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Jabbarzadeh A. Effect of molecular branching and surface wettability on solid-liquid surface tension and line-tension of liquid alkane surface nanodroplets. J Colloid Interface Sci 2024; 666:355-370. [PMID: 38603878 DOI: 10.1016/j.jcis.2024.04.021] [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: 02/16/2024] [Revised: 03/27/2024] [Accepted: 04/02/2024] [Indexed: 04/13/2024]
Abstract
HYPOTHESIS Surface nanodroplets have important technological applications. Previous experiments and simulations have shown that their contact angle deviates from Young's equation. A modified version of Young's equation considering the three-phase line tension (τ) has been widely used in literature, and a wide range of values for τ are reported. We have recently shown that molecular branching affects the liquid-vapour surface tension γlv of liquid alkanes. Therefore, the wetting behaviour of surface nanodroplets should be affected by molecular branching. This study conducted molecular dynamics (MD) simulations to gain insight into the wetting behaviour of linear and branched alkane nanodroplets on oleophilic and oleophobic surfaces. We aim to examine the Young equation's validity and branching's effect on fundamental properties, including solid-liquid surface tension γsl and line tension τ. SIMULATIONS The simulations were performed on a linear alkane, triacontane (C30H62), as well as four of its branched isomers: 2,6,13,17-tetrapropyloctadecane,2,6,9,10,13,17-hexaethyloctadecane, 2,5,7,8,11,12,15-heptaethylhexadecane and 2,3,6,7,10,11-hexapropyldodecane. Nanodroplets with a diameter of approximately 15 nm were released onto the surfaces, and their contact angles were measured. Additionally, using a novel approach, the solid-liquid surface tension (γsl), the validity of Young's equation and line tension for all alkane and surface combinations are determined. FINDINGS It was discovered that the calculated γsl, deviated from the theoretical γsl,Young predicted from Young's equation for all alkanes on oleophilic surfaces. However, this deviation was minimal for branched alkanes on the oleophobic surfaces but more significant for the linear alkane. The findings indicated that γsl < 0 for oleophilic surfaces and γsl > 0 for oleophobic surfaces. Moreover, it was observed that |γsl| was lower for branched molecules and decreased as branching increased. Line tension values were then determined through a novel method, showing τ was positive for oleophilic surfaces ranging from 1.30 × 10-10 to 6.27 × 10-11N. On an oleophobic surface, linear alkane shows a negative line tension of -1.15 × 10-10N and branched alkanes up to two orders of magnitude lower values ranging from -2.09 × 10-12 to 2.43 × 10-11N. Line tension values between -1.15 × 10-10 and + 1.1 × 10-10N are calculated for various linear alkane and surface combinations. These findings show the dependence of line tension on the contact angle and branching, demonstrating that for linear alkanes, τ is significant, whereas, for branched alkanes, line tension is smaller or negligible for large contact angles.
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Affiliation(s)
- Ahmad Jabbarzadeh
- School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, NSW 2006, Australia; Sydney Nano Institute, The University of Sydney, NSW 2006, Australia.
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Nurrohman N, Almisbahi H, Tocci E, Abulkhair H, Albeirutty M, Othman R, Bamaga O. Enhancement in Heat Transfer Performance of Water Vapor Condensation on Graphene-Coated Copper Surfaces: A Molecular Dynamics Study. NANOMATERIALS (BASEL, SWITZERLAND) 2024; 14:1137. [PMID: 38998742 PMCID: PMC11243593 DOI: 10.3390/nano14131137] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2024] [Revised: 06/20/2024] [Accepted: 06/26/2024] [Indexed: 07/14/2024]
Abstract
The condensation of water vapor plays a crucial role in various applications, including combating water scarcity. In this study, by employing molecular dynamics simulations, we delved into the impact of graphene coatings on water vapor condensation on copper surfaces. Unique to this work was the exploration of various levels of graphene coverage and distribution, a facet largely unexplored in prior investigations. The findings demonstrated a notable increase in the rate of water vapor condensation and heat transfer performance as the graphene coverage was reduced. Using graphene coverages of 84%, 68%, and 52%, the numbers of condensed water molecules were 664, 735, and 880 molecules/ns, respectively. One of the most important findings was that when using the same graphene coverage of 68%, the rate of water vapor condensation and heat transfer performance increased as the graphene coating became more distributed. The overall performance of the water condensation correlated well with the energy and vibrational interaction between the graphene and the copper. This phenomenon suggests how a hybrid surface can enhance the nucleation and growth of a droplet, which might be beneficial for tailoring graphene-coated copper surfaces for applications demanding efficient water vapor condensation.
