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Li D, Ji Y, Wei Z, Wang L. Toward a Comprehensive Understanding of the Anomalously Small Contact Angle of Surface Nanobubbles. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:8721-8729. [PMID: 38598618 DOI: 10.1021/acs.langmuir.4c00609] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2024]
Abstract
Experimental studies have demonstrated that the gas phase contact angle (CA) of a surface nanobubble (SNB) is much smaller than that of a macroscopic gas bubble. This reduced CA plays a crucial role in prolonging the lifetime of SNBs by lowering the bubble pressure and preventing gas molecules from dissolving in the surrounding liquids. Despite extensive efforts to explain the anomalously small CA, a consensus about the underlying reasons is yet to be reached. In this study, we conducted experimental investigations to explore the influence of gas molecules adsorbed at the solid-liquid interface on the CA of SNBs created through the solvent exchange (SE) method and temperature difference (TD). Interestingly, no significant change is observed in the CA of SNBs on highly oriented pyrolytic graphite (HOPG) surfaces. Even for nanobubbles on micro/nano pancakes, the CA only exhibited a slight reduction compared to SNBs on bare HOPG surfaces. These findings suggest that gas adsorption at the immersed solid surface may not be the primary factor contributing to the small CA of the SNBs. Furthermore, the CA of SNBs formed on polystyrene (PS) and octadecyltrichlorosilane (OTS) substrates was also investigated, and a considerable increase in CA was observed. In addition, the effects of other factors including impurity, electric double layer (EDL) line tension, and pinning force upon the CA of SNBs were discussed, and a comprehensive model about multiple factors affecting the CA of SNBs was proposed, which is helpful for understanding the abnormally small CA and the stability of SNBs.
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Affiliation(s)
- Dayong Li
- School of Electromechanical and Automotive Engineering, Yantai University, Yantai 264005, China
| | - Yutong Ji
- School of Electromechanical and Automotive Engineering, Yantai University, Yantai 264005, China
| | - Zhenlin Wei
- School of Electromechanical and Automotive Engineering, Yantai University, Yantai 264005, China
| | - Lixin Wang
- School of Mechanical Engineering, Heilongjiang University of Science and Technology, Harbin 150022, China
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Jonosono Y, Tsuda SI, Tokumasu T, Nagashima H. Molecular Dynamics Study of the Microscopic Mechanical Balance at the Three-Phase Contact Line of Interfacial Nanobubble. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:8440-8449. [PMID: 38604804 DOI: 10.1021/acs.langmuir.3c04027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/13/2024]
Abstract
This study reveals the microscopic mechanical balance at the three-phase contact line (TPCL) of an interfacial nanobubble on a substrate with a wettability pattern using molecular dynamics simulations. The apparent contact angle was compared to that evaluated using Young's equation, in which the interfacial tensions were computed using a mechanical route. The comparison was conducted by changing the wettability of the substrate from hydrophilic to neutral while maintaining a hydrophobic region in the center of the substrate. When the wettability pattern pins the TPCL at the wettability boundary, the contact angle computed by Young's equation is larger than the apparent contact angle because a pinning force exists in the inward direction of the nanobubble. Conversely, on the surfaces where the wettability pattern does not pin the TPCL, the contact angle computed by Young's equation agrees with the apparent contact angle because the pinning force disappears. The distribution of principal stresses around the TPCL, which was visualized for the first time in this study, indicates that large compressive principal stresses exist between the liquid phase and the solid substrate interface, which pin the TPCL at the surface wettability boundary, and that the maximum principal stress occurs in the inward direction of the nanobubbles at the TPCL. The normalized pinning force estimated from the maximum principal stress is equivalent to that measured experimentally.
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Affiliation(s)
- Yusuke Jonosono
- Faculty of Engineering, University of the Ryukyus, 1, Senbaru, Nishihara-cho ,Okinawa 903-0213, Japan
| | - Shin-Ichi Tsuda
- Department of Mechanical Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, Fukuoka 819-0395, Japan
| | - Takashi Tokumasu
- Institute of Fluid Science, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577, Japan
| | - Hiroki Nagashima
- Faculty of Engineering, University of the Ryukyus, 1, Senbaru, Nishihara-cho ,Okinawa 903-0213, Japan
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Ma D, Zhang X, Dong R, Wang H. The impact of low-velocity shock waves on the dynamic behaviour characteristics of nanobubbles. Phys Chem Chem Phys 2024; 26:11945-11957. [PMID: 38573064 DOI: 10.1039/d3cp06259g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/05/2024]
Abstract
Low-velocity shock wave-induced contraction and expansion of nanobubbles can be applied to biocarriers and microfluidic systems. Although experiments have been conducted to study the application effects, the dynamic behavior characteristics of nanobubbles remain unexplored. In this work, we utilize molecular dynamics (MD) simulations to investigate the dynamic behavior characteristics of nanobubbles influenced by low-velocity shock waves in a liquid argon system. The DBSCAN (Density-Based Spatial Clustering of Applications with Noise) machine learning method is used to calculate the equivalent radius of nanobubbles. Two statistical methods are then utilized to predict the time series changes in the equivalent radius of nanobubbles without rebound shock waves. The piston velocity is analyzed using the bisection method to obtain the critical impact states of the nanobubble. The results show that at the low velocity shock wave (piston velocity of 0.1 km s-1), the shock wave pressure is small, the non-vacuum nanobubbles contract and expand in a circular shape, and the gas particles inside the bubble are not dispersed. In contrast, the vacuum nanobubbles collapse directly. As the shock wave rebounds upon impact, it triggers periodic contraction and expansion of the nanobubbles. The predictions indicate that the equivalent radius will vary within a small range according to the pre-predicted values in the absence of the rebound shock wave. Nanobubbles are present in four critical impact states: dispersed gaps, multiple smaller bubbles, two split bubbles, and a concave bubble.
