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Li Q, Zhu G, Liu Z, Xu J. Molecular dynamics simulation studies on the ionic liquid N-butylpyridinium tetrafluoroborate on the gold surface. Heliyon 2024; 10:e32710. [PMID: 38975103 PMCID: PMC11225740 DOI: 10.1016/j.heliyon.2024.e32710] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2023] [Revised: 05/26/2024] [Accepted: 06/07/2024] [Indexed: 07/09/2024] Open
Abstract
The study of solid/liquid interface is of great significance for understanding various phenomena such as the nanostructure of the interface, liquid wetting, crystal growth and nucleation. In this work, the nanostructure of the pyridinium ionic liquid [BPy]BF4 on different gold surfaces was studied by molecular dynamics simulation. The results indicate that the density of the ionic liquids near the gold surface is significantly higher than that in the bulk phase. Cation's tail (the alkyl chain) orients parallel to the surface under all studied conditions. Cation's head (the pyridine ring) orientation varies from parallel to perpendicular, which depends on the temperature and corrugation of the Au(hkl) surface. Interestingly, analysis of simulated mass and number densities revealed that surface corrugation randomizes the cations packing. On smooth Au(111) and Au(100) surfaces, parallel and perpendicular orientations are well distinguished for densely packed cations. While on corrugated Au(110), cations' packing density and order are decreased. Overall, this study explores the adsorption effect of the gold surface on ionic liquids, providing some valuable insights into their behavior on the solid/liquid interface.
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Affiliation(s)
- Qiang Li
- Anhui Province Key Laboratory for Control and Applications of Optoelectronic Information Materials, School of Physics and Electronic Information, Anhui Normal University, Wuhu, 241002, China
- Faculty of Engineering, Anhui Sanlian University, Hefei, 230601, China
| | - Guanglai Zhu
- Anhui Province Key Laboratory for Control and Applications of Optoelectronic Information Materials, School of Physics and Electronic Information, Anhui Normal University, Wuhu, 241002, China
| | - Zhicong Liu
- Anhui Province Key Laboratory for Control and Applications of Optoelectronic Information Materials, School of Physics and Electronic Information, Anhui Normal University, Wuhu, 241002, China
| | - Jianqiang Xu
- Anhui Province Key Laboratory for Control and Applications of Optoelectronic Information Materials, School of Physics and Electronic Information, Anhui Normal University, Wuhu, 241002, China
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2
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Pontoni D, DiMichiel M, Murphy BM, Honkimäki V, Deutsch M. Ordering of ionic liquids at a charged sapphire interface: Evolution with cationic chain length. J Colloid Interface Sci 2024; 661:33-45. [PMID: 38295701 DOI: 10.1016/j.jcis.2024.01.126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2023] [Revised: 01/09/2024] [Accepted: 01/18/2024] [Indexed: 02/27/2024]
Abstract
HYPOTHESIS Room Temperature Ionic Liquids (RTILs) bulk's molecular layering dominates their structure also at the RTIL/sapphire interface, increasing the layer spacing with the cationic alkyl chain length n. However, the negatively-charged sapphire surface compresses the layers, increases the layering range, and affects the intra-layer structure in yet unknown ways. EXPERIMENTS X-ray reflectivity (XR) off the RTIL/sapphire interface, for a broad homologous RTIL series 1-alkyl-3-methylimidazolium bis(trifluoromethansulfonyl)imide, hitherto unavailable for any RTIL. FINDINGS RTIL layers against the sapphire, exhibit two spacings: da and db. da is n-varying, follows the behavior of the bulk spacing but exhibits a downshift, thus showing significant layer compression, and over twofold polar slab thinning. The latter suggests exclusion of anions from the interfacial region due to the negative sapphire charging by x-ray-released electrons. The layering range is larger than the bulk's. db is short and near n-independent, suggesting polar moieties' layering, the coexistence mode of which with the da-spaced layering is unclear. Comparing the present layering with the bulk's and the RTIL/air interface's provides insight into the Coulomb and dispersion interaction balance dominating the RTIL's structure and the impact thereon of the presence of a charged solid interface.
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Affiliation(s)
- Diego Pontoni
- ESRF - The European Synchrotron, 71 Avenue des Martyrs, 38043 Grenoble, France
| | - Marco DiMichiel
- ESRF - The European Synchrotron, 71 Avenue des Martyrs, 38043 Grenoble, France
| | - Bridget M Murphy
- Institute of Experimental and Applied Physics, Kiel University, Kiel D-24098, Germany; Ruprecht-Haensel Laboratory, Kiel University, Kiel D-24118, Germany
| | - Veijo Honkimäki
- ESRF - The European Synchrotron, 71 Avenue des Martyrs, 38043 Grenoble, France
| | - Moshe Deutsch
- Physics Dept. & Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat Gan, Israel.