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Affiliation(s)
- Nurrohman Nurrohman
- Department of Mechanical Engineering, King Abdulaziz University, P.O. Box 80204, Jeddah 21589, Saudi Arabia; (H.A.); (R.O.)
| | - Hind Almisbahi
- Department of Information Technology, King Abdulaziz University, P.O. Box 80220, Jeddah 21589, Saudi Arabia
| | - Elena Tocci
- Institute on Membrane Technology (CNR-ITM), Via P. Bucci 17/C, 87036 Rende, Cosenza, Italy;
| | - Hani Abulkhair
- Department of Mechanical Engineering, King Abdulaziz University, P.O. Box 80204, Jeddah 21589, Saudi Arabia; (H.A.); (R.O.)
- Center of Excellence in Desalination Technology, King Abdulaziz University, P.O. Box 80200, Jeddah 21589, Saudi Arabia;
| | - Mohammed Albeirutty
- Department of Mechanical Engineering, King Abdulaziz University, P.O. Box 80204, Jeddah 21589, Saudi Arabia; (H.A.); (R.O.)
- Center of Excellence in Desalination Technology, King Abdulaziz University, P.O. Box 80200, Jeddah 21589, Saudi Arabia;
| | - Ramzi Othman
- Department of Mechanical Engineering, King Abdulaziz University, P.O. Box 80204, Jeddah 21589, Saudi Arabia; (H.A.); (R.O.)
| | - Omar Bamaga
- Center of Excellence in Desalination Technology, King Abdulaziz University, P.O. Box 80200, Jeddah 21589, Saudi Arabia;
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Dong H, Zhu Q, Wang L, Yue X, Fang H, Wang Z, Liu S, Wei S, Lu X. Effects of Shale Pore Size and Connectivity on scCO 2 Enhanced Oil Recovery: A Molecular Dynamics Simulation Investigation. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:6287-6299. [PMID: 37079912 DOI: 10.1021/acs.langmuir.3c00904] [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 differences in pore width distributions and connectivity of shale reservoirs have significant influences on supercritical carbon dioxide (scCO2)-enhanced oil recovery (CO2 EOR) in shale. Herein, the molecular dynamics simulation was adopted to investigate the microscopic mechanism of CO2 EOR in the shale nanopores with different pore size width distributions and pore connectivity. The results show that the pore connectivity has significant effects on the oil displacement, and the recovery efficiency is ordered as: connected pore > double pore > single pore for the 3 nm pore, which are 91.32, 74.43, and 65.93%, respectively. Therefore, the increase in pore connectivity can significantly improve the recovery efficiency of the small pore of the connected pore system. For the shale reservoirs with different pore width distributions, the oil recovery rate of large pores is generally higher than that of small pores. In addition, the displacement of oil in the small pore of the double pore system is accelerated due to the pushing effect of the discharge fluid from the large pore. The results furnish a certain theoretical support for the research of the microscopic mechanism of CO2 EOR in the shale pore with different pore width distributions and connectivity and the exploit of shale oil.
