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Tóth Ugyonka H, Hantal G, Szilágyi I, Idrissi A, Jorge M, Jedlovszky P. Spatial organization of the ions at the free surface of imidazolium-based ionic liquids. J Colloid Interface Sci 2024; 676:989-1000. [PMID: 39068842 DOI: 10.1016/j.jcis.2024.07.041] [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: 04/08/2024] [Revised: 07/02/2024] [Accepted: 07/05/2024] [Indexed: 07/30/2024]
Abstract
HYPOTHESIS Experimental information on the molecular scale structure of ionic liquid interfaces is controversial, giving rise to two competing scenarios, namely the double layer-like and "chessboard"-like structures. This issue can be resolved by computer simulation methods, at least for the underlying molecular model. Systematically changing the anion type can elucidate the relative roles of electrostatic interactions, hydrophobic (or, strictly speaking, apolar) effects and steric restrictions on the interfacial properties. SIMULATIONS Molecular dynamics simulation is combined with intrinsic analysis methods both at the molecular and atomic levels, supplemented by Voronoi analysis of self-association. FINDINGS We see no evidence for the existence of a double-layer-type arrangement of the ions, or for their self-association at the surface of the liquid. Instead, our results show that cation chains associate into apolar domains that protrude into the vapour phase, while charged groups form domains that are embedded in this apolar environment at the surface. However, the apolar chains largely obscure the cation groups, to which they are bound, while the smaller and more mobile anions can more easily access the free surface, leading to a somewhat counterintuitive net excess of negative charge at the interface. Importantly, this excess charge could only be identified by applying intrinsic analysis.
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Affiliation(s)
- Helga Tóth Ugyonka
- Department of Chemistry, Eszterházy Károly Catholic University, Leányka utca 12, H-3300 Eger, Hungary
| | - György Hantal
- PULS Group, Department of Physics, Friedrich-Alexander-Universität Erlangen-Nürnberg, Cauerstr. 3, D-91058 Erlangen, Germany
| | - István Szilágyi
- MTA-SZTE Lendület Biocolloids Research Group, Department of Physical Chemistry and Materials Science, Interdisciplinary Excellence Center, University of Szeged, H-6720 Szeged, Hungary
| | - Abdenacer Idrissi
- University of Lille, CNRS UMR 8516 -LASIRe - Laboratoire Avancé de Spectroscopie pour les Interactions la Réactivité et l'environnement, 59000 Lille, France
| | - Miguel Jorge
- Department of Chemical and Process Engineering, University of Strathclyde, 75 Montrose Street, Glasgow G1 1XJ, United Kingdom
| | - Pál Jedlovszky
- Department of Chemistry, Eszterházy Károly Catholic University, Leányka utca 12, H-3300 Eger, Hungary.
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2
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Jeschke S, Eiden P, Deng Q, Cole IS, Keil P. Structure and Dynamics of Aqueous 2-Aminothiazole/NaCl Electrolytes at Electrified Interfaces. J Phys Chem B 2024; 128:6189-6196. [PMID: 38872079 DOI: 10.1021/acs.jpcb.4c01479] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2024]
Abstract
A computational study was performed to investigate the dynamics of aqueous electrolytes containing organic corrosion inhibitors near electrified interfaces by using the constant-charge model in classical molecular dynamics simulations. The results showed that when inhibitors form films at the interface, the surface charge of the electrode causes displacement of the molecules, referred to as electroporation. The hydrophobicity of the inhibitor molecules affects both the stability of the films and their recovery time. This study highlights the value of computational investigations of the dynamics within inhibitor films as a complementary approach to the traditional focus on inhibitor-substrate interactions, leading to deeper insights into the mechanisms of corrosion inhibition mechanisms.
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Affiliation(s)
- Steffen Jeschke
- Manufacturing Materials and Mechatronics Engineering, School of Engineering, RMIT University, Melbourne 3001, Australia
| | | | - Qiushi Deng
- Manufacturing Materials and Mechatronics Engineering, School of Engineering, RMIT University, Melbourne 3001, Australia
| | - Ivan S Cole
- Manufacturing Materials and Mechatronics Engineering, School of Engineering, RMIT University, Melbourne 3001, Australia
| | - Patrick Keil
- BASF Coatings GmbH, Glasuritstrasse 1, Münster 48165, Germany
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3
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de la Puente M, Laage D. Impact of interfacial curvature on molecular properties of aqueous interfaces. J Chem Phys 2024; 160:234504. [PMID: 38888129 DOI: 10.1063/5.0210884] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2024] [Accepted: 05/28/2024] [Indexed: 06/20/2024] Open
Abstract
The curvature of soft interfaces plays a crucial role in determining their mechanical and thermodynamic properties, both at macroscopic and microscopic scales. In the case of air/water interfaces, particular attention has recently focused on water microdroplets, due to their distinctive chemical reactivity. However, the specific impact of curvature on the molecular properties of interfacial water and interfacial reactivity has so far remained elusive. Here, we use molecular dynamics simulations to determine the effect of curvature on a broad range of structural, dynamical, and thermodynamical properties of the interface. For a droplet, a flat interface, and a cavity, we successively examine the structure of the hydrogen-bond network and its relation to vibrational spectroscopy, the dynamics of water translation, rotation, and hydrogen-bond exchanges, and the thermodynamics of ion solvation and ion-pair dissociation. Our simulations show that curvature predominantly impacts the hydrogen-bond structure through the fraction of dangling OH groups and the dynamics of interfacial water molecules. In contrast, curvature has a limited effect on solvation and ion-pair dissociation thermodynamics. For water microdroplets, this suggests that the curvature alone cannot fully account for the distinctive reactivity measured in these systems, which are of great importance for catalysis and atmospheric chemistry.
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Affiliation(s)
- M de la Puente
- PASTEUR, Department of Chemistry, École Normale Supérieure, PSL University, Sorbonne Université, CNRS, 75005 Paris, France
| | - D Laage
- PASTEUR, Department of Chemistry, École Normale Supérieure, PSL University, Sorbonne Université, CNRS, 75005 Paris, France
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4
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Davoy X, Devémy J, Garruchet S, Dequidt A, Hauret P, Malfreyt P. Toward a Better Understanding of the Poly(glycerol sebacate)-Water Interface. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:11599-11609. [PMID: 38768448 DOI: 10.1021/acs.langmuir.4c00797] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2024]
Abstract
Molecular simulations were conducted to provide a better description of the poly(glycerol sebacate) (PGS)-water interface. The density and the glass-transition temperature as well as their dependencies on the degree of esterification were examined in close connection with the available experimental data. The work of adhesion and water contact angle were calculated as a function of the degree of esterification. A direct correlation was established between the strength of the hydrogen bond network in the interfacial region and the change in the water contact angle with respect to the degree of esterification. The interfacial region was described by local density profiles and orientations of the water molecules.
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Affiliation(s)
- Xavier Davoy
- Université Clermont Auvergne, CNRS, Clermont Auvergne INP, Institut de Chimie de Clermont-Ferrand, F-63000 Clermont-Ferrand, France
- Manufacture Française des Pneumatiques Michelin, 23 Place des Carmes, Clermont-Ferrand 63040, France
| | - Julien Devémy
- Université Clermont Auvergne, CNRS, Clermont Auvergne INP, Institut de Chimie de Clermont-Ferrand, F-63000 Clermont-Ferrand, France
| | - Sébastien Garruchet
- Manufacture Française des Pneumatiques Michelin, 23 Place des Carmes, Clermont-Ferrand 63040, France
| | - Alain Dequidt
- Université Clermont Auvergne, CNRS, Clermont Auvergne INP, Institut de Chimie de Clermont-Ferrand, F-63000 Clermont-Ferrand, France
| | - Patrice Hauret
- Manufacture Française des Pneumatiques Michelin, 23 Place des Carmes, Clermont-Ferrand 63040, France
| | - Patrice Malfreyt
- Université Clermont Auvergne, CNRS, Clermont Auvergne INP, Institut de Chimie de Clermont-Ferrand, F-63000 Clermont-Ferrand, France
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5
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Ojha D, Henao A, Zysk F, Kühne TD. Nuclear quantum effects on the vibrational dynamics of the water-air interface. J Chem Phys 2024; 160:204114. [PMID: 38804494 DOI: 10.1063/5.0204071] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2024] [Accepted: 04/11/2024] [Indexed: 05/29/2024] Open
Abstract
We have applied path-integral molecular dynamics simulations to investigate the impact of nuclear quantum effects on the vibrational dynamics of water molecules at the water-air interface. The instantaneous fluctuations in the frequencies of the O-H stretch modes are calculated using the wavelet method of time series analysis, while the time scales of vibrational spectral diffusion are determined from frequency-time correlation functions and joint probability distributions. We find that the inclusion of nuclear quantum effects leads not only to a redshift in the vibrational frequency distribution by about 120 cm-1 for both the bulk and interfacial water molecules but also to an acceleration of the vibrational dynamics at the water-air interface by as much as 35%. In addition, a blueshift of about 45 cm-1 is seen in the vibrational frequency distribution of interfacial water molecules compared to that of the bulk. Furthermore, the dynamics of water molecules beyond the topmost molecular layer was found to be rather similar to that of bulk water.
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Affiliation(s)
- Deepak Ojha
- Dynamics of Condensed Matter and Center for Sustainable Systems Design, Department of Chemistry, University of Paderborn, Warburger Str. 100, D-33098 Paderborn, Germany
| | - Andrés Henao
- Dynamics of Condensed Matter and Center for Sustainable Systems Design, Department of Chemistry, University of Paderborn, Warburger Str. 100, D-33098 Paderborn, Germany
| | - Frederik Zysk
- Dynamics of Condensed Matter and Center for Sustainable Systems Design, Department of Chemistry, University of Paderborn, Warburger Str. 100, D-33098 Paderborn, Germany
| | - Thomas D Kühne
- Center for Advanced Systems Understanding (CASUS), Untermarkt 20, D-02826 Görlitz, Germany, Helmholtz Zentrum Dresden-Rossendorf, Bautzner Landstraße 400, D-01328 Dresden, Germany, and TU Dresden, Institute of Artificial Intelligence, Chair of Computational System Sciences, Nöthnitzer Straße 46, D-01187 Dresden, Germany
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6
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Lin M, Tian B, Huang R, Xiao C. Study on the Transport Properties of SO 2 and NO at the Interface of H 2O 2 Solutions Using Molecular Dynamics. J Phys Chem B 2024. [PMID: 38656112 DOI: 10.1021/acs.jpcb.4c00013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/26/2024]
Abstract
Gas-liquid interfaces have a unique structure different from the bulk phase due to the complex intermolecular interactions within them and are regarded as barriers that prevent gases from entering solution or as channels that affect gas reactions. In this study, the adsorption and mass-transfer mechanisms of sulfur dioxide and nitric oxide at the gas-liquid interface of a H2O2 solution were comprehensively analyzed using molecular dynamics (MD) simulations. The analysis on molecule angle showed that H2O molecules tended to align parallel to the solution surface on the surface of the H2O2 solution. Regardless of whether the gas was adsorbed on the surface of the solution or not, H2O2 molecules were always perpendicular to the interface of the solution. The analysis on molecule angle and radial distribution function revealed that the H atoms of H2O molecules had a corresponding turn, and SO2 molecules were greatly affected by the attraction of H2O2 molecules during the adsorption of gas molecules on the interface. Steered MD was utilized to investigate the mass-transfer process of SO2 and NO molecules across the gas-liquid interface. The S atoms of SO2 molecules were significantly influenced by H2O2 molecules, while the O atoms of NO molecules gradually transitioned from the gas phase to the liquid phase. The results provided information on how gas molecules interacted with the surface of the solution and the specific details of the molecular orientation at the solution surface.
