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Gu H, Meng K, Yuan R, Xiao S, Shan Y, Zhu R, Deng Y, Luo X, Li R, Liu L, Chen X, Shi Y, Wang X, Duan C, Wang H. Rewritable printing of ionic liquid nanofilm utilizing focused ion beam induced film wetting. Nat Commun 2024; 15:2949. [PMID: 38580645 PMCID: PMC10997651 DOI: 10.1038/s41467-024-47018-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Accepted: 03/14/2024] [Indexed: 04/07/2024] Open
Abstract
Manipulating liquid flow over open solid substrate at nanoscale is important for printing, sensing, and energy devices. The predominant methods of liquid maneuvering usually involve complicated surface fabrications, while recent attempts employing external stimuli face difficulties in attaining nanoscale flow control. Here we report a largely unexplored ion beam induced film wetting (IBFW) technology for open surface nanofluidics. Local electrostatic forces, which are generated by the unique charging effect of Helium focused ion beam (HFIB), induce precursor film of ionic liquid and the disjoining pressure propels and stabilizes the nanofilm with desired patterns. The IBFW technique eliminates the complicated surface fabrication procedures to achieve nanoscale flow in a controllable and rewritable manner. By combining with electrochemical deposition, various solid materials with desired patterns can be produced.
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Affiliation(s)
- Haohao Gu
- Laboratory of Heat and Mass Transport at Micro-Nano Scale, College of Engineering, Peking University, Beijing, 100871, PR China
| | - Kaixin Meng
- Laboratory of Heat and Mass Transport at Micro-Nano Scale, College of Engineering, Peking University, Beijing, 100871, PR China
| | - Ruowei Yuan
- Laboratory of Heat and Mass Transport at Micro-Nano Scale, College of Engineering, Peking University, Beijing, 100871, PR China
| | - Siyang Xiao
- Department of Mechanical Engineering, Boston University, Boston, 02215, MA, USA
| | - Yuying Shan
- Laboratory of Heat and Mass Transport at Micro-Nano Scale, College of Engineering, Peking University, Beijing, 100871, PR China
| | - Rui Zhu
- Electron Microscopy Lab, School of Physics, Peking University, Beijing, 100871, PR China
| | - Yajun Deng
- Future Technology School, Shenzhen Technology University, Shenzhen, 518118, PR China
| | - Xiaojin Luo
- School of Materials Science and Engineering, Peking University, Beijing, 100871, PR China
| | - Ruijie Li
- School of Materials Science and Engineering, Peking University, Beijing, 100871, PR China
| | - Lei Liu
- School of Materials Science and Engineering, Peking University, Beijing, 100871, PR China
| | - Xu Chen
- Research Center of Engineering Thermophysics, North China Electric Power University, Beijing, 102206, PR China
| | - Yuping Shi
- School of Materials Science and Engineering, Peking University, Beijing, 100871, PR China
| | - Xiaodong Wang
- Research Center of Engineering Thermophysics, North China Electric Power University, Beijing, 102206, PR China
| | - Chuanhua Duan
- Department of Mechanical Engineering, Boston University, Boston, 02215, MA, USA
| | - Hao Wang
- Laboratory of Heat and Mass Transport at Micro-Nano Scale, College of Engineering, Peking University, Beijing, 100871, PR China.
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Dynamic wetting of various liquids: Theoretical models, experiments, simulations and applications. Adv Colloid Interface Sci 2023; 313:102861. [PMID: 36842344 DOI: 10.1016/j.cis.2023.102861] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2022] [Revised: 02/12/2023] [Accepted: 02/13/2023] [Indexed: 02/23/2023]
Abstract
Dynamic wetting is a ubiquitous phenomenon and frequently observed in our daily life, as exemplified by the famous lotus effect. It is also an interfacial process of upmost importance involving many cutting-edge applications and has hence received significantly increasing academic and industrial attention for several decades. However, we are still far away to completely understand and predict wetting dynamics for a given system due to the complexity of this dynamic process. The physics of moving contact lines is mainly ascribed to the full coupling with the solid surface on which the liquids contact, the atmosphere surrounding the liquids, and the physico-chemical characteristics of the liquids involved (small-molecule liquids, metal liquids, polymer liquids, and simulated liquids). Therefore, to deepen the understanding and efficiently harness wetting dynamics, we propose to review the major advances in the available literature. After an introduction providing a concise and general background on dynamic wetting, the main theories are presented and critically compared. Next, the dynamic wetting of various liquids ranging from small-molecule liquids to simulated liquids are systematically summarized, in which the new physical concepts (such as surface segregation, contact line fluctuations, etc.) are particularly highlighted. Subsequently, the related emerging applications are briefly presented in this review. Finally, some tentative suggestions and challenges are proposed with the aim to guide future developments.
