1
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Marlow JB, Atkin R, Warr GG. How Does Nanostructure in Ionic Liquids and Hybrid Solvents Affect Surfactant Self-Assembly? J Phys Chem B 2023; 127:1490-1498. [PMID: 36786772 DOI: 10.1021/acs.jpcb.2c07458] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/15/2023]
Abstract
Ionic liquids (ILs) have recently emerged as novel classes of solvents that support surfactant self-assembly into micelles, liquid crystals, and microemulsions. Their low volatility and wide liquid stability ranges make them attractive for many diverse applications, especially in extreme environments. However, the number of possible ion combinations makes systematic investigations both challenging and rare; this is further amplified when mixtures are considered, whether with water or other H-bonding components such as those found in deep eutectics. In this Perspective we examine what factors determine amphiphilicity, solvophobicity and solvophilicity, in ILs and related exotic environments, in what ways these differ from water, and how the underlying nanostructure of the liquid itself affects the formation and structure of micelles and other self-assembled materials.
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Affiliation(s)
- Joshua B Marlow
- School of Chemistry and Sydney Nano Institute, The University of Sydney, Sydney, NSW 2006, Australia
| | - Rob Atkin
- School of Molecular Sciences, The University of Western Australia, Perth, Western Australia 6009, Australia
| | - Gregory G Warr
- School of Chemistry and Sydney Nano Institute, The University of Sydney, Sydney, NSW 2006, Australia
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2
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Shi L, McMillan JR, Yu D, Chen X, Tucker CJ, Wasserman E, Mohler C, Chen Z. Effect of Surfactant Concentration and Hydrophobicity on the Ordering of Water at a Silica Surface. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:10806-10817. [PMID: 34455791 DOI: 10.1021/acs.langmuir.1c01731] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The performance of nonionic surfactants is mediated by the interfacial interactions at the solid-liquid interface. Here we applied sum frequency generation (SFG) vibrational spectroscopy to probe the molecular structure of the silica-nonionic surfactant solution interface in situ, supplemented by quartz crystal microbalance with dissipation monitoring (QCM-D) and molecular dynamics (MD) simulations. The combined studies elucidated the effects of nonionic surfactant solution concentration, surfactant composition, and rinsing on the silica-surfactant solution interfacial structure. The nonionic surfactants studied include ethylene-oxide (EO) and butylene oxide (BO) components with different ratios. It was found that the CH groups of the surfactants at the silica-surfactant solution interfaces are disordered, but the interfacial water molecules are ordered, generating strong SFG OH signals. Solutions with higher concentrations of surfactant lead to a slightly higher amount of adsorbed surfactant at the silica interface, resulting in more water molecules being ordered at the interface, or a higher ordering of water molecules at the interface, or both. MD simulation results indicated that the nonionic surface molecules preferentially adsorb onto silanol sites on silica. A surfactant with a higher EO/BO ratio leads to more water molecules being ordered and a higher degree of ordering of water molecules at the silica-surfactant solution interface, exhibiting stronger SFG OH signal, although less material is adsorbed according to the QCM-D data. A thin layer of surfactants remained on the silica surface after multiple water rinses. To the best of our knowledge, this is the first time the combined approaches of SFG, QCM-D and MD simulation techniques have been applied to study nonionic surfactants at the silica-solution interface, which enhances our understanding on the interfacial interactions between nonionic surfactants, water and silica. The knowledge obtained from this study can be helpful to design the optimal surfactant concentration and composition for future applications.
