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Wang X, Gao Q, Li L, Tatrari G, Shah FU, Laaksonen A, Ji X, An R. Quantifying and Decoupling Molecular Interactions of Ionic Liquids with Gold Electrodes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:12017-12026. [PMID: 38804259 DOI: 10.1021/acs.langmuir.4c00688] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2024]
Abstract
This work combined gold colloid probe atomic force microscopy (AFM) with a quartz crystal microbalance (QCM) to accurately quantify the molecular interactions of fluorine-free phosphonium-based ionic liquids (ILs) with gold electrode surfaces. First, the interactions of ILs with the gold electrode per unit area (F A ' , N/m2) were obtained via the force-distance curves measured by gold probe AFM. Second, a QCM was employed to detect the IL amount to acquire the equilibrium number of IL molecules adsorbed onto the gold electrode per unit area (NIL, Num/m2). Finally, the quantified molecular interactions of ILs with the gold electrode (F0, nN/Num) were estimated. F0 is closely related to the IL composition, in which the IL with the same anion but a longer phosphonium cation exhibits a stronger molecular interaction. The changes in the quantified interactions of gold with different ILs are consistent with the interactions predicted by the extended Derjaguin-Landau-Verwey-Overbeek theory, and the van der Waals interaction was identified as the major contribution of the overall interaction. The quantified molecular interaction is expected to enable the direct experimental-derived interaction parameters for molecular simulations and provide the virtual design of novel ILs for energy storage applications.
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Affiliation(s)
- Xin Wang
- School of Materials Science and Engineering/Herbert Gleiter Institute of Nanoscience, Nanjing University of Science and Technology, Nanjing 210094, P. R. China
- Shandong Laboratory of Advanced Materials and Green Manufacturing at Yantai, Yantai 264006, P. R. China
| | - Qingwei Gao
- College of Environmental and Chemical Engineering, Shanghai Key Laboratory of Materials Protection and Advanced Materials in Electric Power, Shanghai University of Electric Power, Shanghai 200090, China
| | - Licheng Li
- Innovation Research Center of Lignocellulosic Functional Materials, College of Chemical Engineering, Nanjing Forestry University, Nanjing 210037, China
| | - Gaurav Tatrari
- Chemistry of Interfaces, Luleå University of Technology, Luleå 97187, Sweden
| | - Faiz Ullah Shah
- Chemistry of Interfaces, Luleå University of Technology, Luleå 97187, Sweden
| | - Aatto Laaksonen
- Department of Engineering Sciences and Mathematics, Division of Energy Science, Luleå University of Technology, Luleå 97187, Sweden
- Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, Stockholm 10691, Sweden
- Centre of Advanced Research in Bionanoconjugates and Biopolymers, Petru Poni Institute of Macromolecular Chemistry, Aleea Grigore Ghica-Voda, 41A, Iasi 700487, Romania
| | - Xiaoyan Ji
- Department of Engineering Sciences and Mathematics, Division of Energy Science, Luleå University of Technology, Luleå 97187, Sweden
| | - Rong An
- School of Materials Science and Engineering/Herbert Gleiter Institute of Nanoscience, Nanjing University of Science and Technology, Nanjing 210094, P. R. China
- Shandong Laboratory of Advanced Materials and Green Manufacturing at Yantai, Yantai 264006, P. R. China
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An R, Wu N, Gao Q, Dong Y, Laaksonen A, Shah FU, Ji X, Fuchs H. Integrative studies of ionic liquid interface layers: bridging experiments, theoretical models and simulations. NANOSCALE HORIZONS 2024; 9:506-535. [PMID: 38356335 DOI: 10.1039/d4nh00007b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/16/2024]
Abstract
Ionic liquids (ILs) are a class of salts existing in the liquid state below 100 °C, possessing low volatility, high thermal stability as well as many highly attractive solvent and electrochemical capabilities, etc., making them highly tunable for a great variety of applications, such as lubricants, electrolytes, and soft functional materials. In many applications, ILs are first either physi- or chemisorbed on a solid surface to successively create more functional materials. The functions of ILs at solid surfaces can differ considerably from those of bulk ILs, mainly due to distinct interfacial layers with tunable structures resulting in new ionic liquid interface layer properties and enhanced performance. Due to an almost infinite number of possible combinations among the cations and anions to form ILs, the diversity of various solid surfaces, as well as different external conditions and stimuli, a detailed molecular-level understanding of their structure-property relationship is of utmost significance for a judicious design of IL-solid interfaces with appropriate properties for task-specific applications. Many experimental techniques, such as atomic force microscopy, surface force apparatus, and so on, have been used for studying the ion structuring of the IL interface layer. Molecular Dynamics simulations have been widely used to investigate the microscopic behavior of the IL interface layer. To interpret and clarify the IL structure and dynamics as well as to predict their properties, it is always beneficial to combine both experiments and simulations as close as possible. In another theoretical model development to bridge the structure and properties of the IL interface layer with performance, thermodynamic prediction & property modeling has been demonstrated as an effective tool to add the properties and function of the studied nanomaterials. Herein, we present recent findings from applying the multiscale triangle "experiment-simulation-thermodynamic modeling" in the studies of ion structuring of ILs in the vicinity of solid surfaces, as well as how it qualitatively and quantitatively correlates to the overall ILs properties, performance, and function. We introduce the most common techniques behind "experiment-simulation-thermodynamic modeling" and how they are applied for studying the IL interface layer structuring, and we highlight the possibilities of the IL interface layer structuring in applications such as lubrication and energy storage.
