1
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Wang J, Wang Y, Zhang K, Liu X, Zhang S, Wang D, Xie L. Understanding the role of infusing lubricant composition in the interfacial interactions and properties of slippery surface. J Colloid Interface Sci 2024; 659:289-298. [PMID: 38176238 DOI: 10.1016/j.jcis.2023.12.174] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Revised: 12/25/2023] [Accepted: 12/29/2023] [Indexed: 01/06/2024]
Abstract
Liquid-infused surfaces (LISs) have attracted tremendous attention in recent years owing to their excellent surface properties, such as self-cleaning and anti-fouling. Understanding the effect of lubricant composition on LIS performance is of vital importance, which will help establish the criteria to choose suitable infusing lubricants for specific applications. In this work, the role of chemical composition of lubricant in the properties of LISs was investigated. The apparent water contact angle θapp was dependent on the temperature and beeswax/silicone oil ratio. Nevertheless, the trend of moving velocity of water drop on the tilted LISs did not follow that of θapp at 20 °C and 37 °C, which was attributed to the increased lubricant viscosity with beeswax/silicone oil ratio. At 60 °C, the drop velocity and θapp shared the similar variation trend with beeswax/silicone oil ratio, highlighting the significant role of chemistry of the components in beeswax. The alkanes and fatty acids promoted the drop movement, while the fatty acid esters impeded the movement. The interaction forces between water drop and lubricant surfaces were measured using atomic force microscopy. It was demonstrated that the interaction between water drop and lubricant was not the only factor to control the drop movement, while the interaction between lubricant and substrate as well as of lubricant itself also determined the movement. When the adhesions of water-lubricant and lubricant-substrate were similar for different lubricants, the influence of cohesion of lubricant became significant. This work provides useful insights into the fundamental understanding of the interfacial interactions of test drop, infusing lubricant and solid substrate of LISs, and the effect of infusing lubricant composition on the LIS performance.
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Affiliation(s)
- Jingyi Wang
- College of Chemistry and Chemical Engineering, Southwest Petroleum University, Chengdu, Sichuan 610500, China; Sichuan Provincial Key Laboratory of Oil and Gas Fields Applied Chemistry, Chengdu, Sichuan 610500, China.
| | - Yifan Wang
- College of Chemistry and Chemical Engineering, Southwest Petroleum University, Chengdu, Sichuan 610500, China
| | - Kuanjun Zhang
- College of Chemistry and Chemical Engineering, Southwest Petroleum University, Chengdu, Sichuan 610500, China
| | - Xun Liu
- College of Chemistry and Chemical Engineering, Southwest Petroleum University, Chengdu, Sichuan 610500, China
| | - Shishuang Zhang
- School of Minerals Processing and Bioengineering, Central South University, Changsha, Hunan 410083, China; Key Laboratory of Icing and Anti/De-icing, China Aerodynamics Research and Development Center, Mianyang, Sichuan 621000, China
| | - Dianlin Wang
- College of Chemistry and Chemical Engineering, Southwest Petroleum University, Chengdu, Sichuan 610500, China; Sichuan Provincial Key Laboratory of Oil and Gas Fields Applied Chemistry, Chengdu, Sichuan 610500, China.
| | - Lei Xie
- School of Minerals Processing and Bioengineering, Central South University, Changsha, Hunan 410083, China; Key Laboratory of Icing and Anti/De-icing, China Aerodynamics Research and Development Center, Mianyang, Sichuan 621000, China.
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2
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Wang F, Nestler B. Wetting and Contact-Angle Hysteresis: Density Asymmetry and van der Waals Force. PHYSICAL REVIEW LETTERS 2024; 132:126202. [PMID: 38579226 DOI: 10.1103/physrevlett.132.126202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Accepted: 01/23/2024] [Indexed: 04/07/2024]
Abstract
A droplet depositing on a solid substrate leads to the wetting phenomenon, such as dew on plant leaves. On an ideally smooth substrate, the classic Young's law has been employed to describe the wetting effect. However, no real substrate is ideally smooth at the microscale. Given this fact, we introduce a surface composition concept to scrutinize the wetting mechanism via considering the liquid-gas density asymmetry and the fluid-solid van der Waals interaction. The current concept enables one to comprehend counterintuitive phenomenon of contact-angle hysteresis on a smooth substrate and increase of contact angle with temperature as well as gas bubble wetting.
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Affiliation(s)
- Fei Wang
- Institute for Applied Materials-Microstructure Modelling and Simulation (IAM-MMS), Karlsruhe Institute of Technology (KIT), Strasse am Forum 7, 76131 Karlsruhe, Germany and Institute of Nanotechnology (INT), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - Britta Nestler
- Institute for Applied Materials-Microstructure Modelling and Simulation (IAM-MMS), Karlsruhe Institute of Technology (KIT), Strasse am Forum 7, 76131 Karlsruhe, Germany; Institute of Nanotechnology (INT), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany and Institute of Digital Materials Science, Karlsruhe University of Applied Sciences, Moltkestrasse 30, 76133 Karlsruhe, Germany
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3
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Nazeer SS, Venkataraman RK, Jayasree RS, Bayry J. Infrared Spectroscopy for Rapid Triage of Cancer Using Blood Derivatives: A Reality Check. Anal Chem 2024; 96:957-965. [PMID: 38164878 DOI: 10.1021/acs.analchem.3c02590] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2024]
Abstract
Infrared (IR) spectroscopy of serum/plasma represents an alluring molecular diagnostic tool, especially for cancer, as it can provide a molecular fingerprint of clinical samples based on vibrational modes of chemical bonds. However, despite the superior performance, the routine adoption of this technique for clinical settings has remained elusive. This is due to the potential confounding factors that are often overlooked and pose a significant barrier to clinical translation. In this Perspective, we summarize the concerns associated with various confounding factors, such as fluid sampling, optical effects, hemolysis, abnormal cardiovascular and/or hepatic functions, infections, alcoholism, diet style, age, and gender of a patient or normal control cohort, and improper selection of numerical methods that ultimately would lead to improper spectral diagnosis. We also propose some precautionary measures to overcome the challenges associated with these confounding factors.
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Affiliation(s)
- Shaiju S Nazeer
- Department of Chemistry, Indian Institute of Space Sciences and Technology, Thiruvananthapuram, Kerala 695547, India
| | - Ravi Kumar Venkataraman
- Ultrafast Laser Spectroscopy Lab, Center for Integrative Petroleum Research, King Fahd University of Petroleum and Minerals, Dhahran 31261, Kingdom of Saudi Arabia
| | - Ramapurath S Jayasree
- Division of Biophotonics and Imaging, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Thiruvananthapuram, Kerala 695012, India
| | - Jagadeesh Bayry
- Department of Biological Sciences and Engineering, Indian Institute of Technology Palakkad, Palakkad 678623, India
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4
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Orejon D, Maeda Y, Zhang P, Lv F, Takata Y. Nanorough Is Not Slippery Enough: Implications on Shedding and Heat Transfer. ACS APPLIED MATERIALS & INTERFACES 2024; 16:1779-1793. [PMID: 38164911 PMCID: PMC10788867 DOI: 10.1021/acsami.3c14232] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2023] [Revised: 12/08/2023] [Accepted: 12/11/2023] [Indexed: 01/03/2024]
Abstract
Lowering droplet-surface interactions via the implementation of lubricant-infused surfaces (LISs) has received important attention in the past years. LISs offer enhanced droplet mobility with low sliding angles and the recently reported slippery Wenzel state, among others, empowered by the presence of the lubricant infused in between the structures, which eventually minimizes the direct interactions between liquid droplets and LISs. Current strategies to increase heat transfer during condensation phase-change relay on minimizing the thickness of the coating as well as enhancing condensate shedding. While further surface structuring may impose an additional heat transfer resistance, the presence of micro-structures eventually reduces the effective condensate-surface intimate interactions with the consequently decreased adhesion and enhanced shedding performance, which is investigated in this work. This is demonstrated by macroscopic and optical microscopy condensation experimental observations paying special attention at the liquid-lubricant and liquid-solid binary interactions at the droplet-LIS interface, which is further supported by a revisited force balance at the droplet triple contact line. Moreover, the occurrence of a condensation-coalescence-shedding regime is quantified for the first time with droplet growth rates one and two orders of magnitude greater than during condensation-coalescence and direct condensation regimes, respectively. Findings presented here are of great importance for the effective design and implementation of LISs via surface structure endowing accurate droplet mobility and control for applications such as anti-icing, self-cleaning, water harvesting, and/or liquid repellent surfaces as well as for condensation heat transfer.
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Affiliation(s)
- Daniel Orejon
- Institute
for Multiscale Thermofluids, School of Engineering, University of Edinburgh, Scotland EH9 3BF, United
Kingdom
- International
Institute for Carbon-Neutral Energy Research (WPI-I2CNER), Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
| | - Yota Maeda
- Department
of Mechanical Engineering, Thermofluid Physics Laboratory, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
| | - Peng Zhang
- Institute
of Refrigeration and Cryogenics, Shanghai
Jiao Tong University, Shanghai 200240, China
| | - Fengyong Lv
- School
of Urban Construction and Safety Engineering, Shanghai Institute of Technology, Shanghai 201418, China
| | - Yasuyuki Takata
- Institute
for Multiscale Thermofluids, School of Engineering, University of Edinburgh, Scotland EH9 3BF, United
Kingdom
- International
Institute for Carbon-Neutral Energy Research (WPI-I2CNER), Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
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5
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Hou L, Liu X, Ge X, Hu R, Cui Z, Wang N, Zhao Y. Designing of anisotropic gradient surfaces for directional liquid transport: Fundamentals, construction, and applications. Innovation (N Y) 2023; 4:100508. [PMID: 37753526 PMCID: PMC10518492 DOI: 10.1016/j.xinn.2023.100508] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2023] [Accepted: 09/01/2023] [Indexed: 09/28/2023] Open
Abstract
Many biological surfaces are capable of transporting liquids in a directional manner without energy consumption. Inspired by nature, constructing asymmetric gradient surfaces to achieve desired droplet transport, such as a liquid diode, brings an incredibly valuable and promising area of research with a wide range of applications. Enabled by advances in nanotechnology and manufacturing techniques, biomimetics has emerged as a promising avenue for engineering various types of anisotropic material system. Over the past few decades, this approach has yielded significant progress in both fundamental understanding and practical applications. Theoretical studies revealed that the heterogeneous composition and topography mainly govern the wetting mechanisms and dynamics behavior of droplets, including the interdisciplinary aspects of materials, chemistry, and physics. In this review, we provide a concise overview of various biological surfaces that exhibit anisotropic droplet transport. We discussed the theoretical foundations and mechanisms of droplet motion on designed surfaces and reviewed recent research advances in droplet directional transport on designed plane surfaces and Janus membranes. Such liquid-diode materials yield diverse promising applications, involving droplet collection, liquid separation and delivery, functional textiles, and biomedical applications. We also discuss the recent challenges and ongoing approaches to enhance the functionality and application performance of anisotropic materials.