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Affiliation(s)
- Hao Dong
- School of Materials Science and Engineering, China University of Petroleum, Qingdao, Shandong 266580, P. R. China
| | - Qiuying Zhu
- School of Materials Science and Engineering, China University of Petroleum, Qingdao, Shandong 266580, P. R. China
| | - Lu Wang
- College of Science, China University of Petroleum, Qingdao, Shandong 266580, P. R. China
| | - Xiaokun Yue
- School of Materials Science and Engineering, China University of Petroleum, Qingdao, Shandong 266580, P. R. China
| | - Hongxu Fang
- School of Materials Science and Engineering, China University of Petroleum, Qingdao, Shandong 266580, P. R. China
| | - Zhaojie Wang
- School of Materials Science and Engineering, China University of Petroleum, Qingdao, Shandong 266580, P. R. China
| | - Siyuan Liu
- School of Materials Science and Engineering, China University of Petroleum, Qingdao, Shandong 266580, P. R. China
| | - Shuxian Wei
- College of Science, China University of Petroleum, Qingdao, Shandong 266580, P. R. China
| | - Xiaoqing Lu
- School of Materials Science and Engineering, China University of Petroleum, Qingdao, Shandong 266580, P. R. China
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Zhang H, Sundaresan S, Webb MA. Molecular Dynamics Investigation of Nanoscale Hydrophobicity of Polymer Surfaces: What Makes Water Wet? J Phys Chem B 2023. [PMID: 37043668 DOI: 10.1021/acs.jpcb.3c00616] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/14/2023]
Abstract
The wettability of a polymer surface─related to its hydrophobicity or tendency to repel water─can be crucial for determining its utility, such as for a coating or a purification membrane. While wettability is commonly associated with the macroscopic measurement of a contact angle between surface, water, and air, the molecular physics that underlie these macroscopic observations are not fully known, and anticipating the relative behavior of different polymers is challenging. To address this gap in molecular-level understanding, we use molecular dynamics simulations to investigate and contrast interactions of water with six chemically distinct polymers: polytetrafluoroethylene, polyethylene, polyvinyl chloride, poly(methyl methacrylate), Nylon-66, and poly(vinyl alcohol). We show that several prospective quantitative metrics for hydrophobicity agree well with experimental contact angles. Moreover, the behavior of water in proximity to these polymer surfaces can be distinguished with analysis of interfacial water dynamics, extent of hydrogen bonding, and molecular orientation─even when macroscopic measures of hydrophobicity are similar. The predominant factor dictating wettability is found to be the extent of hydrogen bonding between polymer and water, but the precise manifestation of hydrogen bonding and its impact on surface water structure varies. In the absence of hydrogen bonding, other molecular interactions and polymer mechanics control hydrophobic ordering. These results provide new insights into how polymer chemistry specifically impacts water-polymer interactions and translates to surface hydrophobicity. Such factors may facilitate the design or processing of polymer surfaces to achieve targeted wetting behavior, and presented analyses can be useful in studying the interfacial physics of other systems.
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Affiliation(s)
- Hang Zhang
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Sankaran Sundaresan
- Department of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey 08544, United States
| | - Michael A Webb
- Department of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey 08544, United States
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Dai X, Wang M, Zhang J, Xin G, Wang X. Vapor Condensation on Bioinspired Hierarchical Nanostructured Surfaces with Hybrid Wettabilities. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:11099-11108. [PMID: 36037002 DOI: 10.1021/acs.langmuir.2c01796] [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
Vapor condensation on bioinspired hierarchical nanostructured surfaces with hybrid wettabilities has been investigated using molecular dynamics simulations. A series of hierarchical surfaces consisting of nanocylinder arrays with hydrophilic top and hydrophobic nanopillar arrays are constructed. The results manifest that the condensed nanodroplets undergo three states in the whole water vapor condensation process, and the total condensed atom number on surfaces increases with the increase of nanocylinder diameter (D), which indicates that the introduction of hydrophilic nanocylinders is conducive to improving the condensation performance compared with that on the hydrophobic surface patterned with homogeneous nanopillars. However, the nucleation sites on hierarchical nanostructured surfaces are covered by the condensed nanodroplets at the end of condensation, which suppresses the further enhancement of condensation performance. To solve these problems, we add a collection region close to the edge of the nanostructured surface. It is noticed that the condensed nanodroplets can roll into the collection regions gradually during the condensation process, which keeps the nucleation sites on nanostructured surfaces exposed effectively, especially for the cases of 20 Å ≤ D ≤ 40 Å. Moreover, the cluster number, the total condensed atom number, and the condensation enhancement efficiency on hierarchical nanostructured surfaces with collection regions at 20 Å ≤ D ≤ 40 Å are higher obviously compared with those on surfaces without collection regions. Our study demonstrates that the bioinspired hierarchical nanostructured surface with the collection region is beneficial to boost the vapor condensation performance, which can bring new insights into water vapor condensation.