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3
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Manasi I, Schweins R, Ma K, Edler KJ. Nanostructure in Amphiphile-Based Deep Eutectic Solvents. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:16776-16784. [PMID: 37965899 PMCID: PMC10688184 DOI: 10.1021/acs.langmuir.3c02105] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Revised: 11/01/2023] [Accepted: 11/02/2023] [Indexed: 11/16/2023]
Abstract
Deep eutectic solvents (DESs) are an emerging class of modern, often "green" solvents with unique properties. Recently, a deep eutectic system based on amphiphilic surfactant N-alkyl-N,N-dimethyl-3-ammonio-1-propanesulfonate (C12 & C14 sulfobetaine) and (1S)-(+)-10-camphor-sulfonic acid in the molar ratio 1:1.5 has been reported. Nanostructuring can be expected in this DES due to the nature of the components. In this work, we have investigated the native nanostructure in the DES comprising C12-C18 alkyl chain sulfobetaines with camphor sulfonic acid and how it interacts with polar and nonpolar species, water and dodecane, respectively, using small angle neutron scattering. By using contrast variation to highlight the relative position of the solvent components and additives, we can resolve the structure of the solvent and how it changes upon interaction with water and dodecane. Scattering from the neat DES shows structures corresponding to the self-assembly of sulfobetaines; the size of the structure increases as the alkyl chain length of the sulfobetaines increases. Water and dodecane interact, respectively, with the hydrophilic and hydrophobic moieties in the DES structure, primarily the sulfobetaine, thereby swelling and solvating the entire structure. The extent of the shift of the peak position, and the swelling, depend on concentration of the additive. The solution phase organization and the interaction of polar and nonpolar species as observed here, have the potential to affect the ordering of inorganic or polymeric materials grown in such solvents, paving new avenues for templating applications.
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Affiliation(s)
- Iva Manasi
- Department
of Chemistry, University of Bath, Claverton Down, Bath BA2 7AX, U.K.
| | - Ralf Schweins
- Institut
Laue-Langevin, CS 20156, Grenoble Cedex 9 38042, France
| | - Kun Ma
- ISIS
Neutron and Muon Source, STFC, Rutherford
Appleton Laboratory, Didcot OX11 0QX, U.K.
| | - Karen J. Edler
- Department
of Chemistry, University of Bath, Claverton Down, Bath BA2 7AX, U.K.
- Department
of Chemistry, Centre for Analysis and Synthesis (CAS), Lund University, Lund 221 00, Sweden
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4
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Dolynchuk O, Thurn‐Albrecht T. On Thermodynamics and Kinetics of Interface‐Induced Crystallization in Polymers. MACROMOL CHEM PHYS 2023. [DOI: 10.1002/macp.202200455] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Affiliation(s)
- Oleksandr Dolynchuk
- Experimental Polymer Physics Institute of Physics Martin Luther University Halle‐Wittenberg D‐06120 Halle Germany
| | - Thomas Thurn‐Albrecht
- Experimental Polymer Physics Institute of Physics Martin Luther University Halle‐Wittenberg D‐06120 Halle Germany
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5
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Karunaratne W, Zhao M, Castner EW, Margulis CJ. Vacuum Interfacial Structure and X-ray Reflectivity of Imidazolium-Based Ionic Liquids with Perfluorinated Anions from a Theory and Simulations Perspective. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2022; 126:13936-13945. [PMID: 36017361 PMCID: PMC9394757 DOI: 10.1021/acs.jpcc.2c03311] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Revised: 07/22/2022] [Indexed: 06/15/2023]
Abstract
We report studies of the vacuum interfacial structure of a series of 1-methyl-3-alkylimidazolium bis(perfluoroalkanesulfonyl)imide ionic liquids (ILs) and predict and explain their Fresnel-normalized X-ray reflectivity. To better interpret the results, we use a theory we recently developed dubbed "the peaks and antipeaks analysis of reflectivity" which splits the overall signal into that of different pair subcomponents. Whereas the overall reflectivity signal is not very informative, the peak and trough intensities for the pair subcomponents provide rich information for analysis. When species containing cationic alkyl or anionic fluoroalkyl tails are present at the interface, a tail layer is found next to a vacuum, and this tail layer can be composed of both alkyl and fluoroalkyl moieties. To maintain the positive-negative alternation of charged groups, alkyl and fluoroalkyl tails must necessarily be nearby and cannot segregate. Charged groups are found in the subsequent layer just below the interface and arranged to achieve lateral charge neutrality. In general, fluctuations at and away from the interface are based on polarity (i.e., heads and tails) and not on charge; when there are no significant alkyl or fluoroalkyl moieties in the IL, atomic density fluctuations away from the interface are small and appear to exist for the purpose of achieving lateral charge balance. For all the systems reported here, the persistence length of density fluctuations does not go beyond ∼7 nm.
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Affiliation(s)
| | - Man Zhao
- Department
of Chemistry and Chemical Biology, Rutgers,
The State University of New Jersey, Piscataway, New Jersey 08854, United States
| | - Edward W. Castner
- Department
of Chemistry and Chemical Biology, Rutgers,
The State University of New Jersey, Piscataway, New Jersey 08854, United States
| | - Claudio J. Margulis
- Department
of Chemistry, University of Iowa, Iowa City, Iowa 52242, United States
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6
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Liu M, Liu H, Peng H. Orientational wetting and dynamical correlations toward glass transition on the surface of imidazolium-based ionic liquids. J Chem Phys 2022; 157:034701. [DOI: 10.1063/5.0099845] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Surface induces many fascinating physical phenomena, such as dynamic acceleration, surface anchoring, and orientational wetting, and, thus, is of great interest to study. Here, we report classic molecular dynamics simulations on the free-standing surface of imidazolium-based ionic liquids (ILs) [C4mim][PF6] and [C10mim][PF6]. On [C10mim][PF6] surface, a significant orientational wetting is observed, with the wetting strength showing a diverging tendency. Depth of the wetting was captured from the density and orientational order profile by a static length, which remarkably increases below the temperature Tstat upon cooling down. The dynamical correlation length that measures the distance of surface-dynamics acceleration into the bulk was characterized via the spatial-dependent mobility. The translational correlation exhibits a similar drastic increment at Tstat, while the rotational correlation drastically increases at a lower temperature Trot. We connect these results to the dynamics in bulk liquids, by finding Tstat and Trot that correspond to the onset temperatures where the liquids become cooperative for translational and rotational relaxation, respectively. This signifies the importance of collective dynamics in the bulk on the orientational wetting and surface dynamics in the ILs.