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3
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Deng Y, Wu Q, Li Z, Huang X, Rao S, Liang Y, Lu H. Crystal face dependent wettability of α-quartz: Elucidation by time-of-flight secondary ion mass spectrometry techniques combined with molecular dynamics. J Colloid Interface Sci 2021; 607:1699-1708. [PMID: 34592555 DOI: 10.1016/j.jcis.2021.09.047] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Revised: 08/26/2021] [Accepted: 09/08/2021] [Indexed: 11/30/2022]
Abstract
HYPOTHESIS Quartz is one of the most common but important minerals, and its wettability plays a significant role in affecting various natural and industrial processes. Studies have revealed that different crystal faces of quartz are with different wettabilities, but its mechanism is still vague. EXPERIMENTS AND SIMULATIONS For specifying the mechanism of crystal face dependent wettability, the contact angles of three different liquids on the crystal faces of α-quartz are measured; the time-of-flight secondary ion mass spectrometry (ToF-SIMS) is employed to establish the crystal surface models; molecular dynamics (MD) simulations with the surface models are performed to understand the wetting behavior at molecular scale. FINDINGS Based on the contact angle measurements, the wettabilities of different crystal faces of α-quartz are found different, which can be directly attributed to the concentration of hydroxyl group on crystal faces based on ToF-SIMS results. MD simulations yield consistent results with the contact angle order recognized from experiments, revealing that the surface hydroxyl group controls the wettability of α-quartz crystal faces. It is also recognized that the pristine surface atomic arrangement, especially the surface concentration of unsaturated bond (an intrinsic property of α-quartz), is the intrinsic cause of the difference in the concentration of hydroxyl group of the crystal surface.
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Affiliation(s)
- Yajun Deng
- Beijing International Center for Gas Hydrate, Peking University, No.5 Yiheyuan Road Haidian District, Beijing 100871, China; College of Engineering, Peking University, No.5 Yiheyuan Road Haidian District, Beijing 100871, China; Department of Mechanical Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong 999077, China.
| | - Qianhong Wu
- Beijing International Center for Gas Hydrate, Peking University, No.5 Yiheyuan Road Haidian District, Beijing 100871, China; School of Physics, Peking University, No.5 Yiheyuan Road Haidian District, Beijing 100871, China.
| | - Zhenchao Li
- Beijing International Center for Gas Hydrate, Peking University, No.5 Yiheyuan Road Haidian District, Beijing 100871, China; School of Earth and Space Sciences, Peking University, No.5 Yiheyuan Road Haidian District, Beijing 100871, China.
| | - Xin Huang
- Beijing International Center for Gas Hydrate, Peking University, No.5 Yiheyuan Road Haidian District, Beijing 100871, China; College of Engineering, Peking University, No.5 Yiheyuan Road Haidian District, Beijing 100871, China.
| | - Shihang Rao
- Beijing International Center for Gas Hydrate, Peking University, No.5 Yiheyuan Road Haidian District, Beijing 100871, China; College of Engineering, Peking University, No.5 Yiheyuan Road Haidian District, Beijing 100871, China.
| | - Yunfeng Liang
- Department of Systems Innovation, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
| | - Hailong Lu
- Beijing International Center for Gas Hydrate, Peking University, No.5 Yiheyuan Road Haidian District, Beijing 100871, China; School of Earth and Space Sciences, Peking University, No.5 Yiheyuan Road Haidian District, Beijing 100871, China.
