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Li S, Hammond OS, Nelson A, de Campo L, Moir M, Recsei C, Shimpi MR, Glavatskih S, Pilkington GA, Mudring AV, Rutland MW. Anion Architecture Controls Structure and Electroresponsivity of Anhalogenous Ionic Liquids in a Sustainable Fluid. J Phys Chem B 2024; 128:4231-4242. [PMID: 38639329 DOI: 10.1021/acs.jpcb.3c08189] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/20/2024]
Abstract
Three nonhalogenated ionic liquids (ILs) dissolved in 2-ethylhexyl laurate (2-EHL), a biodegradable oil, are investigated in terms of their bulk and electro-interfacial nanoscale structures using small-angle neutron scattering (SANS) and neutron reflectivity (NR). The ILs share the same trihexyl(tetradecyl)phosphonium ([P6,6,6,14]+) cation paired with different anions, bis(mandelato)borate ([BMB]-), bis(oxalato)borate ([BOB]-), and bis(salicylato)borate ([BScB]-). SANS shows a high aspect ratio tubular self-assembly structure characterized by an IL core of alternating cations and anions with a 2-EHL-rich shell or corona in the bulk, the geometry of which depends upon the anion structure and concentration. NR also reveals a solvent-rich interfacial corona layer. Their electro-responsive behavior, pertaining to the structuring and composition of the interfacial layers, is also influenced by the anion identity. [P6,6,6,14][BOB] exhibits distinct electroresponsiveness to applied potentials, suggesting an ion exchange behavior from cation-dominated to anion-rich. Conversely, [P6,6,6,14][BMB] and [P6,6,6,14][BScB] demonstrate minimal electroresponses across all studied potentials, related to their different dissociative and diffusive behavior. A mixed system is dominated by the least soluble IL but exhibits an increase in disorder. This work reveals the subtlety of anion architecture in tuning bulk and electro-interfacial properties, offering valuable molecular insights for deploying nonhalogenated ILs as additives in biodegradable lubricants and supercapacitors.
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Affiliation(s)
- Sichao Li
- Division of Surface and Corrosion Science, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, Stockholm SE-100 44, Sweden
| | - Oliver S Hammond
- Department of Materials and Environmental Chemistry, Stockholm University, Stockholm SE-114 18, Sweden
- intelligent Advanced Materials, Department of Biological & Chemical Engineering and iNANO, Aarhus University, Aarhus C 8000, Denmark
| | - Andrew Nelson
- Australian Centre for Neutron Scattering, ANSTO, Lucas Heights, New South Wales 2234, Australia
| | - Liliana de Campo
- Australian Centre for Neutron Scattering, ANSTO, Lucas Heights, New South Wales 2234, Australia
| | - Michael Moir
- National Deuteration Facility, ANSTO, Lucas Heights, New South Wales 2234, Australia
| | - Carl Recsei
- National Deuteration Facility, ANSTO, Lucas Heights, New South Wales 2234, Australia
| | - Manishkumar R Shimpi
- Department of Materials and Environmental Chemistry, Stockholm University, Stockholm SE-114 18, Sweden
- Chemistry of Interfaces, Department of Civil and Environmental Engineering, Luleå University of Technology, Luleå SE-97187, Sweden
| | - Sergei Glavatskih
- System and Component Design, Department of Engineering Design, KTH Royal Institute of Technology, Stockholm SE-100 44, Sweden
- School of Chemistry, University of New South Wales, Sydney, New South Wales 2052, Australia
- Department of Electromechanical, Systems and Metal Engineering, Ghent University, Ghent B-9052, Belgium
| | - Georgia A Pilkington
- Division of Surface and Corrosion Science, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, Stockholm SE-100 44, Sweden
| | - Anja-Verena Mudring
- Department of Materials and Environmental Chemistry, Stockholm University, Stockholm SE-114 18, Sweden
- intelligent Advanced Materials, Department of Biological & Chemical Engineering and iNANO, Aarhus University, Aarhus C 8000, Denmark