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Affiliation(s)
- Lanlan Hou
- Key Laboratory of Bioinspired Smart Interfacial Science and Technology of Ministry of Education, Beijing Key Laboratory of Bioinspired Energy Materials and Devices, School of Chemistry, Beijing Advanced Innovation Center for Biomedical Engineering, Beihang University, Beijing 100191, China
- School of Printing and Packaging Engineer, Beijing Institute of Graphic Communication, Beijing 102600, China
- Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Xiaofei Liu
- Key Laboratory of Bioinspired Smart Interfacial Science and Technology of Ministry of Education, Beijing Key Laboratory of Bioinspired Energy Materials and Devices, School of Chemistry, Beijing Advanced Innovation Center for Biomedical Engineering, Beihang University, Beijing 100191, China
| | - Xinran Ge
- Key Laboratory of Bioinspired Smart Interfacial Science and Technology of Ministry of Education, Beijing Key Laboratory of Bioinspired Energy Materials and Devices, School of Chemistry, Beijing Advanced Innovation Center for Biomedical Engineering, Beihang University, Beijing 100191, China
| | - Rongjun Hu
- Key Laboratory of Bioinspired Smart Interfacial Science and Technology of Ministry of Education, Beijing Key Laboratory of Bioinspired Energy Materials and Devices, School of Chemistry, Beijing Advanced Innovation Center for Biomedical Engineering, Beihang University, Beijing 100191, China
- Institute of Applied Chemistry, Jiangxi Academy of Sciences, Nanchang 330096, China
| | - Zhimin Cui
- Key Laboratory of Bioinspired Smart Interfacial Science and Technology of Ministry of Education, Beijing Key Laboratory of Bioinspired Energy Materials and Devices, School of Chemistry, Beijing Advanced Innovation Center for Biomedical Engineering, Beihang University, Beijing 100191, China
| | - Nü Wang
- Key Laboratory of Bioinspired Smart Interfacial Science and Technology of Ministry of Education, Beijing Key Laboratory of Bioinspired Energy Materials and Devices, School of Chemistry, Beijing Advanced Innovation Center for Biomedical Engineering, Beihang University, Beijing 100191, China
| | - Yong Zhao
- Key Laboratory of Bioinspired Smart Interfacial Science and Technology of Ministry of Education, Beijing Key Laboratory of Bioinspired Energy Materials and Devices, School of Chemistry, Beijing Advanced Innovation Center for Biomedical Engineering, Beihang University, Beijing 100191, China
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Pelizzari M, McHale G, Armstrong S, Zhao H, Ledesma-Aguilar R, Wells GG, Kusumaatmaja H. Droplet Self-Propulsion on Slippery Liquid-Infused Surfaces with Dual-Lubricant Wedge-Shaped Wettability Patterns. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:15676-15689. [PMID: 37874819 PMCID: PMC10634355 DOI: 10.1021/acs.langmuir.3c02205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Revised: 10/02/2023] [Indexed: 10/26/2023]
Abstract
Young's equation is fundamental to the concept of the wettability of a solid surface. It defines the contact angle for a droplet on a solid surface through a local equilibrium at the three-phase contact line. Recently, the concept of a liquid Young's law contact angle has been developed to describe the wettability of slippery liquid-infused porous surfaces (SLIPS) by droplets of an immiscible liquid. In this work, we present a new method to fabricate biphilic SLIP surfaces and show how the wettability of the composite SLIPS can be exploited with a macroscopic wedge-shaped pattern of two distinct lubricant liquids. In particular, we report the development of composite liquid surfaces on silicon substrates based on lithographically patterning a Teflon AF1600 coating and a superhydrophobic coating (Glaco Mirror Coat Zero), where the latter selectively dewets from the former. This creates a patterned base surface with preferential wetting to matched liquids: the fluoropolymer PTFE with a perfluorinated oil Krytox and the hydrophobic silica-based GLACO with olive oil (or other mineral oils or silicone oil). This allows us to successively imbibe our patterned solid substrates with two distinct oils and produce a composite liquid lubricant surface with the oils segregated as thin films into separate domains defined by the patterning. We illustrate that macroscopic wedge-shaped patterned SLIP surfaces enable low-friction droplet self-propulsion. Finally, we formulate an analytical model that captures the dependence of the droplet motion as a function of the wettability of the two liquid lubricant domains and the opening angle of the wedge. This allows us to derive scaling relationships between various physical and geometrical parameters. This work introduces a new approach to creating patterned liquid lubricant surfaces, demonstrates long-distance droplet self-propulsion on such surfaces, and sheds light on the interactions between liquid droplets and liquid surfaces.
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Affiliation(s)
- Michele Pelizzari
- Institute
for Multiscale Thermofluids, School of Engineering, The University of Edinburgh, Edinburgh EH9 3FB, U.K.
| | - Glen McHale
- Institute
for Multiscale Thermofluids, School of Engineering, The University of Edinburgh, Edinburgh EH9 3FB, U.K.
| | - Steven Armstrong
- Institute
for Multiscale Thermofluids, School of Engineering, The University of Edinburgh, Edinburgh EH9 3FB, U.K.
| | - Hongyu Zhao
- 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.
| | - Gary G. Wells
- Institute
for Multiscale Thermofluids, School of Engineering, The University of Edinburgh, Edinburgh EH9 3FB, U.K.
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7
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McHale G, Ledesma-Aguilar R, Neto C. Cassie's Law Reformulated: Composite Surfaces from Superspreading to Superhydrophobic. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:11028-11035. [PMID: 37487028 PMCID: PMC10413937 DOI: 10.1021/acs.langmuir.3c01313] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2023] [Revised: 07/11/2023] [Indexed: 07/26/2023]
Abstract
In 1948, Cassie provided an equation describing the wetting of a smooth, heterogeneous surface. He proposed that the cosine of the contact angle, θc, for a droplet on a composite surface could be predicted from a weighted average using the fractional surface areas, fi, of the cosines of contact angles of a droplet on the individual component surfaces, i.e., cos θc = f1 cos θ1 + f2 cos θ2. This was a generalization of an earlier equation for porous materials, which has recently proven fundamental to underpinning the theoretical description of wetting of superhydrophobic and superoleophobic surfaces. However, there has been little attention paid to what happens when a liquid exhibits complete wetting on one of the surface components. Here, we show that Cassie's equation can be reformulated using spreading coefficients. This reformulated equation is capable of describing composite surfaces where the individual surface components have negative (droplet state/partial wetting) or positive (film-forming/complete wetting) spreading coefficients. The original Cassie equation is then a special case when the combination of interfacial tensions results in a droplet state on the composite surface for which a contact angle can be defined. In the case of a composite surface created from a partial wetting (droplet state) surface and a complete wetting (film-forming) surface, there is a threshold surface area fraction at which a liquid on the composite surface transitions from a droplet to a film state. The applicability of this equation is demonstrated from literature data including data on mixed self-assembled monolayers on copper, silver, and gold surfaces that was regarded as definitive in establishing the validity of the Cassie equation. Finally, we discuss the implications of these ideas for super-liquid repellent surfaces.
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Affiliation(s)
- Glen McHale
- 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.
| | - Chiara Neto
- School
of Chemistry and the University of Sydney Nano Institute, The University of Sydney, Sydney, New South Wales 2006, Australia
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8
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Memon H, Wang J, Hou X. Interdependence of Surface Roughness on Icephobic Performance: A Review. MATERIALS (BASEL, SWITZERLAND) 2023; 16:4607. [PMID: 37444925 DOI: 10.3390/ma16134607] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Revised: 06/06/2023] [Accepted: 06/20/2023] [Indexed: 07/15/2023]
Abstract
Ice protection techniques have attracted significant interest, notably in aerospace and wind energy applications. However, the current solutions are mostly costly and inconvenient due to energy-intensive and environmental concerns. One of the appealing strategies is the use of passive icephobicity, in the form of coatings, which is induced by means of several material strategies, such as hydrophobicity, surface texturing, surface elasticity, and the physical infusion of ice-depressing liquids, etc. In this review, surface-roughness-related icephobicity is critically discussed to understand the challenges and the role of roughness, especially on superhydrophobic surfaces. Surface roughness as an intrinsic, independent surface property for anti-icing and de-icing performance is also debated, and their interdependence is explained using the related physical mechanisms and thermodynamics of ice nucleation. Furthermore, the role of surface roughness in the case of elastomeric or low-modulus polymeric coatings, which typically instigate an easy release of ice, is examined. In addition to material-centric approaches, the influence of surface roughness in de-icing evaluation is also explored, and a comparative assessment is conducted to understand the testing sensitivity to various surface characteristics. This review exemplifies that surface roughness plays a crucial role in incorporating and maintaining icephobic performance and is intrinsically interlinked with other surface-induced icephobicity strategies, including superhydrophobicity and elastomeric surfaces. Furthermore, the de-icing evaluation methods also appear to be roughness sensitive in a certain range, indicating a dominant role of mechanically interlocked ice.
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Affiliation(s)
- Halar Memon
- Faculty of Engineering, University of Nottingham, University Park Campus, Nottingham NG7 2RD, UK
| | - Jie Wang
- School of Materials Science and Engineering, Nanjing Institute of Technology, Nanjing 211167, China
| | - Xianghui Hou
- State Key Laboratory of Solidification Processing, Shaanxi Key Laboratory of Fiber Reinforced Light Composite Materials, Northwestern Polytechnical University, Xi'an 710072, China
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9
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Üçüncüoğlu R, Erbil HY. Water Drop Evaporation on Slippery Liquid-Infused Porous Surfaces (SLIPS): Effect of Lubricant Thickness, Viscosity, Ridge Height, and Pattern Geometry. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:6514-6528. [PMID: 37103333 PMCID: PMC10173461 DOI: 10.1021/acs.langmuir.3c00471] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Sessile drop evaporation and condensation on slippery liquid-infused porous surfaces (SLIPS) is crucial for many applications. However, its modeling is complex since the infused lubricant forms a wetting ridge around the drop close to the contact line, which partially blocks the free surface area and decreases the drop evaporation rate. Although a good model was available after 2015, the effects of initial lubricant heights (hoil)i above the pattern, and the corresponding initial ridge heights (hr)i, lubricant viscosity, and solid pattern type were not well studied. This work fills this gap where water drop evaporations from SLIPS, which are obtained by infusing silicone oils (20 and 350 cSt) onto hydrophobized Si wafer micropatterns having both cylindrical and square prism pillars, are investigated under constant relative humidity and temperature conditions. With the increase of (hoil)i, the corresponding (hr)i increased almost linearly on lower parts of the drops for all SLIPS samples, resulting in slower drop evaporation rates. A novel diffusion-limited evaporation equation from SLIPS is derived depending on the available free liquid-air interfacial area, ALV, which represents the unblocked part of the total drop surface. The calculation of the diffusion constant, D, of water vapor in air from (dALV/dt) values obtained by drop evaporation was successful up to a threshold value of (hoil)i = 8 μm within ±7%, and large deviations (13-27%) were obtained when (hoil)i > 8 μm, possibly due to the formation of thin silicone oil cloaking layers on drop surfaces, which partially blocked evaporation. The increase of infused silicone oil viscosity caused only a slight increase (12-17%) in drop lifetimes. The effects of the geometry and size of the pillars on the drop evaporation rates were minimal. These findings may help optimize the lubricant oil layer thickness and viscosity used for SLIPS to achieve low operational costs in the future.