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Affiliation(s)
- Rong An
- Herbert Gleiter Institute of Nanoscience, School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, China.
| | - Nanhua Wu
- Key Laboratory of Advanced Catalytic Materials and Technology, School of Petrochemical Engineering, Changzhou University, Changzhou 213164, China
| | - Qingwei Gao
- College of Environmental and Chemical Engineering, Shanghai Key Laboratory of Materials Protection and Advanced Materials in Electric Power, Shanghai University of Electric Power, Shanghai 200090, China
| | - Yihui Dong
- Department of Molecular Chemistry and Materials Science, Weizmann Institute of Science, Rehovot, 76100, Israel
| | - Aatto Laaksonen
- Energy Engineering, Division of Energy Science, Luleå University of Technology, 97187 Luleå, Sweden.
- Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, SE-10691 Stockholm, Sweden.
- Center of Advanced Research in Bionanoconjugates and Biopolymers, ''Petru Poni" Institute of Macromolecular Chemistry, Iasi 700469, Romania
- State Key Laboratory of Materials-Oriented and Chemical Engineering, Nanjing Tech University, Nanjing 211816, China
| | - Faiz Ullah Shah
- Chemistry of Interfaces, Luleå University of Technology, 97187 Luleå, Sweden
| | - Xiaoyan Ji
- Energy Engineering, Division of Energy Science, Luleå University of Technology, 97187 Luleå, Sweden.
| | - Harald Fuchs
- Herbert Gleiter Institute of Nanoscience, School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, China.
- Center for Nanotechnology (CeNTech), Westfälische Wilhelms-Universität Münster, 48149 Münster, Germany.
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Su Y, Wang T, Zhang F, Huang J, Zhu Z, Shah FU, Xu F, An R. Effect of Electrode Surface Chemistry on Ion Structuring of Imidazolium Ionic Liquids. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023. [PMID: 37289976 DOI: 10.1021/acs.langmuir.3c00710] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Surface chemistry plays a critical role in the ion structuring of ionic liquids (ILs) at the interfaces of electrodes and controls the overall energy storage performance of the system. Herein, we functionalized the gold (Au) colloid probe of an atomic force microscope with -COOH and -NH2 groups to explore the effect of different surface chemical properties on the ion structuring of an IL. Aided by colloid-probe atomic force microscopy (AFM), the ion structuring of an imidazolium IL, 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6], abbreviated as BP hereafter), on the Au electrode surface and the ion response to the change in the surface chemistry are investigated. AFM morphologies, contact angles, and approaching force-distance curves of the BP IL on the functionalized Au surfaces exhibited that the IL forms a more obvious layering structure on the -COOH-terminated Au surface (Au-COOH), while it forms heterogeneous and aggregating droplets on the -NH2 surface (Au-NH2). The formed uniform and aggregation-free ion layers in the vicinity of the Au-COOH surface are due to the π-π+ stacking interaction between the delocalized π+ electrons from the imidazolium ring in the IL [BMIM]+ cation and the localized π electrons from the sp2 carbon on the -COOH group. The in situ observation of nano-friction and torsional resonance frequency at the IL-electrode interfaces further demonstrated the ion structuring of the IL at Au-COOH, which results in a more sensitive electrochemical response associated with a faster capacitive process.
