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Effects of surface nanotexturing on the wickability of microtextured metal surfaces. J Colloid Interface Sci 2023; 638:788-800. [PMID: 36791477 DOI: 10.1016/j.jcis.2023.01.148] [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: 11/17/2022] [Revised: 01/25/2023] [Accepted: 01/31/2023] [Indexed: 02/05/2023]
Abstract
HYPOTHESIS Achieving spontaneous, rapid, and long-distance liquid transport is crucial for many practical applications such as phase change heat transfer and reactions at solid-liquid interfaces. Surface nanotexturing has been widely reported to improve the wickability of microtextured metal surfaces. Although surface nanotextures show high capillary pressure, the high fluid flow resistance through nanotextures prevents fluid transport. The underlying mechanisms responsible for the enhanced wickability of nanotextured surfaces are still unclear. EXPERIMENTS Herein, we prepared a variety of microtextures and nanotextures on copper surfaces by femtosecond laser micromachining and chemical oxidation, respectively. The wickability of these textured surfaces was quantitively compared by measuring wicking coefficient and capillary rise speed. We designed experiments to eliminate any possible effects of surface oxidation and metal composition on wickability. A theoretical model describing the vertical and horizontal capillary flow in V-shaped microgrooves was proposed and utilized to analyze the experimental results. The effects of time-dependent wettability on wickability were also examined. FINDINGS Surface nanotexturing can enhance surface wettability while altering the micrometer-scale structural characteristics. The greatly enhanced wickability of nanotextured surfaces can only be observed when the surface microtextures have a very small aspect ratio. Otherwise, for metal surfaces with fine microgrooves, the latter effect is more pronounced, and thus the surface wickability may deteriorate after preparing surface nanotextures; for surfaces with wide microgrooves, both effects are minimal, and the surface wickability enhances only marginally after surface nanotexturing. Furthermore, the wickability of microtextured surfaces will decay rapidly due to the adsorption of airborne organics, whereas adding surface nanotextures can significantly inhibit this degradation. The anti-contamination capability of surface nanotextures is considered likely to be a potential mechanism responsible for the greatly enhanced wickability of nanotextured surfaces noted in some studies.
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Zhang RP, Mei M, Qiu H. Effect of Micropillar Array Morphology on Liquid Propagation Coefficient Enhancement. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:3083-3093. [PMID: 36802613 DOI: 10.1021/acs.langmuir.2c03175] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Roughness on hydrophilic surfaces allows for fast propagation of liquids. In this paper, the hypothesis is tested which theorizes that pillar array structures with nonuniform pillar height levels can enhance wicking rates. In this work, within a unit cell, nonuniform micropillars were arranged with one pillar at constant height, while other shorter pillars were varied in height to study these nonuniform effects. Subsequently, a new microfabrication technique was developed to fabricate a nonuniform pillar array surface. Capillary rising-rate experiments were conducted with water, decane, and ethylene glycol as working liquids to determine the behavior of propagation coefficients that were dependent on pillar morphology. It is found that a nonuniform pillar height structure leads to a separation of layers in the liquid spreading process and the propagation coefficient increases with declining micropillar height for all liquids tested. This indicated a significant enhancement of wicking rates compared to uniform pillar arrays. A theoretical model was subsequently developed to explain and predict the enhancement effect by considering capillary force and viscous resistance of nonuniform pillar structures. The insights and implications from this model thus advance our understanding of the physics of the wicking process and can inform the design of pillar structures with an enhanced wicking propagation coefficient.