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Affiliation(s)
- Rana Üçüncüoğlu
- Department of Chemical Engineering, Gebze Technical University, Gebze, 41400 Kocaeli, Türkiye
| | - H Yildirim Erbil
- Department of Chemical Engineering, Gebze Technical University, Gebze, 41400 Kocaeli, Türkiye
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10
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Bottone D, Seeger S. Droplet Memory on Liquid-Infused Surfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:6160-6168. [PMID: 37067495 PMCID: PMC10157887 DOI: 10.1021/acs.langmuir.3c00289] [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 knowledge of droplet friction on liquid-infused surfaces (LIS) is of paramount importance for applications involving liquid manipulation. While the possible dissipation mechanisms are well-understood, the effect of surface texture has thus far been mainly investigated on LIS with highly regular solid topographies. In this work, we aim to address this experimental gap by studying the friction experienced by water droplets on LIS based on both random and regular polysilsesquioxane nanostructures. We show that the available models apply to the tested surfaces, but we observe a previously unreported droplet memory effect: as consecutive droplets travel along the same path, their velocity increases up to a plateau value before returning to the original state after a sufficiently long time. We study the features of this phenomenon by evaluating the motion of droplets when they cross the path of a previous sequence of droplets, discovering that moving droplets create a low-friction trace in their wake, whose size matches their base diameter. Finally, we attribute this to the temporary smoothing out of an initially conformal lubricant layer by means of a Landau-Levich-Derjaguin liquid film deposition behind the moving droplet. The proposed mechanism might apply to any LIS with a conformal lubricant layer.
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Affiliation(s)
- Davide Bottone
- Department of Chemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Stefan Seeger
- Department of Chemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
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11
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Zhao Y, Li H, Lei J, Xie J, Li L, Gan Y, Deng J, Qi R, Liu Y. Study on the surface wetting mechanism of bituminous coal based on the microscopic molecular structure. RSC Adv 2023; 13:5933-5945. [PMID: 36816080 PMCID: PMC9936267 DOI: 10.1039/d2ra07908a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2022] [Accepted: 02/01/2023] [Indexed: 02/19/2023] Open
Abstract
The chemical wet dust removal method is one of the hot methods for coal dust control, and the key to its success lies in whether the surface of coal dust can be well wetted or not. Nowadays, the wetting mechanism of the coal dust surface is understudied, limiting the further application of chemical wet dust removal. Thus, the exploration of the wetting mechanism based on the microscopic molecular structure characteristics of the coal surface provides a new solution to improve the wet dust removal efficiency. Herein, the bituminous coal collected from 3 groups of coal seams in the Pingdingshan mining area was used as the object of study to reveal the microscopic wetting mechanism. Proximate analysis, nuclear magnetic resonance carbon spectroscopy (13C NMR) and X-ray photoelectron spectroscopy (XPS) can well distinguish the microstructural information of the coal surface, enabling building the molecular structure models of three groups of coal. Joint contact angle experiments were conducted to explore the influencing factors between the molecular structure of coal dust and its wettability. Molecular simulation techniques, combined with indoor experiments, were used to explore the essential causes of the differences in the wetting mechanisms of bituminous coal dust. The results showed that the composition and structure of carbon and oxygen elements on the coal surface has a significant effect on the wettability of coal dust. The higher the relative content of aromatic carbon and oxygen elements, the better the wettability of the coal surface. An opposite trend occurred for the aliphatic carbon. The difference in wettability of coal surfaces mainly stems from the ability of hydrophilic functional groups on coal surfaces to form hydrogen bonds with water molecules. The aromatic hydrocarbon structure has a much greater ability to adsorb water molecules than the aliphatic hydrocarbon structure. The research results can provide scientific guidance for the design of efficient and environmentally friendly dust suppressants to realize clean coal production in mines.
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Affiliation(s)
- Yun Zhao
- School of Mechanical Engineering, Chengdu UniversityChengdu610106China
| | - Hongmei Li
- College of Food and Bioengineering, Chengdu University Chengdu 610106 China .,State Key Lab of Hydraulics and Mountain River Engineering, College of Water Resource & Hydropower, Sichuan University Chengdu Sichuan 610065 China
| | - Jinming Lei
- College of Food and Bioengineering, Chengdu University Chengdu 610106 China
| | - Jing Xie
- State Key Lab of Hydraulics and Mountain River Engineering, College of Water Resource & Hydropower, Sichuan UniversityChengduSichuan 610065China
| | - Luming Li
- College of Food and Bioengineering, Chengdu University Chengdu 610106 China
| | - Ya Gan
- College of Food and Bioengineering, Chengdu University Chengdu 610106 China
| | - Jie Deng
- College of Food and Bioengineering, Chengdu University Chengdu 610106 China
| | - Rui Qi
- College of Food and Bioengineering, Chengdu University Chengdu 610106 China
| | - Yongliang Liu
- School of Mechanical Engineering, Chengdu UniversityChengdu610106China
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12
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Gupta S, Bhatt B, Sharma M, Khare K. Numerical and experimental investigation of static wetting morphologies of aqueous drops on lubricated slippery surfaces using a quasi-static approach. SOFT MATTER 2023; 19:1164-1173. [PMID: 36637154 DOI: 10.1039/d2sm01485h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
The static wetting behavior of drops on surfaces with thin lubricating films is very different compared to solid surfaces. Due to the slow dynamics of the wetting ridge, it is challenging to predict the apparent contact angles of such drops. It is hypothesized that for a sinking drop on a lubricated surface, quasi-static wetting morphology can be numerically computed from the knowledge of interfacial energies, lubricant thickness, and drop volume. In this study, we use Surface Evolver to numerically compute the static wetting morphology for the four-phase system using a quasi-static approach with a sinking time similar to the early-intermediate times, and the results agree well with the corresponding experiments. We find that the apparent contact angles depend significantly on the lubricant thickness and substrate wettability compared to other parameters.
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Affiliation(s)
- Shivam Gupta
- Department of Physics, Indian Institute of Technology Kanpur, Kanpur 208016, India.
| | - Bidisha Bhatt
- Department of Physics, Indian Institute of Technology Kanpur, Kanpur 208016, India.
| | - Meenaxi Sharma
- Department of Physics, Indian Institute of Technology Kanpur, Kanpur 208016, India.
| | - Krishnacharya Khare
- Department of Physics, Indian Institute of Technology Kanpur, Kanpur 208016, India.
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13
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Hauer L, Cai Z, Skabeev A, Vollmer D, Pham JT. Phase Separation in Wetting Ridges of Sliding Drops on Soft and Swollen Surfaces. PHYSICAL REVIEW LETTERS 2023; 130:058205. [PMID: 36800444 DOI: 10.1103/physrevlett.130.058205] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Accepted: 01/11/2023] [Indexed: 06/18/2023]
Abstract
Drops in contact with swollen, elastomeric substrates can induce a capillary mediated phase separation in wetting ridges. Using confocal microscopy, we visualize phase separation of oligomeric silicone oil from a cross-linked silicone network during steady-state sliding of water drops. We find an inverse relationship between the oil tip height and the drop sliding speed, which is rationalized by competing transport timescales of the oil molecules: separation rate versus drop-advection speed. Separation rates in highly swollen networks are as fast as diffusion in pure melts.
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Affiliation(s)
- Lukas Hauer
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
- Department of Chemical and Materials Engineering, University of Kentucky, Lexington, 40506 Kentucky, USA
| | - Zhuoyun Cai
- Department of Chemical and Materials Engineering, University of Kentucky, Lexington, 40506 Kentucky, USA
| | - Artem Skabeev
- Institute of Organic Chemistry and Macromolecular Chemistry, Friedrich Schiller University Jena, Lessingstrasse 8, 07743 Jena, Germany
| | - Doris Vollmer
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Jonathan T Pham
- Department of Chemical and Materials Engineering, University of Kentucky, Lexington, 40506 Kentucky, USA
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14
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Xiang B, Liu Q, Sun Q, Gong J, Mu P, Li J. Recent advances in eco-friendly fabrics with special wettability for oil/water separation. Chem Commun (Camb) 2022; 58:13413-13438. [PMID: 36398621 DOI: 10.1039/d2cc05780h] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Considering the serious damage to aquatic ecosystems and marine life caused by oil spills and oily wastewater discharge, efficient, environment-friendly and sustainable oil/water separation technology has become an inevitable trend for current development. Herein, fabrics are recognized as eco-friendly materials for water treatment due to their good degradability and low cost. Particularly, fabrics with rough structures and natural hydrophilicity/oleophilicity enable the construction of superwetting surfaces for the selective separation of oil/water mixtures and even complex emulsions. Therefore, superwetting fabrics for efficiently solving oil spills and purifying oily wastewater have received extensive attention. Especially, Janus and smart fabrics are highly anticipated to enable the on-demand and sustainable treatment of oil spills and oily wastewater due to their changeable wettability. Moreover, the fabrication of superwetting fabrics with multifunctional performances for oily wastewater purification can further promote their practical industrial applications, such as photocatalytic, self-cleaning, and self-healing characteristics. However, some potential challenges still exist, which urgently need to be systematically summarized to guide the future development of this research field. In this review, firstly, the fundamental theories of wettability and the separation mechanisms based on special wettability are discussed. Then, superwetting fabrics for efficient oil/water separation are systematically reviewed, such as superhydrophobic/superoleophilic (SHB/SOL), superhydrophilic/superoleophobic (SHL/SOB), SHL/underwater superoleophobic (SHL/UWSOB), and UWSOB/underoil superoleophobic (UWSOB/UOSHB) fabrics. Most importantly, we highlight Janus, smart, and multifunctional fabrics based on their superwetting property. Correspondingly, the advantages and disadvantages of each superwetting fabric are comprehensively analyzed. Besides, super-antiwetting fabrics with superhydrophobic/superoleophobic (SHB/SOB) property are also introduced. Finally, the challenges and future research directions are explained.
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Affiliation(s)
- Bin Xiang
- Key Laboratory of Eco-functional Polymer Materials of the Ministry of Education, College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou 730070, P. R. China.
| | - Qiuqiu Liu
- Key Laboratory of Eco-functional Polymer Materials of the Ministry of Education, College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou 730070, P. R. China.
| | - Qing Sun
- Key Laboratory of Eco-functional Polymer Materials of the Ministry of Education, College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou 730070, P. R. China.
| | - Jingling Gong
- Key Laboratory of Eco-functional Polymer Materials of the Ministry of Education, College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou 730070, P. R. China.
| | - Peng Mu
- Key Laboratory of Eco-functional Polymer Materials of the Ministry of Education, College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou 730070, P. R. China.
| | - Jian Li
- Key Laboratory of Eco-functional Polymer Materials of the Ministry of Education, College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou 730070, P. R. China.
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15
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He X, Li J, Guan Y, Wang Z. Nanodroplet Wetting and Electrowetting Behavior on Liquid-infused Surfaces: A Molecular Simulation Study. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.121157] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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16
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Sahoo S, Mukherjee R. Evaporative Drying of a Water droplet on Liquid Infused Sticky Surfaces. Colloids Surf A Physicochem Eng Asp 2022. [DOI: 10.1016/j.colsurfa.2022.130514] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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17
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Yang X, Wang J, Gao Z, Zhang W, Zhu H, Song Y, Wang Q, Liu M, Jiang L, Huang Y, Xia F. An orthogonal dual-regulation strategy for sensitive biosensing applications. Natl Sci Rev 2022; 9:nwac048. [PMID: 36285294 PMCID: PMC9584063 DOI: 10.1093/nsr/nwac048] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Revised: 10/22/2021] [Accepted: 02/15/2022] [Indexed: 10/27/2023] Open
Abstract
Biosensing systems based on controllable motion behaviors of droplets have attracted extensive attention, but still face challenges of insufficient sensitivity and uncontrollable dynamic range due to imprecise manipulation of droplet motion on the surfaces. Here, we report an orthogonal dual-regulation strategy for precise motion control of droplets and we demonstrate its utility as a sensitive sensing system with controllable dynamic ranges of sensing for adenosine triphosphate, miRNA, thrombin and kanamycin, as well as discrimination of five kinds of DNA. We endowed a DNA-contained bio-droplet sliding on a lubricant-infused structural surface with micro-grooves to separately adjust the resistance from liquid phase and solid phase. The resistance from liquid phase mainly depended on hydrophobic interaction between DNA and lubricant, which can be finely tuned by different DNA's average chain length. Meanwhile, the resistance from solid surface was determined by the energy barrier from the periodic micro-grooves, which can be adjusted by varying the droplet's sliding direction on the surface. The hydrophobic interaction is conformed to be orthogonal to the micro-grooves' anisotropic resistance by three different methods. This orthogonal dual-regulation strategy thus demonstrated its ability to precisely control bio-droplets' motion behaviors and sensitive detection with adjustable dynamic ranges for various bio-targets. The dual-regulation strategy will provide significant insights for super-wettable biosensors, visual inspection and beyond.