- Department of Physics, Umeå University, Umeå SE-901 87, Sweden
| | - Mark W Rutland
- Division of Surface and Corrosion Science, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, Stockholm SE-100 44, Sweden
- School of Chemistry, University of New South Wales, Sydney, New South Wales 2052, Australia
- Bioeconomy and Health Department Materials and Surface Design, RISE Research Institutes of Sweden, Stockholm SE-114 28, Sweden
- Laboratoire de Tribologie et Dynamique des Systèmes, École Centrale de Lyon, Ecully Cedex 69134, France
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Li S, Pilkington GA, Mehler F, Hammond OS, Boudier A, Vorobiev A, Glavatskih S, Rutland MW. Tuneable interphase transitions in ionic liquid/carrier systems via voltage control. J Colloid Interface Sci 2023; 652:1240-1249. [PMID: 37657223 DOI: 10.1016/j.jcis.2023.08.111] [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: 06/22/2023] [Revised: 08/09/2023] [Accepted: 08/18/2023] [Indexed: 09/03/2023]
Abstract
The structure and interaction of ionic liquids (ILs) influence their interfacial composition, and their arrangement (i.e., electric double-layer (EDL) structure), can be controlled by an electric field. Here, we employed a quartz crystal microbalance (QCM) to study the electrical response of two non-halogenated phosphonium orthoborate ILs, dissolved in a polar solvent at the interface. The response is influenced by the applied voltage, the structure of the ions, and the solvent polarizability. One IL showed anomalous electro-responsivity, suggesting a self-assembly bilayer structure of the IL cation at the gold interface, which transitions to a typical EDL structure at higher positive potential. Neutron reflectivity (NR) confirmed this interfacial structuring and compositional changes at the electrified gold surface. A cation-dominated self-assembly structure is observed for negative and neutral voltages, which abruptly transitions to an anion-rich interfacial layer at positive voltages. An interphase transition explains the electro-responsive behaviour of self-assembling IL/carrier systems, pertinent for ILs in advanced tribological and electrochemical contexts.
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Affiliation(s)
- Sichao Li
- Division of Surface and Corrosion Science, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden
| | - Georgia A Pilkington
- Division of Surface and Corrosion Science, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden
| | - Filip Mehler
- Division of Surface and Corrosion Science, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden
| | - Oliver S Hammond
- Department of Materials and Environmental Chemistry, Stockholm University, SE-114 18 Stockholm, Sweden; Department of Biological and Chemical Engineering, Aarhus University, Aarhus C 8000 Denmark
| | - Anthony Boudier
- Department of Materials and Environmental Chemistry, Stockholm University, SE-114 18 Stockholm, Sweden
| | - Alexei Vorobiev
- Department of Physics and Astronomy, Division of Materials Physics, Uppsala University, SE-751 20 Uppsala, Sweden
| | - Sergei Glavatskih
- System and Component Design, Department of Engineering Design, KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden; School of Chemistry, University of New South Wales, Sydney, NSW 2052, Australia; Department of Electromechanical, Systems and Metal Engineering, Ghent University, B-9052 Ghent, Belgium
| | - Mark W Rutland
- Division of Surface and Corrosion Science, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden; School of Chemistry, University of New South Wales, Sydney, NSW 2052, Australia; Bioeconomy and Health Department Materials and Surface Design, RISE Research Institutes of Sweden, SE-114 28 Stockholm, Sweden; Laboratoire de Tribologie et Dynamique des Systèmes, École Centrale de Lyon, 69134 Ecully Cedex, France.