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Affiliation(s)
- Mingqi Lin
- Department of Energy and Power Engineering, College of Electrical Engineering, Guizhou University, Huaxi District, Guiyang 550025, China
| | - Bobing Tian
- Department of Energy and Power Engineering, College of Electrical Engineering, Guizhou University, Huaxi District, Guiyang 550025, China
| | - Ren Huang
- Department of Energy and Power Engineering, College of Electrical Engineering, Guizhou University, Huaxi District, Guiyang 550025, China
| | - Chao Xiao
- Department of Energy and Power Engineering, College of Electrical Engineering, Guizhou University, Huaxi District, Guiyang 550025, China
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7
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Ramos TN, Champagne B. Disentangling the molecular polarizability and first hyperpolarizability of methanol-air interfaces. Phys Chem Chem Phys 2024; 26:8658-8669. [PMID: 38437015 DOI: 10.1039/d4cp00043a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/05/2024]
Abstract
Liquid-air interfaces have extensive implications in different areas of interest because the dynamical processes at the interface can be different from those in bulk. Thus, its characterization, understanding, and control may be pivotal in advancing discoveries. However, characterizing the interface requires special and selective tools to avoid signals from the bulk region. This surface specificity and versatility is achieved by using the second harmonic generation (SHG) responses. This study adopts multiscale simulation methods to evaluate the surface SHG responses of methanol-air interfaces with submonolayer resolution tackled by sequentially using classical molecular dynamics simulations under different temperatures and then employing quantum chemistry methods to compute the molecular first hyperpolarizabilities (β). This approach ensures the configurational diversity required to evaluate the average β values. The main achievements are (i) a quasi-absence of surface sensitivity of the mean polarizability 〈α〉 with values about 2% larger than those obtained in bulk, (ii) conversely, smooth variations on the polarizability anisotropy Δα are observed up to the fourth molecular layer at around 20 Å from the interface, and (iii) narrow interfacial effects on the SHG responses, β(-2ω;ω,ω), which are limited to the first molecular layer (∼3.0 Å) and characterized by a high contrast in the βZZZ(-2ω;ω,ω) tensor component between the first and the subsequent layers. Similar trends are obtained at different temperatures or when increasing the number of methanol molecules treated at the quantum chemistry level, indicating the robustness of the approach for describing the dipolar molecular responses of air-liquid interfaces.
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Affiliation(s)
- Tárcius N Ramos
- Theoretical Chemistry Lab, Unit of Theoretical and Structural Physical Chemistry, Namur Institute of Structured Matter, University of Namur, rue de Bruxelles, 61, B-5000 Namur, Belgium.
| | - Benoît Champagne
- Theoretical Chemistry Lab, Unit of Theoretical and Structural Physical Chemistry, Namur Institute of Structured Matter, University of Namur, rue de Bruxelles, 61, B-5000 Namur, Belgium.
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8
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Cupp SS, Engle AE, Hardin AW, Lindberg GE. Identifying Local Interfaces. J Phys Chem B 2024; 128:1527-1534. [PMID: 38118072 DOI: 10.1021/acs.jpcb.3c06364] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2023]
Abstract
While interfacial regions often occupy a relatively small portion of a system, physical and chemical processes often proceed differently within them. It is therefore useful to identify interfacial regions to answer many questions in physical chemistry. Thermodynamic phases are often described by their density and local structure; therefore, interfacial regions can then be defined as regions with densities and structures that deviate from the properties of the neighboring phases. Using this perspective of local density and structure around an atom, we describe a "directed search cone" method that has proved useful in identifying atoms that sit at the interface between two regions of a system. We call the set of atoms found to be sitting on the surface "leading atoms", and we construct an interface from these atoms that we call the "leading layer interface". We demonstrate the leading layer interface on solid-vacuum, liquid-vacuum, and liquid-vapor systems. In addition to presenting our method and example calculations, we discuss some observations of local density fluctuations that may be useful for the analysis of heterogeneous systems. Depending on the circumstances, there are various perspectives of an interface that may be insightful, and our leading layer interface will be useful in situations where the correlation between interfacial dynamics and local molecular composition is investigated.
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Affiliation(s)
- Shane S Cupp
- Department of Chemistry and Biochemistry, Northern Arizona University, Flagstaff, Arizona 86011, United States
- Department of Applied Physics and Materials Science, Northern Arizona University, Flagstaff, Arizona 86011, United States
| | - Anna E Engle
- Department of Astronomy and Planetary Science, Northern Arizona University, Flagstaff, Arizona 86011, United States
- Lowell Observatory, Flagstaff, Arizona 86001, United States
| | - Alex W Hardin
- Department of Applied Physics and Materials Science, Northern Arizona University, Flagstaff, Arizona 86011, United States
- MIRA, The Center for Materials Interfaces in Research and Applications, Northern Arizona University, Flagstaff, Arizona 86011, United States
| | - Gerrick E Lindberg
- Department of Chemistry and Biochemistry, Northern Arizona University, Flagstaff, Arizona 86011, United States
- Department of Astronomy and Planetary Science, Northern Arizona University, Flagstaff, Arizona 86011, United States
- MIRA, The Center for Materials Interfaces in Research and Applications, Northern Arizona University, Flagstaff, Arizona 86011, United States
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9
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Gaur A, Balasubramanian S. Liquid-Vapor Interface of Aqueous Ethylene Glycol Solutions: A Molecular Dynamics Study. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:230-240. [PMID: 38150706 DOI: 10.1021/acs.langmuir.3c02431] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2023]
Abstract
While the organic constituent in an aqueous binary solution enriches its liquid-vapor (l-v) interface, the extent of enrichment can depend nonlinearly on its mole fraction. A microscopic quantification and rationalization of this behavior are crucial to understand the dependence of properties such as surface tension and evaporation rate of the solution on its composition. Extensive all-atom molecular dynamics simulations of aqueous ethylene glycol (EG) solutions show that the composition of the solution at the l-v interface deviates the most from that in the bulk solution at an EG mole fraction of 0.3. The population of EG molecules with their central C-C dihedral in the gauche conformation was found to be higher at the l-v interface than that in the bulk solution to facilitate the orientation of its hydrophobic methyl groups toward the vapor phase. Free energy calculations reveal that in dilute EG solutions, an EG molecule is most stable at the l-v interface. The behavior of vapor pressure in aqueous EG solutions is ideal and follows Raoult's law, while in contrast, the aqueous solution of dimethyl sulfoxide does not. A rationale for the same is provided through the orientational distribution of interfacial water molecules in the respective solutions.
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Affiliation(s)
- Anjali Gaur
- Chemistry and Physics of Materials Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560 064, India
| | - Sundaram Balasubramanian
- Chemistry and Physics of Materials Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560 064, India
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10
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Yasui K, Tuziuti T, Kanematsu W. Mechanism of the Decrease in Surface Tension by Bulk Nanobubbles (Ultrafine Bubbles). LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:16574-16583. [PMID: 37934653 DOI: 10.1021/acs.langmuir.3c02545] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2023]
Abstract
The mechanism of the decrease in the surface tension of water containing bulk nanobubbles (ultrafine bubbles) is studied theoretically by numerical simulations of the adsorption of bulk nanobubbles at the liquid's surface based on the dynamic equilibrium model for the stability of a bulk nanobubble under the conditions of the Tuziuti experiment (Tuziuti, T., et al., Langmuir, 2023, 39, 5771-5778). It is predicted that the concentration of bulk nanobubbles in the bulk liquid decreases considerably with time, as many bulk nanobubbles are gradually adsorbed at the liquid's surface. A part of the decrease in surface tension is due to the Janus-like structure of a bulk nanobubble that could partly break the hydrogen bond network of water molecules at the liquid's surface because more than 50% of the bubble's surface is covered with hydrophobic impurities, according to the dynamic equilibrium model. The theoretically estimated decrease in surface tension due to the Janus-like structure of a bulk nanobubble agrees with the experimental data of the decrease in surface tension solely by bulk nanobubbles obtained by the comparison of before and after the elimination of bulk nanobubbles by the freeze-thaw process. This effect cannot be explained by the electric charge stabilization model widely discussed for the stability of a bulk nanobubble, although the present model is only applicable to the solution containing hydrophobic impurities. Another part of the decrease in surface tension should be due to impurities produced from a nanobubble generator, such as a mechanical seal, which was partly confirmed by the TOC measurements.