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Affiliation(s)
- Lirong Shi
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Janet R McMillan
- Core R&D, The Dow Chemical Company, Midland, Michigan 48674, United States
| | - Decai Yu
- Core R&D, The Dow Chemical Company, Midland, Michigan 48674, United States
| | - Xiaoyun Chen
- Core R&D, The Dow Chemical Company, Midland, Michigan 48674, United States
| | | | - Eric Wasserman
- Dow Home & Personal Care, The Dow Chemical Company, Collegeville, Pennsylvania 19426, United States
| | - Carol Mohler
- Core R&D, The Dow Chemical Company, Midland, Michigan 48674, United States
| | - Zhan Chen
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
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3
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Gawali SL, Barick KC, Aswal VK, Basu M, Hassan PA. Altering the X-ray Scattering Contrast of Triton X-100 Micelles and Its Trapping in a Supercooled Solvent. J Phys Chem B 2020; 124:3418-3427. [PMID: 32239938 DOI: 10.1021/acs.jpcb.9b11952] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The structure of core-shell micelles formed by nonionic surfactant Triton X-100 (TX-100) in a supercooled glucose-urea melt is investigated by contrast variation small-angle X-ray scattering (SAXS), small angle neutron scattering (SANS), and HR-TEM. Cooling a molten mixture of glucose-urea (weight ratio of 3:2) to room temperature yields a supercooled solvent without crystallization that can be used for trapping micelles of TX-100. By use of a combination of water and glucose-urea mixture at different proportions as solvent for micellization, the scattering length density (SLD) of the solvent can be tuned to match the shell contrast of the micelles. A systematic analysis of SAXS and SANS data with different SLD of solvent permits a quantitative evaluation of electron density profile of micelles in different matrices. The core of TX-100 micelles shows significant swelling in glucose-urea melt, as compared to that in water. The dimension and morphology of micelles were evaluated by scattering techniques and HR-TEM. Dynamic light scattering (DLS) studies suggest that, unlike micelles in water, the diffusion of micelles in supercooled glucose-urea melt decreased by several orders of magnitude.
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Affiliation(s)
- Santosh L Gawali
- Chemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085, India.,Training School Complex, Homi Bhabha National Institute, Anushaktinagar, Mumbai 400 094, India
| | - Kanhu C Barick
- Chemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085, India.,Training School Complex, Homi Bhabha National Institute, Anushaktinagar, Mumbai 400 094, India
| | - Vinod K Aswal
- Training School Complex, Homi Bhabha National Institute, Anushaktinagar, Mumbai 400 094, India.,Solid State Physics Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085, India
| | - M Basu
- Chemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085, India.,Training School Complex, Homi Bhabha National Institute, Anushaktinagar, Mumbai 400 094, India
| | - Puthusserickal A Hassan
- Chemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085, India.,Training School Complex, Homi Bhabha National Institute, Anushaktinagar, Mumbai 400 094, India
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4
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Tang F, Ohto T, Hasegawa T, Bonn M, Nagata Y. π+–π+ stacking of imidazolium cations enhances molecular layering of room temperature ionic liquids at their interfaces. Phys Chem Chem Phys 2017; 19:2850-2856. [DOI: 10.1039/c6cp07034e] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The interfacial structure of room temperature ionic liquids (RTILs) is governed by the competing effects of the randomization due to the molecular polarizability and the ordered structure stabilized by π+–π+ interactions between the cationic molecules of RTILs.