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3
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Hammond OS, Bousrez G, Mehler F, Li S, Shimpi MR, Doutch J, Cavalcanti L, Glavatskih S, Antzutkin ON, Rutland MW, Mudring AV. Molecular Architecture Effects on Bulk Nanostructure in Bis(Orthoborate) Ionic Liquids. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2023; 19:e2300912. [PMID: 37395635 DOI: 10.1002/smll.202300912] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Revised: 04/11/2023] [Indexed: 07/04/2023]
Abstract
A series of 19 ionic liquids (ILs) based on phosphonium and imidazolium cations of varying alkyl-chain lengths with the orthoborate anions bis(oxalato)borate [BOB]- , bis(mandelato)borate, [BMB]- and bis(salicylato)borate, [BScB]- , are synthesized and studied using small-angle neutron scattering (SANS). All measured systems display nanostructuring, with 1-methyl-3-n-alkyl imidazolium-orthoborates forming clearly bicontinuous L3 spongelike phases when the alkyl chains are longer than C6 (hexyl). L3 phases are fitted using the Teubner and Strey model, and diffusely-nanostructured systems are primarily fitted using the Ornstein-Zernicke correlation length model. Strongly-nanostructured systems have a strong dependence on the cation, with molecular architecture variation explored to determine the driving forces for self-assembly. The ability to form well-defined complex phases is effectively extinguished in several ways: methylation of the most acidic imidazolium ring proton, replacing the imidazolium 3-methyl group with a longer hydrocarbon chain, substitution of [BOB]- by [BMB]- , or exchanging the imidazolium for phosphonium systems, irrespective of phosphonium architecture. The results suggest there is only a small window of opportunity, in terms of molecular amphiphilicity and cation:anion volume matching, for the formation of stable extensive bicontinuous domains in pure bulk orthoborate-based ILs. Particularly important for self-assembly processes appear to be the ability to form H-bonding networks, which offer additional versatility in imidazolium systems.
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Affiliation(s)
- Oliver S Hammond
- Department of Materials and Environmental Chemistry, Stockholm University, Stockholm, SE-114 18, Sweden
- Department of Biological and Chemical Engineering and iNANO, Aarhus University, Aarhus C, 8000, Denmark
| | - Guillaume Bousrez
- Department of Materials and Environmental Chemistry, Stockholm University, Stockholm, SE-114 18, Sweden
- Department of Biological and Chemical Engineering and iNANO, Aarhus University, Aarhus C, 8000, Denmark
| | - Filip Mehler
- Division of Surface and Corrosion Science, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, Stockholm, SE-100 40, Sweden
| | - Sichao Li
- Division of Surface and Corrosion Science, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, Stockholm, SE-100 40, Sweden
| | - Manishkumar R Shimpi
- Department of Materials and Environmental Chemistry, Stockholm University, Stockholm, SE-114 18, Sweden
- Chemistry of Interfaces, Luleå University of Technology, Luleå, SE-971 87, Sweden
| | - James Doutch
- ISIS Neutron & Muon Source, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell-Oxford, OX11 0QX, UK
| | - Leide Cavalcanti
- ISIS Neutron & Muon Source, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell-Oxford, OX11 0QX, UK
| | - Sergei Glavatskih
- Department of Engineering Design, KTH Royal Institute of Technology, Stockholm, SE-10044, Sweden
- School of Chemistry, University of New South Wales, Sydney, 2052, Australia
- Department of Electromechanical, Systems and Metal Engineering, Ghent University, Ghent, B-9052, Belgium
| | - Oleg N Antzutkin
- Chemistry of Interfaces, Luleå University of Technology, Luleå, SE-971 87, Sweden
| | - Mark W Rutland
- Division of Surface and Corrosion Science, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, Stockholm, SE-100 40, Sweden
- School of Chemistry, University of New South Wales, Sydney, 2052, Australia
- Bioeconomy and Health Department Materials and Surface Design, RISE Research Institutes of Sweden, Stockholm, SE-114 86, Sweden
- Laboratoire de Tribologie et Dynamique des Systèmes, École Centrale de Lyon, Lyon, 69130, France
| | - Anja-Verena Mudring
- Department of Materials and Environmental Chemistry, Stockholm University, Stockholm, SE-114 18, Sweden
- Department of Biological and Chemical Engineering and iNANO, Aarhus University, Aarhus C, 8000, Denmark