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Affiliation(s)
- Kyuichi Yasui
- National Institute of Advanced Industrial Science and Technology (AIST), Nagoya 463-8560, Japan
| | - Toru Tuziuti
- National Institute of Advanced Industrial Science and Technology (AIST), Nagoya 463-8560, Japan
| | - Wataru Kanematsu
- National Institute of Advanced Industrial Science and Technology (AIST), Nagoya 463-8560, Japan
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11
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Hantal G, Klíma M, McFegan L, Kolafa J, Jedlovszky P. Does the Sign of Charge Affect the Surface Affinity of Simple Ions? J Phys Chem B 2023. [PMID: 37399285 DOI: 10.1021/acs.jpcb.3c02641] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/05/2023]
Abstract
The role the charge sign of simple ions plays in determining their surface affinity in aqueous solutions is investigated by computer simulation methods. For this purpose, the free surface of aqueous solutions of fictitious salts is simulated at finite concentration both with nonpolarizable point-charge and polarizable Gaussian-charge potential models. The salts consist of monovalent cations and anions that are, apart from the sign of their charge, identical to each other. In particular, we consider the small Na+ and the large I- ions together with their charge-inverted counterparts. In an attempt to avoid the interference even between the behavior of cations and anions, we also simulate systems containing only one of the above ions, and determine the free energy profile of these ions across the liquid-vapor interface of water at infinite dilution by potential of mean force (PMF) calculations. The obtained results reveal that, in the case of small ions, the anion is hydrated considerably stronger than the cation due to the close approach of water H atoms, bearing a positive fractional charge. As a consequence, the surface affinity of a small anion is even smaller than that of its cationic counterpart. However, considering that small ions are effectively repelled from the water surface, the importance of this difference is negligible. Further, a change in the hydration energy trends of the two oppositely charged ions is observed with their increasing size. This change is largely attributed to the fact that, with increasing ion size, the factor of 2 in the magnitude of the fractional charge of the closely approaching water atoms (i.e., O around cations and H around anions) outweighs the closer approach of the H than the O atom in the hydration energy. Thus, for large ions, being already surface active themselves, the surface affinity of the anion is larger than that of its positively charged counterpart. Further, such a difference is seen even in the case when the sign of the surface potential favors the adsorption of cations.
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Affiliation(s)
- György Hantal
- Institute of Physics and Materials Science, University of Natural Resources and Life Sciences, Peter Jordan Straße 82, A-1190 Vienna, Austria
| | - Martin Klíma
- Department of Physical Chemistry, University of Chemistry and Technology, 166 28 Prague 6, Czech Republic
| | - Louisa McFegan
- Budapest University of Technology and Economics, Szt. Gellért tér 4, H-1111 Budapest, Hungary
| | - Jiří Kolafa
- Department of Physical Chemistry, University of Chemistry and Technology, 166 28 Prague 6, Czech Republic
| | - Pál Jedlovszky
- Department of Chemistry, Eszterházy Károly Catholic University, Leányka utca 6, H-3300 Eger, Hungary
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12
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McFegan L, Juhász Á, Márton P, Hórvölgyi Z, Jedlovszky-Hajdu A, Hantal G, Jedlovszky P. Surface Affinity of Tetramethylammonium Iodide in Aqueous Solutions: A Combined Experimental and Computer Simulation Study. J Phys Chem B 2023. [PMID: 37276239 DOI: 10.1021/acs.jpcb.3c01370] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The surface affinity of tetramethylammonium iodide (TMAI) in aqueous solutions is investigated by surface tension measurements and molecular dynamics computer simulations. Experiments, performed in the entire composition range of solubility using the pendant drop method with two different setups, clearly reveal that TMAI is a weakly capillary active salt. Computer simulations performed with the AMBER force field reproduce the experimental data very well, while two other major force fields (i.e., CHARMM and OPLS) can still reproduce the experimental trend qualitatively; however, even qualitative reproduction of the experimental trend requires scaling down the ion charges according to the Leontyev-Stuchebrukhov correction. On the other hand, the GROMOS force field fails in reproducing the experimentally confirmed capillary activity of TMAI. Molecular dynamics simulation results show that, among the two ions, iodide has a clearly larger surface affinity than tetramethylammonium (TMA+). Further, the adsorption of the I- anions is strictly limited to the first molecular layer beneath the liquid-vapor interface, which is followed by several layers of their depletion. On the other hand, the net negative charge of the surface layer, caused by the excess amount of I- with respect to TMA+, is compensated by a diffuse layer of adsorbed TMA+ cations, extending to or beyond the fourth molecular layer beneath the liquid surface.
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Affiliation(s)
- Louisa McFegan
- Faculty of Chemical Technology and Biotechnology, Budapest University of Technology and Economics, Szt. Gellért tér 4, H-1111 Budapest, Hungary
| | | | - Péter Márton
- Department of Physical Chemistry and Materials Science, Budapest University of Technology and Economics, Budafoki út 8, H-1111 Budapest, Hungary
| | - Zoltán Hórvölgyi
- Department of Physical Chemistry and Materials Science, Budapest University of Technology and Economics, Budafoki út 8, H-1111 Budapest, Hungary
| | | | - György Hantal
- Institute of Physics and Materials Science, University of Natural Resources and Life Sciences, Peter Jordan Straße 82, A-1190 Vienna, Austria
| | - Pál Jedlovszky
- Department of Chemistry, Eszterházy Károly Catholic University, Leányka utca 6, H-3300 Eger, Hungary
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13
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Hantal G, Jedlovszky P, Sega M. Local structure of liquid/vapour interfaces approaching the critical point. SOFT MATTER 2023; 19:3773-3782. [PMID: 37098698 DOI: 10.1039/d3sm00176h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Investigating the structure of fluid interfaces at high temperatures is a particularly delicate task that requires effective ways of discriminating liquid from vapour and identifying the location of the liquid phase boundary, thereby allowing to distinguish intrinsic from capillary fluctuations. Several numerical approaches require introducing a coarse-graining length scale, often heuristically chosen to be the molecular size, to determine the location of the liquid phase boundary. Here, we propose an alternative rationale for choosing this coarse-graining length scale; we require the average position of the local liquid phase dividing surface to match its flat, macroscopic counterpart. We show that this approach provides additional insight into the structure of the liquid/vapour interface, suggesting the presence of another length scale beyond the bulk correlation one that plays an important role in determining the interface structure.
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Affiliation(s)
- György Hantal
- Institute of Physics and Materials Science, University of Natural Resources and Life Sciences, Peter Jordan Strasse 82, A-1190 Vienna, Austria
| | - Pál Jedlovszky
- Department of Chemistry, Eszterhazy Karoly University, Leanyka utca 6, H-3300 Eger, Hungary
| | - Marcello Sega
- Department of Chemical Engineering, University College London, London WC1E 7JE, UK.
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14
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Fayon P, Devémy J, Emeriau-Viard C, Ballerat-Busserolles K, Goujon F, Dequidt A, Marty A, Hauret P, Malfreyt P. Energetic and Structural Characterizations of the PET-Water Interface as a Key Step in Understanding Its Depolymerization. J Phys Chem B 2023; 127:3543-3555. [PMID: 37018548 DOI: 10.1021/acs.jpcb.3c00600] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/07/2023]
Abstract
We report molecular simulations of the interaction between poly(ethylene terephthalate) (PET) surfaces and water molecules with a short-term goal to better evaluate the different energy contributions governing the enzymatic degradation of amorphous PET. After checking that the glass transition temperature, density, entanglement mass, and mechanical properties of an amorphous PET are well reproduced by our molecular model, we extend the study to the extraction of a monomer from the bulk surface in different environments, i.e., water, vacuum, dodecane, and ethylene glycol. We complete this energetic characterization by the calculation of the work of adhesion of PET surfaces with water and dodecane molecules and by the determination of the contact angle of water droplets. These calculations are compared with experiments and should help us to better understand the enzymatic degradation of PET from both the thermodynamic and molecular viewpoints.
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Affiliation(s)
- Pierre Fayon
- Université Clermont Auvergne, Clermont Auvergne INP, CNRS, Institut de Chimie de Clermont-Ferrand, F-63000 Clermont-Ferrand, France
| | - Julien Devémy
- Université Clermont Auvergne, Clermont Auvergne INP, CNRS, Institut de Chimie de Clermont-Ferrand, F-63000 Clermont-Ferrand, France
| | - Constance Emeriau-Viard
- Manufacture Française des Pneumatiques Michelin, 23, Place des Carmes, 63040 Clermont-Ferrand, France
| | - Karine Ballerat-Busserolles
- Université Clermont Auvergne, Clermont Auvergne INP, CNRS, Institut de Chimie de Clermont-Ferrand, F-63000 Clermont-Ferrand, France
| | - Florent Goujon
- Université Clermont Auvergne, Clermont Auvergne INP, CNRS, Institut de Chimie de Clermont-Ferrand, F-63000 Clermont-Ferrand, France
| | - Alain Dequidt
- Université Clermont Auvergne, Clermont Auvergne INP, CNRS, Institut de Chimie de Clermont-Ferrand, F-63000 Clermont-Ferrand, France
| | - Alain Marty
- Carbios, Parc Cataroux, Batiment B80, 8 rue de la Grolière, 63100 Clermont-Ferrand, France
| | - Patrice Hauret
- Manufacture Française des Pneumatiques Michelin, 23, Place des Carmes, 63040 Clermont-Ferrand, France
| | - Patrice Malfreyt
- Université Clermont Auvergne, Clermont Auvergne INP, CNRS, Institut de Chimie de Clermont-Ferrand, F-63000 Clermont-Ferrand, France
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15
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Malgaretti P, Bafile U, Vallauri R, Jedlovszky P, Sega M. Surface viscosity in simple liquids. J Chem Phys 2023; 158:114705. [PMID: 36948818 DOI: 10.1063/5.0141971] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/18/2023] Open
Abstract
The response of Newtonian liquids to small perturbations is usually considered to be fully described by homogeneous transport coefficients like shear and dilatational viscosity. However, the presence of strong density gradients at the liquid/vapor boundary of fluids hints at the possible existence of an inhomogeneous viscosity. Here, we show that a surface viscosity emerges from the collective dynamics of interfacial layers in molecular simulations of simple liquids. We estimate the surface viscosity to be 8-16 times smaller than that of the bulk fluid at the thermodynamic point considered. This result can have important implications for reactions at liquid surfaces in atmospheric chemistry and catalysis.