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Affiliation(s)
- Min Liu
- School of Materials Science and Engineering, Central South University, 932 South Lushan Rd., 410083 Changsha, China
| | - Huashan Liu
- School of Materials Science and Engineering, Central South University, 932 South Lushan Rd., 410083 Changsha, China
| | - Hailong Peng
- School of Materials Science and Engineering, Central South University, 932 South Lushan Rd., 410083 Changsha, China
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7
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Pontoni D, DiMichiel M, Deutsch M. Binary mixtures of homologous room-temperature ionic liquids: Nanoscale structure evolution with alkyl lengths’ difference. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.118874] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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8
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Zhang S, Baba H, Sakka T, Nishi N. Interfacial Viscosity and Ionic Reorientation Probed Using Electrochemical Surface Plasmon Resonance at the Gold Electrode Interface of Ionic Liquids. J Electroanal Chem (Lausanne) 2022. [DOI: 10.1016/j.jelechem.2022.116299] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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9
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Pontoni D, DiMichiel M, Deutsch M. Binary mixtures of homologous room-temperature ionic liquids: Temperature and composition evolution of the nanoscale structure. J Mol Liq 2021. [DOI: 10.1016/j.molliq.2021.116587] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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10
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Zhang S, Nishi N, Katakura S, Sakka T. Evaluation of static differential capacitance at the [C 4mim +][TFSA -]/electrode interface using molecular dynamics simulation combined with electrochemical surface plasmon resonance measurements. Phys Chem Chem Phys 2021; 23:13905-13917. [PMID: 34132289 DOI: 10.1039/d1cp01435h] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Molecular dynamic (MD) simulations have been performed for 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amide ([C4mim+][TFSA-]), an ionic liquid (IL), on a charged graphene electrode to achieve the quantitative analysis of the static differential capacitance using the electrochemical surface plasmon resonance (ESPR). The MD simulations have provided the surface charge density on the electrode and ionic distributions in the electric double layer, both of which are indispensable for the evaluation of static differential capacitance using ESPR but are difficult to be measured by experimental techniques. This approach has allowed the quantitative analysis and explanation of the SPR angle shift in ESPR. The major contribution to the SPR angle shift is found to be the change in ionic concentrations of the first ionic layer on the electrode, owing to higher polarizabilities of ions in the first ionic layer than those in the overlayers. Moreover, the ionic orientation on the electrode and ionic multilayer structure have also been investigated in detail. The butyl group of C4mim+ in the first ionic layer is found to provide extra room for C4mim+ in the second ionic layer but exclude TFSA-, which affects the interval and regularity of ionic multilayers.
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Affiliation(s)
- Shiwei Zhang
- Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan.
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11
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Deutsch M, Magnussen OM, Haddad J, Pontoni D, Murphy BM, Ocko BM. Comment on "Bi-layering at ionic liquid surfaces: a sum - frequency generation vibrational spectroscopy - and molecular dynamics simulation-based study" by T. Iwahashi, T. Ishiyama, Y. Sakai, A. Morita, D. Kim and Y. Ouchi, Phys. Chem. Chem. Phys., 2020, 22, 12565. Phys Chem Chem Phys 2021; 23:5020-5027. [PMID: 33595568 DOI: 10.1039/d0cp04882h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
This Comment raises several questions concerning the surface structure concluded in the paper referenced in the title. Specifically, that paper ignores previous experiments and simulations which demonstrate for the same ionic liquids depth-decaying, multilayered surface-normal density profiles rather than the claimed molecular mono- or bi-layers. We demonstrate that the claimed structure does not reproduce the measured X-ray reflectivity, which probes directly the surface-normal density profile. The measured reflectivities are found, however, to be well-reproduced by a multilayered density model. These results, and previous experimental and simulation results, cast severe doubt on the validity of the surface structure claimed in the paper referenced in the title.
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Affiliation(s)
- Moshe Deutsch
- Physics Department and Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat Gan 5290002, Israel.
| | - Olaf M Magnussen
- Institute for Experimental and Applied Physics and Ruprecht-Haensel Laboratory, Kiel University, 24118 Kiel, Germany
| | - Julia Haddad
- Physics Department and Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat Gan 5290002, Israel.
| | - Diego Pontoni
- Partnership for Soft Condensed Matter (PSCM), ESRF - The European Synchrotron, 71 Avenue des Martyrs, 38000 Grenoble, France
| | - Bridget M Murphy
- Institute for Experimental and Applied Physics and Ruprecht-Haensel Laboratory, Kiel University, 24118 Kiel, Germany
| | - Benjamin M Ocko
- NSLS-II, Brookhaven National Laboratory, Upton, New York 11973, USA
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12
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Prihoda A, Will J, Duchstein P, Becit B, Lossin F, Schindler T, Berlinghof M, Steinrück HG, Bertram F, Zahn D, Unruh T. Interface between Water-Solvent Mixtures and a Hydrophobic Surface. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:12077-12086. [PMID: 32960065 DOI: 10.1021/acs.langmuir.0c02745] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The mechanism behind the stability of organic nanoparticles prepared by liquid antisolvent (LAS) precipitation without a specific stabilizing agent is poorly understood. In this work, we propose that the organic solvent used in the LAS process rapidly forms a molecular stabilizing layer at the interface of the nanoparticles with the aqueous dispersion medium. To confirm this hypothesis, n-octadecyltrichlorosilane (OTS)-functionalized silicon wafers in contact with water-solvent mixtures were used as a flat model system mimicking the solid-liquid interface of the organic nanoparticles. We studied the equilibrium structure of the interface by X-ray reflectometry (XRR) for water-solvent mixtures (methanol, ethanol, 1-propanol, 2-propanol, acetone, and tetrahydrofuran). The formation of an organic solvent-rich layer at the solid-liquid interface was observed. The layer thickness increases with the organic solvent concentration and correlates with the polar and hydrogen bond fraction of Hansen solubility parameters. We developed a self-consistent adsorption model via complementing adsorption isotherms obtained from XRR data with molecular dynamics simulations.
