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Walenszus F, Bon V, Evans JD, Krause S, Getzschmann J, Kaskel S, Dvoyashkin M. On the role of history-dependent adsorbate distribution and metastable states in switchable mesoporous metal-organic frameworks. Nat Commun 2023; 14:3223. [PMID: 37270577 DOI: 10.1038/s41467-023-38737-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2022] [Accepted: 05/10/2023] [Indexed: 06/05/2023] Open
Abstract
A unique feature of metal-organic frameworks (MOFs) in contrast to rigid nanoporous materials is their structural switchabilty offering a wide range of functionality for sustainable energy storage, separation and sensing applications. This has initiated a series of experimental and theoretical studies predominantly aiming at understanding the thermodynamic conditions to transform and release gas, but the nature of sorption-induced switching transitions remains poorly understood. Here we report experimental evidence for fluid metastability and history-dependent states during sorption triggering the structural change of the framework and leading to the counterintuitive phenomenon of negative gas adsorption (NGA) in flexible MOFs. Preparation of two isoreticular MOFs differing by structural flexibility and performing direct in situ diffusion studies aided by in situ X-ray diffraction, scanning electron microscopy and computational modelling, allowed assessment of n-butane molecular dynamics, phase state, and the framework response to obtain a microscopic picture for each step of the sorption process.
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Affiliation(s)
- Francesco Walenszus
- Department of Inorganic Chemistry, Technische Universität Dresden, 01069, Dresden, Germany
| | - Volodymyr Bon
- Department of Inorganic Chemistry, Technische Universität Dresden, 01069, Dresden, Germany
| | - Jack D Evans
- Centre for Advanced Nanomaterials and Department of Chemistry, The University of Adelaide, Adelaide, SA, 5000, Australia
| | - Simon Krause
- Nanochemistry department, Max Planck Institute for Solid State Research, 70569, Stuttgart, Germany
| | - Jürgen Getzschmann
- Department of Inorganic Chemistry, Technische Universität Dresden, 01069, Dresden, Germany
| | - Stefan Kaskel
- Department of Inorganic Chemistry, Technische Universität Dresden, 01069, Dresden, Germany.
- Fraunhofer Institute IWS, Winterbergstr. 28, 01277, Dresden, Germany.
| | - Muslim Dvoyashkin
- Institute of Chemical Technology, Universität Leipzig, 04103, Leipzig, Germany.
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2
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Unveiling the Molecular Origin of Vapor-Liquid Phase Transition of Bulk and Confined Fluids. Molecules 2022; 27:molecules27092656. [PMID: 35566010 PMCID: PMC9103202 DOI: 10.3390/molecules27092656] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Revised: 04/16/2022] [Accepted: 04/19/2022] [Indexed: 02/04/2023] Open
Abstract
At temperatures below the critical temperature, discontinuities in the isotherms are one critical issue in the design and construction of separation units, affecting the level of confidence for a prediction of vapor–liquid equilibriums and phase transitions. In this work, we study the molecular mechanisms of fluids that involve the vapor–liquid phase transition in bulk and confinement, utilizing grand canonical (GCE) and meso-canonical (MCE) ensembles of the Monte Carlo simulation. Different geometries of the mesopores, including slit, cylindrical, and spherical, were studied. During phase transitions, condensation/evaporation hysteretic isotherms can be detected by GCE simulation, whereas employing MCE simulation allows us to investigate van der Waals (vdW) loop with a vapor spinodal point, intermediate states, and a liquid spinodal point in the isotherms. Depending on the system, the size of the simulation box, and the MCE method, we are able to identify three distinct groups of vdW-type isotherms for the first time: (1) a smooth S-shaped loop, (2) a stepwise S-shaped loop, and (3) a stepwise S-shaped loop with just a vertical segment. The first isotherm type is noticed in the bulk and pores having small box sizes, in which vapor and liquid phases are close and not clearly identified. The second and the third types occurred in the bulk, cylindrical, and slit mesopores with sufficiently large spaces, where vapor and liquid phases are distinctly separated. Results from our studies provide an insight analysis into vapor–liquid phase transitions, elucidating the effect of the confinement of fluid behaviors in a visual manner.