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Affiliation(s)
- Fujie Tang
- International Center for Quantum Materials
- Peking University
- Beijing 100871
- China
- Max-Planck Institute for Polymer Research
| | - Tatsuhiko Ohto
- Graduate School of Engineering Science
- Osaka University
- Toyonaka
- Japan
| | - Taisuke Hasegawa
- Department of Chemistry
- Graduate School of Science
- Kyoto University
- Kyoto 606-8502
- Japan
| | - Mischa Bonn
- Max-Planck Institute for Polymer Research
- Mainz
- Germany
| | - Yuki Nagata
- Max-Planck Institute for Polymer Research
- Mainz
- Germany
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5
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Greaves TL, Drummond CJ. Protic Ionic Liquids: Evolving Structure-Property Relationships and Expanding Applications. Chem Rev 2015; 115:11379-448. [PMID: 26426209 DOI: 10.1021/acs.chemrev.5b00158] [Citation(s) in RCA: 498] [Impact Index Per Article: 55.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Tamar L Greaves
- School of Applied Sciences, College of Science, Engineering and Health, RMIT University , GPO Box 2476, Melbourne, Victoria 3001, Australia
| | - Calum J Drummond
- School of Applied Sciences, College of Science, Engineering and Health, RMIT University , GPO Box 2476, Melbourne, Victoria 3001, Australia
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6
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Affiliation(s)
- Robert Hayes
- Discipline
of Chemistry, The University of Newcastle, NSW 2308, Callaghan, Australia
| | - Gregory G. Warr
- School
of Chemistry, The University of Sydney, NSW 2006, Sydney, Australia
| | - Rob Atkin
- Discipline
of Chemistry, The University of Newcastle, NSW 2308, Callaghan, Australia
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7
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Li H, Atkin R, Page AJ. Combined friction force microscopy and quantum chemical investigation of the tribotronic response at the propylammonium nitrate–graphite interface. Phys Chem Chem Phys 2015; 17:16047-52. [DOI: 10.1039/c5cp01952d] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The energetic origins of the variation in friction with potential at the propylammonium nitrate–graphite interface are revealed using friction force microscopy (FFM) in combination with quantum chemical simulations.
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Affiliation(s)
- H. Li
- Newcastle Institute for Energy and Resources
- The University of Newcastle
- Callaghan
- Australia
| | - R. Atkin
- Newcastle Institute for Energy and Resources
- The University of Newcastle
- Callaghan
- Australia
| | - A. J. Page
- Newcastle Institute for Energy and Resources
- The University of Newcastle
- Callaghan
- Australia
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8
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Sweeney J, Webber GB, Rutland MW, Atkin R. Effect of ion structure on nanoscale friction in protic ionic liquids. Phys Chem Chem Phys 2014; 16:16651-8. [DOI: 10.1039/c4cp02320j] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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9
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Ehmann HA, Baumgartner R, Kunert B, Zimmer A, Roblegg E, Werzer O. Morphologies of Phenytoin Crystals at Silica Model Surfaces: Vapor Annealing versus Drop Casting. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2014; 118:12855-12861. [PMID: 24966892 PMCID: PMC4065161 DOI: 10.1021/jp502330e] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2014] [Revised: 05/27/2014] [Indexed: 05/11/2023]
Abstract
The controlled preparation of different crystal morphologies with varying preferential orientation with respect to the substrate is of crucial importance in many fields of applications. In this work, the controlled preparation of different phenytoin morphologies and the dependency of the preferential orientation of those crystallites is related with the preparation method (solvent annealing vs drop casting), as well as the physical-chemical interaction with the solvents in use. While solvent annealing induces the formation of particular structures that are partially dewetted, the drop casting technique from various solvent results in the formation of needle-like and elongated structures, with each having a distinct morphology. The morphologies are explained via the Hansen solubility parameters and correlated with the solvent vapor pressures. X-ray diffraction experiments reveal preferential orientations with respect to the solid substrate and indicate the surface-mediated stabilization of an unknown polymorph of phenytoin with an elongated unit cell in the b-axis.
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Affiliation(s)
- Heike
M. A. Ehmann
- Institute
of Pharmaceutical Science, Department of Pharmaceutical Technology, University of Graz, 8010 Graz, Austria
| | | | - Birgit Kunert
- Institute
for Solid State Physics, Graz University
of Technology, 8010 Graz, Austria
| | - Andreas Zimmer
- Institute
of Pharmaceutical Science, Department of Pharmaceutical Technology, University of Graz, 8010 Graz, Austria
| | - Eva Roblegg
- Institute
of Pharmaceutical Science, Department of Pharmaceutical Technology, University of Graz, 8010 Graz, Austria
- Research Center
Pharmaceutical Engineering GmbH, 8010 Graz, Austria
| | - Oliver Werzer
- Institute
of Pharmaceutical Science, Department of Pharmaceutical Technology, University of Graz, 8010 Graz, Austria
- E-mail:
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10
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Shear dependent viscosity of poly(ethylene oxide) in two protic ionic liquids. J Colloid Interface Sci 2014; 430:56-60. [PMID: 24998054 DOI: 10.1016/j.jcis.2014.05.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2014] [Revised: 05/07/2014] [Accepted: 05/10/2014] [Indexed: 11/24/2022]
Abstract
Steady shear viscosity measurements have been performed on 100 kDa poly(ethylene oxide) (PEO) dissolved in the protic ionic liquids ethylammonium nitrate (EAN) and propylammonium nitrate (PAN) and in water. The zero shear viscosity in all three solvents increases with polymer concentration, falling into three concentration regimes corresponding to dilute, semi-dilute and network solutions. Huggins plots reveal three distinct solvent conditions: good (water), good-theta (EAN) and theta (PAN). However, differences in the transition concentrations, power law behaviour of the viscosities, and relaxation times arising from shear thinning in the two ILs can be directly related to the effects of solvent nanostructure.