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Affiliation(s)
- Xingbo Dai
- Institute of Thermal Science and Technology, Shandong University, Jinan 250061, China
| | - Man Wang
- School of Mechanical Engineering, Shandong University, Jinan 250061, China
| | - Jingzhi Zhang
- School of Energy and Power Engineering, Shandong University, Jinan 250061, China
- Shenzhen Research Institute of Shandong University, Shenzhen 518057, China
| | - Gongming Xin
- School of Energy and Power Engineering, Shandong University, Jinan 250061, China
- Shenzhen Research Institute of Shandong University, Shenzhen 518057, China
| | - Xinyu Wang
- Institute of Thermal Science and Technology, Shandong University, Jinan 250061, China
- Shenzhen Research Institute of Shandong University, Shenzhen 518057, China
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Qiang W, Lan Z, Du B, Ren W, Xu W, Wen R, Ma X. Enrichment Effects Induced by Non-uniform Wettability Surfaces in the Presence of Non-condensable Gas: A Molecular Dynamics Simulation. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:10192-10201. [PMID: 35959936 DOI: 10.1021/acs.langmuir.2c01264] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
For vapor condensation, the control of heterogeneous nucleation and spatial distribution of nuclei are crucial for regulating droplet dynamics and improving condensation efficiency. However, due to the complex characteristics of multicomponent, multiphase, and multiscale, the underlying mechanism of mixed vapor condensation remains unclear, especially at the nucleation stage. In this paper, we focus on the enrichment effects of non-uniform wettability surfaces by molecular dynamics simulation, which could intensify the droplet nucleation and growth processes in a water-air mixed system. The results clarify the inhibitory effect of non-condensable gas on droplet nucleation and prove that only 1% of non-condensable gas could reduce one half of the condensation performance from a molecular perspective. Furthermore, non-uniform surfaces are designed to promote the efficient enrichment of vapor molecules on nucleation sites, and the synergistic effect of hydrophilic and hydrophobic regions is proposed. In addition, the non-uniform wettability surfaces are characterized by varying the proportion and dispersion of hydrophilic regions. The results reveal that an optimal proportion of hydrophilic region (R = 5/6) could furnish the non-uniform surface with the best transfer performance. Moreover, the enhancement of condensation performance can also be achieved through the dispersed arrangement of hydrophilic regions. The results provide guidance for the optimized design of functionalized surfaces with enhanced mixed vapor condensation.