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3
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Morishige K. Pore Size Distribution Analysis Using Developing Hysteresis of Nitrogen in the Cylindrical Pores of Silica. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:4222-4233. [PMID: 35360908 DOI: 10.1021/acs.langmuir.1c03219] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
A new method of mesopore size analysis was developed for the cylindrical pores of silica using a developing hysteresis of nitrogen measured at liquid nitrogen temperature. The method is based on the semimacroscopic approach of a modified Bonnet-Wolf model that deals with the grand potential of a vapor bubble in the cylindrical pore. It is capable of assessing correctly the pore structures of mesoporous materials with cylindrical pores using the narrow hysteresis loop of the developing hysteresis. When the mesoporous materials possess cylindrical pores of minor imperfections, two pore size distributions (PSDs) from the adsorption and desorption branches overlap. On the other hand, for cylindrical pores with an enhanced amplitude of pore corrugations and/or constrictions, PSD from the desorption branch is shifted to smaller pore sizes compared to the one from the adsorption branch, and at the same time, both the PSDs evaluated are shifted to lower pore sizes compared to the actual ones. The actual PSD can be assessed from the reversible isotherm measured at a hysteresis critical temperature. In principle, the present method may enable the determination of the PSDs from the adsorption hysteresis measured at any given temperature for mesoporous materials with cylindrical pores.
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Affiliation(s)
- Kunimitsu Morishige
- Department of Chemistry, Okayama University of Science, 1-1 Ridai-cho, Kita-ku, Okayama 700-0005, Japan
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4
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Machine-Learned Free Energy Surfaces for Capillary Condensation and Evaporation in Mesopores. ENTROPY 2022; 24:e24010097. [PMID: 35052123 PMCID: PMC8774451 DOI: 10.3390/e24010097] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Revised: 12/29/2021] [Accepted: 01/05/2022] [Indexed: 12/04/2022]
Abstract
Using molecular simulations, we study the processes of capillary condensation and capillary evaporation in model mesopores. To determine the phase transition pathway, as well as the corresponding free energy profile, we carry out enhanced sampling molecular simulations using entropy as a reaction coordinate to map the onset of order during the condensation process and of disorder during the evaporation process. The structural analysis shows the role played by intermediate states, characterized by the onset of capillary liquid bridges and bubbles. We also analyze the dependence of the free energy barrier on the pore width. Furthermore, we propose a method to build a machine learning model for the prediction of the free energy surfaces underlying capillary phase transition processes in mesopores.
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5
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Berim GO, Ruckenstein E. Structure of a nanodrop of a binary mixture on a solid surface. Mol Phys 2021. [DOI: 10.1080/00268976.2021.1976857] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- Gersh O. Berim
- Department of Chemical and Biological Engineering, State University of New York at Buffalo, Buffalo, NY, USA
| | - Eli Ruckenstein
- Department of Chemical and Biological Engineering, State University of New York at Buffalo, Buffalo, NY, USA
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6
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Morishige K. Revisiting the Nature of Adsorption and Desorption Branches: Temperature Dependence of Adsorption Hysteresis in Ordered Mesoporous Silica. ACS OMEGA 2021; 6:15964-15974. [PMID: 34179641 PMCID: PMC8223431 DOI: 10.1021/acsomega.1c01643] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Accepted: 05/28/2021] [Indexed: 06/13/2023]
Abstract
To gain a deeper understanding as to the nature of the adsorption hysteresis due to capillary condensation of nitrogen in ordered mesoporous silicas, we calculated the temperature dependences of the activated condensation, equilibrium transition, and activated desorption pressures for nitrogen in spherical and cylindrical silica pores with several different pore sizes on the basis of semimacroscopic continuum models. The results clearly indicate that the models capture the exact nature of capillary condensation and evaporation phenomena of a fluid in cagelike and cylindrical mesopores. The temperature dependences of the adsorption hysteresis of nitrogen measured confirm previous theoretical predictions for cylindrical pores: for the ordered mesoporous silicas with cylindrical mesopores at least greater than ∼7 nm in diameter, the capillary condensation takes place via a nucleation process followed by a growth process of a bridging meniscus at pressures higher than the equilibrium transition, while the capillary evaporation takes place via a receding meniscus from pore ends at the equilibrium. For SBA-15 and MCM-41 with smaller mesopore sizes, on the other hand, the capillary condensation takes place close to the equilibrium transition pressures, while the capillary evaporation takes place at pressures lower than the equilibrium, owing to single pore blocking due to corrugation of the cylindrical pores. We discuss the effect of curvature on surface tension in capillary condensation, as well as the relation between a change in the mechanisms of adsorption and desorption and the pore corrugation in the cylindrical pores.