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4
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Study of the contact angle of water droplet on the surface of natural K-feldspar with the combination of Ar+ polishing and atomic force microscopy scanning. Chem Eng Sci 2021. [DOI: 10.1016/j.ces.2021.116705] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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5
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Davoodabadi A, Ghasemi H. Evaporation in nano/molecular materials. Adv Colloid Interface Sci 2021; 290:102385. [PMID: 33662599 DOI: 10.1016/j.cis.2021.102385] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Revised: 02/17/2021] [Accepted: 02/18/2021] [Indexed: 12/29/2022]
Abstract
Evaporation is a physical phenomenon with fundamental significance to both nature and technology ranging from plant transpiration to DNA engineering. Various analytical and empirical relationships have been proposed to characterize evaporation kinetics at macroscopic scales. However, theoretical models to describe the kinetics of evaporation from nano and sub-nanometer (molecular) confinements are absent. On the other hand, the fast advancements in technology concentrated on development of nano/molecular-scale devices demand appropriate models that can accurately predict physics of phase-change in these systems. A thorough understanding of the physics of evaporation in nano/molecular materials is, thus, of critical importance to develop the required models. This understanding is also crucial to explain the intriguing evaporation-related phenomena that only take place when the characteristic length of the system drops to several nanometers. Here, we comprehensively review the underlying physics of evaporation phenomenon and discuss the effects of nano/molecular confinement on evaporation. The role of liquid-wall interface-related phenomena including the effects of disjoining pressure and flow slippage on evaporation from nano/molecular confinements are discussed. Different driving forces that can induce evaporation in small confinements, such as heat transfer, pressure drop, cavitation and density fluctuations are elaborated. Hydrophobic confinement induced evaporation and its potential application for synthetic ion channels are discussed in detail. Evaporation of water as molecular clusters rather than isolated molecules is discussed. Despite the lack of experimental investigations on evaporation at nanoscale, there exist an extensive body of literature that have applied different simulation techniques to predict the phase change behavior of liquids in nanoconfinements. We infer that exploring the effect of electrostatic interactions and flow slippage to enhance evaporation from nanoconduits is an interesting topic for future endeavors. Further future studies could be devoted to developing nano/molecular channels with evaporation-based gating mechanism and utilization of 2D materials to tune energy barrier for evaporation leading to enhanced evaporation.
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Chen G, Bau HH, Li CH. In Situ Transmission Electron Microscope Liquid Cell 3D Profile Reconstruction and Analysis of Nanoscale Liquid Water Contact Line Movements. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:16712-16717. [PMID: 31756112 DOI: 10.1021/acs.langmuir.9b01428] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Static nanodroplets and dynamic contact line (CL) movements were visualized by an in situ transmission electron microscope (TEM) liquid cell technique at nanometer spatial resolution. Crawling and sliding movements of nanoscale CL were observed. The crawling happened at a capillary number (Ca) range of ∼10-9 to ∼10-8, and the sliding happened at a Ca range of ∼10-8 to ∼10-7. Three dimensional (3D) image construction had been employed to study static and dynamic contact angles (CAs) at nanoscale. CA hysteresis at nanoscale was observed in the sliding but not in the crawling. The energies associated with sliding were analyzed to investigate the CA hysteresis. An empirical model of the relationship between nanoscale CAs and Ca was developed. Both the experimental observation and the empirical analysis suggested that the competition among substrate defect, CL elastic, and molecular activation energies dictated different CL movements at nanoscale.
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Affiliation(s)
- Guanglei Chen
- Department of Mechanical Engineering , Villanova University , Villanova , Pennsylvania 19085 , United States
| | - Haim H Bau
- Department of Mechanical Engineering & Applied Mechanics , University of Pennsylvania , Philadelphia , Pennsylvania 19104 , United States
| | - Calvin H Li
- Department of Mechanical Engineering , Villanova University , Villanova , Pennsylvania 19085 , United States
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7
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Wang H. From Contact Line Structures to Wetting Dynamics. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:10233-10245. [PMID: 31150247 DOI: 10.1021/acs.langmuir.9b00294] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
An important reason for the century-long debate concerning wetting dynamics is the lack of decisive information about the contact line. The contact line cannot be treated as a geometric line but is rather a region with complex structures. The contact line regions have been intensively explored in recent years by utilizing advanced nanoscopic experimental and modeling methods. This feature article summarizes the primary observation results and related modeling progress. A framework is then proposed for understanding the wetting dynamics. Basic questions are raised for future research on the partial wetting of nonvolatile as well as volatile liquids.