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Affiliation(s)
- Weili Qiang
- 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, PR China
| | - Zhong Lan
- 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, PR China
| | - Bingang Du
- 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, PR China
| | - Wenzhi Ren
- 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, PR China
| | - Wei 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, PR 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, PR 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, PR China
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7
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Wang X, Xu B, Chen Z, Del Col D, Li D, Zhang L, Mou X, Liu Q, Yang Y, Cao Q. Review of droplet dynamics and dropwise condensation enhancement: Theory, experiments and applications. Adv Colloid Interface Sci 2022; 305:102684. [PMID: 35525088 DOI: 10.1016/j.cis.2022.102684] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Revised: 03/21/2022] [Accepted: 04/23/2022] [Indexed: 02/06/2023]
Abstract
Droplet dynamics and condensation phenomena are widespread in nature and industrial applications, and the fundamentals of various technological applications. Currently, with the rapid development of interfacial materials, microfluidics, micro/nano fabrication technology, as well as the intersection of fluid mechanics, interfacial mechanics, heat and mass transfer, thermodynamics and reaction kinetics and other disciplines, the preparation and design of various novel functional surfaces have contributed to the local modulation of droplets (including nucleation, jumping and directional migration) and the improvement of condensation heat transfer, further deepening the understanding of relevant mechanisms. The wetting and dynamic characteristics of droplets involve complex solid-liquid interfacial interactions, so that the local modulation of microdroplets and the extension of enhanced condensation heat transfer by means of complex micro/nano structures and hydrophilic/hydrophobic properties is one of the current hot topics in heat and mass transfer research. This work presents a detailed review of several scientific issues related to the droplet dynamics and dropwise condensation heat transfer under the influence of multiple factors (including fluid property, surface structure, wettability, temperature external field, etc.). Firstly, the basic theory of droplet wetting on the solid wall is introduced, and the mechanism of solid-liquid interfacial interaction involving droplet jumping and directional migration on the functional surfaces under the various influencing factors is discussed. Optimizing the surface structure for the local modulation of droplets is of guidance for condensation heat transfer. Secondly, we summarize the existing theoretical models of dropwise condensation applicable to various functional surfaces and briefly outline the current numerical models for simulating dropwise condensation at different scales, as well as the fabricating techniques of coatings and functional surfaces for enhancing heat transfer. Finally, the relevant problems and challenges are summarized and future research is discussed.
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Affiliation(s)
- Xin Wang
- School of Energy and Environment, Southeast University, Nanjing, PR China
| | - Bo Xu
- School of Energy and Environment, Southeast University, Nanjing, PR China
| | - Zhenqian Chen
- School of Energy and Environment, Southeast University, Nanjing, PR China; Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education, School of Energy and Environment, Southeast University, Nanjing, PR China; Jiangsu Provincial Key Laboratory of Solar Energy Science and Technology, School of Energy and Environment, Southeast University, Nanjing, PR China.
| | - Davide Del Col
- Department of Industrial Engineering, University of Padua, Italy
| | - Dong Li
- School of Energy and Power Engineering, Zhengzhou University of Light Industry, Zhengzhou, PR China
| | - Leigang Zhang
- School of Energy and Mechanical Engineering, Nanjing Normal University, Nanjing, PR China
| | - Xinzhu Mou
- School of Energy and Environment, Southeast University, Nanjing, PR China
| | - Qiusheng Liu
- Key Laboratory of Microgravity, Institute of Mechanics, Chinese Academy of Sciences, Beijing, PR China
| | - Yang Yang
- Engineering and technology center for space applications, Chinese academy of sciences, Beijing, PR China
| | - Qian Cao
- Engineering and technology center for space applications, Chinese academy of sciences, Beijing, PR China
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Sofos F, Karakasidis TE, Sarris IE. Effects of channel size, wall wettability, and electric field strength on ion removal from water in nanochannels. Sci Rep 2022; 12:641. [PMID: 35022494 PMCID: PMC8755770 DOI: 10.1038/s41598-021-04620-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Accepted: 12/20/2021] [Indexed: 12/24/2022] Open
Abstract
Molecular dynamics simulations are employed to estimate the effect of nanopore size, wall wettability, and the external field strength on successful ion removal from water solutions. It is demonstrated that the presence of ions, along with the additive effect of an external electric field, constitute a multivariate environment that affect fluidic interactions and facilitate, or block, ion drift to the walls. The potential energy is calculated across every channel case investigated, indicating possible ion localization, while electric field lines are presented, to reveal ion routing throughout the channel. The electric field strength is the dominant ion separation factor, while wall wettability strength, which characterizes if the walls are hydrophobic or hydrophilic has not been found to affect ion movement significantly at the scale studied here. Moreover, the diffusion coefficient values along the three dimensions are reported. Diffusion coefficients have shown a decreasing tendency as the external electric field increases, and do not seem to be affected by the degree of wall wettability at the scale investigated here.