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11
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Elola MD, Rodriguez J. Structure and dynamics of nonionic surfactants adsorbed at vacuum/ionic liquid interfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:13379-13387. [PMID: 24156286 DOI: 10.1021/la402683j] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Structural and dynamical properties related to the adsorption of nonionic surfactants at vacuum/ionic liquid interfaces were studied using molecular dynamics simulations. Specifically, the surface activity of pentaethylene glycol monododecyl ether (C12E5) was investigated at the free interface of an imidazolium-based room temperature ionic liquid (RTIL), at different surface densities. At low surface coverages, the incorporation of C12E5 does not produce meaningful changes in the vacuum/RTIL interface: the C12E5 hydrophobic tails remain entangled with those of the RTIL cation groups in the outer shell, whereas the C12E5 hydrophilic heads reside at an inner layer. At high surface coverages, the structure in the substrate-in terms of the features exhibited by the local density profiles-practically vanishes; the interface becomes wider and the surfactant molecules shift toward more external positions. Information about the local structure of the interface at high surface densities can be recovered by performing a tessellation procedure. For the sake of comparison, the surface behavior of two commonly used ionic surfactants, sodium dodecyl sulfate and dodecyl trimethyl ammonium chloride, were also studied. The modifications in the width and structure of the bare vacuum/RTIL interface due to the presence of the ionic surfactants are markedly milder than those observed for the nonionic surfactant. Moreover, the RTIL seemed to behave as a better solvent for the chloride counterions than for sodium ones; which were found to remain bound to the surfactant head groups. An analysis of the dynamics at the surface was also performed. Our results indicate that the presence of increasing amounts of nonionic surfactants leads to a gradual reduction of the mobility of the RTIL species. When ionic surfactants are adsorbed, these retardations are even more severe for the surfactant head groups, where the corresponding diffusion coefficients show reductions of practically 1 order of magnitude.
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Affiliation(s)
- M Dolores Elola
- Departamento de Física, Comisión Nacional de Energía Atómica , Avenida Libertador 8250, 1429 Buenos Aires, Argentina , and
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12
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Li H, Rutland MW, Atkin R. Ionic liquid lubrication: influence of ion structure, surface potential and sliding velocity. Phys Chem Chem Phys 2013; 15:14616-23. [DOI: 10.1039/c3cp52638k] [Citation(s) in RCA: 126] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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13
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Wakeham D, Warr GG, Atkin R. Surfactant adsorption at the surface of mixed ionic liquids and ionic liquid water mixtures. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:13224-13231. [PMID: 22909055 DOI: 10.1021/la302184h] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Surface tensiometry and neutron reflectivity have been used to elucidate the structure of the adsorbed layer of nonionic surfactant tetraethylene glycol tetradecyl ether (C(14)E(4)) at the free surface of the ionic liquids ethylammonium nitrate (EAN) and ethanolammonium nitrate (EtAN) and their binary mixtures with each other and with water. Surface tensions reveal that the critical micelle concentration (cmc) depends strongly on solvent composition. The adsorbed surfactant structure elucidated by neutron reflectivity shows that the level of solvation of the ethylene oxide groups varies for both the pure and mixed solvents. This is attributed to solvent-solvent interactions dominating solvent-surfactant interactions.