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Affiliation(s)
- Paolo Malgaretti
- Forschungszentrum Jülich GmbH, Helmholtz Institute Erlangen-Nürnberg for Renewable Energy (IEK-11), Cauerstr.1, D-91058 Erlangen, Germany
| | - Ubaldo Bafile
- Consiglio Nazionale delle Ricerche, Istituto di Fisica Applicata "Nello Carrara," I-50019 Sesto Fiorentino, Italy
| | - Renzo Vallauri
- Consiglio Nazionale delle Ricerche, Istituto di Fisica Applicata "Nello Carrara," I-50019 Sesto Fiorentino, Italy
| | - Pál Jedlovszky
- Department of Chemistry, Eszterházy Károly University, Leányka u. 6, H-3300 Eger, Hungary
| | - Marcello Sega
- Department of Chemical Engineering, University College London, London WC1E 7JE, United Kingdom
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16
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Chen S, Voth GA. How Does Electronic Polarizability or Scaled-Charge Affect the Interfacial Properties of Room Temperature Ionic Liquids? J Phys Chem B 2023; 127:1264-1275. [PMID: 36701801 PMCID: PMC9924258 DOI: 10.1021/acs.jpcb.2c07981] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2022] [Revised: 01/01/2023] [Indexed: 01/27/2023]
Abstract
The room temperature ionic liquid (RTIL) air-liquid interface plays an important role in many applications. Herein, we present molecular dynamics simulation results for the air-liquid interface of a common RTIL, 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide, [C4mim][NTf2]. To elucidate the effects of electronic polarizability and scaled-charge ions on the properties of the RTIL air-liquid interface, we employ three different kinds of force fields: a nonpolarizable force field (FF) with united ion charges (FixQ), a nonpolarizable FF with scaled-charge by 0.8 (ScaleQ), and a polarizable FF (Drude). To identify whether the ions reside at the interface or not, the method of identification of the truly interfacial molecules is used. The structural and dynamical properties in the interfacial, subinterfacial, and central layers are evaluated. In general for bulk liquids, the FixQ model predicts too-ordered structures and too-sluggish dynamics, while the ScaleQ model can serve as a simple cure. However, the ScaleQ model cannot reproduce the results of the Drude model at the interface, due to an inappropriate scaled-down charge near the interface.
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Affiliation(s)
- Sijia Chen
- Department of Chemistry,
Chicago Center for Theoretical Chemistry, The James Franck Institute,
and Institute for Biophysical Dynamics, The University of Chicago, Chicago, Illinois60637, United States
| | - Gregory A. Voth
- Department of Chemistry,
Chicago Center for Theoretical Chemistry, The James Franck Institute,
and Institute for Biophysical Dynamics, The University of Chicago, Chicago, Illinois60637, United States
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17
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Gorfer A, Dellago C, Sega M. High-density liquid (HDL) adsorption at the supercooled water/vapor interface and its possible relation to the second surface tension inflection point. J Chem Phys 2023; 158:054503. [PMID: 36754827 DOI: 10.1063/5.0132985] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
We investigate the properties of water along the liquid/vapor coexistence line in the supercooled regime down to the no-man's land. Extensive molecular dynamics simulations of the TIP4P/2005 liquid/vapor interface in the range 198-348 K allow us to locate the second surface tension inflection point with a high accuracy at 283 ± 5 K, close to the temperature of maximum density. This temperature also coincides with the appearance of a density anomaly at the interface known as the apophysis. We relate the emergence of the apophysis to the observation of high-density liquid (HDL) water adsorption in the proximity of the liquid/vapor interface.
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Affiliation(s)
- Alexander Gorfer
- Faculty of Physics, University of Vienna, Boltzmanngasse 5, Wien A-1090, Austria
| | - Christoph Dellago
- Faculty of Physics, University of Vienna, Boltzmanngasse 5, Wien A-1090, Austria
| | - Marcello Sega
- Department of Chemical Engineering, University College London, London WC1E 7JE, United Kingdom
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18
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Honti B, Fábián B, Idrissi A, Jedlovszky P. Surface Properties of N,N-Dimethylformamide-Water Mixtures, As Seen from Computer Simulations. J Phys Chem B 2023; 127:1050-1062. [PMID: 36652674 DOI: 10.1021/acs.jpcb.2c07572] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The liquid-vapor interface of N,N-dimethylformamide (DMF)-water mixtures, spanning the entire composition range, is investigated in detail at 298 K by molecular dynamics simulation and intrinsic surface analysis. DMF molecules are found to adsorb strongly at the liquid surface, but this adsorption extends only to the first molecular layer. Water and DMF molecules mix with each other on the molecular scale even in the surface layer; thus, no marked self-association of any of the components is seen at the liquid surface. The major surface component prefers such orientation in which the molecular dipole vector lays parallel with the macroscopic plane of the surface. On the other hand, the preferred orientation of the minor component is determined, at both ends of the composition range, by the possibility of H-bond formation with the major component. The lack of H-donating ability of DMF leads to a rapid breakup of the percolating H-bond network at the surface; due to the strong adsorption of DMF, this breakup occurs below the bulk phase DMF mole fraction of 0.03. The disruption of the surface H-bond network also accelerates the exchange of both species between the liquid surface and bulk liquid phase, although, for water, this effect becomes apparent only above a bulk phase DMF mole fraction of 0.4. H-bonds formed by a DMF and a water molecule live, on average, 25-60% longer than those formed by two water molecules at the liquid surface. A similar, but smaller (i.e., about 10-20%) difference is seen in the bulk liquid phase. The enhanced surface mobility of the molecules results in 2-6 times larger diffusion coefficient and 2-5 times shorter H-bond lifetime values at the liquid surface than in the bulk liquid phase. The diffusion of both molecules is slowed down in the presence of the other species; in the case of DMF, this effect is caused by the formation of water-DMF H-bonds, whereas for water, steric hindrances imposed by the bulky DMF neighbors are responsible for this slowing down.
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Affiliation(s)
- Barbara Honti
- Department of Organic Chemistry and Technology, Budapest University of Technology and Economics, Budapest 1111, Hungary
| | - Balázs Fábián
- Department of Theoretical Biophysics, Max Planck Institute of Biophysics, Frankfurt am Main 60438, Germany
| | - Abdenacer Idrissi
- University of Lille, CNRS UMR 8516 -LASIRe - Laboratoire Avancé de Spectroscopie pour les Interactions la Réactivité et l'environnement, 59000 Lille, France
| | - Pál Jedlovszky
- Department of Chemistry, Eszterházy Károly University, Leányka u. 6, H-3300 Eger, Hungary
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19
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20
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González-Barramuño B, Cea-Klapp E, Piñeiro MM, Polishuk I, Quinteros-Lama H, Garrido JM. Surface anomalies in ethanol plus n-octane mixture: An effect of molecular orientations and hydrogen bonds. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.119630] [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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21
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Sujith K. Effect of methanol as an amphiphile on water structuring around a hydrate forming gas molecule: Insights from molecular dynamics simulations. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.119628] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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22
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Ramos TN, Champagne B. Investigation of the Second Harmonic Generation at the Water-Vacuum Interface by Using Multi-Scale Modeling Methods. Chemistry 2022; 12:e202200045. [PMID: 35950561 PMCID: PMC9806952 DOI: 10.1002/open.202200045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Revised: 06/16/2022] [Indexed: 01/28/2023]
Abstract
The Sequential Quantum Mechanics/Molecular Mechanics scheme has been enacted to perform a systematic investigation of the polarizability (α) and first hyperpolarizability (β) responses at the water-vacuum interface. After performing classical molecular dynamics simulations to provide snapshots of the structures, quantum chemistry calculations of the linear and nonlinear optical responses have been performed for clusters of five water molecules at the time-dependent DFT level in combination with different embedding schemes, ranging from point charges to polarizable point charges, with and without local field effects. When going from the bulk to the interface, the main observations of these calculations encompass i) a modest increase of the average polarizability but an increase by about a factor of two of its anisotropy, ii) an increase by about 20 % of the βHRS response, accompanied by a small increase of its depolarization ratio, and iii) a net increase of the component of the β tensor normal to the interface (βzzz ) as well as of β// . Globally, the interfacial effects on β are localized at the first molecular layer while they are observed up to the fourth molecular layer on α.
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Affiliation(s)
- Tárcius N. Ramos
- Laboratory of Theoretical ChemistryNamur Institute of Structured Matter (NISM)University of NamurRue de Bruxelles, 61B-5000NamurBelgium
| | - Benoît Champagne
- Laboratory of Theoretical ChemistryNamur Institute of Structured Matter (NISM)University of NamurRue de Bruxelles, 61B-5000NamurBelgium
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23
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Molecular Insights into Factors Affecting the Generation Behaviors, Dynamic Properties, and Interfacial Structures of Methane Gas Bubbles. WATER 2022. [DOI: 10.3390/w14152327] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Molecular dynamics simulations were performed to study the effects of temperatures, pressures, and methane mole fractions on the generation behaviors, dynamic properties, and interfacial structures of methane gas bubbles. Methane gas bubbling can be promoted by high temperatures and high mole fractions of methane, which come from the generation of larger methane clusters in solution. Bubbles were found to be highly dynamic, with more methane molecules exchanging between bubbles and the surrounding solution at high pressures and in systems with high mole fractions of methane. The interfacial structures between bubbles and the surrounding solution were rough at a molecular level, and the roughness of the outermost methane and water molecules was high at high temperatures, low pressures, and in systems with high methane mole fractions. The dissolution of methane molecules depended on the interactions between the outermost methane and water molecules, which would become stronger with decreasing temperatures, increasing pressures, and decreasing methane mole fractions. The results obtained can help in understanding both the generation behaviors of bubbles when gas hydrates decompose and the re-nucleation behaviors of gas hydrates in the presence of bubbles.
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24
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Walker-Gibbons R, Kubincová A, Hünenberger PH, Krishnan M. The Role of Surface Chemistry in the Orientational Behavior of Water at an Interface. J Phys Chem B 2022; 126:4697-4710. [PMID: 35726865 PMCID: PMC9251758 DOI: 10.1021/acs.jpcb.2c01752] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
![]()
Molecular dynamics
studies have demonstrated that molecular water
at an interface, with either a gas or a solid, displays anisotropic
orientational behavior in contrast to its bulk counterpart. This effect
has been recently implicated in the like-charge attraction problem
for colloidal particles in solution. Here, negatively charged particles
in solution display a long-ranged attraction where continuum electrostatic
theory predicts monotonically repulsive interactions, particularly
in solutions with monovalent salt ions at low ionic strength. Anisotropic
orientational behavior of solvent molecules at an interface gives
rise to an excess interfacial electrical potential which we suggest
generates an additional solvation contribution to the total free energy
that is traditionally overlooked in continuum descriptions of interparticle
interactions in solution. In the present investigation we perform
molecular dynamics simulation based calculations of the interfacial
potential using realistic surface models representing various chemistries
as well as different solvents. Similar to previous work that focused
on simple model surfaces constructed by using oxygen atoms, we find
that solvents at more realistic model surfaces exhibit substantial
anisotropic orientational behavior. We explore the dependence of the
interfacial solvation potential on surface properties such as surface
group chemistry and group density at silica and carboxylated polystyrene
interfaces. For water, we note surprisingly good agreement between
results obtained for a simple O-atom wall and more complex surface
models, suggesting a general qualitative consistency of the interfacial
solvation effect for surfaces in contact with water. In contrast,
for an aprotic solvent such as DMSO, surface chemistry appears to
exert a stronger influence on the sign and magnitude of the interfacial
solvation potential. The study carries broad implications for molecular-scale
interactions and may find relevance in explaining a range of phenomena
in soft-matter physics and cell biology.