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Affiliation(s)
- Kunimitsu Morishige
- Department of Chemistry, Okayama University of Science, 1-1 Rida-cho, Kita-ku, Okayama 700-0005, Japan
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7
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Doebele V, Benoit-Gonin A, Souris F, Cagnon L, Spathis P, Wolf PE, Grosman A, Bossert M, Trimaille I, Rolley E. Direct Observation of Homogeneous Cavitation in Nanopores. PHYSICAL REVIEW LETTERS 2020; 125:255701. [PMID: 33416391 DOI: 10.1103/physrevlett.125.255701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Revised: 10/16/2020] [Accepted: 10/30/2020] [Indexed: 06/12/2023]
Abstract
We report on the evaporation of hexane from porous alumina and silicon membranes. These membranes contain billions of independent nanopores tailored to an ink-bottle shape, where a cavity several tens of nanometers in diameter is separated from the bulk vapor by a constriction. For alumina membranes with narrow enough constrictions, we demonstrate that cavity evaporation proceeds by cavitation. Measurements of the pressure dependence of the cavitation rate follow the predictions of the bulk, homogeneous, classical nucleation theory, definitively establishing the relevance of homogeneous cavitation as an evaporation mechanism in mesoporous materials. Our results imply that porous alumina membranes are a promising new system to study liquids in a deeply metastable state.
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Affiliation(s)
- V Doebele
- Université Grenoble Alpes, CNRS, Institut Néel, F-38042 Grenoble, France
| | - A Benoit-Gonin
- Université Grenoble Alpes, CNRS, Institut Néel, F-38042 Grenoble, France
| | - F Souris
- Université Grenoble Alpes, CNRS, Institut Néel, F-38042 Grenoble, France
| | - L Cagnon
- Université Grenoble Alpes, CNRS, Institut Néel, F-38042 Grenoble, France
| | - P Spathis
- Université Grenoble Alpes, CNRS, Institut Néel, F-38042 Grenoble, France
| | - P E Wolf
- Université Grenoble Alpes, CNRS, Institut Néel, F-38042 Grenoble, France
| | - A Grosman
- Sorbonne Université, CNRS, Institut des NanoSciences de Paris, INSP, F-75005 Paris, France
| | - M Bossert
- Sorbonne Université, CNRS, Institut des NanoSciences de Paris, INSP, F-75005 Paris, France
| | - I Trimaille
- Sorbonne Université, CNRS, Institut des NanoSciences de Paris, INSP, F-75005 Paris, France
| | - E Rolley
- Laboratoire de Physique de l'Ecole Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université de Paris, F-75005 Paris, France
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8
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Desgranges C, Delhommelle J. Nucleation of Capillary Bridges and Bubbles in Nanoconfined CO 2. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:15401-15409. [PMID: 31675236 DOI: 10.1021/acs.langmuir.9b01744] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Using molecular simulation, we examine the capillary condensation and the capillary evaporation of CO2 in cylindrical nanopores. More specifically, we employ the recently developed μV T-S method to determine the microscopic mechanism associated with these processes and the corresponding free energy profiles. We calculate the free energy barrier for capillary condensation and identify that the key step consists in the nucleation of a liquid bridge of a critical size. Similarly, the free energy maximum found for the capillary evaporation process is found to correspond to the nucleation of a vapor bubble of a critical size. In addition, we assess the impact of the strength of the wall-fluid on the height of the free energy barrier and on the critical size of liquid bridges (condensation process) and vapor bubbles (evaporation process). We observe that the height of the free energy barrier increases with the strength of the wall-fluid interactions. Finally, we build a theoretical model, based on capillary theory, to rationalize our findings. In particular, the simulation results reveal a linear scaling of the free energy barrier with the critical size, in excellent agreement with the theoretical predictions.
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Affiliation(s)
- Caroline Desgranges
- Department of Chemistry , New York University , New York , New York 10003 , United States
- Department of Chemistry , University of North Dakota , Grand Forks , North Dakota 58202 , United States
| | - Jerome Delhommelle
- Department of Chemistry , New York University , New York , New York 10003 , United States
- Department of Chemistry , University of North Dakota , Grand Forks , North Dakota 58202 , United States
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9
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Gommes CJ, Roberts AP. Stochastic analysis of capillary condensation in disordered mesopores. Phys Chem Chem Phys 2018; 20:13646-13659. [PMID: 29737990 DOI: 10.1039/c8cp01628c] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Most mesoporous materials of practical interest are inherently disordered, which has a significant impact on the condensation and evaporation of vapours in their pores. Traditionally, the effect of disorder is theoretically analyzed in a perturbative approach whereby slight elements of disorder (constriction, corrugation) are added to geometrically ideal pores. We propose an alternative approach, which consists of using a stochastic geometrical model to describe both the porous material and the condensate within the pores. This is done through a multiphase generalisation of the standard Gaussian random field model of disordered materials. The model parameters characterising the condensate provide a low-dimensional approximation of its configuration space, and we use a Derjaguin-Broekhoff-de Boer approximation to calculate the free-energy landscape. Our analysis notably questions the existence of vapour-like metastable states in realistically disordered mesoporous materials. Beyond capillary condensation, our general methodology is applicable to a broad array of confined phenomena.