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Affiliation(s)
- Annemarie Prihoda
- Institute for Crystallography and Structural Physics (ICSP), Friedrich-Alexander-Universität Erlangen-Nürnberg, Staudtstr. 3, 91058 Erlangen, Germany
- Center for Nanoanalysis and Electron Microscopy (CENEM) and Interdisciplinary Center for Nanostructured Films (IZNF), Friedrich-Alexander-Universität Erlangen-Nürnberg, Cauerstr. 3, 91058 Erlangen, Germany
| | - Johannes Will
- Center for Nanoanalysis and Electron Microscopy (CENEM) and Interdisciplinary Center for Nanostructured Films (IZNF), Friedrich-Alexander-Universität Erlangen-Nürnberg, Cauerstr. 3, 91058 Erlangen, Germany
- Lehrstuhl für Werkstoffwissenschaften (Mikro- und Nanostrukturforschung), Friedrich-Alexander-Universität Erlangen-Nürnberg, Cauerstr. 3, 91058 Erlangen, Germany
| | - Patrick Duchstein
- Computer Chemistry Centre (CCC), Friedrich-Alexander-Universität Erlangen-Nürnberg, Nägelsbachstr. 25, 91052 Erlangen, Germany
| | - Bahanur Becit
- Computer Chemistry Centre (CCC), Friedrich-Alexander-Universität Erlangen-Nürnberg, Nägelsbachstr. 25, 91052 Erlangen, Germany
| | - Felix Lossin
- Institute for Crystallography and Structural Physics (ICSP), Friedrich-Alexander-Universität Erlangen-Nürnberg, Staudtstr. 3, 91058 Erlangen, Germany
| | - Torben Schindler
- Institute for Crystallography and Structural Physics (ICSP), Friedrich-Alexander-Universität Erlangen-Nürnberg, Staudtstr. 3, 91058 Erlangen, Germany
| | - Marvin Berlinghof
- Institute for Crystallography and Structural Physics (ICSP), Friedrich-Alexander-Universität Erlangen-Nürnberg, Staudtstr. 3, 91058 Erlangen, Germany
| | - Hans-Georg Steinrück
- Department Chemie, Universität Paderborn, Warburger Straße 100, 33098 Paderborn, Germany
| | | | - Dirk Zahn
- Computer Chemistry Centre (CCC), Friedrich-Alexander-Universität Erlangen-Nürnberg, Nägelsbachstr. 25, 91052 Erlangen, Germany
| | - Tobias Unruh
- Institute for Crystallography and Structural Physics (ICSP), Friedrich-Alexander-Universität Erlangen-Nürnberg, Staudtstr. 3, 91058 Erlangen, Germany
- Center for Nanoanalysis and Electron Microscopy (CENEM) and Interdisciplinary Center for Nanostructured Films (IZNF), Friedrich-Alexander-Universität Erlangen-Nürnberg, Cauerstr. 3, 91058 Erlangen, Germany
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Nishikawa K, Fujii K, Hashimoto Y, Tozaki KI. Unique phase behavior of a room-temperature ionic liquid, trimethylpropylammonium bis(fluorosulfonyl)amide: surface melting and its crystallization. Phys Chem Chem Phys 2020; 22:20634-20642. [PMID: 32966414 DOI: 10.1039/d0cp03073b] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The phase behavior of a representative ammonium-based ionic liquid, trimethylpropylammonium bis(fluorosulfonyl)amide ([N1113][FSA]), was investigated using a laboratory-made differential scanning calorimeter (DSC). The apparatus possesses extremely high sensitivities with stability of ±2 nW in thermal flux and ±1 mK in temperature and a very slow scanning rate of 0.001 mK s-1 in the slowest scanning speed. Besides two ordinary signals from crystallization and melting, a very weak exothermic peak, 1/1000 times that of the main crystallization peak, was observed during the cooling process. The peak was assigned to the crystallization of the surface-melting layer. Both the normal and novel crystallizations occurred during the structural relaxation process. The thickness of the surface-melting layer was estimated to be roughly 70-200 nm. To study the details of the melting processes, DSC experiments were performed with very slow scanning rates (0.02 and 0.03 mK s-1). Two novel endothermic peaks were found in the usual melting trace for the sample with the surface crystallization, and no unusual peaks were observed in the sample without the surface crystallization. We believe that the structure of the surface crystallization phase is different from that of the bulk crystalline phase.