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Affiliation(s)
- Xian Yang
- State Key Laboratory of Biogeology and Environmental Geology, Engineering Research Center of Nano-Geomaterials of Ministry of Education, Faculty of Material Science and Chemistry, China University of Geosciences, Wuhan 430074, China
- State Grid Integrated Energy Service Group CO. LTD., Beijing 100052, China
| | - Jinhua Wang
- State Key Laboratory of Biogeology and Environmental Geology, Engineering Research Center of Nano-Geomaterials of Ministry of Education, Faculty of Material Science and Chemistry, China University of Geosciences, Wuhan 430074, China
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, National Center for Protein Sciences (Beijing), Beijing Institute of Lifeomics, Beijing 102206, China
| | - Zhongfeng Gao
- State Key Laboratory of Biogeology and Environmental Geology, Engineering Research Center of Nano-Geomaterials of Ministry of Education, Faculty of Material Science and Chemistry, China University of Geosciences, Wuhan 430074, China
- Shandong Provincial Key Laboratory of Detection Technology for Tumor Markers, College of Chemistry and Chemical Engineering, Linyi University, Linyi 276005, China
| | - Weiqi Zhang
- State Key Laboratory of Biogeology and Environmental Geology, Engineering Research Center of Nano-Geomaterials of Ministry of Education, Faculty of Material Science and Chemistry, China University of Geosciences, Wuhan 430074, China
| | - Hai Zhu
- State Key Laboratory of Biogeology and Environmental Geology, Engineering Research Center of Nano-Geomaterials of Ministry of Education, Faculty of Material Science and Chemistry, China University of Geosciences, Wuhan 430074, China
| | - Yongjun Song
- State Key Laboratory of Biogeology and Environmental Geology, Engineering Research Center of Nano-Geomaterials of Ministry of Education, Faculty of Material Science and Chemistry, China University of Geosciences, Wuhan 430074, China
| | - Quan Wang
- State Key Laboratory of Biogeology and Environmental Geology, Engineering Research Center of Nano-Geomaterials of Ministry of Education, Faculty of Material Science and Chemistry, China University of Geosciences, Wuhan 430074, China
| | - Mingjie Liu
- Key Laboratory of Bio-Inspired Smart Interfacial Science and Technology of the Ministry of Education, School of Chemistry and Environment, Beihang University, Beijing 100191, China
| | - Lei Jiang
- Key Laboratory of Bio-Inspired Smart Interfacial Science and Technology of the Ministry of Education, School of Chemistry and Environment, Beihang University, Beijing 100191, China
| | - Yu Huang
- State Key Laboratory of Biogeology and Environmental Geology, Engineering Research Center of Nano-Geomaterials of Ministry of Education, Faculty of Material Science and Chemistry, China University of Geosciences, Wuhan 430074, China
- Zhejiang Institute, China University of Geosciences, Hangzhou 311305, China
| | - Fan Xia
- State Key Laboratory of Biogeology and Environmental Geology, Engineering Research Center of Nano-Geomaterials of Ministry of Education, Faculty of Material Science and Chemistry, China University of Geosciences, Wuhan 430074, China
- Zhejiang Institute, China University of Geosciences, Hangzhou 311305, China
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18
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McHale G, Afify N, Armstrong S, Wells GG, Ledesma-Aguilar R. The Liquid Young's Law on SLIPS: Liquid-Liquid Interfacial Tensions and Zisman Plots. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:10032-10042. [PMID: 35921631 PMCID: PMC9387105 DOI: 10.1021/acs.langmuir.2c01470] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Revised: 07/26/2022] [Indexed: 05/19/2023]
Abstract
Slippery liquid-infused porous surfaces (SLIPS) are an innovation that reduces droplet-solid contact line pinning and interfacial friction. Recently, it has been shown that a liquid analogue of Young's law can be deduced for the apparent contact angle of a sessile droplet on SLIPS despite there never being contact by the droplet with the underlying solid. Since contact angles on solids are used to characterize solid-liquid interfacial interactions and the wetting of a solid by a liquid, it is our hypothesis that liquid-liquid interactions and the wetting of a liquid surface by a liquid can be characterized by apparent contact angles on SLIPS. Here, we first present a theory for deducing liquid-liquid interfacial tensions from apparent contact angles. This theory is valid irrespective of whether or not a film of the infusing liquid cloaks the droplet-vapor interface. We show experimentally that liquid-liquid interfacial tensions deduced from apparent contact angles of droplets on SLIPS are in excellent agreement with values from the traditional pendant drop technique. We then consider whether the Zisman method for characterizing the wettability of a solid surface can be applied to liquid surfaces created using SLIPS. We report apparent contact angles for a homologous series of alkanes on Krytox-infused SLIPS and for water-IPA mixtures on both the Krytox-infused SLIPS and a silicone oil-infused SLIPS. The alkanes on the Krytox-infused SLIPS follow a linear relationship in the liquid form of the Zisman plot provided that the effective droplet-vapor interfacial tension is used. All three systems follow a linear relationship on a modified Zisman plot. We interpret these results using the concept of the critical surface tension (CST) for the wettability of a solid surface introduced by Zisman. In our liquid surface case, the obtained critical surface tensions were found to be lower than the infusing liquid-vapor surface tensions.
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19
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Self-assembly of highly ordered micro- and nanoparticle deposits. Nat Commun 2022; 13:3085. [PMID: 35654770 PMCID: PMC9163176 DOI: 10.1038/s41467-022-30660-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Accepted: 05/06/2022] [Indexed: 11/08/2022] Open
Abstract
The evaporation of particle-laden sessile droplets is associated with capillary-driven outward flow and leaves nonuniform coffee-ring-like particle patterns due to far-from-equilibrium effects. Traditionally, the surface energies of the drop and solid phases are tuned, or external forces are applied to suppress the coffee-ring; however, achieving a uniform and repeatable particle deposition is extremely challenging. Here, we report a simple, scalable, and noninvasive technique that yields uniform and exceptionally ordered particle deposits on a microscale surface area by placing the droplet on a near neutral-wet shadow mold attached to a hydrophilic substrate. The simplicity of the method, no external forces, and no tuning materials' physiochemical properties make the present generic approach an excellent candidate for a wide range of sensitive applications. We demonstrate the utility of this method for fabricating ordered mono- and multilayer patternable coatings, producing nanofilters with controlled pore size, and creating reproducible functionalized nanosensors.
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20
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Sun X, Kong D, Liang C, Hu Y, Duan JA. Flexible and Precise Droplet Manipulation by a Laser-Induced Shape Temperature Field on a Lubricant-Infused Surface. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:6731-6740. [PMID: 35587878 DOI: 10.1021/acs.langmuir.2c00680] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Light actuation on a lubricant-infused surface (LIS) has attracted great attention because of its flexibility and remote control of droplet motion. However, to actuate a droplet on a LIS flexibly and precisely by light, the key issue is to control two degrees of freedom of the droplet motion in real time. In this paper, we propose a C-shape temperature field (CSTF) induced by rapid and selective laser irradiation on a LIS. The CSTF could not only manipulate a single droplet precisely and flexibly but also process multiple droplets automatically and orderly in real time. The mechanism showed that the droplet was confined by the Marangoni force in two orthogonal directions. For single droplet manipulation, the CSTF had the capability of correcting the off-track droplet motion. Moreover, the droplet motion, including rectilinear motion and curvilinear motion, could be precisely and flexibly controlled by the motion of the CSTF. For manipulation of multiple droplets, coalescence of multiple droplets was successfully achieved by triple rotating CSTFs. Such a method was applied in the detection of 5 μL of bovine serum albumin (BSA) by triggering chromogenic reactions automatically and orderly, which improved the efficiency of the whole process. We believe that this method is a significant candidate for intelligent droplet manipulation.
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Affiliation(s)
- Xiaoyan Sun
- State Key Laboratory of High Performance and Complex Manufacturing, College of Mechanical and Electrical Engineering, Central South University, Changsha 410083, Hunan, China
| | - Dejian Kong
- State Key Laboratory of High Performance and Complex Manufacturing, College of Mechanical and Electrical Engineering, Central South University, Changsha 410083, Hunan, China
| | - Chang Liang
- State Key Laboratory of High Performance and Complex Manufacturing, College of Mechanical and Electrical Engineering, Central South University, Changsha 410083, Hunan, China
| | - Youwang Hu
- State Key Laboratory of High Performance and Complex Manufacturing, College of Mechanical and Electrical Engineering, Central South University, Changsha 410083, Hunan, China
- Science and Technology on Reliability Physics and Application Technology of Electronic Component Laboratory, Guangzhou 510610, China
| | - Ji-An Duan
- State Key Laboratory of High Performance and Complex Manufacturing, College of Mechanical and Electrical Engineering, Central South University, Changsha 410083, Hunan, China
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21
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Pan X, Lin X, Xu X, Li J, Xi H. The synthesis, characterization and decontamination of surface radioactive contamination of ethyl cellulose/polyacrylate strippable detergent at low temperature. Colloids Surf A Physicochem Eng Asp 2022. [DOI: 10.1016/j.colsurfa.2022.128463] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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22
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Agrawal A, Gopu M, Mukherjee R, Mampallil D. Microfluidic Droplet Cluster with Distributed Evaporation Rates as a Model for Bioaerosols. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:4567-4577. [PMID: 35394793 DOI: 10.1021/acs.langmuir.1c03273] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Aerosols and microdroplets are known to act as carriers for pathogens or vessels for chemical reactions. The natural occurrence of evaporation of these droplets has implications for the viability of pathogens or chemical processes. For example, it is important to understand how pathogens survive extreme physiochemical conditions such as confinement and osmotic stress induced by evaporation of aerosol droplets. Previously, larger evaporating droplets were proposed as model systems as the processes in the tiny aerosol droplets are difficult to image. In this context, we propose the concept of evaporation of capillary-clustered aqueous microdroplets dispersed in a thin oil layer. The configuration produces spatially segregated evaporation rates. It allows comparing the consequences of evaporation and its rate for processes occurring in droplets. As a proof of concept, we study the consequences of evaporation and its rate using Escherichia coli (E. coli) and Bacillus subtilis as model organisms. Our experiments indicate that the rate of evaporation of microdroplets is an important parameter in deciding the viability of contained microorganisms. With slow evaporation, E. coli could mitigate the osmotic stress by K+ ion uptake. Our method may also be applicable to other evaporating droplet systems, for example, microdroplet chemistry to understand the implications of evaporation rates.