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Affiliation(s)
- Rowan Walker-Gibbons
- Physical & Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QZ, United Kingdom
| | - Alžbeta Kubincová
- Laboratory of Physical Chemistry, Department of Chemistry and Applied Biosciences, ETH Zurich, Vladimir-Prelog-Weg 2, CH-8093 Zürich, Switzerland
| | - Philippe H Hünenberger
- Laboratory of Physical Chemistry, Department of Chemistry and Applied Biosciences, ETH Zurich, Vladimir-Prelog-Weg 2, CH-8093 Zürich, Switzerland
| | - Madhavi Krishnan
- Physical & Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QZ, United Kingdom
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25
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Odendahl NL, Geissler PL. Local Ice-like Structure at the Liquid Water Surface. J Am Chem Soc 2022; 144:11178-11188. [PMID: 35696525 DOI: 10.1021/jacs.2c01827] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Experiments and computer simulations have established that liquid water's surfaces can deviate in important ways from familiar bulk behavior. Even in the simplest case of an air-water interface, distinctive layering, orientational biases, and hydrogen bond arrangements have been reported, but an overarching picture of their origins and relationships has been incomplete. Here we show that a broad set of such observations can be understood through an analogy with the basal face of crystalline ice. Using simulations, we demonstrate a number of structural similarities between water and ice surfaces, suggesting the presence of domains at the air-water interface with ice-like features that persist over 2-3 molecular diameters. Most prominent is a shared characteristic layering of molecular density and orientation perpendicular to the interface. Lateral correlations of hydrogen bond network geometry point to structural similarities in the parallel direction as well. Our results bolster and significantly extend previous conceptions of ice-like structure at the liquid's boundary and suggest that the much-discussed quasi-liquid layer on ice evolves subtly above the melting point into a quasi-ice layer at the surface of liquid water.
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Affiliation(s)
- Nathan L Odendahl
- Department of Chemistry, University of California, Berkeley, California 94720, United States.,Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Phillip L Geissler
- Department of Chemistry, University of California, Berkeley, California 94720, United States.,Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
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26
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Balbisi M, Horváth RA, Szőri M, Jedlovszky P. Computer simulation investigation of the adsorption of acetamide on low density amorphous ice. An astrochemical perspective. J Chem Phys 2022; 156:184703. [PMID: 35568547 DOI: 10.1063/5.0093561] [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
The adsorption of acetamide on low density amorphous (LDA) ice is investigated by grand canonical Monte Carlo computer simulations at the temperatures 50, 100, and 200 K, characteristic of certain domains of the interstellar medium (ISM). We found that the relative importance of the acetamide-acetamide H-bonds with respect to the acetamide-water ones increases with decreasing temperature. Thus, with decreasing temperature, the existence of the stable monolayer, characterizing the adsorption at 200 K, is gradually replaced by the occurrence of marked multilayer adsorption, preceding even the saturation of the first layer at 50 K. While isolated acetamide molecules prefer to lay parallel to the ice surface to maximize their H-bonding with the surface water molecules, this orientational preference undergoes a marked change upon saturation of the first layer due to increasing competition of the adsorbed molecules for H-bonds with water and to the possibility of their H-bond formation with each other. As a result, molecules stay preferentially perpendicular to the ice surface in the saturated monolayer. The chemical potential value corresponding to the point of condensation is found to decrease linearly with increasing temperature. We provide, in analogy with the Clausius-Clapeyron equation, a thermodynamic explanation of this behavior and estimate the molar entropy of condensed phase acetamide to be 34.0 J/mol K. For the surface concentration of the saturated monolayer, we obtain the value 9.1 ± 0.8 µmol/m2, while the heat of adsorption at infinitely low surface coverage is estimated to be -67.8 ± 3.0 kJ/mol. Our results indicate that the interstellar formation of peptide chains through acetamide molecules, occurring at the surface of LDA ice, might well be a plausible process in the cold (i.e., below 50 K) domains of the ISM; however, it is a rather unlikely scenario in its higher temperature (i.e., 100-200 K) domains.
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Affiliation(s)
- Mirjam Balbisi
- Institute of Chemistry, Eötvös Loránd University, Pázmány P. stny. 1/A, H-1117 Budapest, Hungary
| | - Réka A Horváth
- Department of Physical Chemistry and Materials Science, Budapest University of Technology and Economics, Budafoki út 8, H-1111 Budapest, Hungary
| | - Milán Szőri
- Institute of Chemistry, University of Miskolc, Egyetemváros A/2, H-3515 Miskolc, Hungary
| | - Pál Jedlovszky
- Department of Chemistry, Eszterházy Károly University, Leányka u. 6, H-3300 Eger, Hungary
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27
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Balbisi M, Horváth RA, Szőri M, Jedlovszky P. Adsorption of acetamide on crystalline and amorphous ice under atmospheric conditions. A grand canonical Monte Carlo simulation study. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.118870] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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28
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Li L, Lin J, Fu F, Dai Z, Zhou G, Yang Z. Molecular-Level Understanding of Surface Roughness Boosting Segregation Behavior at the ZIF-8/Ionic Liquid Interfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:4175-4187. [PMID: 35349284 DOI: 10.1021/acs.langmuir.1c02922] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Here, we perform a series of classical molecular dynamics simulations for two different [HEMIM][DCA] and [BMIM][BF4] ionic liquids (ILs) on the ZIF-8 surface to explore the interfacial properties of metal-organic framework (MOFs)/IL composite materials at the molecular level. Our simulation results reveal that the interfacial structures of anions and cations on the ZIF-8 surface are dominated by the surface roughness due to the steric hindrance, which is extremely different from the driving mechanism based on solid-ion interactions of ILs on flat solid surfaces. At the ZIF-8/IL interfaces, the open sodalite (SOD) cages of the ZIF-8 surface can block most of the large-size cations outside and significantly boost the segregation behavior of anions and cations. In comparison with the [BMIM][BF4] IL, the [HEMIM][DCA] IL has much more anions entering into the open SOD cages owing to the combination of stronger ZIF-8-[DCA]- interactions and more ordered arrangement of [DCA]- anions on the ZIF-8 surface. Furthermore, more and stronger ZIF-8-[BF4]- hydrogen bonds (HBs) are found to exist on the cage edges than the ZIF-8-[DCA]- HBs, further preventing [BF4]- anions from entering into SOD cages. By more detailed analyses, we find that the hydrophobic interaction has an important influence on the interfacial structures of the side chains of [HEMIM]+ and [BMIM]+ cations, while the π-π stacking interaction plays a key role in determining the interfacial structures of the imidazolium rings of both cations. Our simulation results in this work provide a molecular-level understanding of the underlying driving mechanism on segregation behavior at the ZIF-8/IL interfaces.
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Affiliation(s)
- Li Li
- Institute of Advanced Materials (IAM), State-Province Joint Engineering Laboratory of Zeolite Membrane Materials, College of Chemistry and Chemical Engineering, Jiangxi Normal University, Nanchang 330022, People's Republic of China
| | - Jie Lin
- Institute of Advanced Materials (IAM), State-Province Joint Engineering Laboratory of Zeolite Membrane Materials, College of Chemistry and Chemical Engineering, Jiangxi Normal University, Nanchang 330022, People's Republic of China
| | - Fangjia Fu
- School of Mathematical Sciences, Peking University, Beijing 100871, People's Republic of China
| | - Zhongyang Dai
- National Supercomputing Center in Shenzhen, Shenzhen 518055, People's Republic of China
| | - Guobing Zhou
- Institute of Advanced Materials (IAM), State-Province Joint Engineering Laboratory of Zeolite Membrane Materials, College of Chemistry and Chemical Engineering, Jiangxi Normal University, Nanchang 330022, People's Republic of China
| | - Zhen Yang
- Institute of Advanced Materials (IAM), State-Province Joint Engineering Laboratory of Zeolite Membrane Materials, College of Chemistry and Chemical Engineering, Jiangxi Normal University, Nanchang 330022, People's Republic of China
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29
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Honti B, Szőri M, Jedlovszky P. Description of the Interfacial Behavior of Benzonitrile at Icy Surfaces by Grand Canonical Monte Carlo Simulations. J Phys Chem A 2022; 126:1221-1232. [PMID: 35168326 DOI: 10.1021/acs.jpca.1c10749] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The adsorption of benzonitrile at the surface of crystalline (Ih) and low-density amorphous (LDA) ice has been investigated by grand canonical Monte Carlo simulations at temperatures ranging from 50 to 200 K. It is found that, in spite of its rather large dipole moment of 4.5 D, benzonitrile molecules can only form a highly unsaturated monolayer on LDA ice, reaching not more than 50% of the surface concentration of the saturated monolayer even at the lowest temperature considered, and they practically do not adsorb on Ih ice. In spite of the observed weak ability of the benzonitrile molecules for being adsorbed, the estimated heat of adsorption at an infinitely low surface concentration of -66.8 ± 2.2 kJ/mol is rather large. This value includes the contribution of roughly -30 to -35 kJ/mol of a benzene ring, about -10 kJ/mol of a large molecular dipole moment, and about -20 to -25 kJ/mol of a benzonitrile-water H-bond, as estimated from comparisons with the heat of adsorption values of similar molecules. The surprisingly weak ability of benzonitrile for adsorption is thus attributed to the unusually strong cohesion between the molecules, considerably exceeding their adhesion to ice, as reflected in the 70-80 kJ/mol difference of the lateral and ice contributions to the binding energy of surface benzonitrile molecules in the presence of condensed benzonitrile.