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Affiliation(s)
- Deborah Wakeham
- Centre for Organic Electronics, The University of Newcastle, Callaghan, New South Wales, 2308, Australia
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14
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Werzer O, Cranston ED, Warr GG, Atkin R, Rutland MW. Ionic liquid nanotribology: mica–silica interactions in ethylammonium nitrate. Phys Chem Chem Phys 2012; 14:5147-52. [DOI: 10.1039/c1cp23134k] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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15
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Wakeham D, Niga P, Ridings C, Andersson G, Nelson A, Warr GG, Baldelli S, Rutland MW, Atkin R. Surface structure of a “non-amphiphilic” protic ionic liquid. Phys Chem Chem Phys 2012; 14:5106-14. [DOI: 10.1039/c2cp23694j] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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16
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Wakeham D, Nelson A, Warr GG, Atkin R. Probing the protic ionic liquid surface using X-ray reflectivity. Phys Chem Chem Phys 2011; 13:20828-35. [PMID: 22006195 DOI: 10.1039/c1cp22351h] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The structure of the free liquid surface of three protic ionic liquids, ethylammonium nitrate (EAN), propylammonium nitrate (PAN), and ethylammonium formate (EAF), has been elucidated using X-ray reflectivity. The results show all three liquids have an extended interfacial region, spanning at least five ion pairs, which can be divided into two parts. Adjacent to the gas phase are aggregates consisting of multiple cations and anions. Below this are layers oriented parallel to the macroscopic surface that are alternately enriched and depleted in cation alkyl chains and polar domains of cation ammonium groups and their anions, gradually decaying to the isotropic sponge-like bulk structure. The most pronounced layering is observed for PAN, driven by strong solvophobic interactions, while reduced hydrogen bonding in EAF results in the least structured and least extensive interfacial region.
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Affiliation(s)
- Deborah Wakeham
- Centre for Organic Electronics, The University of Newcastle, Callaghan, NSW 2308, Australia
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17
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Nishi N, Uruga T, Tanida H, Kakiuchi T. Temperature dependence of multilayering at the free surface of ionic liquids probed by X-ray reflectivity measurements. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:7531-7536. [PMID: 21595446 DOI: 10.1021/la200252z] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The effect of the temperature on the surface layering of ionic liquids has been studied for two ionic liquids, trioctylmethylammonium bis(nonafluorobutanesulfonyl)amide([TOMA(+)][C(4)C(4)N(-)]) and trihexyltetradecylphosphonium bis(nonafluorobutanesulfonyl)amide ([THTDP(+)][C(4)C(4)N(-)]), using X-ray reflectivity measurements at 285, 300, and 315 K. Both [TOMA(+)][C(4)C(4)N(-)] and [THTDP(+)][C(4)C(4)N(-)] develop multilayers at the surface. The structure of the multilayers at the [TOMA(+)][C(4)C(4)N(-)] surface shows little temperature-dependent change, whereas that at the [THTDP(+)][C(4)C(4)N(-)] surface clearly becomes diffused with increasing temperature. The different temperature dependence seems to be related to the difference in the recently reported ultraslow dynamics of the interfacial structure of [TOMA(+)][C(4)C(4)N(-)] and [THTDP(+)][C(4)C(4)N(-)] at the ionic liquid|water interface.
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Affiliation(s)
- Naoya Nishi
- Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan.