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Affiliation(s)
- Hao Wang
- The Laboratory of Heat and Mass Transport at Micro-Nano Scale, College of Engineering , Peking University , Beijing 100871 , China
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8
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Li Z, Han L, Wang Y, Li X, Lu J, Hu X. Microstructure Characteristics of Cathode Materials for Rechargeable Magnesium Batteries. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2019; 15:e1900105. [PMID: 30848086 DOI: 10.1002/smll.201900105] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2019] [Revised: 02/08/2019] [Indexed: 05/18/2023]
Abstract
Rechargeable magnesium batteries (RMBs) that use pure Mg or Mg alloy as anode and materials allowing Mg ions to insert/extract as cathode have many advantages such as high energy density, environmental friendliness, low cost, and safety of handling. RMBs are regarded as a promising candidate for portable power sources and heavy load energy devices. However, there are still some technological issues impeding their commercial application. The most important issue is the absence of applicable cathode materials because of the high charge density, strong polarization effect, and very slow insertion/extraction speed of Mg2+ ions. In recent years, the research reports on the cathode materials of RMBs have increased significantly. Here, an extensive number of research papers are reviewed in terms of the microstructure characteristics of cathode materials for RMBs. The status and issues of cathode materials are analyzed and discussed in detail. The future development directions and perspectives are prospected for providing an understanding of the related research activities on RMBs.
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Affiliation(s)
- Zhuo Li
- School of Materials and Metallurgy, University of Science and Technology Liaoning, Anshan, 114051, China
- School of Metallurgy, Northeastern University, Shenyang, 110819, China
| | - Lu Han
- School of Materials and Metallurgy, University of Science and Technology Liaoning, Anshan, 114051, China
| | - Yongfei Wang
- School of Materials and Metallurgy, University of Science and Technology Liaoning, Anshan, 114051, China
| | - Xinyan Li
- School of Materials and Metallurgy, University of Science and Technology Liaoning, Anshan, 114051, China
| | - Jinlin Lu
- School of Materials and Metallurgy, University of Science and Technology Liaoning, Anshan, 114051, China
| | - Xianwei Hu
- School of Metallurgy, Northeastern University, Shenyang, 110819, China
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9
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Scarratt LRJ, Zhu L, Neto C. How Slippery are SLIPS? Measuring Effective Slip on Lubricated Surfaces with Colloidal Probe Atmoc Force Microscopy. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:2976-2982. [PMID: 30720284 DOI: 10.1021/acs.langmuir.8b03767] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Lubricant-infused surfaces have attracted great attention recently and are described as slippery liquid-infused porous surfaces (SLIPS). Here, we measured the hydrodynamic drainage forces on SLIPS by colloid probe atomic force microscopy (AFM) and quantified the effective slip length over a nanothin silicone oil layer on hydrophobized [octadecyltrichlorosilane (OTS)-coated] silicon wafers. The thickness of a stable silicone oil film on OTS-Si under sucrose solution was determined to be 1.8 ± 1.3 nm and was found to induce an average effective slip length of 29 ± 3 nm, very close to that of an uninfused OTS substrate. These relatively low values of effective slip are confirmed by the relatively large macroscopic roll-off angle values of water droplets on the same substrates. Both nano- and macroscale results reflect the immobilized nature of a silicone oil layer of thickness around 2 nm within an underlying monolayer. These results have important implications in the design of drag-reducing coatings using lubricant infusion.