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Affiliation(s)
- Barbara Honti
- Budapest University of Technology and Economics, Szt. Gellért tér 4, H-1111 Budapest, Hungary
| | - Milán Szőri
- Institute of Chemistry, University of Miskolc, Egyetemváros A/2, H-3515 Miskolc, Hungary
| | - Pál Jedlovszky
- Department of Chemistry, Eszterházy Károly University, Leányka u. 6, H-3300 Eger, Hungary
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30
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Lbadaoui-Darvas M, Idrissi A, Jedlovszky P. Computer Simulation of the Surface of Aqueous Ionic and Surfactant Solutions. J Phys Chem B 2022; 126:751-765. [PMID: 34904437 PMCID: PMC9161821 DOI: 10.1021/acs.jpcb.1c08553] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The surface of aqueous solutions of simple salts was not the main focus of scientific attention for a long while. Considerable interest in studying such systems has only emerged in the past two decades, following the pioneering finding that large halide ions, such as I-, exhibit considerable surface affinity. Since then, a number of issues have been clarified; however, there are still several unresolved points (e.g., the effect of various salts on lateral water diffusion at the surface) in this respect. Computer simulation studies of the field have largely benefited from the appearance of intrinsic surface analysis methods, by which the particles staying right at the boundary of the two phases can be unambiguously identified. Considering complex ions instead of simple ones opens a number of interesting questions, both from the theoretical point of view and from that of the applications. Besides reviewing the state-of-the-art of intrinsic surface analysis methods as well as the most important advances and open questions concerning the surface of simple ionic solutions, we focus on two such systems in this Perspective, namely, the surface of aqueous mixtures of room temperature ionic liquids and that of ionic surfactants. In the case of the former systems, for which computer simulation studies have still scarcely been reported, we summarize the theoretical advances that could trigger such investigations, which might well be of importance also from the point of view of industrial applications. Computer simulation methods are, on the other hand, widely used in studies of the surface of surfactant solutions. Here we review the most important theoretical advances and issues to be addressed and discuss two areas of applications, namely, the inclusion of information gathered from such simulations in large scale atmospheric models and the better understanding of the airborne transmission of viruses, such as SARS-CoV-2.
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Affiliation(s)
- Mária Lbadaoui-Darvas
- Laboratory
of Atmospheric Processes and their Impacts, EPFL, CH-1015 Lausanne, Switzerland
| | - Abdenacer Idrissi
- CNRS,
UMR 8516 -LASIRe - Laboratoire Avancé de Spectroscopie pour
les Interactions la Réactivité et l’environnement, University of Lille, F-5900 Lille, France
| | - Pál Jedlovszky
- Department
of Chemistry, Eszterházy Károly
University, Leányka utca 6, H-3300 Eger, Hungary,
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31
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Zhou J, Ranjith P. Insights into interfacial behaviours of surfactant and polymer: A molecular dynamics simulation. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2021.117865] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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32
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Bui T, Frampton H, Huang S, Collins IR, Striolo A, Michaelides A. Water/oil interfacial tension reduction - an interfacial entropy driven process. Phys Chem Chem Phys 2021; 23:25075-25085. [PMID: 34738605 DOI: 10.1039/d1cp03971g] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The interfacial tension (IFT) of a fluid-fluid interface plays an important role in a wide range of applications and processes. When low IFT is desired, surface active compounds (e.g. surfactants) can be added to the system. Numerous attempts have been made to relate changes in IFT arising from such compounds to the specific nature of the interface. However, the IFT is controlled by an interplay of factors such as temperature and molecular structure of surface-active compounds, which make it difficult to predict IFT as those conditions change. In this study, we present the results from molecular dynamics simulations revealing the specific role surfactants play in IFT. We find that, in addition to reducing direct contact between the two fluids, surfactants serve to increase the disorder at the interface (related to interfacial entropy) and consequently reduce the water/oil IFT, especially when surfactants are present at high surface density. Our results suggest that surfactants that yield more disordered interfacial films (e.g. with flexible and/or unsaturated tails) reduce the water/oil IFT more effectively than surfactants which yield highly ordered interfacial films. Our results shed light on some of the factors that control IFT and could have important practical implications in industrial applications such as the design of cosmetics, food products, and detergents.
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Affiliation(s)
- Tai Bui
- Thomas Young Centre and London Centre for Nanotechnology, and Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, UK. .,BP Exploration Operating Co. Ltd, Chertsey Road, Sunbury-on-Thames TW16 7LN, UK.,Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK
| | - Harry Frampton
- BP Exploration Operating Co. Ltd, Chertsey Road, Sunbury-on-Thames TW16 7LN, UK
| | - Shanshan Huang
- BP Exploration Operating Co. Ltd, Chertsey Road, Sunbury-on-Thames TW16 7LN, UK
| | - Ian R Collins
- BP Exploration Operating Co. Ltd, Chertsey Road, Sunbury-on-Thames TW16 7LN, UK
| | - Alberto Striolo
- Department of Chemical Engineering, University College London, Gower Street, London WC1E 6BT, UK.,School of Chemical, Biological and Materials Engineering, University of Oklahoma, Norman, OK 73019, USA
| | - Angelos Michaelides
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK
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33
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Bonakala S, Hasan MI. Comparative study of external electric field and potential effects on liquid water ions. Mol Phys 2021. [DOI: 10.1080/00268976.2021.1998689] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
- Satyanarayana Bonakala
- Department of Electrical Engineering and Electronics, Centre for Plasma Microbiology, University of Liverpool, Liverpool, UK
| | - Mohammad I. Hasan
- Department of Electrical Engineering and Electronics, Centre for Plasma Microbiology, University of Liverpool, Liverpool, UK
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34
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Svoboda M, Jiménez S MG, Kowalski A, Cooke M, Mendoza C, Lísal M. Structural properties of cationic surfactant-fatty alcohol bilayers: insights from dissipative particle dynamics. SOFT MATTER 2021; 17:9967-9984. [PMID: 34704992 DOI: 10.1039/d1sm00850a] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Bilayers, self-assembled by cationic surfactants and fatty alcohols in water, are the basic units of lamellar gel networks - creamy formulations extensively used in cosmetics and pharmaceutics. Mesoscopic modelling and study of the bilayers formed by single- or double-tail cationic surfactants (CTAC or DHDAC), and fatty alcohols (FAs) in the lamellar fluid and gel phases were employed. Fatty alcohols with alkyl tail equal to or greater than the surfactant alkyl tail, i.e., C16FA or C18FA and C22FA, were considered. A model formulation was explored with the FA concentration greater than that of the surfactant and the structure of the fluid and gel bilayers in tensionless state characterised via the density profiles across the bilayers, orientational order parameters of the surfactant and FA chains, intrinsic analysis of the bilayer interfaces, and bending rigidity. The intrinsic analysis allows identification and quantification of the coexistence of the interdigitated and non-interdigitated phases present within the gel bilayers. The FA chains were found to conform the primary scaffolding of the bilayers while the surfactant chains tessellate bilayer monolayers from their water-hydrophobic interface. Further, the overlap of the FA chains from the apposed monolayers of the fluid bilayers rises with increasing FA length. Finally, the prevalence of the non-interdigitated phase over the interdigitated phase within the gel bilayers becomes enhanced upon the FA length increase with a preference of the surfactant chains to reside in the non-interdigitated phase rather than the interdigitated phase.
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Affiliation(s)
- Martin Svoboda
- Department of Molecular and Mesoscopic Modelling, The Czech Academy of Sciences, Institute of Chemical Process Fundamentals, Rozvojová 135/1, Prague, Czech Republic.
- Department of Physics, Faculty of Science, Jan Evangelista Purkyně University in Úst nad Labem, Pasteurova 1, Úst nad Labem, Czech Republic
| | | | - Adam Kowalski
- Unilever R&D, Port Sunlight Laboratory, Quarry Road East, Bebington, Wirral CH63 3JW, UK
| | - Michael Cooke
- Unilever R&D, Port Sunlight Laboratory, Quarry Road East, Bebington, Wirral CH63 3JW, UK
| | - César Mendoza
- Unilever R&D, Port Sunlight Laboratory, Quarry Road East, Bebington, Wirral CH63 3JW, UK
| | - Martin Lísal
- Department of Molecular and Mesoscopic Modelling, The Czech Academy of Sciences, Institute of Chemical Process Fundamentals, Rozvojová 135/1, Prague, Czech Republic.
- Department of Physics, Faculty of Science, Jan Evangelista Purkyně University in Úst nad Labem, Pasteurova 1, Úst nad Labem, Czech Republic
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35
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Kumar N, Clark AE. Unexpected inverse correlations and cooperativity in ion-pair phase transfer. Chem Sci 2021; 12:13930-13939. [PMID: 34760180 PMCID: PMC8549775 DOI: 10.1039/d1sc04004a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Accepted: 09/16/2021] [Indexed: 11/21/2022] Open
Abstract
Liquid/liquid extraction is one of the most widely used separation and purification methods, where a forefront of research is the study of transport mechanisms for solute partitioning and the relationships that these have to solution structure at the phase boundary. To date, organized surface features that include protrusions, water-fingers, and molecular hinges have been reported. Many of these equilibrium studies have focused upon small-molecule transport – yet the extent to which the complexity of the solute, and the competition between different solutes, influence transport mechanisms have not been explored. Here we report molecular dynamics simulations that demonstrate that a metal salt (LiNO3) can be transported via a protrusion mechanism that is remarkably similar to that reported for H2O by tri-butyl phosphate (TBP), a process that involves dimeric assemblies. Yet the LiNO3 out-competes H2O for a bridging position between the extracting TBP dimer, which in-turn changes the preferred transport pathway of H2O. Examining the electrolyte concentration dependence on ion-pair transport unexpectedly reveals an inverse correlation with the extracting surfactant concentration. As [LiNO3] increases, surface adsorbed TBP becomes a limiting reactant in correlation with an increased negative surface charge induced by excess interfacial NO3−, however the rate of transport is enhanced. Within the highly dynamic interfacial environment, we hypothesize that this unique cooperative effect may be due to perturbed surface organization that either decreases the energy of formation of transporting protrusion motifs or makes it easier for these self-assembled species to disengage from the surface. A forefront of research in separations science (specifically liquid–liquid extraction) is the study of transport mechanisms for solute partitioning, and the relationships that these have to solution structure at the phase boundary.![]()
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Affiliation(s)
- Nitesh Kumar
- Department of Chemistry, Washington State University Pullman Washington 99164 USA
| | - Aurora E Clark
- Department of Chemistry, Washington State University Pullman Washington 99164 USA.,Pacific Northwest National Laboratory Richland Washington 99354 USA
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36
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Lbadaoui-Darvas M, Garberoglio G, Karadima KS, Cordeiro MNDS, Nenes A, Takahama S. Molecular simulations of interfacial systems: challenges, applications and future perspectives. MOLECULAR SIMULATION 2021. [DOI: 10.1080/08927022.2021.1980215] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Affiliation(s)
- Mária Lbadaoui-Darvas
- ENAC/IIE; Swiss Federal Institute of Technology Lausanne (EPFL), Lausanne, Switzerland
| | - Giovanni Garberoglio
- European Centre for Theoretical Studies in Nuclear Physics and Related Areas (FBK-ECT*), Trento, Italy
- Trento Institute for Fundamental Physics and Applications (TIFPA-INFN), Trento, Italy
| | - Katerina S. Karadima
- Department of Chemical Engineering, University of Patras, Patras, Greece
- Institute of Chemical Engineering Sciences, Foundation for Research and Technology Hellas(FORTH-ICE/HT), Patras, Greece
| | | | - Athanasios Nenes
- ENAC/IIE; Swiss Federal Institute of Technology Lausanne (EPFL), Lausanne, Switzerland
- Institute of Chemical Engineering Sciences, Foundation for Research and Technology Hellas(FORTH-ICE/HT), Patras, Greece
| | - Satoshi Takahama
- ENAC/IIE; Swiss Federal Institute of Technology Lausanne (EPFL), Lausanne, Switzerland
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37
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Ozsipahi M, Akkus Y, Nguyen CT, Beskok A. Energy-Based Interface Detection for Phase Change Processes of Monatomic Fluids in Nanoconfinements. J Phys Chem Lett 2021; 12:8397-8403. [PMID: 34435788 DOI: 10.1021/acs.jpclett.1c02517] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
An energy-based liquid-vapor interface detection method is presented using molecular dynamics simulations of liquid menisci confined between two parallel plates under equilibrium and evaporation/condensation conditions. This method defines the liquid-vapor interface at the location where the average kinetic energy of atoms first exceeds the average potential energy imposed by all neighboring molecules. This definition naturally adapts to the location of the menisci relative to the walls and can properly model the behavior of the liquid adsorbed layers. Unlike the density cutoff methods frequently used in the literature that suffer from density layering effects, this new method gives smooth and continuous liquid-vapor interfaces in nanoconfinements. Surface tension values calculated from the equilibrium MD simulations match the Young-Laplace equation better when using the radius of curvatures calculated from this method. Overall, this energy-based liquid-vapor interface detection method can be used in studies of nanoscale phase change processes and other relevant applications.