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18
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Werzer O, Warr GG, Atkin R. Compact poly(ethylene oxide) structures adsorbed at the ethylammonium nitrate-silica interface. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:3541-3549. [PMID: 21351777 DOI: 10.1021/la104577a] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The adsorption of poly(ethylene oxide) (PEO) and poly(propylene oxide) (PPO) onto silica from ethylammonium nitrate (a protic ionic liquid) has been investigated using colloid probe AFM force curve measurements. Steric repulsive forces were measured for PEO, confirming that PEO can compete with the ethylammonium cation and adsorb onto silica. The range of the repulsion increases with polymer molecular weight (e.g., from 1.4 nm for 0.01 wt % 10 kDa PEO to 40 nm for 0.01 wt % 300 kDa PEO) and with concentration (e.g., from 16 nm at 0.001 wt % to 78 nm at 0.4 wt % for 300 kDa PEO). Fits to the force curve data could not be obtained using standard models for a polymer brush, but excellent fits were obtained using the mushroom model, suggesting the adsorbed polymer films are compressed and relatively poorly solvated. No evidence for adsorption of 3.5 kDa PPO could be detected up to its solubility limit.
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Affiliation(s)
- Oliver Werzer
- Centre for Organic Electronics, The University of Newcastle, Callaghan, NSW 2308 Australia
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19
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Werzer O, Warr GG, Atkin R. Conformation of Poly(ethylene oxide) Dissolved in Ethylammonium Nitrate. J Phys Chem B 2010; 115:648-52. [DOI: 10.1021/jp110216k] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Oliver Werzer
- Centre for Organic Electronics, The University of Newcastle, Callaghan, NSW, 2308, Australia and School of Chemistry, The University of Sydney, Sydney, NSW, 2006, Australia
| | - Gregory G. Warr
- Centre for Organic Electronics, The University of Newcastle, Callaghan, NSW, 2308, Australia and School of Chemistry, The University of Sydney, Sydney, NSW, 2006, Australia
| | - Rob Atkin
- Centre for Organic Electronics, The University of Newcastle, Callaghan, NSW, 2308, Australia and School of Chemistry, The University of Sydney, Sydney, NSW, 2006, Australia
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20
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Chen LG, Lerum RV, Aranda-Espinoza H, Bermudez H. Surfactant-Mediated Ion Exchange and Charge Reversal at Ionic Liquid Interfaces. J Phys Chem B 2010; 114:11502-8. [DOI: 10.1021/jp106582t] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Lang G. Chen
- Department of Polymer Science and Engineering, University of Massachusetts, Amherst, Massachusetts, and Fischell Department of Bioengineering, University of Maryland, College Park, Maryland
| | - Ronald V. Lerum
- Department of Polymer Science and Engineering, University of Massachusetts, Amherst, Massachusetts, and Fischell Department of Bioengineering, University of Maryland, College Park, Maryland
| | - Helim Aranda-Espinoza
- Department of Polymer Science and Engineering, University of Massachusetts, Amherst, Massachusetts, and Fischell Department of Bioengineering, University of Maryland, College Park, Maryland
| | - Harry Bermudez
- Department of Polymer Science and Engineering, University of Massachusetts, Amherst, Massachusetts, and Fischell Department of Bioengineering, University of Maryland, College Park, Maryland
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Niga P, Wakeham D, Nelson A, Warr GG, Rutland M, Atkin R. Structure of the ethylammonium nitrate surface: an X-ray reflectivity and vibrational sum frequency spectroscopy study. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:8282-8288. [PMID: 20302344 DOI: 10.1021/la904697g] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
X-ray reflectivity and vibrational sum frequency spectroscopy are used to probe the structure of the ethylammonium nitrate (EAN)-air interface. X-ray reflectivity reveals that the EAN-air interface is structured and consists of alternating nonpolar and charged layers that extend 31 A into the bulk. Vibrational sum frequency spectroscopy reveals interfacial cations have their ethyl moieties oriented toward air, with the CH(3) C(3) axis positioned approximately 36.5 degrees from interface normal. This structure is invariant between 15 and 51 degrees C. On account of its molecular symmetry, the orientation of the nitrate anion cannot be determined with certainty.
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Affiliation(s)
- Petru Niga
- Department of Chemistry, Surface and Corrosion Science, Royal Institute of Technology, Drottning Kristinas Vag 51, SE-100 44 Stockholm, Sweden
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