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Reddy AB, Pilkington GA, Rutland MW, Glavatskih S. Tribotronic control of an ionic boundary layer in operando extends the limits of lubrication. Sci Rep 2022; 12:20479. [DOI: 10.1038/s41598-022-22504-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2022] [Accepted: 10/17/2022] [Indexed: 11/29/2022] Open
Abstract
AbstractThe effect of electric potential on the lubrication of a non-halogenated phosphonium orthoborate ionic liquid used as an additive in a biodegradable oil was studied. An in-house tribotronic system was built around an instrument designed to measure lubricant film thickness between a rolling steel ball and a rotating silica-coated glass disc. The application of an electric field between the steel ball and a set of customized counter-electrodes clearly induced changes in the thickness of the lubricant film: a marked decrease at negative potentials and an increase at positive potentials. Complementary neutron reflectivity studies demonstrated the intrinsic electroresponsivity of the adsorbate: this was performed on a gold-coated silicon block and made possible in the same lubricant system by deuterating the oil. The results indicate that the anions, acting as anchors for the adsorbed film on the steel surface, are instrumental in the formation of thick and robust lubricating ionic boundary films. The application of a high positive potential, outside the electrochemical window, resulted in an enormous boost to film thickness, implicating the formation of ionic multi-layers and demonstrating the plausibility of remote control of failing contacts in inaccessible machinery, such as offshore wind and wave power installations.
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Nishi N, Uchiyashiki J, Oda T, Hino M, Yamada NL. Overscreening Induced by Ionic Adsorption at the Ionic Liquid/Electrode Interface Detected Using Neutron Reflectometry with a Rational Material Design. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2021. [DOI: 10.1246/bcsj.20210328] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Naoya Nishi
- Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University, Kyoto 615-8510
| | - Junya Uchiyashiki
- Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University, Kyoto 615-8510
| | - Tatsuro Oda
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581
| | - Masahiro Hino
- Institute for Integrated Radiation and Nuclear Science, Kyoto University, Kumatori, Osaka 590-0494
| | - Norifumi L. Yamada
- Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), Ibaraki 305-0801
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Nemoto F, Nakamura SY, Abe H. Surface structure of the mixture of 1-alkyl-3-methylimidazolium iodide and polyiodide observed by surface tension measurement and X-ray reflectivity. J Mol Liq 2021. [DOI: 10.1016/j.molliq.2021.116381] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Murashima M, Hojo K, Ito S, Umehara N, Tokoroyama T, Takahashi T, Imaeda M. Nanotextured Mold Surface with DLC Coating for Reduction in Residual Ceramic Particles. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:3563-3574. [PMID: 33730499 DOI: 10.1021/acs.langmuir.0c03435] [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
In the ceramic industry, ceramic particles remain on a mold surface due to which the mold requires frequent cleaning during press molding, reducing productivity. Surface texturing and tetrahedral amorphous carbon (ta-C) coatings are well-known surface-energy controllable treatments developed for low adhesion, low friction, and high wear resistance. In the present paper, we demonstrate the effect of reducing ceramic residues using nanotexturing, ta-C coatings, and their combination. We compare two surface morphologies (i.e., 770 nm pitch nanotexturing and flat) and five materials (i.e., nonhardened steel, hardened steel, ta-C, and two types of nitrogen-doped ta-C (ta-CNx). Molding test results show that the ta-C coating on flat surfaces with the highest hardness of 30 GPa shows the lowest residual amount of 5.9 μg for Al2O3 ceramic particles. The amount is 82% less than that of the nonhardened steel. The ta-CNx20, made with a nitrogen flow rate of 20 sccm, shows the lowest residual amount of 234 μg for SiO2 ceramic particles, which is 81% less than that of the nontextured ta-CNx20. In conclusion, we provide design guidelines for nanotextured mold surfaces including the texturing pitch should be small enough for ceramic particles; the mold surface should be sufficiently hard; the lower the surface energy per unit area, the less residues of ceramic particles.