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Affiliation(s)
- Akanksha Agrawal
- Indian Institute of Science Education and Research Tirupati, Mangalam P.O. PIN 517507 Tirupati, Andhra Pradesh, India
| | - Maheshwar Gopu
- Indian Institute of Science Education and Research Tirupati, Mangalam P.O. PIN 517507 Tirupati, Andhra Pradesh, India
| | - Raju Mukherjee
- Indian Institute of Science Education and Research Tirupati, Mangalam P.O. PIN 517507 Tirupati, Andhra Pradesh, India
| | - Dileep Mampallil
- Indian Institute of Science Education and Research Tirupati, Mangalam P.O. PIN 517507 Tirupati, Andhra Pradesh, India
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23
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Zhu Y, McHale G, Dawson J, Armstrong S, Wells G, Han R, Liu H, Vollmer W, Stoodley P, Jakubovics N, Chen J. Slippery Liquid-Like Solid Surfaces with Promising Antibiofilm Performance under Both Static and Flow Conditions. ACS APPLIED MATERIALS & INTERFACES 2022; 14:6307-6319. [PMID: 35099179 PMCID: PMC9096797 DOI: 10.1021/acsami.1c14533] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Biofilms are central to some of the most urgent global challenges across diverse fields of application, from medicine to industries to the environment, and exert considerable economic and social impact. A fundamental assumption in anti-biofilms has been that the coating on a substrate surface is solid. The invention of slippery liquid-infused porous surfaces─a continuously wet lubricating coating retained on a solid surface by capillary forces─has led to this being challenged. However, in situations where flow occurs, shear stress may deplete the lubricant and affect the anti-biofilm performance. Here, we report on the use of slippery omniphobic covalently attached liquid (SOCAL) surfaces, which provide a surface coating with short (ca. 4 nm) non-cross-linked polydimethylsiloxane (PDMS) chains retaining liquid-surface properties, as an antibiofilm strategy stable under shear stress from flow. This surface reduced biofilm formation of the key biofilm-forming pathogens Staphylococcus epidermidis and Pseudomonas aeruginosa by three-four orders of magnitude compared to the widely used medical implant material PDMS after 7 days under static and dynamic culture conditions. Throughout the entire dynamic culture period of P. aeruginosa, SOCAL significantly outperformed a typical antibiofilm slippery surface [i.e., swollen PDMS in silicone oil (S-PDMS)]. We have revealed that significant oil loss occurred after 2-7 day flow for S-PDMS, which correlated to increased contact angle hysteresis (CAH), indicating a degradation of the slippery surface properties, and biofilm formation, while SOCAL has stable CAH and sustainable antibiofilm performance after 7 day flow. The significance of this correlation is to provide a useful easy-to-measure physical parameter as an indicator for long-term antibiofilm performance. This biofilm-resistant liquid-like solid surface offers a new antibiofilm strategy for applications in medical devices and other areas where biofilm development is problematic.
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Affiliation(s)
- Yufeng Zhu
- School
of Engineering, Newcastle University, Newcastle Upon Tyne NE1
7RU, U.K.
| | - Glen McHale
- School
of Engineering, University of Edinburgh, Edinburgh EH9 3FB, U.K.
| | - Jack Dawson
- School
of Engineering, Newcastle University, Newcastle Upon Tyne NE1
7RU, U.K.
| | - Steven Armstrong
- School
of Engineering, University of Edinburgh, Edinburgh EH9 3FB, U.K.
| | - Gary Wells
- School
of Engineering, University of Edinburgh, Edinburgh EH9 3FB, U.K.
| | - Rui Han
- School
of Engineering, Newcastle University, Newcastle Upon Tyne NE1
7RU, U.K.
| | - Hongzhong Liu
- School
of Mechanical Engineering, Xi’an
Jiaotong University, Xi’an 710054, China
| | - Waldemar Vollmer
- Centre
for Bacterial Cell Biology, Biosciences Institute, Newcastle University, Newcastle
Upon Tyne NE2 4AX, U.K.
| | - Paul Stoodley
- Department
of Microbial Infection and Immunity and the Department of Orthopaedics, The Ohio State University, Columbus, Ohio 43210, United States
- National
Centre for Advanced Tribology at Southampton (nCATS), National Biofilm
Innovation Centre (NBIC), Mechanical Engineering, University of Southampton, Southampton S017 1BJ, U.K.
| | - Nicholas Jakubovics
- School
of Dental Sciences, Faculty of Medical Sciences, Newcastle University, Newcastle
Upon Tyne NE2 4BW, U.K.
| | - Jinju Chen
- School
of Engineering, Newcastle University, Newcastle Upon Tyne NE1
7RU, U.K.
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24
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Jiang L, Hou P, He S, Han M, Xiang P, Xiao T, Tan X. The robust superhydrophobic SiO2/Diatomite/PDMS/KH-570/Me-MQ composite coating for self-cleaning application of building surface. Colloids Surf A Physicochem Eng Asp 2022. [DOI: 10.1016/j.colsurfa.2021.127936] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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25
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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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26
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Kazaryan PS, Gallyamov MO, Kondratenko MS. Study of the Droplet Pinning Force in the Transition from Dry to Liquid-Infused Thin Polymer Films. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:1114-1123. [PMID: 35015553 DOI: 10.1021/acs.langmuir.1c02767] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The change in the pinning force during the transition from dry to oil-impregnated thin polymer films is studied for droplets of water and hexadecane. A careful variation of the oil amount in the films is performed by means of supercritical impregnation. The film thickness dependence on the oil content is measured using ellipsometry and compared to gel swelling theory estimates. Depending on the oil content, two cases of pinning force behavior have been identified. For each case, the factors that determine the pinning force are discussed. The pinning force in the transition from dry to equilibrium swollen gel films is well approximated by the Joanny and de Gennes hysteresis model of dilute defects.
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Affiliation(s)
- Polina S Kazaryan
- Faculty of Physics, M. V. Lomonosov Moscow State University, Leninskie Gory 1-2, Moscow 119991, Russian Federation
| | - Marat O Gallyamov
- Faculty of Physics, M. V. Lomonosov Moscow State University, Leninskie Gory 1-2, Moscow 119991, Russian Federation
- A. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Vavilova 28, Moscow 119991, Russian Federation
| | - Mikhail S Kondratenko
- Faculty of Physics, M. V. Lomonosov Moscow State University, Leninskie Gory 1-2, Moscow 119991, Russian Federation
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27
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Manipulation and control of droplets on surfaces in a homogeneous electric field. Nat Commun 2022; 13:289. [PMID: 35022399 PMCID: PMC8755840 DOI: 10.1038/s41467-021-27879-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Accepted: 12/07/2021] [Indexed: 01/17/2023] Open
Abstract
A method to manipulate and control droplets on a surface is presented. The method is based on inducing electric dipoles inside the droplets using a homogeneous external electric field. It is shown that the repulsive dipole force efficiently suppresses the coalescence of droplets moving on a liquid-infused surface (LIS). Using a combination of experiments, numerical computations and semi-analytical models, the dependence of the repulsion force on the droplet volumes, the distance between the droplets and the electric field strength is revealed. The method allows to suppress coalescence in complex multi-droplet flows and is real-time adaptive. When the electric field strength exceeds a critical value, tip streaming from the droplets sets in. Based on that, it becomes possible to withdraw minute samples from an array of droplets in a parallel process. Control of droplet coalescence is a major challenge of droplet microfluidics. Here, the authors show that homogenous external electric field can induce dipoles inside droplets, which can be used to withdraw samples from an array of droplets.
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28
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Chen F, Wang Y, Tian Y, Zhang D, Song J, Crick CR, Carmalt CJ, Parkin IP, Lu Y. Robust and durable liquid-repellent surfaces. Chem Soc Rev 2022; 51:8476-8583. [DOI: 10.1039/d0cs01033b] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
This review provides a comprehensive summary of characterization, design, fabrication, and application of robust and durable liquid-repellent surfaces.
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Affiliation(s)
- Faze Chen
- School of Mechanical Engineering, Tianjin University, Tianjin 300350, China
- Key Laboratory of Mechanism Theory and Equipment Design of Ministry of Education, Tianjin University, Tianjin 300350, China
| | - Yaquan Wang
- Department of Chemistry, School of Physical and Chemical Sciences, Queen Mary University of London, London E1 4NS, UK
| | - Yanling Tian
- School of Engineering, University of Warwick, Coventry CV4 7AL, UK
| | - Dawei Zhang
- School of Mechanical Engineering, Tianjin University, Tianjin 300350, China
- Key Laboratory of Mechanism Theory and Equipment Design of Ministry of Education, Tianjin University, Tianjin 300350, China
| | - Jinlong Song
- School of Mechanical Engineering, Dalian University of Technology, Dalian 116024, China
| | - Colin R. Crick
- School of Engineering and Materials Science, Queen Mary University of London, London E1 4NS, UK
| | - Claire J. Carmalt
- Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, UK
| | - Ivan P. Parkin
- Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, UK
| | - Yao Lu
- Department of Chemistry, School of Physical and Chemical Sciences, Queen Mary University of London, London E1 4NS, UK
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Li Y, Zhang Q, Chen R, Yan Y, Sun Z, Zhang X, Tian D, Jiang L. Stretch-Enhanced Anisotropic Wetting on Transparent Elastomer Film for Controlled Liquid Transport. ACS NANO 2021; 15:19981-19989. [PMID: 34841855 DOI: 10.1021/acsnano.1c07512] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Direction-controlled wetting surfaces, special for lubricating oil infused anisotropic surfaces, have attracted great research interest in directional liquid collection, expelling, transfer, and separation. Nonetheless, there are still existing difficulties in achieving directional and continuous liquid transport. Herein, we present a strategy to achieve directional liquid transport on transparent lubricating oil infused elastomer film with V-shaped prisms microarray (VPM). The results reveal that the water wetting direction in the parallel and staggered arrangement of the VPM structure surface with lubricating oil infusion is the opposite, which is completely different from the wetting direction on the usual VPM surface in air. Moreover, asymmetric stretching can enhance or weaken the directional water wetting tendency on the lubricating oil infused VPM elastomer film and even can reverse the droplet wetting direction. In a closed moist environment, tiny droplets gradually coalesce and then slip away from the lubricating oil infused VPM surface to keep the surface transparent, due to the cooperation of imbalanced Laplace pressure, resulting from the anisotropic geometric structures, varying VPMs spacing, and gravity. Thus, this work provides a paradigm to design and fabricate a type of surface engineering material in the application fields of directional expelling, liquid collection, anti-biofouling, anti-icing, drag reduction, anticorrosion, etc.