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Affiliation(s)
- Cedric J Gommes
- Department of Chemical Engineering, University of Liège, Allée du Six Août, 3, B-4000 Liège, Belgium.
| | - Anthony P Roberts
- School of Mathematics and Physics, The University of Queensland, Brisbane, QLD 4072, Australia
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10
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Moritz C, Tröster A, Dellago C. Interplay of fast and slow dynamics in rare transition pathways: The disk-to-slab transition in the 2d Ising model. J Chem Phys 2017; 147:152714. [DOI: 10.1063/1.4997479] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Affiliation(s)
- Clemens Moritz
- Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna, Austria
| | - Andreas Tröster
- Institute of Materials Chemistry, Vienna University of Technology, Getreidemarkt 9, 1060 Vienna, Austria
| | - Christoph Dellago
- Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna, Austria
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11
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Desgranges C, Delhommelle J. Free energy calculations along entropic pathways. III. Nucleation of capillary bridges and bubbles. J Chem Phys 2017. [DOI: 10.1063/1.4982943] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Caroline Desgranges
- Department of Chemistry, University of North Dakota, Grand Forks, North Dakota 58202, USA
| | - Jerome Delhommelle
- Department of Chemistry, University of North Dakota, Grand Forks, North Dakota 58202, USA
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12
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Hiratsuka T, Tanaka H, Miyahara MT. Critical energy barrier for capillary condensation in mesopores: Hysteresis and reversibility. J Chem Phys 2017; 144:164705. [PMID: 27131561 DOI: 10.1063/1.4947243] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Capillary condensation in the regime of developing hysteresis occurs at a vapor pressure, Pcond, that is less than that of the vapor-like spinodal. This is because the energy barrier for the vapor-liquid transition from a metastable state at Pcond becomes equal to the energy fluctuation of the system; however, a detailed mechanism of the spontaneous transition has not been acquired even through extensive experimental and simulation studies. We therefore construct accurate atomistic silica mesopore models for MCM-41 and perform molecular simulations (gauge cell Monte Carlo and grand canonical Monte Carlo) for argon adsorption on the models at subcritical temperatures. A careful comparison between the simulation and experiment reveals that the energy barrier for the capillary condensation has a critical dimensionless value, Wc (*) = 0.175, which corresponds to the thermal fluctuation of the system and depends neither on the mesopore size nor on the temperature. We show that the critical energy barrier Wc (*) controls the capillary condensation pressure Pcond and also determines a boundary between the reversible condensation/evaporation regime and the developing hysteresis regime.
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Affiliation(s)
| | - Hideki Tanaka
- Department of Chemical Engineering, Kyoto University, Kyoto 615-8025, Japan
| | - Minoru T Miyahara
- Department of Chemical Engineering, Kyoto University, Kyoto 615-8025, Japan
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13
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Hofmann T, Wallacher D, Perlich J, Koyiloth Vayalil S, Huber P. Formation of Periodically Arranged Nanobubbles in Mesopores: Capillary Bridge Formation and Cavitation during Sorption and Solidification in an Hierarchical Porous SBA-15 Matrix. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:2928-2936. [PMID: 26940230 DOI: 10.1021/acs.langmuir.5b04560] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We report synchrotron-based small-angle X-ray scattering experiments on a template-grown porous silica matrix (Santa Barbara Amorphous-15) upon in situ sorption of fluorinated pentane C5F12 along with volumetric gas sorption isotherm measurements. Within the mean-field model of Saam and Cole for vapor condensation in cylindrical pores, a nitrogen and C5F12 sorption isotherm is well described by a bimodal pore radius distribution dominated by meso- and micropores with 3.4 and 1.6 nm mean radius, respectively. In the scattering experiments, two different periodicities become evident. One of them (d1 = 11.5 nm) reflects the next nearest neighbor distance in a 2D-hexagonal lattice of tubular mesopores. A second periodicity (d2 = 11.4 nm) found during in situ sorption and freezing experiments is traced back to a superstructure along the cylindrical mesopores. It is compatible with periodic pore corrugations found in electron tomograms of empty SBA-15 by Gommes et al. ( Chem. Mater. 2009, 21, 1311 - 1317). A Rayleigh-Plateau instability occurring at the cylindrical blockcopolymer micelles characteristic of the SBA-15 templating process quantitatively accounts for the superstructure and thus the spatial periodicity of the pore wall corrugation. The consequences of this peculiar morphological feature on the spatial arrangement of C5F12, in particular the formation of periodically arranged nanobubbles (or voids) upon adsorption, desorption, and freezing of liquids, are discussed in terms of capillary bridge formation and cavitation in tubular but periodically corrugated pores.