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Affiliation(s)
- Motoyuki Murashima
- Department of Micro-Nano Mechanical Science and Engineering, Nagoya University Furo-cho, Chikusa-ku, Nagoya City, Aichi 464-8603, Japan
| | - Koki Hojo
- Department of Micro-Nano Mechanical Science and Engineering, Nagoya University Furo-cho, Chikusa-ku, Nagoya City, Aichi 464-8603, Japan
| | - Shigehiro Ito
- Department of Micro-Nano Mechanical Science and Engineering, Nagoya University Furo-cho, Chikusa-ku, Nagoya City, Aichi 464-8603, Japan
| | - Noritsugu Umehara
- Department of Micro-Nano Mechanical Science and Engineering, Nagoya University Furo-cho, Chikusa-ku, Nagoya City, Aichi 464-8603, Japan
| | - Takayuki Tokoroyama
- Department of Micro-Nano Mechanical Science and Engineering, Nagoya University Furo-cho, Chikusa-ku, Nagoya City, Aichi 464-8603, Japan
| | - Tomonori Takahashi
- NGK Insulators, Ltd., 2-56, Suda-cho, Mizuho-ku, Nagoya City, Aichi 467-8530, Japan
| | - Minoru Imaeda
- NGK Insulators, Ltd., 2-56, Suda-cho, Mizuho-ku, Nagoya City, Aichi 467-8530, Japan
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8
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Pilkington GA, Welbourn R, Oleshkevych A, Watanabe S, Pedraz P, Radiom M, Glavatskih S, Rutland MW. Effect of water on the electroresponsive structuring and friction in dilute and concentrated ionic liquid lubricant mixtures. Phys Chem Chem Phys 2020; 22:28191-28201. [PMID: 33295339 DOI: 10.1039/d0cp05110a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The effect of water on the electroactive structuring of a tribologically relevant ionic liquid (IL) when dispersed in a polar solvent has been investigated at a gold electrode interface using neutron reflectivity (NR). For all solutions studied, the addition of small amounts of water led to clear changes in electroactive structuring of the IL at the electrode interface, which was largely determined by the bulk IL concentration. At a dilute IL concentration, the presence of water gave rise to a swollen interfacial structuring, which exhibited a greater degree of electroresponsivity with applied potential compared to an equivalent dry solution. Conversely, for a concentrated IL solution, the presence of water led to an overall thinning of the interfacial region and a crowding-like structuring, within which the composition of the inner layer IL layers varied systematically with applied potential. Complementary nanotribotronic atomic force microscopy (AFM) measurements performed for the same IL concentration, in dry and ambient conditions, show that the presence of water reduces the lubricity of the IL boundary layers. However, consistent with the observed changes in the IL layers observed by NR, reversible and systematic control of the friction coefficient with applied potential was still achievable. Combined, these measurements provide valuable insight into the implications of water on the interfacial properties of ILs at electrified interfaces, which inevitably will determine their applicability in tribotronic and electrochemical contexts.
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Affiliation(s)
- Georgia A Pilkington
- Division of Surface and Corrosion Science, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden.
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9
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Pilkington GA, Oleshkevych A, Pedraz P, Watanabe S, Radiom M, Reddy AB, Vorobiev A, Glavatskih S, Rutland MW. Electroresponsive structuring and friction of a non-halogenated ionic liquid in a polar solvent: effect of concentration. Phys Chem Chem Phys 2020; 22:19162-19171. [PMID: 32812565 DOI: 10.1039/d0cp02736g] [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
Neutron reflectivity (NR) measurements have been employed to study the interfacial structuring and composition of electroresponsive boundary layers formed by an ionic liquid (IL) lubricant at an electrified gold interface when dispersed in a polar solvent. The results reveal that both the composition and extent of the IL boundary layers intricately depend on the bulk IL concentration and the applied surface potential. At the lowest concentration (5% w/w), a preferential adsorption of the IL cation at the gold electrode is observed, which hinders the ability to electro-induce changes in the boundary layers. In contrast, at higher IL bulk concentrations (10 and 20% w/w), the NR results reveal a significantly larger concentration of the IL ions at the gold interface that exhibit significantly greater electroresponsivity, with clear changes in the layer composition and layer thickness observed for different potentials. In complementary atomic force microscopy (AFM) measurements on an electrified gold surface, such IL boundary layers are demonstrated to provide excellent friction reduction and electroactive friction (known as tribotronics). In agreement with the NR results obtained, clear concentration effects are also observed. Together such results provide valuable molecular insight into the electroactive structuring of ILs in solvent mixtures, as well as provide mechanistic understanding of their tribotronic behaviours.