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Affiliation(s)
- Filippos Sofos
- Condensed Matter Physics Laboratory, Physics Department, University of Thessaly, 35100, Lamia, Greece.
| | - Theodoros E Karakasidis
- Condensed Matter Physics Laboratory, Physics Department, University of Thessaly, 35100, Lamia, Greece
| | - Ioannis E Sarris
- Department of Mechanical Engineering, University of West Attica, 12244, Athens, Greece
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Wu P, Sun T, Jiang X. Non-monotonic variation of flow strength in nanochannels grafted with end-charged polyelectrolyte layers. RSC Adv 2022; 12:4061-4071. [PMID: 35425443 PMCID: PMC8981053 DOI: 10.1039/d1ra06601c] [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: 09/02/2021] [Accepted: 10/25/2021] [Indexed: 11/30/2022] Open
Abstract
The electrokinetic transport of fluids, also called the electroosmotic flow (EOF), in micro/nanoscale devices occurs in promising applications such as electrokinetic energy conversion (EKEC) systems. Recently, EKEC systems grafted with end-charged polyelectrolyte (PE) layers (PELs) have been reported to exhibit higher efficiencies than those of intrinsic systems. Understanding the interplay between the end-charged PELs and electrical double layers (EDLs) on the EOF is crucial for designing highly efficient EKEC systems. The interplay between the end-charged PELs and EDLs on the strength of the EOF (V0) is studied by explicitly modeling the EOF through nanochannels grafted with end-charged PELs using atomic simulations. The variation of V0 is examined for nanochannels grafted with PELs at various separations (d = 3.5–0.4 nm) to cover various conformations of PEs, inlcuding mushroom, semi-dilute brushes, and concentrated brushes. We find that V0 follows a non-monotonic variation as d decreases and this is correlated with the conformation of the PEs. Specifically, as d decreases, V0 decreases first in the mushroom regime (d = 3.5–2.0 nm), and then V0 increases in the concentrated brush regime (d = 0.75–0.4 nm). Navigated by the continuum Navier–Stokes–Brinkman model, the above observations are rationalized by the competition between the driving effect from the spatial shift of ions in EDLs and the drag effect from PELs. The insights obtained in this work are important to guide the design of highly efficient EKEC systems by grafting end-charged PELs onto channel surfaces. A non-monotonic variation of the strength of electroosmotic flow (V0) is reported for the electroosmotic flow through nanochannels grafted with end-charged polyelectrolytes at various separation using atomic simulations.![]()
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Affiliation(s)
- Peng Wu
- College of Energy and Power Engineering, Inner Mongolia University of Technology, Inner Mongolia, Hohhot, 010051, China
- China–EU Institute of Clean and Renewable Energy, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, China
| | - Tao Sun
- China–EU Institute of Clean and Renewable Energy, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, China
| | - Xikai Jiang
- State Key Laboratory of Nonlinear Mechanics, Institute of Mechanics, Chinese Academy of Sciences, Beijing, 100190, China
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Effects and Mechanism of Surface Water Wettability and Operating Frequency on Response Linearity of Flexible IDE Capacitive Humidity Sensor. SENSORS 2021; 21:s21196633. [PMID: 34640953 PMCID: PMC8512117 DOI: 10.3390/s21196633] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Revised: 09/24/2021] [Accepted: 09/27/2021] [Indexed: 11/19/2022]
Abstract
Flexible capacitive humidity sensors are promising for low-cost, wearable, and radio frequency identification sensors, but their nonlinear response is an important issue for practical applications. Herein, the linearity of humidity response was controlled by surface water wettability and operating frequency of sensor, and the mechanism was explained in detail by surface water condensation. For a sensor with a Ag interdigitated electrode (IDE) on a poly(ethylene terephthalate) substrate, the capacitance showed a small linear increase with humidity up to 70% RH but a large nonlinear increase in the higher range. The response linearity was increased by a hydrophobic surface treatment of self-assembled monolayer coating while it was decreased by an ultraviolet/ozone irradiation for hydrophilicity. It was also increased by increasing the frequency in the range of 1–100 kHz, more prominently on a more hydrophilic surface. Based on experiment and simulation, the increase in sensor capacitance was greatly dependent on the geometric pattern (e.g., size, number, and contact angle) and electrical permittivity of surface water droplets. A larger and more nonlinear humidity response resulted from a larger increase in the number of droplets with a smaller contact angle on a sensor surface with higher water wettability and also from a higher permittivity of water at a lower frequency.