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Affiliation(s)
- Keiko Nishikawa
- Toyota Physical & Chemical Research Institute, Nagakute, Aichi 480-1192, Japan. and Graduate School of Science, Chiba University, Chiba, Chiba 263-8522, Japan
| | - Kozo Fujii
- Graduate School of Science, Chiba University, Chiba, Chiba 263-8522, Japan
| | - Yusuke Hashimoto
- WPI Advanced Institute for Materials Research, Tohoku University, Sendai, Miyagi 980-8577, Japan
| | - Ken-Ichi Tozaki
- Faculty of Education, Chiba University, Chiba, Chiba 263-8522, Japan
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14
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Nishi N, Yamazawa T, Sakka T, Hotta H, Ikeno T, Hanaoka K, Takahashi H. How Viscous Is the Solidlike Structure at the Interface of Ionic Liquids? A Study Using Total Internal Reflection Fluorescence Spectroscopy with a Fluorescent Molecular Probe Sensitive to High Viscosity. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:10397-10403. [PMID: 32787009 DOI: 10.1021/acs.langmuir.0c01528] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Aiming at the evaluation of the viscosity of the interfacial solidlike structure of ionic liquids (ILs), we performed total internal reflection fluorescence (TIRF) spectroscopy for N,N-diethyl-N'-phenyl-rhodamine (Ph-DER), a fluorescent probe that is sensitive to viscosity in a high-viscosity range. TIRF spectra at the glass interface of trioctylmethylammonium bis(nonafluorobutanesulfonyl)amide (TOMAC4C4N), a hydrophobic IL, showed that the fluorescence intensity of Ph-DER increases with the decrease of the evanescence penetration depth, suggesting that there exists a high-viscosity region at the interface. In contrast, glycerol, which is a molecular liquid with a bulk viscosity similar to that of TOMAC4C4N, did not show such a fluorescence increase, supporting that the formation of a highly viscous solidlike structure at the interface is intrinsic to ILs. A model analysis suggested that the high viscous region at the glass interface of TOMAC4C4N is at least twice thicker than the ionic multilayers at the air interface, implying that the solid substrate enhances the ordering of the interfacial structure of ILs. The viscosity at the glass interface of TOMAC4C4N was found to be at least 40 times higher than that of the liquid bulk.
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Affiliation(s)
- Naoya Nishi
- Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University, Kyotodaigakukatsura, Nishikyo-ku, Kyoto 615-8510, Japan
| | - Takashi Yamazawa
- Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University, Kyotodaigakukatsura, Nishikyo-ku, Kyoto 615-8510, Japan
| | - Tetsuo Sakka
- Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University, Kyotodaigakukatsura, Nishikyo-ku, Kyoto 615-8510, Japan
| | - Hiroki Hotta
- Graduate School of Maritime Sciences, Kobe University, 5-1-1 Fukaeminami-machi, Higashinada-ku, Kobe 658-0022, Japan
| | - Takayuki Ikeno
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Kenjiro Hanaoka
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Hiromi Takahashi
- System Instruments Co., Ltd, 776-2, Komiya-machi, Hachioji 192-0031, Tokyo, Japan
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15
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Pontoni D, DiMichiel M, Deutsch M. Nanoscale Structure in Short‐Chain Ionic Liquids. Chemphyschem 2020; 21:1887-1897. [DOI: 10.1002/cphc.202000548] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Indexed: 02/03/2023]
Affiliation(s)
- Diego Pontoni
- Partnership for Soft Condensed Matter (PSCM) ESRF – The European Synchrotron 71 Avenue des Martyrs 38043 Grenoble France
| | - Marco DiMichiel
- ESRF – The European Synchrotron 71 Avenue des Martyrs 38043 Grenoble France
| | - Moshe Deutsch
- Physics Dept. & Institute of Nanotechnology and Advanced Materials Bar-Ilan University Ramat Gan Israel
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16
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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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17
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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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18
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Bader K, Müller C, Molard Y, Baro A, Ehni P, Knelles J, Laschat S. Fluorenone imidazolium salts as novel de Vries materials. RSC Adv 2020; 10:23999-24016. [PMID: 35517358 PMCID: PMC9055108 DOI: 10.1039/d0ra04650g] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Accepted: 06/15/2020] [Indexed: 01/09/2023] Open
Abstract
In ionic liquid crystals (ILCs) tilted mesophases such as SmC required for electro-optic devices are quite rare. We report a design concept that induced the SmC phase and enabled de Vries-like behaviour in ILCs. For this purpose, we synthesized and characterized a library of ILC derivatives ImR(On,Ym)X which consist of a rigid central fluorenone core containing an alkoxy or thioether side chain and connected via a flexible spacer to an imidazolium head group. The mesomorphic properties were studied by differential scanning calorimetry (DSC), polarizing optical microscopy (POM) and X-ray diffraction (XRD). Temperature-dependent measurements of smectic layer spacing d by small-angle X-ray scattering (SAXS) and of optical tilt angles by POM demonstrate that ILCs ImR(On,Ym)X undergo SmA–SmC phase transitions with maximum layer contraction values between 0.4% and 2.1%. The lowest reduction factor R of 0.2 at the reduced temperature T − TAC = −10 K was calculated for Im(O12,S14)Br. Electron density calculations indicated a bilayer structure. Furthermore, temperature dependent emission studies show that self-assembling has a strong influence on the emission intensity of these ILCs. ILCs consisting of cationic head group–spacer–fluorenone central core–side chain show de Vries-like behaviour.![]()
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Affiliation(s)
- Korinna Bader
- Institut für Organische Chemie, Universität Stuttgart Pfaffenwaldring 55 70569 Stuttgart Germany
| | - Carsten Müller
- Institut für Physikalische Chemie, Universität Stuttgart Pfaffenwaldring 55 70569 Stuttgart Germany
| | - Yann Molard
- CNRS, ISCR-UMR 6226, ScanMAT-UMS 2001, University Rennes 35000 Rennes France
| | - Angelika Baro
- Institut für Organische Chemie, Universität Stuttgart Pfaffenwaldring 55 70569 Stuttgart Germany
| | - Philipp Ehni
- Institut für Organische Chemie, Universität Stuttgart Pfaffenwaldring 55 70569 Stuttgart Germany
| | - Jakob Knelles
- Institut für Organische Chemie, Universität Stuttgart Pfaffenwaldring 55 70569 Stuttgart Germany
| | - Sabine Laschat
- Institut für Organische Chemie, Universität Stuttgart Pfaffenwaldring 55 70569 Stuttgart Germany
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19
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Zhang Y, Wu Z, Wang Y, He H, Yu Z. Excess spectroscopy and its applications in the study of solution chemistry. PURE APPL CHEM 2020. [DOI: 10.1515/pac-2020-0107] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Abstract
Characterization of structural heterogeneity of liquid solutions and the pursuit of its nature have been challenging tasks to solution chemists. In the last decade, an emerging method called excess spectroscopy has found applications in this area. The method, combining the merits of molecular spectroscopy and excess thermodynamic functions, shows the ability to enhance the apparent resolution of spectra, provides abundant information concerning solution structures and intermolecular interactions. In this review, the thinking and mathematics of the method, as well as its developments, are presented first. Then, research progress related to the exploration of the method is thoroughly reviewed. The materials are classified into two parts, small-molecular solutions and ionic liquid solutions. Finally, potential challenges and the perspective for further development of the method are discussed.