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Affiliation(s)
- Ruo Peng Zhang
- Department of Mechanical and Aerospace Engineering, The Hong Kong University of Science & Technology, Clear Water Bay, Kowloon 999077, Hong Kong SAR, China
| | - Mei Mei
- Department of Mechanical and Aerospace Engineering, The Hong Kong University of Science & Technology, Clear Water Bay, Kowloon 999077, Hong Kong SAR, China
| | - Huihe Qiu
- Department of Mechanical and Aerospace Engineering, The Hong Kong University of Science & Technology, Clear Water Bay, Kowloon 999077, Hong Kong SAR, China
- Thrust of Sustainable Energy and Environment, The Hong Kong University of Science and Technology (Guangzhou), Guangzhou 511453, China
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Capillary spreading of ethanol-water on hierarchical nanowire surfaces with interconnected V-groove. Colloids Surf A Physicochem Eng Asp 2022. [DOI: 10.1016/j.colsurfa.2022.130786] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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Lee J, Mohraz A, Won Y. Enhanced Capillary Wicking through Hierarchically Porous Constructs Derived from Bijel Templates. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:14063-14072. [PMID: 36342818 DOI: 10.1021/acs.langmuir.2c01965] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Liquid capillarity through porous media can be enhanced by a rational design of hierarchically porous constructs that suggest sufficiently large liquid pathways from an upper-level hierarchy as well as capillary pressure enabled by a lower hierarchy. Here, we demonstrate a material design strategy utilizing a new class of self-assembled soft materials, called bicontinuous interfacially jammed emulsion gels (bijels), to produce hierarchically porous copper, which enables the unique combination of unprecedented control over both macropores and mesopores in a regular, uniform, and continuous arrangement. The dynamic droplet topologies on the hierarchically copper pores prove the significant enhancement in liquid capillarity compared to homogeneous porous structures. The role of nanoscale morphology in liquid infiltration is further investigated through environmental scanning electron microscopy, in which wetting through the mesopores occurs at the beginning, followed by liquid transport through macropores. This understanding on capillary wicking will allow us to design better hierarchically porous media that can address performance breakthroughs in interfacial applications, ranging from battery electrodes, cell delivery in biomedical devices, to capillary-fed thermal management systems.
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Affiliation(s)
- Jonggyu Lee
- Department of Mechanical and Aerospace Engineering, University of California, Irvine, Irvine, California92697, United States
| | - Ali Mohraz
- Department of Chemical and Biomolecular Engineering, University of California, Irvine, Irvine, California92697, United States
- Department of Materials Science and Engineering, University of California, Irvine, Irvine, California92697, United States
| | - Yoonjin Won
- Department of Mechanical and Aerospace Engineering, University of California, Irvine, Irvine, California92697, United States
- Department of Materials Science and Engineering, University of California, Irvine, Irvine, California92697, United States
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Jiang G, Tian Z, Wang L, Luo X, Chen C, Hu X, Peng R, Zhang H, Zhong M. Anisotropic Hemiwicking Behavior on Laser Structured Prismatic Microgrooves. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:6665-6675. [PMID: 35578803 DOI: 10.1021/acs.langmuir.2c00568] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
The wicking phenomenon, including wicking and hemiwicking, has attracted increasing attention for its critical importance to a wide range of engineering applications, such as thermal management, water harvesting, fuel cells, microfluidics, and biosciences. There exists a more urgent demand for anisotropic wicking behaviors since an increasing number of advanced applications are significantly complex. For example, special-shaped vapor chambers and heating atomizers in some electronic cigarettes need liquid replenishing with various velocities in different directions. Here, we report two-dimensional anisotropic hemiwicking behaviors with elliptical shapes on laser structured prismatic microgrooves. The prismatic microgrooves were fabricated via one-step femtosecond laser direct writing, and the anisotropic hemiwicking behaviors were observed when utilizing glycerol, glycol, and water as the test liquid. Specifically, the ratios of horizontal wicking distance in directions along short and long axes were tan 0°, tan 15°, tan 30°, and tan 45° for samples with cross-angles of 0°, 30°, 60°, and 90°, respectively. The vertical water wicking front displayed corresponding angles under the guidance of laser structured prismatic microgrooves. Theoretical analysis shows that the wicking distance is mainly dependent on the cross-angle θ and surface roughness, in which the wicking distance is proportional to cos(θ/2). Driven by the capillary pressure forming in the narrow microgrooves, the liquid initially filled the valleys of microgrooves and then surrounded and covered the prismatic ridges with laser-induced nanoparticles. The abundant nanoparticles increased the surface roughness, leading to the enhancement of wicking performance, which was further evidenced by the larger wicking speed of the sample with more nanoparticles. The mechanism of anisotropic hemiwicking behaviors revealed in this work paves the way for wicking control, and the proposed prismatic microgrooved surfaces with two-dimensional anisotropic hemiwicking performance and superhydrophilicity could serve in a broad range of applications, especially for the advanced thermal management with specific heat load configurations.