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Affiliation(s)
- Georgia A Pilkington
- Division of Surface and Corrosion Science, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden.
| | - Anna Oleshkevych
- Division of Surface and Corrosion Science, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden.
| | - Patricia Pedraz
- Division of Surface and Corrosion Science, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden.
| | - Seiya Watanabe
- Division of Surface and Corrosion Science, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden.
| | - Milad Radiom
- Division of Surface and Corrosion Science, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden.
| | - Akepati Bhaskar Reddy
- System and Component Design, Department of Machine Design, KTH Royal Institute of Technology, SE-100 44 Stockholm, 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, SE-100 44 Stockholm, Sweden and Department of Electromechanical, Systems and Metal Engineering, Ghent University, B-9052 Ghent, Belgium
| | - Mark W Rutland
- Division of Surface and Corrosion Science, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden. and Surfaces, Processes and Formulation, RISE Research Institutes of Sweden, SE-100 44 Stockholm, Sweden
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10
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Katakura S, Amano KI, Sakka T, Bu W, Lin B, Schlossman ML, Nishi N. Evolution and Reversible Polarity of Multilayering at the Ionic Liquid/Water Interface. J Phys Chem B 2020; 124:6412-6419. [PMID: 32600035 DOI: 10.1021/acs.jpcb.0c03711] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Highly correlated positioning of ions underlies Coulomb interactions between ions and electrified interfaces within dense ionic fluids such as biological cells and ionic liquids. Recent work has shown that highly correlated ionic systems behave differently than dilute electrolyte solutions, and interest is focused upon characterizing the electrical and structural properties of the dense electrical double layers (EDLs) formed at internal interfaces. It has been a challenge for experiments to characterize the progressive development of the EDL on the nanoscale as the interfacial electric potential is varied over a range of positive and negative values. Here we address this challenge by measuring X-ray reflectivity from the interface between an ionic liquid (IL) and a dilute aqueous electrolyte solution over a range of interfacial potentials from -450 to 350 mV. The growth of alternately charged cation-rich and anion-rich layers was observed along with a polarity reversal of the layers as the potential changed sign. These data show that the structural development of an ionic multilayer-like EDL with increasing potential is similar to that suggested by phenomenological theories and MD simulations, although our data also reveal that the excess charge beyond the first ionic layer decays more rapidly than predicted.