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Affiliation(s)
- Yaqin Zhang
- CAS Key Laboratory of Green Process and Engineering, State Key Laboratory of Multiphase Complex Systems, Beijing Key Laboratory of Ionic Liquids Clean Process , Institute of Process Engineering, Chinese Academy of Sciences , Beijing 100190 , P.R. China
| | - Zhiwei Wu
- CAS Key Laboratory of Green Process and Engineering, State Key Laboratory of Multiphase Complex Systems, Beijing Key Laboratory of Ionic Liquids Clean Process , Institute of Process Engineering, Chinese Academy of Sciences , Beijing 100190 , P.R. China
| | - Yaqian Wang
- MOE Key Laboratory of Bioorganic Phosphorous Chemistry and Chemical Biology, Department of Chemistry , Tsinghua University , Beijing 100084 , P.R. China
| | - Hongyan He
- CAS Key Laboratory of Green Process and Engineering, State Key Laboratory of Multiphase Complex Systems, Beijing Key Laboratory of Ionic Liquids Clean Process , Institute of Process Engineering, Chinese Academy of Sciences , Beijing 100190 , P.R. China
| | - Zhiwu Yu
- MOE Key Laboratory of Bioorganic Phosphorous Chemistry and Chemical Biology, Department of Chemistry , Tsinghua University , Beijing 100084 , P.R. China
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20
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21
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Narayanan T, Konovalov O. Synchrotron Scattering Methods for Nanomaterials and Soft Matter Research. MATERIALS (BASEL, SWITZERLAND) 2020; 13:E752. [PMID: 32041363 PMCID: PMC7040635 DOI: 10.3390/ma13030752] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/14/2019] [Revised: 01/29/2020] [Accepted: 01/31/2020] [Indexed: 12/17/2022]
Abstract
This article aims to provide an overview of broad range of applications of synchrotron scattering methods in the investigation of nanoscale materials. These scattering techniques allow the elucidation of the structure and dynamics of nanomaterials from sub-nm to micron size scales and down to sub-millisecond time ranges both in bulk and at interfaces. A major advantage of scattering methods is that they provide the ensemble averaged information under in situ and operando conditions. As a result, they are complementary to various imaging techniques which reveal more local information. Scattering methods are particularly suitable for probing buried structures that are difficult to image. Although, many qualitative features can be directly extracted from scattering data, derivation of detailed structural and dynamical information requires quantitative modeling. The fourth-generation synchrotron sources open new possibilities for investigating these complex systems by exploiting the enhanced brightness and coherence properties of X-rays.
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22
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Pontoni D, DiMichiel M, Deutsch M. Temperature evolution of the bulk nano-structure in a homologous series of room temperature ionic liquids. J Mol Liq 2020. [DOI: 10.1016/j.molliq.2019.112280] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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23
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Weiss H, Cheng HW, Mars J, Li H, Merola C, Renner FU, Honkimäki V, Valtiner M, Mezger M. Structure and Dynamics of Confined Liquids: Challenges and Perspectives for the X-ray Surface Forces Apparatus. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:16679-16692. [PMID: 31614087 PMCID: PMC6933819 DOI: 10.1021/acs.langmuir.9b01215] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2019] [Revised: 10/15/2019] [Indexed: 05/21/2023]
Abstract
The molecular-scale structure and dynamics of confined liquids has increasingly gained relevance for applications in nanotechnology. Thus, a detailed knowledge of the structure of confined liquids on molecular length scales is of great interest for fundamental and applied sciences. To study confined structures under dynamic conditions, we constructed an in situ X-ray surface forces apparatus (X-SFA). This novel device can create a precisely controlled slit-pore confinement down to dimensions on the 10 nm scale by using a cylinder-on-flat geometry for the first time. Complementary structural information can be obtained by simultaneous force measurements and X-ray scattering experiments. The in-plane structure of liquids parallel to the slit pore and density profiles perpendicular to the confining interfaces are studied by X-ray scattering and reflectivity. The normal load between the opposing interfaces can be modulated to study the structural dynamics of confined liquids. The confinement gap distance is tracked simultaneously with nanometer precision by analyzing optical interference fringes of equal chromatic order. Relaxation processes can be studied by driving the system out of equilibrium by shear stress or compression/decompression cycles of the slit pore. The capability of the new device is demonstrated on the liquid crystal 4'-octyl-4-cyano-biphenyl (8CB) in its smectic A (SmA) mesophase. Its molecular-scale structure and orientation confined in 100 nm to 1.7 μm slit pores was studied under static and dynamic nonequilibrium conditions.