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Affiliation(s)
- Mustafa Ozsipahi
- Southern Methodist University, Dallas, Texas 75205, United States
| | | | | | - Ali Beskok
- Southern Methodist University, Dallas, Texas 75205, United States
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38
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Kumar N, Servis MJ, Clark AE. Uranyl Speciation in the Presence of Specific Ion Gradients at the Electrolyte/Organic Interface. SOLVENT EXTRACTION AND ION EXCHANGE 2021. [DOI: 10.1080/07366299.2021.1954323] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- Nitesh Kumar
- Department of Chemistry, Washington State University, Pullman, Washington, USA
| | - Michael J. Servis
- Department of Chemistry, Washington State University, Pullman, Washington, USA
| | - Aurora E. Clark
- Department of Chemistry, Washington State University, Pullman, Washington, USA
- Pacific Northwest National Laboratory, Richland, Washington, USA
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39
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Smith ER. The importance of reference frame for pressure at the liquid–vapour interface. MOLECULAR SIMULATION 2021. [DOI: 10.1080/08927022.2021.1953697] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- Edward R. Smith
- Department of Mechanical and Aerospace Engineering, Brunel University London, Uxbridge, London, UK
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40
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41
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Ziolek RM, Smith P, Pink DL, Dreiss CA, Lorenz CD. Unsupervised Learning Unravels the Structure of Four-Arm and Linear Block Copolymer Micelles. Macromolecules 2021. [DOI: 10.1021/acs.macromol.0c02523] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Robert M. Ziolek
- Biological Physics and Soft Matter Group, Department of Physics, King’s College London, London WC2R 2LS, U.K
| | - Paul Smith
- Biological Physics and Soft Matter Group, Department of Physics, King’s College London, London WC2R 2LS, U.K
| | - Demi L. Pink
- Biological Physics and Soft Matter Group, Department of Physics, King’s College London, London WC2R 2LS, U.K
| | - Cécile A. Dreiss
- Institute of Pharmaceutical Science, King’s College London, London SE1 9NH, U.K
| | - Christian D. Lorenz
- Biological Physics and Soft Matter Group, Department of Physics, King’s College London, London WC2R 2LS, U.K
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42
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Pink DL, Loruthai O, Ziolek RM, Terry AE, Barlow DJ, Lawrence MJ, Lorenz CD. Interplay of lipid and surfactant: Impact on nanoparticle structure. J Colloid Interface Sci 2021; 597:278-288. [PMID: 33872884 DOI: 10.1016/j.jcis.2021.03.136] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Revised: 02/15/2021] [Accepted: 03/24/2021] [Indexed: 11/24/2022]
Abstract
Liquid lipid nanoparticles (LLN) are oil-in-water nanoemulsions of great interest in the delivery of hydrophobic drug molecules. They consist of a surfactant shell and a liquid lipid core. The small size of LLNs makes them difficult to study, yet a detailed understanding of their internal structure is vital in developing stable drug delivery vehicles (DDVs). Here, we implement machine learning techniques alongside small angle neutron scattering experiments and molecular dynamics simulations to provide critical insight into the conformations and distributions of the lipid and surfactant throughout the LLN. We simulate the assembly of a single LLN composed of the lipid, triolein (GTO), and the surfactant, Brij O10. Our work shows that the addition of surfactant is pivotal in the formation of a disordered lipid core; the even coverage of Brij O10 across the LLN shields the GTO from water and so the lipids adopt conformations that reduce crystallisation. We demonstrate the superior ability of unsupervised artificial neural networks in characterising the internal structure of DDVs, when compared to more conventional geometric methods. We have identified, clustered, classified and averaged the dominant conformations of lipid and surfactant molecules within the LLN, providing a multi-scale picture of the internal structure of LLNs.
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Affiliation(s)
- Demi L Pink
- Biological Physics and Soft Matter Group, Department of Physics, King's College London, London, WC2R 2LS, United Kingdom
| | - Orathai Loruthai
- Pharmaceutical Biophysics Group, Institute of Pharmaceutical Science, King's College London, London, SW1 9NH, United Kingdom
| | - Robert M Ziolek
- Biological Physics and Soft Matter Group, Department of Physics, King's College London, London, WC2R 2LS, United Kingdom
| | - Ann E Terry
- CoSAXS beamline, MAX IV Laboratory, Lund University, P.O. Box 118, SE-221 00 Lund, Sweden
| | - David J Barlow
- Division of Pharmacy and Optometry, School of Health Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Stopford Building, Oxford Road, Manchester, United Kingdom
| | - M Jayne Lawrence
- Division of Pharmacy and Optometry, School of Health Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Stopford Building, Oxford Road, Manchester, United Kingdom.
| | - Christian D Lorenz
- Biological Physics and Soft Matter Group, Department of Physics, King's College London, London, WC2R 2LS, United Kingdom.
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43
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Morita A, Koizumi A, Hirano T. Recent progress in simulating microscopic ion transport mechanisms at liquid-liquid interfaces. J Chem Phys 2021; 154:080901. [PMID: 33639756 DOI: 10.1063/5.0039172] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Transport of ions through liquid-liquid interfaces is of fundamental importance to a wide variety of applications. However, since it is quite challenging for experimentalists to directly and selectively observe molecules at the interfaces, microscopic mechanisms of ion transport have been largely presumed from kinetic information. This Perspective illustrates recent examples that molecular dynamics simulations with proper free energy surfaces clarified mechanistic pictures of ion transport. The key is a proper choice of coordinates and defining/calculating free energy surfaces in multidimensional space. Once the free energy surfaces for realistic systems are available, they naturally provide new insight into the ion transport in unprecedented details, including water finger, transient ion pairing, and electron transfer.
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Affiliation(s)
- Akihiro Morita
- Department of Chemistry, Graduate School of Science, Tohoku University, Aoba-ku, Sendai 980-8578, Japan
| | - Ai Koizumi
- Department of Chemistry, Graduate School of Science, Tohoku University, Aoba-ku, Sendai 980-8578, Japan
| | - Tomonori Hirano
- Department of Chemistry, Graduate School of Science, Tohoku University, Aoba-ku, Sendai 980-8578, Japan
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44
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Houle FA, Miles REH, Pollak CJ, Reid JP. A purely kinetic description of the evaporation of water droplets. J Chem Phys 2021; 154:054501. [PMID: 33557551 DOI: 10.1063/5.0037967] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The process of water evaporation, although deeply studied, does not enjoy a kinetic description that captures known physics and can be integrated with other detailed processes such as drying of catalytic membranes embedded in vapor-fed devices and chemical reactions in aerosol whose volumes are changing dynamically. In this work, we present a simple, three-step kinetic model for water evaporation that is based on theory and validated by using well-established thermodynamic models of droplet size as a function of time, temperature, and relative humidity as well as data from time-resolved measurements of evaporating droplet size. The kinetic mechanism for evaporation is a combination of two limiting processes occurring in the highly dynamic liquid-vapor interfacial region: direct first order desorption of a single water molecule and desorption resulting from a local fluctuation, described using third order kinetics. The model reproduces data over a range of relative humidities and temperatures only if the interface that separates bulk water from gas phase water has a finite width, consistent with previous experimental and theoretical studies. The influence of droplet cooling during rapid evaporation on the kinetics is discussed; discrepancies between the various models point to the need for additional experimental data to identify their origin.
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Affiliation(s)
- Frances A Houle
- Joint Center for Artificial Photosynthesis and Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Rachael E H Miles
- School of Chemistry, University of Bristol, Bristol BS8 1TS, United Kingdom
| | - Connor J Pollak
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, California 94720, USA
| | - Jonathan P Reid
- School of Chemistry, University of Bristol, Bristol BS8 1TS, United Kingdom
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45
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Hantal G, Kolafa J, Sega M, Jedlovszky P. Single-Particle Dynamics at the Intrinsic Surface of Aqueous Alkali Halide Solutions. J Phys Chem B 2021; 125:665-679. [PMID: 33423500 DOI: 10.1021/acs.jpcb.0c09989] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The distribution of ions in the proximity of the liquid-vapor interface of their aqueous solution has been the subject of an intense debate during the last decade. The effects of ionic polarizability have been one of its salient aspects. Much less has been said about the corresponding dynamical properties, which are substantially unexplored. Here, we investigate the single-particle dynamics at the liquid-vapor interface of several alkali halide solutions, using molecular dynamics simulations with polarizable and nonpolarizable force fields and intrinsic surface analysis. We analyze the diffusion coefficient, residence time, and velocity autocorrelation function of water and ions and investigate how these properties depend on the molecular layer where they reside. While anions are found in the first molecular layer for relatively long times, cations are only making quick excursions into it, thanks to thermal fluctuations. The in-layer residence time of ions and their molar fraction in the layer turned out to be linearly dependent on each other. We interpret this unexpected result using a simple two-state model. In addition, we found that, unlike water and other neat molecular liquids that show a different diffusion mechanism at the surface than in the bulk of their liquid phase, ions do not enjoy enhanced mobility in the surface layer of their aqueous solution. This result indicates that ions in the surface layer are shielded by their nearest water neighbors from being exposed to the vapor phase as much as possible. Such positions are available for the ions at the negatively curved troughs of the molecularly rugged liquid surface.