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Affiliation(s)
- Guochen Jiang
- Laser Materials Processing Research Centre, School of Materials Science and Engineering, Tsinghua University, Key Laboratory for Advanced Materials Processing Technology, Ministry of Education, Beijing 100084, P. R. China
| | - Ze Tian
- Laser Materials Processing Research Centre, School of Materials Science and Engineering, Tsinghua University, Key Laboratory for Advanced Materials Processing Technology, Ministry of Education, Beijing 100084, P. R. China
| | - Lizhong Wang
- Laser Materials Processing Research Centre, School of Materials Science and Engineering, Tsinghua University, Key Laboratory for Advanced Materials Processing Technology, Ministry of Education, Beijing 100084, P. R. China
| | - Xiao Luo
- Laser Materials Processing Research Centre, School of Materials Science and Engineering, Tsinghua University, Key Laboratory for Advanced Materials Processing Technology, Ministry of Education, Beijing 100084, P. R. China
| | - Changhao Chen
- Laser Materials Processing Research Centre, School of Materials Science and Engineering, Tsinghua University, Key Laboratory for Advanced Materials Processing Technology, Ministry of Education, Beijing 100084, P. R. China
| | - Xinyu Hu
- Laser Materials Processing Research Centre, School of Materials Science and Engineering, Tsinghua University, Key Laboratory for Advanced Materials Processing Technology, Ministry of Education, Beijing 100084, P. R. China
| | - Rui Peng
- Laser Materials Processing Research Centre, School of Materials Science and Engineering, Tsinghua University, Key Laboratory for Advanced Materials Processing Technology, Ministry of Education, Beijing 100084, P. R. China
| | - Hongjun Zhang
- Laser Materials Processing Research Centre, School of Materials Science and Engineering, Tsinghua University, Key Laboratory for Advanced Materials Processing Technology, Ministry of Education, Beijing 100084, P. R. China
| | - Minlin Zhong
- Laser Materials Processing Research Centre, School of Materials Science and Engineering, Tsinghua University, Key Laboratory for Advanced Materials Processing Technology, Ministry of Education, Beijing 100084, P. R. China
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Song Z, Lin ES, Uddin MH, Abid HA, Ong JW, Liew OW, Ng TW. Fog Harvesting with Highly Wetting and Nonwetting Vertical Strips. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:1845-1852. [PMID: 35080398 DOI: 10.1021/acs.langmuir.1c02965] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Highly wetting and nonwetting substrates have been widely used in fogwater collection systems for enhanced water harvesting. In this work, fog harvesting substrates comprising PVC strips of different wetting properties and widths ranging from 1-5 mm were vertically aligned and spaced apart at regular intervals to give the same solid area fraction of 0.8. Evaluation of the water collection efficiencies of the tested configurations revealed that 1 mm wide superhydrophilic strips was the most efficient, achieving double the amount of water harvested compared with 2.8 mm wide strips. This finding was attributed to the low Stokes numbers of the aerosol particle distribution of the fog which tended to result in them being brought by the flow streamlines toward the air gaps between the strips. Stagnant flow regions at the edges of each strip, revealed through potential flow calculations, then caused higher liquid imbibition and impaction there for water harvesting. It was also found that the Cassie nonwetting substrates that originally exhibited contact angles of 161° transformed to Wenzel wetting with zero contact angle within 60 min of fog interception. Optical profilometry revealed no obvious difference in surface roughness between the central region and edges of the strips, indicating that surface morphology was unlikely to be a contributing factor for enhanced water collection at the edges. The findings here indicated that highly wetting vertical strip architectures with narrow widths (1 mm) were favorable over wider strips for water harvesting provided that clogging and re-entrainment were not significant factors.