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Affiliation(s)
- Henning Weiss
- Max
Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Hsiu-Wei Cheng
- Institute
of Applied Physics, Vienna Institute of
Technology, Wiedner Hauptstrasse 8-10/E134, 1040 Wien, Austria
| | - Julian Mars
- Max
Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
- Institute
of Physics, Johannes Gutenberg University
Mainz, 55128 Mainz, Germany
| | - Hailong Li
- Max
Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Claudia Merola
- Institute
of Applied Physics, Vienna Institute of
Technology, Wiedner Hauptstrasse 8-10/E134, 1040 Wien, Austria
| | - Frank Uwe Renner
- Institute
for Materials Research, Hasselt University, 3590 Diepenbeek, Belgium
| | - Veijo Honkimäki
- ESRF-European
Synchrotron Radiation Facility, Avenue des Martyrs 71, 38043 Grenoble, Cedex 9, France
| | - Markus Valtiner
- Institute
of Applied Physics, Vienna Institute of
Technology, Wiedner Hauptstrasse 8-10/E134, 1040 Wien, Austria
- Max-Planck-Institut
für Eisenforschung GmbH, Max-Planck-Strasse 1, 40237 Düsseldorf, Germany
| | - Markus Mezger
- Max
Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
- Institute
of Physics, Johannes Gutenberg University
Mainz, 55128 Mainz, Germany
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24
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Martins MAR, Carvalho PJ, Alves D, Dariva C, Costa MC, Ferreira RAS, André PS, Morgado P, Pinho SP, Filipe EJM, Coutinho JAP. Surface crystallization of ionic liquid crystals. Phys Chem Chem Phys 2019; 21:17792-17800. [PMID: 31372606 DOI: 10.1039/c9cp03947c] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The evidence for surface crystallization in ionic liquids is scarce. The existing reports seem to be contradictory as for its driving forces, since in the two compounds investigated in the literature, the contribution of coloumbic and van der Waals forces is very different. In this work 1-dodecyl-3-methylimidazolium tetrafluoroborate was studied and its surface crystallization characterized by surface tension, ellipsometry and optical microscopy. The results obtained seem to reconcile previous observations, and it was further shown, using the same techniques, that this phenomenon is prevalent in other ionic liquids. MD simulation results illustrate the different possibilities of organization, providing reasonable models to rationalize the experimental observations.
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25
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Curry JN, Shaw SK. Thermotropic Phase Transitions in Butyltrimethylammonium Bis(trifluoromethylsulfonyl)imide Ionic Liquids are Dependent on Heat Flux. J Phys Chem B 2019; 123:4757-4765. [DOI: 10.1021/acs.jpcb.9b01650] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Jaclyn N. Curry
- Department of Chemistry, University of Iowa, Iowa City, Iowa 52245, United States
| | - Scott K. Shaw
- Department of Chemistry, University of Iowa, Iowa City, Iowa 52245, United States
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26
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Akutsu-Suyama K, Cagnes M, Tamura K, Kanaya T, Darwish TA. Controlled deuterium labelling of imidazolium ionic liquids to probe the fine structure of the electrical double layer using neutron reflectometry. Phys Chem Chem Phys 2019; 21:17512-17516. [DOI: 10.1039/c9cp02479d] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The electrical double layer structure formed in an ionic liquid electrolyte was determined by combining the neutron reflectivity and deuterium labelling techniques.
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Affiliation(s)
- Kazuhiro Akutsu-Suyama
- Neutron Science and Technology Center
- Comprehensive Research Organization for Science and Society (CROSS)
- Japan
| | - Marina Cagnes
- Australian Centre for Neutron Scattering and National Deuteration Facility
- Australian Nuclear Science and Technology Organisation
- Kirrawee DC
- Australia
| | - Kazuhisa Tamura
- Quantum Beam Science Center
- Japan Atomic Energy Agency
- Hyogo 679-5148
- Japan
| | | | - Tamim A. Darwish
- Australian Centre for Neutron Scattering and National Deuteration Facility
- Australian Nuclear Science and Technology Organisation
- Kirrawee DC
- Australia
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27
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Cheng HW, Weiss H, Stock P, Chen YJ, Reinecke CR, Dienemann JN, Mezger M, Valtiner M. Effect of Concentration on the Interfacial and Bulk Structure of Ionic Liquids in Aqueous Solution. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:2637-2646. [PMID: 29356544 DOI: 10.1021/acs.langmuir.7b03757] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Bio and aqueous applications of ionic liquids (IL) such as catalysis in micelles formed in aqueous IL solutions or extraction of chemicals from biologic materials rely on surface-active and self-assembly properties of ILs. Here, we discuss qualitative relations of the interfacial and bulk structuring of a water-soluble surface-active IL ([C8MIm][Cl]) on chemically controlled surfaces over a wide range of water concentrations using both force probe and X-ray scattering experiments. Our data indicate that IL structuring evolves from surfactant-like surface adsorption at low IL concentrations, to micellar bulk structure adsorption above the critical micelle concentration, to planar bilayer formation in ILs with <1 wt % of water and at high charging of the surface. Interfacial structuring is controlled by mesoscopic bulk structuring at high water concentrations. Surface chemistry and surface charges decisively steer interfacial ordering of ions if the water concentration is low and/or the surface charge is high. We also demonstrate that controlling the interfacial forces by using self-assembled monolayer chemistry allows tuning of interfacial structures. Both the ratio of the head group size to the hydrophobic tail volume as well as the surface charging trigger the bulk structure and offer a tool for predicting interfacial structures. Based on the applied techniques and analyses, a qualitative prediction of molecular layering of ILs in aqueous systems is possible.