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Affiliation(s)
- Yiqun Su
- School of Materials Science and Engineering/Herbert Gleiter Institute of Nanoscience, Nanjing University of Science and Technology, Nanjing 210094, China
| | - Tiantian Wang
- School of Materials Science and Engineering/Herbert Gleiter Institute of Nanoscience, Nanjing University of Science and Technology, Nanjing 210094, China
| | - Fan Zhang
- Department of Engineering and Design, School of Engineering and Information, University of Sussex, Brighton BN1 9RH, U.K
| | - Junsen Huang
- School of Materials Science and Engineering/Herbert Gleiter Institute of Nanoscience, Nanjing University of Science and Technology, Nanjing 210094, China
| | - Zhehang Zhu
- School of Materials Science and Engineering/Herbert Gleiter Institute of Nanoscience, Nanjing University of Science and Technology, Nanjing 210094, China
| | - Faiz Ullah Shah
- Chemistry of Interfaces, Luleå University of Technology, 97187 Luleå, Sweden
| | - Feng Xu
- School of Materials Science and Engineering/Herbert Gleiter Institute of Nanoscience, Nanjing University of Science and Technology, Nanjing 210094, China
| | - Rong An
- School of Materials Science and Engineering/Herbert Gleiter Institute of Nanoscience, Nanjing University of Science and Technology, Nanjing 210094, China
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An R, Laaksonen A, Wu M, Zhu Y, Shah FU, Lu X, Ji X. Atomic force microscopy probing interactions and microstructures of ionic liquids at solid surfaces. NANOSCALE 2022; 14:11098-11128. [PMID: 35876154 DOI: 10.1039/d2nr02812c] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Ionic liquids (ILs) are room temperature molten salts that possess preeminent physicochemical properties and have shown great potential in many applications. However, the use of ILs in surface-dependent processes, e.g. energy storage, is hindered by the lack of a systematic understanding of the IL interfacial microstructure. ILs on the solid surface display rich ordering, arising from coulombic, van der Waals, solvophobic interactions, etc., all giving near-surface ILs distinct microstructures. Therefore, it is highly important to clarify the interactions of ILs with solid surfaces at the nanoscale to understand the microstructure and mechanism, providing quantitative structure-property relationships. Atomic force microscopy (AFM) opens a surface-sensitive way to probe the interaction force of ILs with solid surfaces in the layers from sub-nanometers to micrometers. Herein, this review showcases the recent progress of AFM in probing interactions and microstructures of ILs at solid interfaces, and the influence of IL characteristics, surface properties and external stimuli is thereafter discussed. Finally, a summary and perspectives are established, in which, the necessities of the quantification of IL-solid interactions at the molecular level, the development of in situ techniques closely coupled with AFM for probing IL-solid interfaces, and the combination of experiments and simulations are argued.
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Affiliation(s)
- Rong An
- Herbert Gleiter Institute of Nanoscience, School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, China.
| | - Aatto Laaksonen
- Energy Engineering, Division of Energy Science, Luleå University of Technology, 97187 Luleå, Sweden.
- Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, SE-10691 Stockholm, Sweden
- Center of Advanced Research in Bionanoconjugates and Biopolymers, "Petru Poni" Institute of Macromolecular Chemistry, Iasi 700469, Romania
- State Key Laboratory of Materials-Oriented and Chemical Engineering, Nanjing Tech University, Nanjing 211816, China
| | - Muqiu Wu
- Herbert Gleiter Institute of Nanoscience, School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, China.
| | - Yudan Zhu
- State Key Laboratory of Materials-Oriented and Chemical Engineering, Nanjing Tech University, Nanjing 211816, China
| | - Faiz Ullah Shah
- Chemistry of Interfaces, Luleå University of Technology, 97187 Luleå, Sweden
| | - Xiaohua Lu
- State Key Laboratory of Materials-Oriented and Chemical Engineering, Nanjing Tech University, Nanjing 211816, China
| | - Xiaoyan Ji
- Energy Engineering, Division of Energy Science, Luleå University of Technology, 97187 Luleå, Sweden.
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Self-assembled nanostructure induced in deep eutectic solvents via an amphiphilic hydrogen bond donor. J Colloid Interface Sci 2022; 616:121-128. [DOI: 10.1016/j.jcis.2022.02.029] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Revised: 02/01/2022] [Accepted: 02/06/2022] [Indexed: 12/19/2022]
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Effect of Water and Salt on the Colloidal Stability of Latex Particles in Ionic Liquid Solutions. COLLOIDS AND INTERFACES 2021. [DOI: 10.3390/colloids6010002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The colloidal stability of sulfate (SL) and polyimidazolium-modified sulfate (SL-IP-2) latex particles was studied in an ionic liquid (IL) of ethylammonium nitrate (EAN) and its water mixtures. Aggregation rates were found to vary systematically as a function of the IL-to-water ratio. Repulsive electrostatic interactions between particles dominated at low IL concentrations, while they were significantly screened at intermediate IL concentrations, leading to destabilization of the dispersions. When the IL concentration was further increased, the aggregation of latex particles slowed down due to the increased viscosity and finally, a striking stabilization was observed in the IL-rich regime close to the pure IL solvent. The latter stabilization is due to the formation of IL layers at the interface between particles and IL, which induce repulsive oscillatory forces. The presence of the added salt in the system affected differently the structure of the interfaces around SL and SL-IP-2 particles. The sign of the charge and the composition of the particle surfaces were found to be the most important parameters affecting the colloidal stability. The nature of the counterions also plays an important role in the interfacial properties due to their influence on the structure of the IL surface layers. No evidence was observed for the presence of long-range electrostatic interactions between the particles in pure ILs. The results indicate that the presence of even low concentrations of water and salt in the system (as undesirable impurities) can strongly alter the interfacial structure and thus, the aggregation mechanism in particle IL dispersions.