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Affiliation(s)
- Zhixiong Song
- Laboratory for Optics and Applied Mechanics, Department of Mechanical & Aerospace Engineering, Monash University, Clayton, Victoria 3800 Australia
| | - Eric Shen Lin
- Laboratory for Optics and Applied Mechanics, Department of Mechanical & Aerospace Engineering, Monash University, Clayton, Victoria 3800 Australia
| | - Md Hemayet Uddin
- Melbourne Centre for Nanofabrication, 151 Wellington Rd, Clayton VIC 3168 Australia
| | - Hassan Ali Abid
- Laboratory for Optics and Applied Mechanics, Department of Mechanical & Aerospace Engineering, Monash University, Clayton, Victoria 3800 Australia
| | - Jian Wern Ong
- Laboratory for Optics and Applied Mechanics, Department of Mechanical & Aerospace Engineering, Monash University, Clayton, Victoria 3800 Australia
| | - Oi Wah Liew
- Cardiovascular Research Institute, Yong Loo Lin School of Medicine, National University of Singapore, National University Health System, Centre for Translational Medicine, 14 Medical Drive 117599, Singapore
| | - Tuck Wah Ng
- Laboratory for Optics and Applied Mechanics, Department of Mechanical & Aerospace Engineering, Monash University, Clayton, Victoria 3800 Australia
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Chun J, Xu C, Li Q, Chen Y, Zhao Q, Yang W, Wen R, Ma X. Microscopic Observation of Preferential Capillary Pumping in Hollow Nanowire Bundles. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:352-362. [PMID: 34812042 DOI: 10.1021/acs.langmuir.1c02647] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Numerous studies have focused on designing micro/nanostructured surfaces to improve wicking capability for rapid liquid transport in many industrial applications. Although hierarchical surfaces have been demonstrated to enhance wicking capability, the underlying mechanism of liquid transport remains elusive. Here, we report the preferential capillary pumping on hollow hierarchical surfaces with internal nanostructures, which are different from the conventional solid hierarchical surfaces with external nanostructures. Specifically, capillary pumping preferentially occurs in the nanowire bundles instead of the interconnected V-groove on hollow hierarchical surfaces, observed by confocal laser scanning fluorescence microscopy. Theoretical analysis shows that capillary pumping capability is mainly dependent on the nanowire diameter and results in 15.5 times higher capillary climbing velocity in the nanowire bundles than that in the microscale V-groove. Driven by the Laplace pressure difference between nanowire bundles and V-grooves, the preferential capillary pumping is increased with the reduction of the nanowire diameter. Capillary pumping of the nanowire bundles provides a preferential path for rapid liquid flow, leading to 2 times higher wicking capability of the hollow hierarchical surface comparing with the conventional hierarchical surface. The unique mechanism of preferential capillary pumping revealed in this work paves the way for wicking enhancement and provides an insight into the design of wicking surfaces for high-performance capillary evaporation in a broad range of applications.