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Affiliation(s)
- H-W Cheng
- Department for Interface Chemistry and Surface Engineering, Max Planck Institut für Eisenforschung GmbH , 40237 Düsseldorf, Germany
- Institute of Applied Physics, Vienna University of Technology , A-1040 Vienna, Austria
| | - H Weiss
- Max Planck Institute for Polymer Research , 55128 Mainz, Germany
| | - P Stock
- Department for Interface Chemistry and Surface Engineering, Max Planck Institut für Eisenforschung GmbH , 40237 Düsseldorf, Germany
| | - Y-J Chen
- Department for Interface Chemistry and Surface Engineering, Max Planck Institut für Eisenforschung GmbH , 40237 Düsseldorf, Germany
| | - C R Reinecke
- Department for Interface Chemistry and Surface Engineering, Max Planck Institut für Eisenforschung GmbH , 40237 Düsseldorf, Germany
| | - J-N Dienemann
- Department for Interface Chemistry and Surface Engineering, Max Planck Institut für Eisenforschung GmbH , 40237 Düsseldorf, Germany
| | - M Mezger
- Max Planck Institute for Polymer Research , 55128 Mainz, Germany
- Institute of Physics, Johannes Gutenberg University Mainz , 55128 Mainz, Germany
| | - M Valtiner
- Department for Interface Chemistry and Surface Engineering, Max Planck Institut für Eisenforschung GmbH , 40237 Düsseldorf, Germany
- Institute of Applied Physics, Vienna University of Technology , A-1040 Vienna, Austria
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28
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Haddad J, Pontoni D, Murphy BM, Festersen S, Runge B, Magnussen OM, Steinrück HG, Reichert H, Ocko BM, Deutsch M. Surface structure evolution in a homologous series of ionic liquids. Proc Natl Acad Sci U S A 2018; 115:E1100-E1107. [PMID: 29358372 PMCID: PMC5819424 DOI: 10.1073/pnas.1716418115] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Interfaces of room temperature ionic liquids (RTILs) are important for both applications and basic science and are therefore intensely studied. However, the evolution of their interface structure with the cation's alkyl chain length [Formula: see text] from Coulomb to van der Waals interaction domination has not yet been studied for even a single broad homologous RTIL series. We present here such a study of the liquid-air interface for [Formula: see text], using angstrom-resolution X-ray methods. For [Formula: see text], a typical "simple liquid" monotonic surface-normal electron density profile [Formula: see text] is obtained, like those of water and organic solvents. For [Formula: see text], increasingly more pronounced nanoscale self-segregation of the molecules' charged moieties and apolar chains yields surface layering with alternating regions of headgroups and chains. The layering decays into the bulk over a few, to a few tens, of nanometers. The layering periods and decay lengths, their linear [Formula: see text] dependence, and slopes are discussed within two models, one with partial-chain interdigitation and the other with liquid-like chains. No surface-parallel long-range order is found within the surface layer. For [Formula: see text], a different surface phase is observed above melting. Our results also impact general liquid-phase issues like supramolecular self-aggregation and bulk-surface structure relations.
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Affiliation(s)
- Julia Haddad
- Physics Department, Bar-Ilan University, Ramat Gan 5290002, Israel
- Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat Gan 5290002, Israel
| | - Diego Pontoni
- European Synchrotron Radiation Facility, The European Synchrotron and Partnership for Soft Condensed Matter (PSCM), 38000 Grenoble, France
| | - Bridget M Murphy
- Institute for Experimental and Applied Physics, Kiel University, 24118 Kiel, Germany
- Ruprecht Haensel Laboratory, Kiel University, 24098 Kiel, Germany
| | - Sven Festersen
- Institute for Experimental and Applied Physics, Kiel University, 24118 Kiel, Germany
| | - Benjamin Runge
- Institute for Experimental and Applied Physics, Kiel University, 24118 Kiel, Germany
| | - Olaf M Magnussen
- Institute for Experimental and Applied Physics, Kiel University, 24118 Kiel, Germany
- Ruprecht Haensel Laboratory, Kiel University, 24098 Kiel, Germany
| | - Hans-Georg Steinrück
- Stanford Synchrotron Radiation Laboratory (SSRL) Materials Science Division, Stanford Linear Accelerator Center (SLAC) National Accelerator Laboratory, Menlo Park, CA 94025
| | - Harald Reichert
- European Synchrotron Radiation Facility, The European Synchrotron, 38000 Grenoble, France
| | - Benjamin M Ocko
- National Synchrotron Light Source II (NSLS-II), Brookhaven National Laboratory, Upton, NY 11973
| | - Moshe Deutsch
- Physics Department, Bar-Ilan University, Ramat Gan 5290002, Israel;
- Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat Gan 5290002, Israel
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