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Affiliation(s)
- Liam R J Scarratt
- School of Chemistry and the University of Sydney Nano Institute , The University of Sydney , Sydney , New South Wales 2006 , Australia
| | - Liwen Zhu
- School of Chemistry and the University of Sydney Nano Institute , The University of Sydney , Sydney , New South Wales 2006 , Australia
| | - 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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10
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Direct measurement of the contact angle of water droplet on quartz in a reservoir rock with atomic force microscopy. Chem Eng Sci 2018. [DOI: 10.1016/j.ces.2017.12.002] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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11
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Abstract
We present a derivation of the triple-line kinetic boundary conditions for a solid film in contact with a solid substrate for both nonconserved (evaporation-condensation) and conserved (surface diffusion) dynamics. The result is obtained via a matched asymptotic expansion from a mesoscopic model with a thickness-dependent wetting potential (or disjoining pressure) and mobility. In the nonconserved case, we obtain a single boundary condition, which relates the triple-line velocity with the deviation of the contact angle from its equilibrium value. In the conserved case, two kinetic boundary conditions are needed. They relate the velocity and mass flux at the triple line to the contact angle deviation and discontinuity of the chemical potential. These linear relations are described by three kinetic coefficients. The conditions under which the kinetic coefficients remain finite are obtained. We find, for example, that some kinetic coefficients diverge within the conserved model in the presence of van der Waals interaction.
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Affiliation(s)
- Ashwani K Tripathi
- Institut Lumière Matière, UMR No. 5306 Université Lyon 1, CNRS, Université de Lyon, 69622 Villeurbanne, France
| | - Olivier Pierre-Louis
- Institut Lumière Matière, UMR No. 5306 Université Lyon 1, CNRS, Université de Lyon, 69622 Villeurbanne, France
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12
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Lu JY, Ge Q, Li H, Raza A, Zhang T. Direct Prediction of Calcite Surface Wettability with First-Principles Quantum Simulation. J Phys Chem Lett 2017; 8:5309-5316. [PMID: 28985077 DOI: 10.1021/acs.jpclett.7b02270] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Prediction of intrinsic surface wettability from first-principles offers great opportunities in probing new physics of natural phenomena and enhancing energy production or transport efficiency. We propose a general quantum mechanical approach to predict the macroscopic wettability of any solid crystal surfaces for different liquids directly through atomic-level density functional simulation. As a benchmark, the wetting characteristics of calcite crystal (10.4) under different types of fluids (water, hexane, and mercury), including either contact angle or spreading coefficient, are predicted and further validated with experimental measurements. A unique feature of our approach lies in its capability of capturing the interactions among various polar fluid molecules and solid surface ions, particularly their charge density difference distributions. Moreover, this approach provides insightful and quantitative predictions of complicated surface wettability alteration problems and wetting behaviors of liquid/liquid/solid triphase systems.
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Affiliation(s)
- Jin You Lu
- Department of Mechanical and Materials Engineering, Masdar Institute, Khalifa University of Science and Technology , P.O. Box 54224, Abu Dhabi, United Arab Emirates
| | - Qiaoyu Ge
- Department of Mechanical and Materials Engineering, Masdar Institute, Khalifa University of Science and Technology , P.O. Box 54224, Abu Dhabi, United Arab Emirates
| | - Hongxia Li
- Department of Mechanical and Materials Engineering, Masdar Institute, Khalifa University of Science and Technology , P.O. Box 54224, Abu Dhabi, United Arab Emirates
| | - Aikifa Raza
- Department of Mechanical and Materials Engineering, Masdar Institute, Khalifa University of Science and Technology , P.O. Box 54224, Abu Dhabi, United Arab Emirates
| | - TieJun Zhang
- Department of Mechanical and Materials Engineering, Masdar Institute, Khalifa University of Science and Technology , P.O. Box 54224, Abu Dhabi, United Arab Emirates
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13
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Li Y, Alibakhshi MA, Zhao Y, Duan C. Exploring Ultimate Water Capillary Evaporation in Nanoscale Conduits. NANO LETTERS 2017; 17:4813-4819. [PMID: 28719216 DOI: 10.1021/acs.nanolett.7b01620] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Capillary evaporation in nanoscale conduits is an efficient heat/mass transfer strategy that has been widely utilized by both nature and mankind. Despite its broad impact, the ultimate transport limits of capillary evaporation in nanoscale conduits, governed by the evaporation/condensation kinetics at the liquid-vapor interface, have remained poorly understood. Here we report experimental study of the kinetic limits of water capillary evaporation in two dimensional nanochannels using a novel hybrid channel design. Our results show that the kinetic-limited evaporation fluxes break down the limits predicated by the classical Hertz-Knudsen equation by an order of magnitude, reaching values up to 37.5 mm/s with corresponding heat fluxes up to 8500 W/cm2. The measured evaporation flux increases with decreasing channel height and relative humidity but decreases as the channel temperature decreases. Our findings have implications for further understanding evaporation at the nanoscale and developing capillary evaporation-based technologies for both energy- and bio-related applications.