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Ranathunga DTS, Arteaga A, Biguetti CC, Rodrigues DC, Nielsen SO. Molecular-Level Understanding of the Influence of Ions and Water on HMGB1 Adsorption Induced by Surface Hydroxylation of Titanium Implants. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:10100-10114. [PMID: 34370950 DOI: 10.1021/acs.langmuir.1c01444] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Due to its excellent chemical and mechanical properties, titanium has become the material of choice for orthopedic and dental implants to promote rehabilitation via bone anchorage and osseointegration. Titanium osseointegration is partially related to its capability to form a TiO2 surface layer and its ability to interact with key endogenous proteins immediately upon implantation, establishing the first bone-biomaterial interface. Surgical trauma caused by implantation results in the release of high-mobility group box 1 (HMGB1) protein, which is a prototypic DAMP (damage-associated molecular pattern) with multiple roles in inflammation and tissue healing. To develop different surface strategies that improve the clinical outcome of titanium-based implants by controlling their biological activity, a molecular-scale understanding of HMGB1-surface interactions is desired. Here, we use molecular dynamics (MD) computer simulations to provide direct insight into the HMGB1 interactions and the possible molecular arrangements of HMGB1 on fully hydroxylated and nonhydroxylated rutile (110) TiO2 surfaces. The results establish that HMGB1 is most likely to be adsorbed directly onto the surface regardless of surface hydroxylation, which is undesirable because it could affect its biological activity by causing structural changes to the protein. The hydroxylated TiO2 surface shows a greater affinity for HMGB1 than the nonhydroxylated surface. The water layer on the nonhydroxylated TiO2 surface prevents ions and the protein from directly contacting the surface. However, it was observed that if the ionic strength increases, the total number of ions adsorbed on the two surfaces increases and the protein's direct adsorption ability decreases. These findings will help to understand the HMGB1-TiO2 interactions upon implantation as well as the development of different surface strategies by introducing ions or ionic materials to the titanium implant surface to modulate its interactions with HMGB1 to preserve biological function.
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Affiliation(s)
- Dineli T S Ranathunga
- Department of Chemistry and Biochemistry, The University of Texas at Dallas, 800 West Campbell Road, Richardson, Texas 75080, United States
| | - Alexandra Arteaga
- Department of Bioengineering, The University of Texas at Dallas, 800 West Campbell Road, Richardson, Texas 75080, United States
| | - Claudia C Biguetti
- Department of Bioengineering, The University of Texas at Dallas, 800 West Campbell Road, Richardson, Texas 75080, United States
| | - Danieli C Rodrigues
- Department of Bioengineering, The University of Texas at Dallas, 800 West Campbell Road, Richardson, Texas 75080, United States
| | - Steven O Nielsen
- Department of Chemistry and Biochemistry, The University of Texas at Dallas, 800 West Campbell Road, Richardson, Texas 75080, United States
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Lyu P, Zhang X, Jiang X, Shang B, Liu X, Deng Z. One-Step Preparation of Hydrophobic Surfaces Containing Hydrophilic Groups for Efficient Water Harvesting. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:9630-9636. [PMID: 34333978 DOI: 10.1021/acs.langmuir.1c01756] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Multifunctional surfaces that are favorable for both droplet nucleation and removal are critical for water-harvesting applications, but there still remain great challenges. Herein, we proposed a facile strategy to construct hydrophobic surfaces containing moderate hydrophilic groups to achieve both exceptional droplet nucleation and removal. Different from natural desert beetle-inspired water-harvesting materials, these surfaces utilize limited hydrophilic domains to condense fog, and transport of formed tiny droplets relies on a hydrophobic background. The total surface area of the presented hydrophobic fabric contains hydrophilic groups, and the areas for trapping fog have increased. This feature is optimized to enhance the droplet nucleation density, and the surface still has excellent liquid repellency, resulting in maximum water collection efficiency of the prepared surface reaching up to 3.145 g·cm-2·h-1, much higher than the most reported water-harvesting materials. Due to its high efficiency and scalability, we believe that the proposed strategy to construct hydrophobic surfaces containing hydrophilic groups has great practical value.