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Affiliation(s)
- Yan Li
- Key Laboratory of Bio-Inspired Smart Interfacial Science and Technology of Ministry of Education, School of Chemistry, Beihang University, Beijing 100191, P. R. China
| | - Qiuya Zhang
- Key Laboratory of Bio-Inspired Smart Interfacial Science and Technology of Ministry of Education, School of Chemistry, Beihang University, Beijing 100191, P. R. China
| | - Rui Chen
- Key Laboratory of Bio-Inspired Smart Interfacial Science and Technology of Ministry of Education, School of Chemistry, Beihang University, Beijing 100191, P. R. China
| | - Yufeng Yan
- Key Laboratory of Bio-Inspired Smart Interfacial Science and Technology of Ministry of Education, School of Chemistry, Beihang University, Beijing 100191, P. R. China
| | - Zhenning Sun
- Key Laboratory of Bio-Inspired Smart Interfacial Science and Technology of Ministry of Education, School of Chemistry, Beihang University, Beijing 100191, P. R. China
| | - Xiaofang Zhang
- School of Mathematics and Physics, University of Science and Technology Beijing, Beijing 100083, P. R. China
| | - Dongliang Tian
- Key Laboratory of Bio-Inspired Smart Interfacial Science and Technology of Ministry of Education, School of Chemistry, Beihang University, Beijing 100191, P. R. China
- Beijing Advanced Innovation Center for Biomedical Engineering, Beihang University, Beijing 100191, P. R. China
| | - Lei Jiang
- Key Laboratory of Bio-Inspired Smart Interfacial Science and Technology of Ministry of Education, School of Chemistry, Beihang University, Beijing 100191, P. R. China
- Beijing Advanced Innovation Center for Biomedical Engineering, Beihang University, Beijing 100191, P. R. China
- Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100191, P. R. China
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Sun J, Jiang X, Weisensee PB. Enhanced Water Nucleation and Growth Based on Microdroplet Mobility on Lubricant-Infused Surfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:12790-12801. [PMID: 34699236 DOI: 10.1021/acs.langmuir.1c01559] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Lubricant-infused surfaces (LISs) can promote stable dropwise condensation and improve heat transfer rates due to a low nucleation free-energy barrier and high droplet mobility. Recent studies showed that oil menisci surrounding condensate microdroplets form distinct oil-rich and oil-poor regions. These topographical differences in the oil surface cause water microdroplets to rigorously self-propel long distances, continuously redistributing the oil film and potentially refreshing the surface for re-nucleation. However, the dynamic interplay between oil film redistribution, microdroplet self-propulsion, and droplet nucleation and growth is not yet understood. Using high-speed microscopy, we reveal that during water condensation on LISs, the smallest visible droplets (diameter: ∼1 μm, qualitatively representing nucleation) predominantly emerge in oil-poor regions due to a lower nucleation free-energy barrier. Considering the significant heat transfer performance of microdroplets (<10 μm) and transient characteristic of microdroplet movement, we compare the apparent nucleation rate density and water collection rate for LISs with oils of different viscosities and a solid hydrophobic surface at a wide range of subcooling temperatures. Generally, the lowest lubricant viscosity leads to the highest nucleation rate density. We characterize the length and frequency of microdroplet movement and attribute the nucleation enhancement primarily to higher droplet mobility and surface refreshing frequency. Interestingly and unexpectedly, hydrophobic surfaces outperform high-viscosity LISs at high subcooling temperatures but are generally inferior to any of the tested LISs at low temperature differences. To explain the observed nonlinearity between LISs and the solid hydrophobic surface, we introduce two dominant regimes that influence the condensation efficiency: mobility-limited and coalescence-limited. We compare these regimes based on droplet growth rates and water collection rates on the different surfaces. Our findings advance the understanding of dynamic water-lubricant interactions and provide new design rationales for choosing surfaces for enhanced dropwise condensation and water collection efficiencies.
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Affiliation(s)
- Jianxing Sun
- Department of Mechanical Engineering & Materials Science, Washington University in St. Louis, Saint Louis, Missouri 63130, United States
| | - Xinyu Jiang
- Department of Mechanical Engineering & Materials Science, Washington University in St. Louis, Saint Louis, Missouri 63130, United States
| | - Patricia B Weisensee
- Department of Mechanical Engineering & Materials Science, Washington University in St. Louis, Saint Louis, Missouri 63130, United States
- Institute of Materials Science and Engineering, Washington University in St. Louis, Saint Louis, Missouri 63130, United States
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Semprebon C, Sadullah MS, McHale G, Kusumaatmaja H. Apparent contact angle of drops on liquid infused surfaces: geometric interpretation. SOFT MATTER 2021; 17:9553-9559. [PMID: 34730600 DOI: 10.1039/d1sm00704a] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
We theoretically investigate the apparent contact angle of drops on liquid infused surfaces as a function of the relative size of the wetting ridge and the deposited drop. We provide an intuitive geometrical interpretation whereby the variation in the apparent contact angle is due to the rotation of the Neumann triangle at the lubricant-drop-gas contact line. We also derive linear and quadratic corrections to the apparent contact angle as power series expansion in terms of pressure differences between the lubricant, drop and gas phases. These expressions are much simpler and more compact compared to those previously derived by Semprebon et al. [Soft Matter, 2017, 13, 101-110].
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Affiliation(s)
- Ciro Semprebon
- Smart Materials and Surfaces Laboratory, Northumbria University, Newcastle upon Tyne NE1 8ST, UK.
| | - Muhammad Subkhi Sadullah
- King Abdullah University of Science and Technology (KAUST), Water Desalination and Reuse Center (WDRC), Biological and Environmental Science and Engineering (BESE) Division, Thuwal 23955-6900, Saudi Arabia
| | - Glen McHale
- School of Engineering, The University of Edinburgh, Kings Buildings, Edinburgh EH9 3FB, UK.
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Numerical simulation of two-phase droplets on a curved surface using Surface Evolver. Colloids Surf A Physicochem Eng Asp 2021. [DOI: 10.1016/j.colsurfa.2021.127418] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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33
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Sun C, McClure J, Berg S, Mostaghimi P, Armstrong RT. Universal description of wetting on multiscale surfaces using integral geometry. J Colloid Interface Sci 2021; 608:2330-2338. [PMID: 34774316 DOI: 10.1016/j.jcis.2021.10.152] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2021] [Revised: 10/11/2021] [Accepted: 10/25/2021] [Indexed: 10/19/2022]
Abstract
HYPOTHESIS Emerging energy-related technologies deal with multiscale hierarchical structures, intricate surface morphology, non-axisymmetric interfaces, and complex contact lines where wetting is difficult to quantify with classical methods. We hypothesise that a universal description of wetting on multiscale surfaces can be developed by using integral geometry coupled to thermodynamic laws. The proposed approach separates the different hierarchy levels of physical description from the thermodynamic description, allowing for a universal description of wetting on multiscale surfaces. THEORY AND SIMULATIONS The theoretical framework is presented followed by application to limiting cases of wetting on multiscale surfaces. Limiting cases include those considered in the Wenzel, Cassie-Baxter, and wicking state models. Wetting characterisation of multiscale surfaces is explored by conducting simulations of a fluid droplet on a structurally rough surface and a chemically heterogeneous surface. FINDINGS The underlying origin of the classical wetting models is shown to be rooted within the proposed theoretical framework. Integral geometry provides a topological-based wetting metric that is not contingent on any type of wetting state. The wetting metric is demonstrated to account for multiscale features along the common line in a scale consistent way; providing a universal description of wetting for multiscale surfaces.
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Affiliation(s)
- Chenhao Sun
- State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Beijing 102249, China
| | - James McClure
- Advanced Research Computing, Virginia Tech, Wright House, W. Campus Drive, Blacksburg, VA 24061, USA
| | - Steffen Berg
- Shell Global Solutions International B.V., Grasweg 31, 1031 WG Amsterdam, Netherlands; Imperial College London, Department of Earth Science & Engineering and Chemical Engineering, Exhibition Rd, South Kensington, London SW7 2BX, United Kingdom
| | - Peyman Mostaghimi
- School of Minerals & Energy Resources Engineering, University of New South Wales, Kensington, New South Wales 2052, Australia
| | - Ryan T Armstrong
- School of Minerals & Energy Resources Engineering, University of New South Wales, Kensington, New South Wales 2052, Australia.
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34
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Zeng Q, Zhou H, Huang J, Guo Z. Review on the recent development of durable superhydrophobic materials for practical applications. NANOSCALE 2021; 13:11734-11764. [PMID: 34231625 DOI: 10.1039/d1nr01936h] [Citation(s) in RCA: 43] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Biomimetic superhydrophobic surfaces show great potential in oil-water separation, anti-icing and self-cleaning. However, due to the instability caused by its fragile structure and non-durable superhydrophobicity, it is difficult to apply them in the actual field. Here, by introducing surface wettability and analysing the mechanism of superhydrophobic failure, it is concluded that the reason for the failure of the superhydrophobic surface comes from the transition of the surface energy and the hysteresis of the contact angle (CA). On the basis of this analysis, it is concluded that the principle of designing a durable superhydrophobic surface is to satisfy one of the following three points: improving the binding force between molecules, introducing durable materials and improving chemical durability. On this basis, a variety of preparation methods are proposed, such as assembly method and spray/dip coating method, and the design and preparation of a self-healing surface inspired by nature will also be included in the introduction. Last but not least, the preparation and application of a durable super-hydrophobic surface in oil-water separation, anti-icing and self-cleaning are also introduced in detail. This review reveals the conclusions and prospects of durable superhydrophobic surfaces, and aims to inspire more researchers to invest in this research.
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Affiliation(s)
- Qinghong Zeng
- Hubei Collaborative Innovation Centre for Advanced Organic Chemical Materials and Ministry of Education Key Laboratory for the Green Preparation and Application of Functional Materials, Hubei University, Wuhan 430062, People's Republic of China.
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35
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Gunjan MR, Kumar A, Raj R. Cloaked Droplets on Lubricant-Infused Surfaces: Union of Constant Mean Curvature Interfaces Dictated by Thin-Film Tension. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:6601-6612. [PMID: 34028279 DOI: 10.1021/acs.langmuir.0c03560] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
It has been recently shown that small-volume droplets on lubricant-infused surfaces (LISs) can be analytically modeled using rotationally symmetric constant mean curvature (CMC) surfaces. While such an approach is available for noncloaked droplets, a similar approach is missing for cloaked droplets that are ubiquitous in a number of LIS-related applications. The presence of a thin cloaking film on the top spherical cap portion and its gradual transition to a bulk meniscus remain unaddressed for its implications on the interfacial profile of cloaked droplets. Here, we take into account the cloaking film tension and the disjoining pressure to present a mean curvature-based framework for modeling cloaked droplets on LISs. The transition of the bulk meniscus to a thin film is formulated as a transition regime, which is then modeled as a single imaginary point akin to the Neumann point of noncloaked droplets. We next show that the shape of a small droplet on a LIS essentially obeys a simple fundamental mean curvature relation that changes forms depending on the regimes of lubrication and whether the droplet is cloaked or noncloaked. We validate our framework with the droplet profiles recorded during the evaporation of cloaked droplets in our experiments, as well as those published in the literature. In addition, we also demonstrate the ability to model the shapes of floating droplets on LISs reported in the literature. In addition to quantifying the effect of disjoining pressure on interfacial profiles, we importantly unmask the behavior of the contact line, which is optically covered by the lubricant meniscus around the droplets on LISs.
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Affiliation(s)
- Madhu Ranjan Gunjan
- Thermal and Fluid Transport Laboratory, Department of Mechanical Engineering, Indian Institute of Technology Patna, R113, Block III, Bihta, Bihar 801103, India
| | - Alok Kumar
- Thermal and Fluid Transport Laboratory, Department of Mechanical Engineering, Indian Institute of Technology Patna, R113, Block III, Bihta, Bihar 801103, India
| | - Rishi Raj
- Thermal and Fluid Transport Laboratory, Department of Mechanical Engineering, Indian Institute of Technology Patna, R113, Block III, Bihta, Bihar 801103, India
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36
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Qian H, Liu B, Wu D, Liu W, Chowwanonthapunya T, Zhang D. Facile fabrication of slippery lubricant-infused porous surface with pressure responsive property for anti-icing application. Colloids Surf A Physicochem Eng Asp 2021. [DOI: 10.1016/j.colsurfa.2021.126457] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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37
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Wu Z, Yin K, Wu J, Zhu Z, Duan JA, He J. Recent advances in femtosecond laser-structured Janus membranes with asymmetric surface wettability. NANOSCALE 2021; 13:2209-2226. [PMID: 33480955 DOI: 10.1039/d0nr06639g] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Janus wettability membranes have received much attention because of their asymmetric surface wettability. On the basis of this distinctiveness from traditional symmetrical membranes, relevant scholars have been inspired to pursue many innovations utilizing such membranes. Femtosecond laser microfabrication shows many advantages, such as precision, short time, and environmental friendliness, over traditional fabrication methods. Now this has been applied in structuring Janus membranes by researchers. This review covers recent advances in femtosecond laser-structured Janus membranes with asymmetric surface wettability. The background in femtosecond laser-structured Janus membranes is first discussed, focusing on the Janus wettability membrane and femtosecond laser microfabrication. Then the applications of Janus membranes are introduced, which are divided into unidirectional fluid transport, oil-water separation, fog harvesting, and seawater desalination. Finally, based on femtosecond laser-structured Janus membranes, some existing problems are pointed out and future perspectives proposed.