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Ausín D, Parajó JJ, Trenzado JL, Varela LM, Cabeza O, Segade L. Influence of Small Quantities of Water on the Physical Properties of Alkylammonium Nitrate Ionic Liquids. Int J Mol Sci 2021; 22:7334. [PMID: 34298957 PMCID: PMC8306069 DOI: 10.3390/ijms22147334] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Revised: 06/28/2021] [Accepted: 07/02/2021] [Indexed: 11/16/2022] Open
Abstract
This paper presents a comprehensive study of two alkylammonium nitrate ionic liquids. As part of this family of materials, mainly ethylammonium nitrate (EAN) and also propylammonium nitrate (PAN) have attracted a great deal of attention during the last decades due to their potential applications in many fields. Although there have been numerous publications focused on the measurement of their physical properties, a great dispersion can be observed in the results obtained for the same magnitude. One of the critical points to be taken into account in their physical characterization is their water content. Thus, the main objective of this work was to determine the degree of influence of the presence of small quantities of water in EAN and PAN on the measurement of density, viscosity, electrical conductivity, refractive index and surface tension. For this purpose, the first three properties were determined in samples of EAN and PAN with water contents below 30,000 ppm in a wide range of temperatures, between 5 and 95 °C, while the last two were obtained at 25 °C. As a result of this study, it has been concluded that the presence of water is critical in those physical properties that involve mass or charge transport processes, resulting in the finding that the absolute value of the average percentage change in both viscosity and electrical conductivity is above 40%. Meanwhile, refractive index (≤0.3%), density (≤0.5%) and surface tension (≤2%) present much less significant changes.
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Affiliation(s)
- David Ausín
- Departamento de Física, Facultade de Ciencias, Campus da Zapateira, Universidade da Coruña, 15071 A Coruña, Spain; (D.A.); (O.C.)
| | - Juan J. Parajó
- Grupo de Nanomateriais, Fotónica e Materia Branda, Departamento de Física de Partículas y Departamento de Física Aplicada, Universidade de Santiago de Compostela, Campus Vida s/n, 15782 Santiago de Compostela, Spain; (J.J.P.); (L.M.V.)
- Departamento de Química e Bioquímica, CIQUP-Centro de Investigaçao em Química da Universidade do Porto, Universidade do Porto, P-4169-007 Porto, Portugal
| | - José L. Trenzado
- Departamento de Física, Universidad de Las Palmas de Gran Canaria, 35017 Las Palmas Gran Canaria, Spain;
| | - Luis M. Varela
- Grupo de Nanomateriais, Fotónica e Materia Branda, Departamento de Física de Partículas y Departamento de Física Aplicada, Universidade de Santiago de Compostela, Campus Vida s/n, 15782 Santiago de Compostela, Spain; (J.J.P.); (L.M.V.)
| | - Oscar Cabeza
- Departamento de Física, Facultade de Ciencias, Campus da Zapateira, Universidade da Coruña, 15071 A Coruña, Spain; (D.A.); (O.C.)
| | - Luisa Segade
- Departamento de Física, Facultade de Ciencias, Campus da Zapateira, Universidade da Coruña, 15071 A Coruña, Spain; (D.A.); (O.C.)
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Kiratidis AL, Miklavcic SJ. Density functional theory of confined ionic liquids: the influence of power-law attractions on molecule distributions and surface forces. RSC Adv 2021; 11:17498-17513. [PMID: 35479724 PMCID: PMC9032692 DOI: 10.1039/d1ra02761a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Accepted: 04/28/2021] [Indexed: 12/13/2022] Open
Abstract
Interaction energies and density profiles for two model ionic liquids, [C4mim+][BF4−] and [C4mim+][TFSI−], confined between charged planar walls are studied within a density functional theory framework. The results of these simulations are also compared with results assuming a simpler linear hexamer–monomer, cation–anion system. We focus attention on the effect on the atom site distributions and the surface forces of an additional, specific attractive potential between oppositely charged molecules. We consider both short- and long-ranged attractive potentials in order to span the degree to which the ionic counterions associate. Independent of its strength, we interpret the results found with the short-ranged potential to be a manifestation of limited molecular association. In contrast, depending on its strength, the results found with the long-ranged potential suggest a much stronger and possibly longer ranged associations of ionic groups. Both potentials are found to influence the behavior of the surface force at small separations, while the long-ranged attractive potential has the greater influence of the two on the long-ranged behavior of the surface force. Interaction energies and density profiles for two model ionic liquids, [C4mim+][BF4−] and [C4mim+][TFSI−], confined between charged planar walls are studied within a density functional theory framework.![]()
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Affiliation(s)