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Affiliation(s)
- Pei Lyu
- State Key Laboratory of New Textile Materials and Advanced Processing Technologies, Wuhan Textile University, Wuhan 430073, P. R. China
- Institute for Frontier Materials, Deakin University, Geelong, VIC 3216, Australia
| | - Xiangyi Zhang
- School of Materials Science and Engineering, Wuhan Textile University, Wuhan 430200, P. R. China
| | - Xin Jiang
- School of Materials Science and Engineering, Wuhan Textile University, Wuhan 430200, P. R. China
| | - Bin Shang
- School of Materials Science and Engineering, Wuhan Textile University, Wuhan 430200, P. R. China
- State Key Laboratory of New Textile Materials and Advanced Processing Technologies, Wuhan Textile University, Wuhan 430073, P. R. China
| | - Xin Liu
- School of Materials Science and Engineering, Wuhan Textile University, Wuhan 430200, P. R. China
- State Key Laboratory of New Textile Materials and Advanced Processing Technologies, Wuhan Textile University, Wuhan 430073, P. R. China
| | - Ziwei Deng
- Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education, Shaanxi Key Laboratory for Advanced Energy Devices, Shaanxi Engineering Lab for Advanced Energy Technology, School of Materials Science and Engineering, Shaanxi Normal University, Xi'an 710119, P. R. China
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Du B, Cheng Y, Yang S, Xu W, Lan Z, Wen R, Ma X. Preferential Vapor Nucleation on Hierarchical Tapered Nanowire Bunches. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:774-784. [PMID: 33382946 DOI: 10.1021/acs.langmuir.0c03125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Controlling vapor nucleation on micro-/nanostructured surfaces is critical to achieving exciting droplet dynamics and condensation enhancement. However, the underlying mechanism of nucleation phenomena remains unclear because of its nature of nanoscale and transience, especially for the complex-structured surfaces. Manipulating vapor nucleation via the rational surface design of micro-/nanostructures is extremely challenging. Here, we fabricate hierarchical surfaces comprising tapered nanowire bunches and crisscross microgrooves. Nanosteps are formed around the top of the nanowire bunches, where the nanowires all around agglomerate densely because of surface tension. The theoretical analysis and molecular dynamics simulation show that nanostep morphologies that are around the top of the nanowire bunches can enable a lower energy barrier and a higher nucleation capability than those of the sparsely packed nanowires at the center and bottom of the nanowire bunches. Vapor condensation experiments demonstrate that the nucleation preferentially occurs around the top of the nanowire bunches. The results provide guidelines to design micro-/nanostructures for promoting vapor nucleation and droplet removal in condensation.
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Affiliation(s)
- Bingang Du
- 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, PR China
| | - Yaqi Cheng
- 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, PR China
| | - Siyan 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, PR China
| | - Wei 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, PR China
| | - Zhong Lan
- 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, PR 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, PR 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, PR China
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