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Affiliation(s)
- Jiang Chun
- State Key Laboratory of Fine Chemicals, Liaoning Key Laboratory of Clean Utilization of Chemical Resources, Institute of Chemical Engineering, Dalian University of Technology, Dalian 116024, P. R. China
| | - Chen Xu
- State Key Laboratory of Fine Chemicals, Liaoning Key Laboratory of Clean Utilization of Chemical Resources, Institute of Chemical Engineering, Dalian University of Technology, Dalian 116024, P. R. China
| | - Qifan Li
- State Key Laboratory of Fine Chemicals, Liaoning Key Laboratory of Clean Utilization of Chemical Resources, Institute of Chemical Engineering, Dalian University of Technology, Dalian 116024, P. R. China
| | - Yansong Chen
- State Key Laboratory of Fine Chemicals, Liaoning Key Laboratory of Clean Utilization of Chemical Resources, Institute of Chemical Engineering, Dalian University of Technology, Dalian 116024, P. R. China
| | - Qishan Zhao
- State Key Laboratory of Fine Chemicals, Liaoning Key Laboratory of Clean Utilization of Chemical Resources, Institute of Chemical Engineering, Dalian University of Technology, Dalian 116024, P. R. China
| | - Wei Yang
- State Key Laboratory of Fine Chemicals, Liaoning Key Laboratory of Clean Utilization of Chemical Resources, Institute of Chemical Engineering, Dalian University of Technology, Dalian 116024, P. R. China
| | - Rongfu Wen
- State Key Laboratory of Fine Chemicals, Liaoning Key Laboratory of Clean Utilization of Chemical Resources, Institute of Chemical Engineering, Dalian University of Technology, Dalian 116024, P. R. China
| | - Xuehu Ma
- State Key Laboratory of Fine Chemicals, Liaoning Key Laboratory of Clean Utilization of Chemical Resources, Institute of Chemical Engineering, Dalian University of Technology, Dalian 116024, P. R. China
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Natarajan B, Jaishankar A, King M, Oktasendra F, Avis SJ, Konicek AR, Wadsworth G, Jusufi A, Kusumaatmaja H, Yeganeh MS. Predicting Hemiwicking Dynamics on Textured Substrates. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:188-195. [PMID: 33347296 DOI: 10.1021/acs.langmuir.0c02737] [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
The ability to predict liquid transport rates on textured surfaces is key to the design and optimization of devices and processes such as oil recovery, coatings, reaction-separation, high-throughput screening, and thermal management. In this work we develop a fully analytical model to predict the propagation coefficients for liquids hemiwicking through micropillar arrays. This is carried out by balancing the capillary driving force and a viscous resistive force and solving the Navier-Stokes equation for representative channels. The model is validated against a large data set of experimental hemiwicking coefficients harvested from the literature and measured in-house using high-speed imaging. The theoretical predictions show excellent agreement with the measured values and improved accuracy compared to previously proposed models. Furthermore, using lattice Boltzmann (LB) simulations, we demonstrate that the present model is applicable over a broad range of geometries. The scaling of velocity with texture geometry, implicit in our model, is compared against experimental data, where good agreement is observed for most practical systems. The analytical expression presented here offers a tool for developing design guidelines for surface chemistry and microstructure selection for liquid propagation on textured surfaces.
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Affiliation(s)
- Bharath Natarajan
- Corporate Strategic Research, ExxonMobil Research and Engineering Co., 1545 U.S. 22, Annandale, New Jersey 08801, United States
| | - Aditya Jaishankar
- Corporate Strategic Research, ExxonMobil Research and Engineering Co., 1545 U.S. 22, Annandale, New Jersey 08801, United States
| | - Mark King
- Corporate Strategic Research, ExxonMobil Research and Engineering Co., 1545 U.S. 22, Annandale, New Jersey 08801, United States
| | - Fandi Oktasendra
- Department of Physics, Durham University, Durham DH1 3LE, United Kingdom
- Department of Physics, Universitas Negeri Padang, Padang 25131, Indonesia
| | - Samuel J Avis
- Department of Physics, Durham University, Durham DH1 3LE, United Kingdom
| | - Andrew R Konicek
- Corporate Strategic Research, ExxonMobil Research and Engineering Co., 1545 U.S. 22, Annandale, New Jersey 08801, United States
| | - Garrett Wadsworth
- Corporate Strategic Research, ExxonMobil Research and Engineering Co., 1545 U.S. 22, Annandale, New Jersey 08801, United States
| | - Arben Jusufi
- Corporate Strategic Research, ExxonMobil Research and Engineering Co., 1545 U.S. 22, Annandale, New Jersey 08801, United States
| | - Halim Kusumaatmaja
- Department of Physics, Durham University, Durham DH1 3LE, United Kingdom
| | - Mohsen S Yeganeh
- Corporate Strategic Research, ExxonMobil Research and Engineering Co., 1545 U.S. 22, Annandale, New Jersey 08801, United States
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