- Adrian L. Kiratidis
- Phenomics and Bioinformatics Research Centre
- UniSA STEM
- University of South Australia
- Mawson Lakes
- Australia
| | - Stanley J. Miklavcic
- Phenomics and Bioinformatics Research Centre
- UniSA STEM
- University of South Australia
- Mawson Lakes
- Australia
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Wang YL, Li B, Sarman S, Mocci F, Lu ZY, Yuan J, Laaksonen A, Fayer MD. Microstructural and Dynamical Heterogeneities in Ionic Liquids. Chem Rev 2020; 120:5798-5877. [PMID: 32292036 PMCID: PMC7349628 DOI: 10.1021/acs.chemrev.9b00693] [Citation(s) in RCA: 192] [Impact Index Per Article: 48.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Indexed: 12/11/2022]
Abstract
Ionic liquids (ILs) are a special category of molten salts solely composed of ions with varied molecular symmetry and charge delocalization. The versatility in combining varied cation-anion moieties and in functionalizing ions with different atoms and molecular groups contributes to their peculiar interactions ranging from weak isotropic associations to strong, specific, and anisotropic forces. A delicate interplay among intra- and intermolecular interactions facilitates the formation of heterogeneous microstructures and liquid morphologies, which further contributes to their striking dynamical properties. Microstructural and dynamical heterogeneities of ILs lead to their multifaceted properties described by an inherent designer feature, which makes ILs important candidates for novel solvents, electrolytes, and functional materials in academia and industrial applications. Due to a massive number of combinations of ion pairs with ion species having distinct molecular structures and IL mixtures containing varied molecular solvents, a comprehensive understanding of their hierarchical structural and dynamical quantities is of great significance for a rational selection of ILs with appropriate properties and thereafter advancing their macroscopic functionalities in applications. In this review, we comprehensively trace recent advances in understanding delicate interplay of strong and weak interactions that underpin their complex phase behaviors with a particular emphasis on understanding heterogeneous microstructures and dynamics of ILs in bulk liquids, in mixtures with cosolvents, and in interfacial regions.
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Affiliation(s)
- Yong-Lei Wang
- Department
of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Bin Li
- School
of Chemical Engineering and Technology, Sun Yat-sen University, Zhuhai 519082, P. R. China
| | - Sten Sarman
- Department
of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Francesca Mocci
- Department
of Chemical and Geological Sciences, University
of Cagliari, I-09042 Monserrato, Italy
| | - Zhong-Yuan Lu
- State
Key Laboratory of Supramolecular Structure and Materials, Institute
of Theoretical Chemistry, Jilin University, Changchun 130021, P. R. China
| | - Jiayin Yuan
- Department
of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Aatto Laaksonen
- Department
of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, SE-106 91 Stockholm, Sweden
- State
Key Laboratory of Materials-Oriented and Chemical Engineering, Nanjing Tech University, Nanjing 210009, P. R. China
- Centre of
Advanced Research in Bionanoconjugates and Biopolymers, Petru Poni Institute of Macromolecular Chemistry Aleea Grigore Ghica-Voda, 41A, 700487 Iasi, Romania
- Department
of Engineering Sciences and Mathematics, Division of Energy Science, Luleå University of Technology, SE-97187 Luleå, Sweden
| | - Michael D. Fayer
- Department
of Chemistry, Stanford University, Stanford, California 94305, United States
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10
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An R, Qiu X, Shah FU, Riehemann K, Fuchs H. Controlling the nanoscale friction by layered ionic liquid films. Phys Chem Chem Phys 2020; 22:14941-14952. [PMID: 32588010 DOI: 10.1039/d0cp02146f] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The nanofriction coefficient of ionic liquids (ILs), 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF4]) and 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]), on the surfaces of mica and graphite was investigated using atomic force microscopy (AFM). A pronounced layered spatial distribution was found in the IL film formed on the solid substrates and can be divided into 3 well distinguishable regions exhibiting different physical properties with increasing distance from the substrate. We found that the friction coefficient (μ) increases monotonically as the layering thickness decreases, no matter what the thickness of the bulk IL is. This suggests that the layering assembled IL at solid surfaces is more important than the bulk phase in determining the magnitude of the nanoscale friction. The increase in the friction coefficient as the layering thickness decreases is most likely attributed to the assembled ordered IL layers closer to the substrate surfaces having a greater activation barrier for unlocking the surfaces to allow shear.