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Affiliation(s)
- Seiji Katakura
- Department of Energy and Hydrocarbon Chemistry, Kyoto University, Kyoto 615-8510, Japan
| | - Ken-Ichi Amano
- Department of Energy and Hydrocarbon Chemistry, Kyoto University, Kyoto 615-8510, Japan.,Faculty of Agriculture, Meijo University, Nagoya, Aichi 468-8502, Japan
| | - Tetsuo Sakka
- Department of Energy and Hydrocarbon Chemistry, Kyoto University, Kyoto 615-8510, Japan
| | - Wei Bu
- ChemMatCARS, Center for Advanced Radiation Sources, University of Chicago, Chicago, Illinois 60637, United States
| | - Binhua Lin
- ChemMatCARS, Center for Advanced Radiation Sources, University of Chicago, Chicago, Illinois 60637, United States
| | - Mark L Schlossman
- Department of Physics, University of Illinois at Chicago, Chicago, Illinois 60607, United States
| | - Naoya Nishi
- Department of Energy and Hydrocarbon Chemistry, Kyoto University, Kyoto 615-8510, Japan
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11
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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: 183] [Impact Index Per Article: 45.8] [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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Pei HW, Li B, Laaksonen A, Wang YL. How Molecular Chiralities of Bis(mandelato)borate Anions Affect Their Binding Structures With Alkali Metal Ions and Microstructural Properties in Tetraalkylphosphonium Ionic Liquids. Front Chem 2020; 8:65. [PMID: 32117888 PMCID: PMC7028760 DOI: 10.3389/fchem.2020.00065] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Accepted: 01/20/2020] [Indexed: 11/13/2022] Open
Abstract
Spiroborate anion-based inorganic electrolytes and ionic liquids (ILs) have fascinating electrochemical and tribological properties and have received widespread attention in industrial applications. The molecular chiralities of spiroborate anions have a significant effect on the microstructures and macroscopic functionalities of these ionic materials in application and thus deserve fundamental consideration. In the current work, we performed quantum chemistry calculations to address the binding strength and coordination structures of chiral bis(mandelato)borate ([BMB]) anions with representative alkali metal ions, as well as the electronic properties of alkali metal ion-[BMB] ion pair complexes. The optimized [BMB] conformers are categorized into V-shaped, bent, and twisted structures with varied electrostatic potential contours and conformational energies and distinct alkali metal ion-[BMB] binding structures. Alkali metal ions have additional associations with phenyl groups in V-shaped [BMB] conformers owing to preferential cation-π interactions. Furthermore, the effects of the molecular chiralities of [BMB] anions on the thermodynamics and microstructural properties of tetraalkylphosphonium [BMB] ILs were studied by performing extensive atomistic interactions. Oxygen atoms in [BMB] anions have competitive hydrogen bonding interactions with hydrogen atoms in cations depending on the molecular chiralities and steric hindrance effects of [BMB] anions. However, the molecular chiralities of [BMB] anions have a negligible effect on the liquid densities of tetraalkylphosphonium [BMB] ILs and the spatial distributions of boron atoms in anions around phosphorous atoms in cations. Enlarging tetraalkylphosphonium cation sizes leads to enhanced cation-anion intermolecular hydrogen bonding and Coulombic interactions due to enhanced segregation of polar groups in apolar networks in heterogeneous IL matrices, as verified by scattering structural functions.
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Affiliation(s)
- Han-Wen Pei
- Arrhenius Laboratory, Department of Materials and Environmental Chemistry, Stockholm University, Stockholm, Sweden
| | - Bin Li
- School of Chemical Engineering and Technology, Sun Yat-sen University, Zhuhai, China
| | - Aatto Laaksonen
- Arrhenius Laboratory, Department of Materials and Environmental Chemistry, Stockholm University, Stockholm, Sweden
- State Key Laboratory of Materials-Oriented and Chemical Engineering, Nanjing Tech University, Nanjing, China
- Centre of Advanced Research in Bionanoconjugates and Biopolymers, Petru Poni Institute of Macromolecular Chemistry, Iasi, Romania
| | - Yong-Lei Wang
- Arrhenius Laboratory, Department of Materials and Environmental Chemistry, Stockholm University, Stockholm, Sweden
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Watanabe S, Pilkington GA, Oleshkevych A, Pedraz P, Radiom M, Welbourn R, Glavatskih S, Rutland MW. Interfacial structuring of non-halogenated imidazolium ionic liquids at charged surfaces: effect of alkyl chain length. Phys Chem Chem Phys 2020; 22:8450-8460. [DOI: 10.1039/d0cp00360c] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Control of the interfacial structures of ionic liquids (ILs) at charged interfaces is important to many of their applications, including in energy storage solutions, sensors and advanced lubrication technologies utilising electric fields.