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Affiliation(s)
- Yinxiao Li
- Department of Mechanical Engineering, Boston University , Boston, Massachusetts 02215, United States
| | - Mohammad Amin Alibakhshi
- Department of Mechanical Engineering, Boston University , Boston, Massachusetts 02215, United States
| | - Yihong Zhao
- Department of Mechanical Engineering, Boston University , Boston, Massachusetts 02215, United States
| | - Chuanhua Duan
- Department of Mechanical Engineering, Boston University , Boston, Massachusetts 02215, United States
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14
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Liu Q, Chen L, Deng Y, Wang H. Residual nano films and patterns formed by non-volatile liquid dewetting on smooth surfaces. Chem Phys Lett 2017. [DOI: 10.1016/j.cplett.2017.05.020] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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15
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Fernandez-Toledano JC, Blake TD, De Coninck J. Young's Equation for a Two-Liquid System on the Nanometer Scale. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:2929-2938. [PMID: 28248509 DOI: 10.1021/acs.langmuir.7b00267] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We use large-scale molecular dynamics simulations to study the Lennard-Jones forces acting at the various interfaces of a liquid bridge (liquid 1) between two realistic solid plates on the scale of few nanometers when the two free surfaces are in contact with a second immiscible liquid (liquid 2) with an interfacial tension of γ12. Each plate comprises a regular square planar lattice of atoms arranged in three atomic layers. To maintain rigidity while allowing momentum exchange with the liquid, solid atoms are allowed to vibrate thermally around their initial positions by a strong harmonic potential. By varying the solid-liquid coupling, we investigate a range of nonzero contact angles between the liquid-liquid interface and the solid. We first compute the forces when the plates are stationary (equilibrium case), from the perspectives of both the liquid and the solid. Our results confirm that the normal and tangential components of the computed interfacial forces at each contact line are consistent with Young's equation on this small scale. In particular, we show that the tangential force exerted by the liquid-liquid interface on the plates is given by the difference in the individual works of adhesion of the two liquids and equal to γ12 cos θ1,20, where θ1,20 is the equilibrium contact angle measured through liquid 1. This result, which differs from that expected for a single liquid, is relevant to the interactions and behavior of two liquid-solid systems in nanotechnology. We then study the forces when the plates are translated at equal speeds in opposite directions over a range of steady velocities (dynamic case) and repeat the measurements of the force exerted by the liquid-liquid interface on the solid. We find that the normal and tangential components of this force are still correctly predicted by the normal and tangential components of the interfacial tension, provided only that the equilibrium contact angle is replaced by its dynamic analogue θ1,2D. Usually assumed without proof, this result is significant for our proper understanding of dynamic wetting at all scales.
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Affiliation(s)
- J-C Fernandez-Toledano
- Laboratory of Surface and Interfacial Physics (LPSI), University of Mons , 7000 Mons, Belgium
| | - T D Blake
- Laboratory of Surface and Interfacial Physics (LPSI), University of Mons , 7000 Mons, Belgium
| | - J De Coninck
- Laboratory of Surface and Interfacial Physics (LPSI), University of Mons , 7000 Mons, Belgium
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16
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Khalkhali M, Kazemi N, Zhang H, Liu Q. Wetting at the nanoscale: A molecular dynamics study. J Chem Phys 2017; 146:114704. [DOI: 10.1063/1.4978497] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Affiliation(s)
- Mohammad Khalkhali
- Department of Chemical and Materials Engineering, University of Alberta, Edmonton, Alberta T6G 1H9, Canada
| | - Nasser Kazemi
- Department of Physics, University of Alberta, Edmonton, Alberta T6G 2E1, Canada
| | - Hao Zhang
- Department of Chemical and Materials Engineering, University of Alberta, Edmonton, Alberta T6G 1H9, Canada
| | - Qingxia Liu
- Department of Chemical and Materials Engineering, University of Alberta, Edmonton, Alberta T6G 1H9, Canada
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