fluid Dynamics, University of Twente, Enschede, Netherlands
- Max Planck Institute for Dynamics and Self-Organization, 37077 Göttingen, Germany
| | - Jonathan T. Pham
- Department of Chemical and Materials Engineering, University of Kentucky, Lexington, KY 40506, USA
| | - Doris Vollmer
- Max Planck Institute for Polymer Research, Mainz, Germany
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50
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Song J, Jia X, Minami K, Hill JP, Nakanishi J, Shrestha LK, Ariga K. Large-Area Aligned Fullerene Nanocrystal Scaffolds as Culture Substrates for Enhancing Mesenchymal Stem Cell Self-Renewal and Multipotency. ACS APPLIED NANO MATERIALS 2020; 3:6497-6506. [DOI: 10.1021/acsanm.0c00973] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/30/2023]
Affiliation(s)
- Jingwen Song
- Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8561, Japan
| | - Xiaofang Jia
- International Research Center for Materials Nanoarchitectonics (MANA), National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
| | - Kosuke Minami
- International Research Center for Materials Nanoarchitectonics (MANA), National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
- International Center for Young Scientists (ICYS), National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
- Center for Functional Sensor and Actuator (CFSN), National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
| | - Jonathan P. Hill
- International Research Center for Materials Nanoarchitectonics (MANA), National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
| | - Jun Nakanishi
- International Research Center for Materials Nanoarchitectonics (MANA), National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
| | - Lok Kumar Shrestha
- International Research Center for Materials Nanoarchitectonics (MANA), National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
| | - Katsuhiko Ariga
- Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8561, Japan
- International Research Center for Materials Nanoarchitectonics (MANA), National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
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