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Affiliation(s)
- György Hantal
- Institute of Physics and Materials Science, University of Natural Resources and Life Sciences, Peter Jordan Straße 82, Vienna A-1190, Austria
| | - Jiří Kolafa
- Department of Physical Chemistry, University of Chemistry and Technology, Prague CZ-166 28 Prague 6, Czech Republic
| | - Marcello Sega
- Forschungszentrum Jülich GmbH, Helmholtz Institute Erlangen-Nürnberg for Renewable Energy (IEK-11), Fürther Straße 248, Nürnberg D-90429, Germany
| | - Pál Jedlovszky
- Department of Chemistry, Eszterházy Károly University, Leányka utca 6, Eger H-3300, Hungary
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46
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Wonglakhon T, Maisel S, Görling A, Zahn D. An embedded atom model for Ga-Pd systems: From intermetallic crystals to liquid alloys. J Chem Phys 2021; 154:014109. [PMID: 33412884 DOI: 10.1063/5.0031185] [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
We present an embedded atom model (EAM) potential for modeling Ga-Pd interactions within intermetallic solids and liquid alloys. The molecular mechanics potential was parameterized on the basis of the structure and mechanical properties of GaPd2, whereas a series of other GaxPd1-x phases and liquid alloy systems allowed rigorous benchmarking. For the intermetallic solids, structures and elastic moduli were found in very reasonable agreement with experimental structures and results from DFT calculations. The liquid models were characterized from molecular dynamics simulations that also showed nice agreement with experimental and ab initio reference data. Moreover, the perspectives of the EAM model are illustrated by the elucidation of an alloy nanodroplet model whose characterization includes the kinetics of Pd dopant diffusion from the Ga droplet surface to the bulk liquid and vice versa.
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Affiliation(s)
- Tanakorn Wonglakhon
- Lehrstuhl für Theoretische Chemie, Computer Chemie Centrum, Friedrich-Alexander Universität Erlangen-Nürnberg, Nägelsbachstraße 25, 91052 Erlangen, Germany
| | - Sven Maisel
- Lehrstuhl für Theoretische Chemie, Friedrich-Alexander Universität Erlangen-Nürnberg, Egerlandstraße 3, D-91058 Erlangen, Germany
| | - Andreas Görling
- Lehrstuhl für Theoretische Chemie, Friedrich-Alexander Universität Erlangen-Nürnberg, Egerlandstraße 3, D-91058 Erlangen, Germany
| | - Dirk Zahn
- Lehrstuhl für Theoretische Chemie, Computer Chemie Centrum, Friedrich-Alexander Universität Erlangen-Nürnberg, Nägelsbachstraße 25, 91052 Erlangen, Germany
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47
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Mosallanejad S, Oluwoye I, Altarawneh M, Gore J, Dlugogorski BZ. Interfacial and bulk properties of concentrated solutions of ammonium nitrate. Phys Chem Chem Phys 2020; 22:27698-27712. [PMID: 33242055 DOI: 10.1039/d0cp04874g] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We conducted molecular dynamics (MD) simulations to calculate the density and surface tension of concentrated ammonium nitrate (AN) solutions up to the solubility limit of ammonium nitrate in water, by combining the SPC/E, SPCE/F and TIP4P/2005 water models with OPLS model for ammonium and nitrate ions. This is the first time that the properties of concentrated solutions of nitrates, especially AN, have been studied by molecular dynamics. We effectively account for the polarisation effects by the electronic continuum correction (ECC), practically realised via rescaling of the ionic charges. We found that, the full-charge force field MD simulations overestimate the experimental results, as the ions experience repulsion from the interface and prefer to remain in the subsurface layer and the bulk solution. In contrast, reducing the ionic charges results in the behaviour that fits well with the experimental data. The nitrate anions display a greater propensity for the interface than the ammonium cations. We accurately predict both the density and the rise in the surface tension of concentrated solutions of AN, recommending TIP4P/2005 for water and the scaled-charge OPLS model (OPLS/ECC) for the ions in the solutions. We observe that, the adsorption of anions to the interface accompanies their depletion in the subsurface layer, which is preferentially occupied by cations, resulting in the formation of the electric double layer. We demonstrate the ion deficiency for up to 3 Å below the surface and establish the requirement to include the polarisability effects in the OPLS model for AN. While these results confirmed the findings of the previous studies for dilute solutions, they are new in the solubility limit. Concentrated solutions exhibit a strong effect of the abundance of solute on the coordination numbers of ions and on the degree of ion pairing. Surprisingly, ion pairing decreases significantly at the interface compared with the bulk. The present study identifies OPLS/ECC, along with TIP4P/2005, to yield accurate predictions of physical properties of concentrated AN, with precision required for industrial applications, such as a formulation of emulsion and fuel-oil explosives that now predominate the civilian use of AN. An application of this model will allow one to predict the surface properties of supersaturated solutions of AN which fall outside the capability of the present laboratory experiments but are important industrially.
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Affiliation(s)
- Sara Mosallanejad
- Discipline of Chemistry and Physics, College of Science, Health, Engineering and Education, Murdoch University, 90 South Street, Murdoch, WA 6150, Australia
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Abstract
Despite their prevalent use as a surrogate for partitioning of pharmacologically active solutes across lipid membranes, the mechanism of transport across water/octanol phase boundaries has remained unexplored. Using molecular dynamics, graph theoretical, cluster analysis, and Langevin dynamics, we reveal an elegant mechanism for the simplest solute, water. Self-assembled octanol at the interface reversibly binds water and swings like the hinge of a door to bring water into a semi-organized second interfacial layer (a “bilayer island”). This mechanism is distinct from well-known lipid flipping and water transport processes in protein-free membranes, highlighting important limitations in the water/octanol proxy. Interestingly, the collective and reversible behavior is well-described by a double well potential energy function, with the two stable states being the water bound to the hinge on either side of the interface. The function of the hinge for transport, coupled with the underlying double well energy landscape, is akin to a molecular switch or shuttle that functions under equilibrium and is driven by the differential free energies of solvation of H2O across the interface. This example successfully operates within the dynamic motion of instantaneous surface fluctuations, a feature that expands upon traditional approaches toward controlled solute transport that act to avoid or circumvent the dynamic nature of the interface. Despite their pharmacological relevance, the mechanism of transport across water/octanol phase boundaries has remained unexplored. Octanol molecular assemblies are demonstrated to reversibly bind water and swing like the hinge of a door.![]()
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Affiliation(s)
- Zhu Liu
- Department of Chemistry, Washington State University Pullman Washington 99164 USA
| | - Aurora E Clark
- Department of Chemistry, Washington State University Pullman Washington 99164 USA .,Voiland School of Chemical Engineering and Bioengineering, Washington State University Pullman WA 99164 USA.,Pacific Northwest National Laboratory Richland Washington 99352 USA
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Ziolek RM, Omar J, Hu W, Porcar L, González-Gaitano G, Dreiss CA, Lorenz CD. Understanding the pH-Directed Self-Assembly of a Four-Arm Block Copolymer. Macromolecules 2020. [DOI: 10.1021/acs.macromol.0c01694] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- Robert M. Ziolek
- Biological Physics and Soft Matter Group, Department of Physics, King’s College London, London WC2R 2LS, United Kingdom
| | - Jasmin Omar
- Institute of Pharmaceutical Science, King’s College London, London SE1 9NH, United Kingdom
| | - Wenjing Hu
- Institute of Pharmaceutical Science, King’s College London, London SE1 9NH, United Kingdom
| | - Lionel Porcar
- Institut Max Von Laue Paul Langevin, F-38042 Grenoble 9, France
| | | | - Cécile A. Dreiss
- Institute of Pharmaceutical Science, King’s College London, London SE1 9NH, United Kingdom
| | - Christian D. Lorenz
- Biological Physics and Soft Matter Group, Department of Physics, King’s College London, London WC2R 2LS, United Kingdom
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Moritz C, Sega M, Innerbichler M, Geissler PL, Dellago C. Weak scaling of the contact distance between two fluctuating interfaces with system size. Phys Rev E 2020; 102:062801. [PMID: 33465946 DOI: 10.1103/physreve.102.062801] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Accepted: 10/30/2020] [Indexed: 06/12/2023]
Abstract
A pair of flat parallel surfaces, each freely diffusing along the direction of their separation, will eventually come into contact. If the shapes of these surfaces also fluctuate, then contact will occur when their centers-of-mass remain separated by a nonzero distance ℓ. An example of such a situation is the motion of interfaces between two phases at conditions of thermodynamic coexistence, and in particular the annihilation of domain wall pairs under periodic boundary conditions. Here we present a general approach to calculate the probability distribution of the contact distance ℓ and determine how its most likely value ℓ^{*} depends on the surfaces' lateral size L. Using the Edward-Wilkinson equation as a model for interfaces, we demonstrate that ℓ^{*} scales weakly with system size, i.e., the dependence of ℓ^{*} on L for both (1+1)- and (2+1)-dimensional interfaces is such that lim_{L→∞}(ℓ^{*}/L)=0. In particular, for (2+1)-dimensional interfaces ℓ^{*} is an algebraic function of logL, a result that is confirmed by computer simulations of slab-shaped domains formed under periodic boundary conditions. This weak scaling implies that such domains remain topologically intact until ℓ becomes very small compared to the lateral size of the interface, contradicting expectations from equilibrium thermodynamics.
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Affiliation(s)
- Clemens Moritz
- Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna, Austria
| | - Marcello Sega
- Forschungszentrum Jülich GmbH, Helmholtz Institute Erlangen-Nürnberg for Renewable Energy (IEK-11), Fürther Straße 248, 90429 Nürnberg, Germany
| | - Max Innerbichler
- Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna, Austria
| | - Phillip L Geissler
- Department of Chemistry, University of California, Berkeley, California 94720, USA
| | - Christoph Dellago
- Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna, Austria
- Erwin Schrödinger Institute for Mathematics and Physics, Boltzmanngasse 9, 1090, Vienna, Austria
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