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Affiliation(s)
- Rong An
- Herbert Gleiter Institute of Nanoscience, Department of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, P. R. China. and Center for Nanotechnology (CeNTech), Institute of Physics, Westfälische Wilhelms-Universität Münster, 48149 Münster, Germany
| | - Xiuhua Qiu
- Herbert Gleiter Institute of Nanoscience, Department of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, P. R. China.
| | - Faiz Ullah Shah
- Chemistry of Interfaces, Luleå University of Technology, SE 971 87 Luleå, Sweden
| | - Kristina Riehemann
- Center for Nanotechnology (CeNTech), Institute of Physics, Westfälische Wilhelms-Universität Münster, 48149 Münster, Germany
| | - Harald Fuchs
- Herbert Gleiter Institute of Nanoscience, Department of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, P. R. China. and Center for Nanotechnology (CeNTech), Institute of Physics, Westfälische Wilhelms-Universität Münster, 48149 Münster, Germany
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11
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Lhermerout R, Perkin S. A new methodology for a detailed investigation of quantized friction in ionic liquids. Phys Chem Chem Phys 2020; 22:455-466. [PMID: 31781711 DOI: 10.1039/c9cp05422g] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
When confined at the nanoscale between smooth surfaces, an ionic liquid forms a structured film responding to shear in a quantized way, i.e., with a friction coefficient indexed by the number of layers in the gap. So far, only a few experiments have been performed to study this phenomenon, because of the delicate nature of the measurements. We propose a new methodology to measure friction with a surface force balance, based on the simultaneous application of normal and lateral motions to the surfaces, allowing for a more precise, comprehensive and rapid determination of the friction response. We report on proof-of-concept experiments with an ionic liquid confined between mica surfaces in dry or wet conditions, showing the phenomenon of quantized friction with an unprecedented resolution. First, we show that the variation of the kinetic friction force with the applied load for a given layer is not linear, but can be quantitatively described by two additive contributions that are respectively proportional to the load and to the contact area. Then, we find that humidity improves the resistance of the layers to be squeezed-out and extends the range of loads in which the liquid behaves as a superlubricant, interpreted by an enhanced dissolution of the potassium ions on the mica leading to a larger surface charge. There, we note a liquid-like friction behavior, and observe in certain conditions a clear variation of the kinetic friction force over two decades of shearing velocities, that does not obey a simple Arrhenius dynamics.
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Affiliation(s)
- Romain Lhermerout
- Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, Oxford, OX1 3QZ, UK.
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12
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An R, Wu M, Li J, Qiu X, Shah FU, Li J. On the ionic liquid films 'pinned' by core-shell structured Fe 3O 4@carbon nanoparticles and their tribological properties. Phys Chem Chem Phys 2019; 21:26387-26398. [PMID: 31793566 DOI: 10.1039/c9cp05905a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
A strongly 'pinned' ionic liquid (IL, [BMIM][PF6]) film on a silicon (Si) surface via carbon capsuled Fe3O4 core-shell (Fe3O4@C) nanoparticles is achieved, revealing excellent friction-reducing ability at a high load. The adhesion force is measured to be ∼198 nN at the Fe3O4@C-Si interface by the Fe3O4@C colloidal AFM tip, which is stronger than that at both Fe3O4@C-Fe3O4@C (∼60 nN) and IL-Si (∼10 nN) interfaces, indicating a strong 'normal pin-force' towards the Si substrate. The resulting strengthened force enables the formation of lateral IL networks via the dipole-dipole attractions among Fe3O4 cores. The observed blue shift of the characteristic band related to the IL anion in the ATR-FTIR spectra confirmed the enhanced interaction. The N-Si, P-O chemical bonds formed as a result of the IL interactions with the Si substrate confirmed by XPS spectroscopy suggested that the IL lay on the Si plane. This orientation is favorable for Fe3O4@C nanoparticles to exert 'normal pin-force' and press the IL film strongly onto surfaces. The IL ions/clusters are thus anchored by these Fe3O4@C 'pins' onto the substrate to form a dense film, resulting in a smaller interaction size parameter, which is responsible for the reduced friction coefficient μ.
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Affiliation(s)
- Rong An
- Herbert Gleiter Institute of Nanoscience, Department of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, P. R. China
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Kiratidis AL, Miklavcic SJ. Density functional theory of confined ionic liquids: A survey of the effects of ion type, molecular charge distribution, and surface adsorption. J Chem Phys 2019; 150:184502. [DOI: 10.1063/1.5093552] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- Adrian L. Kiratidis
- Phenomics and Bioinformatics Research Centre, School of Information Technology and Mathematical Sciences, University of South Australia, Mawson Lakes, SA, Australia
| | - Stanley J. Miklavcic
- Phenomics and Bioinformatics Research Centre, School of Information Technology and Mathematical Sciences, University of South Australia, Mawson Lakes, SA, Australia
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Miklavcic SJ, Fung C. Quantifying the force between mercury and mica across an ionic liquid using white light interferometry. J Colloid Interface Sci 2019; 538:218-227. [PMID: 30508742 DOI: 10.1016/j.jcis.2018.11.079] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Revised: 11/20/2018] [Accepted: 11/20/2018] [Indexed: 11/29/2022]
Abstract
HYPOTHESIS Under axisymmetric conditions, changes in the thickness of the thin film between a fluid drop and a solid revealed by white light interferometry can provide information about the interaction of the bodies. Thus, in principle one can quantify the force between the surfaces using interferometric information of film thickness profile. This is needed to quantify and analyze drop-solid interactions across complex fluids such as an ionic liquid to independently characterize new surface forces. EXPERIMENTS Interferometric fringes were obtained in experiments on the interaction between a mercury drop and mica across a film of room temperature ionic liquid. The data is analyzed using a novel formula giving the total force acting on the drop. The calculations are compared with two other approaches to estimating forces. Qualitative and quantitative differences are discussed. FINDINGS This is the first report of forces measured between mercury and mica across an ionic liquid. The system is subjected to different applied electric potentials. In each case a long ranged, exponentially decaying repulsive force is found. At small separations, the system becomes unstable and the surfaces jump into contact. The comparison of force calculation methods demonstrates the superiority of the force approach proposed here.