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Affiliation(s)
- Ding Ma
- Faculty of Metallurgy and Energy Engineering, Kunming University of Science and Technology, Kunming, Yunnan 650093, P. R. China.
- State Key Laboratory of Complex Nonferrous Metal Resources Clean Utilization, Kunming University of Science and Technology, Kunming, Yunnan 650093, P. R. China
| | - Xiaohui Zhang
- Faculty of Metallurgy and Energy Engineering, Kunming University of Science and Technology, Kunming, Yunnan 650093, P. R. China.
- State Key Laboratory of Complex Nonferrous Metal Resources Clean Utilization, Kunming University of Science and Technology, Kunming, Yunnan 650093, P. R. China
| | - Rensong Dong
- National University Science and Technology Park, Kunming University of Science and Technology, Kunming, Yunnan 650093, P. R. China
| | - Hua Wang
- State Key Laboratory of Complex Nonferrous Metal Resources Clean Utilization, Kunming University of Science and Technology, Kunming, Yunnan 650093, P. R. China
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Heima Y, Teshima H, Takahashi K. Nanoscale Contact Line Pinning Boosted by Ångström-Scale Surface Heterogeneity. J Phys Chem Lett 2023; 14:3561-3566. [PMID: 37017443 DOI: 10.1021/acs.jpclett.3c00428] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
The pinning effect plays an important role in many fluidic systems but remains poorly understood, especially at the nanoscale. In this study, we measured the contact angles of glycerol nanodroplets on three different substrates using atomic force microscopy. By comparison of the shapes of the three-dimensional images of droplets, we found that a possible origin of the long-discussed deviation of the contact angles of nanodroplets from the macroscopic value is the pinning force induced by ångström-scale surface heterogeneity. It was also revealed that the pinning forces acting on glycerol nanodroplets on a silicon dioxide surface are up to twice as large as those acting on macroscale droplets. On a substrate where the effect of pinning was strong, an unexpected irreversible change from an irregularly shaped droplet to an atomically flat liquid film occurred. This was explained by the transition of the dominant force from liquid/gas interfacial tension to an adsorption force.
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Affiliation(s)
- Yuta Heima
- Department of Aeronautics and Astronautics, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
| | - Hideaki Teshima
- Department of Aeronautics and Astronautics, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
- International Institute for Carbon-Neutral Energy Research (WPI-I2CNER), Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
| | - Koji Takahashi
- Department of Aeronautics and Astronautics, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
- International Institute for Carbon-Neutral Energy Research (WPI-I2CNER), Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
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Tagomori K, Kioka A, Nakagawa M, Ueda A, Sato K, Yonezu K, Anzai S. Air nanobubbles retard calcite crystal growth. Colloids Surf A Physicochem Eng Asp 2022. [DOI: 10.1016/j.colsurfa.2022.129319] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Petsev ND, Leal LG, Shell MS. Petsev et al. Reply. PHYSICAL REVIEW LETTERS 2022; 129:099602. [PMID: 36083658 DOI: 10.1103/physrevlett.129.099602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Accepted: 07/27/2022] [Indexed: 06/15/2023]
Affiliation(s)
- Nikolai D Petsev
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - L Gary Leal
- 2Department of Chemical Engineering, University of California at Santa Barbara, Santa Barbara, California 93106-5080, USA
| | - M Scott Shell
- 2Department of Chemical Engineering, University of California at Santa Barbara, Santa Barbara, California 93106-5080, USA
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Watanabe K, Kusudo H, Bistafa C, Omori T, Yamaguchi Y. Quantifying the solid–fluid interfacial tensions depending on the substrate curvature: Young’s equation holds for wetting around nanoscale cylinder. J Chem Phys 2022; 156:054701. [DOI: 10.1063/5.0079816] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Keitaro Watanabe
- Department of Mechanical Engineering, Osaka University, 2-1 Yamadaoka, Suita 565-0871, Japan
| | - Hiroki Kusudo
- Department of Mechanical Engineering, Osaka University, 2-1 Yamadaoka, Suita 565-0871, Japan
| | - Carlos Bistafa
- Department of Mechanical Engineering, Osaka University, 2-1 Yamadaoka, Suita 565-0871, Japan
| | - Takeshi Omori
- Deptartment of Mechanical Engineering, Osaka City University, 3-3-138 Sugimoto, Sumiyoshi, Osaka 558-8585, Japan
| | - Yasutaka Yamaguchi
- Department of Mechanical Engineering, Osaka University, 2-1 Yamadaoka, Suita 565-0871, Japan
- Water Frontier Research Center (WaTUS), Research Institute for Science and Technology, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku-ku, Tokyo 162-8601, Japan
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