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Affiliation(s)
- Seiya Watanabe
- Division of Surface and Corrosion Science
- School of Engineering Sciences in Chemistry
- Biotechnology and Health
- KTH Royal Institute of Technology
- SE-100 44 Stockholm
| | - Georgia A. Pilkington
- Division of Surface and Corrosion Science
- School of Engineering Sciences in Chemistry
- Biotechnology and Health
- KTH Royal Institute of Technology
- SE-100 44 Stockholm
| | - Anna Oleshkevych
- Division of Surface and Corrosion Science
- School of Engineering Sciences in Chemistry
- Biotechnology and Health
- KTH Royal Institute of Technology
- SE-100 44 Stockholm
| | - Patricia Pedraz
- Division of Surface and Corrosion Science
- School of Engineering Sciences in Chemistry
- Biotechnology and Health
- KTH Royal Institute of Technology
- SE-100 44 Stockholm
| | - Milad Radiom
- Division of Surface and Corrosion Science
- School of Engineering Sciences in Chemistry
- Biotechnology and Health
- KTH Royal Institute of Technology
- SE-100 44 Stockholm
| | - Rebecca Welbourn
- ISIS Neutron & Muon Source
- Rutherford Appleton Laboratory
- STFC
- Didcot
- UK
| | - Sergei Glavatskih
- System and Component Design
- Department of Machine Design
- KTH Royal Institute of Technology
- SE-100 44 Stockholm
- Sweden
| | - Mark W. Rutland
- Division of Surface and Corrosion Science
- School of Engineering Sciences in Chemistry
- Biotechnology and Health
- KTH Royal Institute of Technology
- SE-100 44 Stockholm
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Hjalmarsson N, Bergendal E, Wang YL, Munavirov B, Wallinder D, Glavatskih S, Aastrup T, Atkin R, Furó I, Rutland MW. Electro-Responsive Surface Composition and Kinetics of an Ionic Liquid in a Polar Oil. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:15692-15700. [PMID: 31581771 DOI: 10.1021/acs.langmuir.9b02119] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The quartz crystal microbalance (QCM) has been used to study how the interfacial layer of an ionic liquid dissolved in a polar oil at low weight percentages responds to changes in applied potential. The changes in surface composition at the QCM gold surface depend on both the magnitude and sign of the applied potential. The time-resolved response indicates that the relaxation kinetics are limited by the diffusion of ions in the interfacial region and not in the bulk, since there is no concentration dependence. The measured mass changes cannot be explained only in terms of simple ion exchange; the relative molecular volumes of the ions and the density changes in response to ion exclusion must be considered. The relaxation behavior of the potential between the electrodes upon disconnecting the applied potential is more complex than that observed for pure ionic liquids, but a measure of the surface charge can be extracted from the exponential decay when the rapid initial potential drop is accounted for. The adsorbed film at the gold surface consists predominantly of ionic liquid despite the low concentration, which is unsurprising given the surtactant-like structures of (some of) the ionic liquid ions. Changes in response to potential correspond to changes in the relative numbers of cations and anions, rather than a change in the oil composition. No evidence for an electric field induced change in viscosity is observed. This work shows conclusively that electric potentials can be used to control the surface composition, even in an oil-based system, and paves the way for other ion solvent studies.
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Affiliation(s)
| | | | | | | | | | - Sergei Glavatskih
- Department of Electrical Energy, Metals, Mechanical Constructions and Systems , Ghent University , B-9000 , Ghent , Belgium
| | | | - Rob Atkin
- School of Molecular Sciences , University of Western Australia , 6009 Perth , Australia
| | | | - Mark W Rutland
- Surfaces, Processes and Formulation , RISE Research Institutes of Sweden , SE-50115 Stockholm , Sweden
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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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Perkin S, Kirchner B, Fayer MD. Preface: Special Topic on Chemical Physics of Ionic Liquids. J Chem Phys 2018; 148:193501. [DOI: 10.1063/1.5039492] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Affiliation(s)
- Susan Perkin
- Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, Oxford OX1 3QZ, United Kingdom
| | - Barbara Kirchner
- Mulliken Center for Theoretical Chemistry, Universität Bonn, Beringstr. 4, D-53115 Bonn, Germany
| | - Michael D. Fayer
- Department of Chemistry, Stanford University, Stanford, California 94305, USA
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