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Affiliation(s)
- S J Miklavcic
- Phenomics and Bioinformatics Research Centre, School of Information Technology and Mathematical Sciences, University of South Australia, Mawson Lakes, SA 5095, Australia.
| | - C Fung
- Phenomics and Bioinformatics Research Centre, School of Information Technology and Mathematical Sciences, University of South Australia, Mawson Lakes, SA 5095, Australia
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15
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Radiom M. Ionic liquid–solid interface and applications in lubrication and energy storage. Curr Opin Colloid Interface Sci 2019. [DOI: 10.1016/j.cocis.2019.01.013] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
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16
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Anomalous Interfacial Structuring of a Non-Halogenated Ionic Liquid: Effect of Substrate and Temperature. COLLOIDS AND INTERFACES 2018. [DOI: 10.3390/colloids2040060] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
We investigate the interfacial properties of the non-halogenated ionic liquid (IL), trihexyl(tetradecyl)phosphonium bis(mandelato)borate, [P6,6,6,14][BMB], in proximity to solid surfaces, by means of surface force measurement. The system consists of sharp atomic force microscopy (AFM) tips interacting with solid surfaces of mica, silica, and gold. We find that the force response has a monotonic form, from which a characteristic steric decay length can be extracted. The decay length is comparable with the size of the ions, suggesting that a layer is formed on the surface, but that it is diffuse. The long alkyl chains of the cation, the large size of the anion, as well as crowding of the cations at the surface of negatively charged mica, are all factors which are likely to oppose the interfacial stratification which has, hitherto, been considered a characteristic of ionic liquids. The variation in the decay length also reveals differences in the layer composition at different surfaces, which can be related to their surface charge. This, in turn, allows the conclusion that silica has a low surface charge in this aprotic ionic liquid. Furthermore, the effect of temperature has been investigated. Elevating the temperature to 40 °C causes negligible changes in the interaction. At 80 °C and 120 °C, we observe a layering artefact which precludes further analysis, and we present the underlying instrumental origin of this rather universal artefact.
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17
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Ortega Vega MR, Ercolani J, Mattedi S, Aguzzoli C, Ferreira CA, Rocha AS, Malfatti CF. Oleate-Based Protic Ionic Liquids As Lubricants for Aluminum 1100. Ind Eng Chem Res 2018. [DOI: 10.1021/acs.iecr.8b02426] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
| | | | - Silvana Mattedi
- Laboratório de Termodinâmica Aplicada, Universidade Federal da Bahia (UFBA), Aristides Novis Street 2, Salvador, Bahia 40210-630 Brazil
| | - César Aguzzoli
- Programa de Pós-Graduação em Engenharia e Ciência dos Materiais (PGMAT) Universidade de Caxias do Sul (UCS), Francisco Getúlio Vargas Street 1130, Caxias do Sul, Rio Grande do Sul 95070-560, Brazil
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18
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Pilkington GA, Harris K, Bergendal E, Reddy AB, Palsson GK, Vorobiev A, Antzutkin ON, Glavatskih S, Rutland MW. Electro-responsivity of ionic liquid boundary layers in a polar solvent revealed by neutron reflectance. J Chem Phys 2018; 148:193806. [DOI: 10.1063/1.5001551] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Affiliation(s)
- Georgia A. Pilkington
- Surface and Corrosion Science, Department of Chemistry, KTH Royal Institute of Technology, Stockholm, Sweden
| | - Kathryn Harris
- System and Component Design, Department of Machine Design, KTH Royal Institute of Technology, Stockholm, Sweden
| | - Erik Bergendal
- Surface and Corrosion Science, Department of Chemistry, KTH Royal Institute of Technology, Stockholm, Sweden
| | - Akepati Bhaskar Reddy
- System and Component Design, Department of Machine Design, KTH Royal Institute of Technology, Stockholm, Sweden
| | - Gunnar K. Palsson
- Department of Physics and Astronomy, Division of Materials Physics, Uppsala University, Uppsala, Sweden
| | - Alexei Vorobiev
- Department of Physics and Astronomy, Division of Materials Physics, Uppsala University, Uppsala, Sweden
| | | | - Sergei Glavatskih
- System and Component Design, Department of Machine Design, KTH Royal Institute of Technology, Stockholm, Sweden
- Department of Electrical Energy, Systems and Automation, Ghent University, Ghent, Belgium
| | - Mark W. Rutland
- Surface and Corrosion Science, Department of Chemistry, KTH Royal Institute of Technology, Stockholm, Sweden
- Surfaces, Processes and Formulation, RISE Research Institutes of Sweden, Stockholm, Sweden
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Abstract
The application of ionic liquids as lubricants has attracted substantial interest over the past decade and this has produced a rich literature. The aim of this review is to summarize the main findings about frictional behavior of ionic liquids in the boundary lubrication regime. We first recall why the unusual properties of ionic liquids make them very promising lubricants, and the molecular mechanisms at the origin of their lubricating behavior. We then point out the main challenges to be overcome in order to optimise ionic liquid lubricant performance for common applications. We finally discuss their use in the context of electroactive lubrication.