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Affiliation(s)
- Zhipeng Wu
- Hunan Key Laboratory of Super Microstructure and Ultrafast Process, School of Physics and Electronics, Central South University, Changsha 410083, China.
| | - Kai Yin
- Hunan Key Laboratory of Super Microstructure and Ultrafast Process, School of Physics and Electronics, Central South University, Changsha 410083, China. and The State Key Laboratory of High Performance and Complex Manufacturing, College of Mechanical and Electrical Engineering, Central South University, Changsha 410083, China.
| | - Junrui Wu
- Hunan Key Laboratory of Super Microstructure and Ultrafast Process, School of Physics and Electronics, Central South University, Changsha 410083, China.
| | - Zhuo Zhu
- Hunan Key Laboratory of Super Microstructure and Ultrafast Process, School of Physics and Electronics, Central South University, Changsha 410083, China.
| | - Ji-An Duan
- The State Key Laboratory of High Performance and Complex Manufacturing, College of Mechanical and Electrical Engineering, Central South University, Changsha 410083, China.
| | - Jun He
- Hunan Key Laboratory of Super Microstructure and Ultrafast Process, School of Physics and Electronics, Central South University, Changsha 410083, China.
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38
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Hu X, Wang Z, Hwang DJ, Colosqui CE, Cubaud T. Viscous liquid-liquid wetting and dewetting of textured surfaces. SOFT MATTER 2021; 17:879-886. [PMID: 33237108 DOI: 10.1039/d0sm01524e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
We experimentally investigate the spreading and receding behavior of small water droplets immersed in viscous oils on grid-patterned surfaces using synchronized bottom and profile views. In particular, the evolution of apparent advancing and receding contact angles of droplets fed at constant flow rate is studied as a function of grid surface coverage and height for a wide range of external phase viscosity. Detailed examination of droplet aspect ratio during inflation process provides an averaging method for characterization of quasi-static advancing angles on heterogeneous surfaces. Droplets spreading in partial Cassie state on planar microfluidic grids are also shown to capture oil patches that further evolve into trapped oil droplets depending on grid aspect ratio. The natural retraction velocity of thin water films is examined based on external phase velocity and regime maps of trapped droplets are delineated based on control parameters.
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Affiliation(s)
- Xiaoyi Hu
- Department of Mechanical Engineering, Stony Brook University, Stony Brook, NY 11794, USA.
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39
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Holweger HJ, Jamali M, Tafreshi HV. Centrifugal Detachment of Compound Droplets from Fibers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:928-938. [PMID: 33398995 DOI: 10.1021/acs.langmuir.0c03317] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
This article presents the first experimental-computational study on the centrifugal detachment of a compound droplet (e.g., a primary water droplet cloaked by an immiscible oil) from a fiber. The work was intended to establish a method for quantifying the force needed to detach compound droplets of different compositions from a fiber. More importantly, our study was aimed at improving the understanding of the interplay between interfacial and external forces acting on a compound droplet during forceful detachment. The experiments were conducted using DI water, for the primary droplet, and silicone or mineral oil, for the cloaking fluid. It was observed from the experiments that the silicone-oil-cloaked droplets behave differently from the mineral-oil-cloaked droplets. It was also observed that detachment force decreases with increasing the oil-to-water volume ratio. The simulations were performed using the Surface Evolver (SE) finite element code programmed for the complicated four-phase (air, water, oil, and solid) interfacial problem at hand. Our simulations revealed the evolution of the interfacial forces between the interacting phases under an increasing external body force on the droplet. The simulations also allowed us to define effective interfacial tensions and contact angles for detaching compound droplets, for the first time. Reasonable agreement was observed between the experimental measurements and computational results.
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Affiliation(s)
- H J Holweger
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University, Richmond, Virginia 23284-3015, United States
| | - M Jamali
- Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, North Carolina 27695-7910, United States
| | - H Vahedi Tafreshi
- Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, North Carolina 27695-7910, United States
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40
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Shek ACM, Semprebon C, Panter JR, Kusumaatmaja H. Capillary Bridges on Liquid-Infused Surfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:908-917. [PMID: 33395301 DOI: 10.1021/acs.langmuir.0c03220] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
We numerically study two-component capillary bridges formed when a liquid droplet is placed in between two liquid-infused surfaces (LIS). In contrast to commonly studied one-component capillary bridges on noninfused solid surfaces, two-component liquid bridges can exhibit a range of different morphologies where the liquid droplet is directly in contact with two, one, or none of the LIS substrates. In addition, the capillary bridges may lose stability when compressed due to the envelopment of the droplet by the lubricant. We also characterize the capillary force, maximum separation, and effective spring force and find that they are influenced by the shape and size of the lubricant ridge. Importantly, these can be tuned to increase the effective capillary adhesion strength by manipulating the lubricant pressure, Neumann angle, and wetting contact angles. As such, LIS are not only "slippery" parallel to the surface, but they are also "sticky" perpendicular to the surface.
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Affiliation(s)
- Alvin C M Shek
- Department of Physics, Durham University, Durham DH1 3LE, U.K
| | - Ciro Semprebon
- Department of Mathematics, Physics and Electrical Engineering, Northumbria University, Newcastle upon Tyne NE1 8ST, U.K
| | - Jack R Panter
- Department of Physics, Durham University, Durham DH1 3LE, U.K
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41
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Gong Z, Su Z, Liu X, Pan D, Liu J, Zheng H, Joo SW. Boosting Electrically Actuated Manipulation of Water Droplets on Lubricated Surfaces through a Corona Discharge. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:400-405. [PMID: 33356299 DOI: 10.1021/acs.langmuir.0c03048] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Controllable liquid transportation is of great value in various practical applications. Here, we experimentally demonstrate a method of actuating high-speed droplet transport with large manipulation controllability on lubricated surfaces using a corona discharge generated by a simple needle-plate electrode configuration. Linear motion of droplets is realized with a maximum velocity of 30 mm/s. Factors affecting the velocity of these droplets are analyzed systematically, and the mechanism of droplet transport is explained. The lubrication film flow induced by charge deposition is shown to be the dominating factor in the droplet manipulation controllability. The new method presented here opens a new path of high-performance manipulation of liquid droplets by controlling the lubrication liquid film flow with charge deposition.
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Affiliation(s)
- Zheng Gong
- School of Power and Mechanical Engineering, Wuhan University, Wuhan 430072, China
| | - Zhenpeng Su
- The Institute of Technological Sciences, Wuhan University, Wuhan 430072, China
| | - Xiaofeng Liu
- School of Power and Mechanical Engineering, Wuhan University, Wuhan 430072, China
| | - Di Pan
- School of Power and Mechanical Engineering, Wuhan University, Wuhan 430072, China
| | - Jie Liu
- School of Power and Mechanical Engineering, Wuhan University, Wuhan 430072, China
| | - Huai Zheng
- School of Power and Mechanical Engineering, Wuhan University, Wuhan 430072, China
- The Institute of Technological Sciences, Wuhan University, Wuhan 430072, China
| | - Sang Woo Joo
- School of Mechanical Engineering, Yeungnam University, Gyeongsan 712-749, South Korea
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42
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Baumli P, D'Acunzi M, Hegner KI, Naga A, Wong WSY, Butt HJ, Vollmer D. The challenge of lubricant-replenishment on lubricant-impregnated surfaces. Adv Colloid Interface Sci 2021; 287:102329. [PMID: 33302056 DOI: 10.1016/j.cis.2020.102329] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Revised: 11/22/2020] [Accepted: 11/23/2020] [Indexed: 11/18/2022]
Abstract
Lubricant-impregnated surfaces are two-component surface coatings. One component, a fluid called the lubricant, is stabilized at a surface by the second component, the scaffold. The scaffold can either be a rough solid or a polymeric network. Drops immiscible with the lubricant, hardly pin on these surfaces. Lubricant-impregnated surfaces have been proposed as candidates for various applications, such as self-cleaning, anti-fouling, and anti-icing. The proposed applications rely on the presence of enough lubricant within the scaffold. Therefore, the quality and functionality of a surface coating are, to a large degree, given by the extent to which it prevents lubricant-depletion. This review summarizes the current findings on lubricant-depletion, lubricant-replenishment, and the resulting understanding of both processes. A multitude of different mechanisms can cause the depletion of lubricant. Lubricant can be taken along by single drops or be sheared off by liquid flowing across. Nano-interstices and scaffolds showing good chemical compatibility with the lubricant can greatly delay lubricant depletion. Often, depletion of lubricant cannot be avoided under dynamic conditions, which warrants lubricant-replenishment strategies. The strategies to replenish lubricant are presented and range from spraying or stimuli-responsive release to built-in reservoirs.
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Affiliation(s)
- Philipp Baumli
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Maria D'Acunzi
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Katharina I Hegner
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Abhinav Naga
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - William S Y Wong
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Hans-Jürgen Butt
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Doris Vollmer
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany.
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43
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Cao Y, Jana S, Tan X, Bowen L, Zhu Y, Dawson J, Han R, Exton J, Liu H, McHale G, Jakubovics NS, Chen J. Antiwetting and Antifouling Performances of Different Lubricant-Infused Slippery Surfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:13396-13407. [PMID: 33141589 DOI: 10.1021/acs.langmuir.0c00411] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The concept of slippery lubricant-infused surfaces has shown promising potential in antifouling for controlling detrimental biofilm growth. In this study, nontoxic silicone oil was either impregnated into porous surface nanostructures, referred to as liquid-infused surfaces (LIS), or diffused into a polydimethylsiloxane (PDMS) matrix, referred to as a swollen PDMS (S-PDMS), making two kinds of slippery surfaces. The slippery lubricant layers have extremely low contact angle hysteresis, and both slippery surfaces showed superior antiwetting performances with droplets bouncing off or rolling transiently after impacting the surfaces. We further demonstrated that water droplets can remove dust from the slippery surfaces, thus showing a "cleaning effect". Moreover, "coffee-ring" effects were inhibited on these slippery surfaces after droplet evaporation, and deposits could be easily removed. The clinically biofilm-forming species P. aeruginosa (as a model system) was used to further evaluate the antifouling potential of the slippery surfaces. The dried biofilm stains could still be easily removed from the slippery surfaces. Additionally, both slippery surfaces prevented around 90% of bacterial biofilm growth after 6 days compared to the unmodified control PDMS surfaces. This investigation also extended across another clinical pathogen, S. epidermidis, and showed similar results. The antiwetting and antifouling analysis in this study will facilitate the development of more efficient slippery platforms for controlling biofouling.