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Garcia L, Jacquot L, Charlaix E, Cross B. Nano-mechanics of ionic liquids at dielectric and metallic interfaces. Faraday Discuss 2018; 206:443-457. [DOI: 10.1039/c7fd00149e] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Using a dynamic surface force apparatus, we investigate the nano-mechanics and the nano-rheology of an ionic liquid at dielectric and metallic solid surfaces.
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Affiliation(s)
- Léo Garcia
- Université Grenoble Alpes
- CNRS
- LIPhy
- Grenoble
- France
| | - Léa Jacquot
- Université Grenoble Alpes
- CNRS
- LIPhy
- Grenoble
- France
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21
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Gebbie MA, Smith AM, Dobbs HA, Lee AA, Warr GG, Banquy X, Valtiner M, Rutland MW, Israelachvili JN, Perkin S, Atkin R. Long range electrostatic forces in ionic liquids. Chem Commun (Camb) 2017; 53:1214-1224. [DOI: 10.1039/c6cc08820a] [Citation(s) in RCA: 231] [Impact Index Per Article: 33.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Experimental evidence for long range surface forces in ionic liquids is collated and examined, key outstanding questions are identified, and possible mechanisms underpinning these long range forces are explored.
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Affiliation(s)
- Matthew A. Gebbie
- Geballe Laboratory for Advanced Materials
- Stanford University
- Stanford
- USA
| | - Alexander M. Smith
- Department of Chemistry
- Physical & Theoretical Chemistry Laboratory
- University of Oxford
- Oxford
- UK
| | - Howard A. Dobbs
- Department of Chemical Engineering
- University of California
- Santa Barbara
- UK
| | - Alpha A. Lee
- School of Engineering and Applied Sciences
- Harvard University
- Cambridge
- USA
| | - Gregory G. Warr
- School of Chemistry
- F11
- The University of Sydney
- NSW 2006
- Australia
| | - Xavier Banquy
- Faculty of Pharmacy
- Universite de Montreal
- Montreal
- Canada
| | - Markus Valtiner
- Interface Chemistry and Surface Engineering
- Max Planck Institut fur Eisenforschung GmbH
- Dusseldorf
- Germany
| | - Mark W. Rutland
- Surface and Corrosion Science
- KTH Royal Institute of Technology
- SE-10044 Stockholm
- Sweden
- SP Chemistry Materials and Surfaces
| | | | - Susan Perkin
- Department of Chemistry
- Physical & Theoretical Chemistry Laboratory
- University of Oxford
- Oxford
- UK
| | - Rob Atkin
- Priority Research Centre for Advanced Fluid Interfaces
- Newcastle Institute for Energy and Resources
- The University of Newcastle
- Australia
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22
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Hjalmarsson N, Atkin R, Rutland MW. Switchable long-range double layer force observed in a protic ionic liquid. Chem Commun (Camb) 2017; 53:647-650. [DOI: 10.1039/c6cc07396d] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A repulsive double layer force has been measured for ethylammonium nitrate (EAN) at 373 K and 393 K, which is absent at lower temperatures.
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Affiliation(s)
- N. Hjalmarsson
- Surface and Corrosion Science
- KTH Royal Institute of Technology
- SE-10044 Stockholm
- Sweden
| | - R. Atkin
- Priority Research Centre for Advanced Fluids and Interfaces
- The University of Newcastle
- Callaghan
- Australia
| | - M. W. Rutland
- Surface and Corrosion Science
- KTH Royal Institute of Technology
- SE-10044 Stockholm
- Sweden
- Chemistry, Materials and Surfaces
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