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Affiliation(s)
- Yunyi Cao
- School of Engineering, Newcastle University, Newcastle Upon Tyne NE1 7RU, United Kingdom
| | - Saikat Jana
- School of Engineering, Newcastle University, Newcastle Upon Tyne NE1 7RU, United Kingdom
| | - Xiaolong Tan
- School of Pharmacy, Newcastle University, Newcastle Upon Tyne NE1 7RU, United Kingdom
| | - Leon Bowen
- Department of Physics, Durham University, Durham DH1 3LE, United Kingdom
| | - Yufeng Zhu
- School of Engineering, Newcastle University, Newcastle Upon Tyne NE1 7RU, United Kingdom
| | - Jack Dawson
- School of Engineering, Newcastle University, Newcastle Upon Tyne NE1 7RU, United Kingdom
| | - Rui Han
- School of Engineering, Newcastle University, Newcastle Upon Tyne NE1 7RU, United Kingdom
| | - John Exton
- School of Engineering, Newcastle University, Newcastle Upon Tyne NE1 7RU, United Kingdom
| | - Hongzhong Liu
- School of Mechanical Engineering, Xi'an Jiaotong University, Xi'an 710054, P. R. China
| | - Glen McHale
- Smart Materials and Surfaces Laboratory, Faculty of Engineering and Environment, Northumbria University, Newcastle upon Tyne NE1 8ST, United Kingdom
- School of Engineering, University of Edinburgh, Edinburgh EH9 3FB, United Kingdom
| | - Nicholas S Jakubovics
- School of Dental Sciences, Newcastle University, Newcastle Upon Tyne NE2 4BW, United Kingdom
| | - Jinju Chen
- School of Engineering, Newcastle University, Newcastle Upon Tyne NE1 7RU, United Kingdom
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44
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Armstrong S, McHale G, Ledesma-Aguilar R, Wells GG. Evaporation and Electrowetting of Sessile Droplets on Slippery Liquid-Like Surfaces and Slippery Liquid-Infused Porous Surfaces (SLIPS). LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:11332-11340. [PMID: 32882130 PMCID: PMC8011908 DOI: 10.1021/acs.langmuir.0c02020] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Sessile droplet evaporation underpins a wide range of applications from inkjet printing to coating. However, drying times can be variable and contact-line pinning often leads to undesirable effects, such as ring stain formation. Here, we show voltage programmable control of contact angles during evaporation on two pinning-free surfaces. We use an electrowetting-on-dielectric approach and Slippery Liquid-Infused Porous (SLIP) and Slippery Omniphobic Covalently Attached Liquid-Like (SOCAL) surfaces to achieve a constant contact angle mode of evaporation. We report evaporation sequences and droplet lifetimes across a broad range of contact angles from 105°-67°. The values of the contact angles during evaporation are consistent with expectations from electrowetting and the Young-Lippman equation. The droplet contact areas reduce linearly in time, and this provides estimates of diffusion coefficients close to the expected literature value. We further find that the total time of evaporation over the broad contact angle range studied is only weakly dependent on the value of the contact angle. We conclude that on these types of slippery surfaces, droplet lifetimes can be predicted and controlled by the droplet's volume and physical properties (density, diffusion coefficient, and vapor concentration difference to the vapor phase) largely independent of the precise value of contact angle. These results are relevant to applications, such as printing, spraying, coating, and other processes, where controlling droplet evaporation and drying is important.
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Affiliation(s)
- S. Armstrong
- Smart
Materials & Surfaces Laboratory, Faculty of Engineering &
Environment, Northumbria University, Newcastle upon Tyne, NE1
8ST, U.K.
- School
of Engineering, University of Edinburgh, Sanderson Building, Edinburgh, EH9 3FB, U.K.
| | - G. McHale
- Smart
Materials & Surfaces Laboratory, Faculty of Engineering &
Environment, Northumbria University, Newcastle upon Tyne, NE1
8ST, U.K.
- School
of Engineering, University of Edinburgh, Sanderson Building, Edinburgh, EH9 3FB, U.K.
| | - R. Ledesma-Aguilar
- Smart
Materials & Surfaces Laboratory, Faculty of Engineering &
Environment, Northumbria University, Newcastle upon Tyne, NE1
8ST, U.K.
- School
of Engineering, University of Edinburgh, Sanderson Building, Edinburgh, EH9 3FB, U.K.
| | - G. G. Wells
- Smart
Materials & Surfaces Laboratory, Faculty of Engineering &
Environment, Northumbria University, Newcastle upon Tyne, NE1
8ST, U.K.
- School
of Engineering, University of Edinburgh, Sanderson Building, Edinburgh, EH9 3FB, U.K.
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45
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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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46
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Self-propelled droplet transport on shaped-liquid surfaces. Sci Rep 2020; 10:14987. [PMID: 32917910 PMCID: PMC7486897 DOI: 10.1038/s41598-020-70988-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Accepted: 06/24/2020] [Indexed: 11/29/2022] Open
Abstract
The transport of small amounts of liquids on solid surfaces is fundamental for microfluidics applications. Technologies allowing control of droplets of liquid on flat surfaces generally involve the generation of a wettability contrast. This approach is however limited by the resistance to motion caused by the direct contact between the droplet and the solid. We show here that this resistance can be drastically reduced by preventing direct contact with the help of dual-length scale micro-structures and the concept of “liquid-surfaces”. These new surfaces allow the gentle transport of droplets along defined paths and with fine control of their speed. Moreover, their high adhesion permits the capture of impacting droplets, opening new possibilities in applications such as fog harvesting and heat transfer.
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47
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Hu X, Wang Z, Hwang DJ, Cubaud T. Forced Wetting and Dewetting of Water and Oil Droplets on Planar Microfluidic Grids. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:9269-9275. [PMID: 32672977 DOI: 10.1021/acs.langmuir.0c01601] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
We experimentally study the wetting behavior of small water and oil droplets spreading and receding from textured surfaces made using a backside laser processing technique. A dual image acquisition system enables the three-dimensional characterization of both wetted area and dynamic contact angles. In particular, we compare droplet growth on smooth surfaces and planar microfluidic grids of various surface coverages and heights and discuss contact angle characterization. The surface texture is shown to trap liquid in microwells during the stick-and-slip motion of advancing contact lines. Receding wetting dynamics of liquid infused substrates shows similarity with forced spreading on smooth surfaces. Contact angle hysteresis is investigated as a function of surface parameters to better delineate specific wetting behaviors of water and oil on laser-processed surfaces.
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Affiliation(s)
- Xiaoyi Hu
- Department of Mechanical Engineering, Stony Brook University, Stony Brook, New York 11794, United States
| | - Zhen Wang
- Department of Mechanical Engineering, Stony Brook University, Stony Brook, New York 11794, United States
| | - David J Hwang
- Department of Mechanical Engineering, Stony Brook University, Stony Brook, New York 11794, United States
| | - Thomas Cubaud
- Department of Mechanical Engineering, Stony Brook University, Stony Brook, New York 11794, United States
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48
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Evaporating droplets on oil-wetted surfaces: Suppression of the coffee-stain effect. Proc Natl Acad Sci U S A 2020; 117:16756-16763. [PMID: 32616571 DOI: 10.1073/pnas.2006153117] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The evaporation of suspension droplets is the underlying mechanism in many surface-coating and surface-patterning applications. However, the uniformity of the final deposit suffers from the coffee-stain effect caused by contact line pinning. Here, we show that control over particle deposition can be achieved through droplet evaporation on oil-wetted hydrophilic surfaces. We demonstrate by flow visualization, theory, and numerics that the final deposit of the particles is governed by the coupling of the flow field in the evaporating droplet, the movement of its contact line, and the wetting state of the thin film surrounding the droplet. We show that the dynamics of the contact line can be tuned through the addition of a surfactant, thereby controlling the surface energies, which then leads to control over the final particle deposit. We also obtain an analytical expression for the radial velocity profile which reflects the hindering of the evaporation at the rim of the droplet by the nonvolatile oil meniscus, preventing flow toward the contact line, thus suppressing the coffee-stain effect. Finally, we confirm our physical interpretation by numerical simulations that are in qualitative agreement with the experiment.
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49
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Li X, Yang J, Lv K, Papadopoulos P, Sun J, Wang D, Zhao Y, Chen L, Wang D, Wang Z, Deng X. Salvinia-like slippery surface with stable and mobile water/air contact line. Natl Sci Rev 2020; 8:nwaa153. [PMID: 34691630 PMCID: PMC8288347 DOI: 10.1093/nsr/nwaa153] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Revised: 06/04/2020] [Accepted: 06/07/2020] [Indexed: 11/13/2022] Open
Abstract
Superhydrophobic surfaces are widely used in many industrial settings, and mainly consist of rough solid protrusions that entrap air to minimize the liquid/solid area. The stability of the superhydrophobic state favors relatively small spacing between protrusions. However, this in turn increases the lateral adhesion force that retards the mobility of drops. Here we propose a novel approach that optimizes both properties simultaneously. Inspired by the hydrophobic leaves of Salvinia molesta and the slippery Nepenthes pitcher plants, we designed a Salvinia-like slippery surface (SSS) consisting of protrusions with slippery heads. We demonstrate that compared to a control surface, the SSS exhibits increased stability against pressure and impact, and enhanced lateral mobility of water drops as well as reduced hydrodynamic drag. We also systematically investigate the wetting dynamics on the SSS. With its easy fabrication and enhanced performance, we envision that SSS will be useful in a variety of fields in industry.
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Affiliation(s)
- Xiaomei Li
- Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu 610054, China
| | - Jinlong Yang
- Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu 610054, China
| | - Kaixuan Lv
- State Key Laboratory of Polymer Physics and Chemistry, Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China
| | | | - Jing Sun
- Department of Mechanical Engineering, City University of Hong Kong, Hong Kong, China
| | - Dehui Wang
- Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu 610054, China
| | - Yanhua Zhao
- Department of Mechanical Engineering, City University of Hong Kong, Hong Kong, China
| | - Longquan Chen
- School of Physics, University of Electronic Science and Technology of China, Chengdu 610054, China
| | - Dapeng Wang
- State Key Laboratory of Polymer Physics and Chemistry, Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China
| | - Zuankai Wang
- Department of Mechanical Engineering, City University of Hong Kong, Hong Kong, China
| | - Xu Deng
- Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu 610054, China
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50
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Jamali M, Tafreshi HV. Measuring Force of Droplet Detachment from Hydrophobic Surfaces via Partial Cloaking with Ferrofluids. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:6116-6125. [PMID: 32410450 DOI: 10.1021/acs.langmuir.0c00532] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
This paper presents a new approach to measure the force required to detach a water (a polar liquid) droplet from a hydrophobic surface. This is done by partially cloaking the droplet with a high-surface-tension oil-based ferrofluid and using a magnet to apply a controllable body force to the resulting compound droplet. Placing the assembly on a sensitive scale, the magnet can then be brought closer to the droplet to detach it from the surface while recording the forces applied to the droplet. The work presented here is novel as it uses the concept of partial cloaking in which the solid-droplet contact area is not contaminated by the ferrofluid (and the measured forces do not need postprocessing). Our study is accompanied by numerical simulations aimed at improving our understanding of the interplay between the interfacial forces in a two-phase droplet under the influence of a strong (detaching) body force and at providing additional data for in-depth analyses of these forces. In particular, the minimum ferrofluid volume required for successful water droplet detachment from hydrophobic surfaces is computed for ferrofluids of different surface tensions, and they are compared to experimental data obtained from detaching water droplets from electrospun polystyrene coatings. It is also shown that the detachment force measured via partial cloaking is independent of the volume of the ferrofluid used for the experiment.
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Affiliation(s)
- Mohammad Jamali
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University, Richmond, Virginia 23284-3015, United States
| | - Hooman Vahedi Tafreshi
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University, Richmond, Virginia 23284-3015, United States
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