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Affiliation(s)
- Tommy Hofmann
- Helmholtz-Zentrum Berlin für Materialien und Energie GmbH , D-12489 Berlin, Germany
| | - Dirk Wallacher
- Helmholtz-Zentrum Berlin für Materialien und Energie GmbH , D-12489 Berlin, Germany
| | - Jan Perlich
- Deutsches Elektronen Synchrotron , D-22607 Hamburg, Germany
| | | | - Patrick Huber
- Technische Universität Hamburg , D-21073 Hamburg, Germany
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14
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Guo Z, Liu Y, Zhang X. Constrained lattice density functional theory and its applications on vapor–liquid nucleations. Sci Bull (Beijing) 2015. [DOI: 10.1007/s11434-014-0702-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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15
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Puibasset J, Kierlik E, Tarjus G. Influence of system size on the properties of a fluid adsorbed in a nanopore: Physical manifestations and methodological consequences. J Chem Phys 2014; 141:044716. [PMID: 25084946 DOI: 10.1063/1.4891359] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Hysteresis and discontinuities in the isotherms of a fluid adsorbed in a nanopore in general hamper the determination of equilibrium thermodynamic properties, even in computer simulations. A way around this has been to consider both a reservoir of small size and a pore of small extent in order to restrict the fluctuations of density and approach a classical van der Waals loop. We assess this suggestion by thoroughly studying through Monte Carlo simulations and density functional theory the influence of system size on the equilibrium configurations of the adsorbed fluid and on the resulting isotherms. We stress the importance of pore-symmetry-breaking states that even for modest pore sizes lead to discontinuous isotherms and we discuss the physical relevance of these states and the methodological consequences for computing thermodynamic quantities.
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Affiliation(s)
- Joël Puibasset
- CRMD, CNRS FRE 3520, Université d'Orléans, 1b rue de la Férollerie, 45071 Orléans Cedex 02, France
| | - Edouard Kierlik
- LPTMC, CNRS UMR 7600, Université Pierre et Marie Curie, boîte 121, 4 place Jussieu, 75252 Paris Cedex 05, France
| | - Gilles Tarjus
- LPTMC, CNRS UMR 7600, Université Pierre et Marie Curie, boîte 121, 4 place Jussieu, 75252 Paris Cedex 05, France
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16
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Liu Z, Nguyen VT, Do D, Nicholson D. A Monte Carlo study of equilibrium transition in finite cylindrical pores. MOLECULAR SIMULATION 2013. [DOI: 10.1080/08927022.2013.829230] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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17
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Klomkliang N, Do DD, Nicholson D. On the hysteresis loop and equilibrium transition in slit-shaped ink-bottle pores. ADSORPTION 2013. [DOI: 10.1007/s10450-013-9569-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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18
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Miyahara MT, Tanaka H. Determination of phase equilibria in confined systems by open pore cell Monte Carlo method. J Chem Phys 2013; 138:084709. [PMID: 23464174 DOI: 10.1063/1.4792715] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We present a modification of the molecular dynamics simulation method with a unit pore cell with imaginary gas phase [M. Miyahara, T. Yoshioka, and M. Okazaki, J. Chem. Phys. 106, 8124 (1997)] designed for determination of phase equilibria in nanopores. This new method is based on a Monte Carlo technique and it combines the pore cell, opened to the imaginary gas phase (open pore cell), with a gas cell to measure the equilibrium chemical potential of the confined system. The most striking feature of our new method is that the confined system is steadily led to a thermodynamically stable state by forming concave menisci in the open pore cell. This feature of the open pore cell makes it possible to obtain the equilibrium chemical potential with only a single simulation run, unlike existing simulation methods, which need a number of additional runs. We apply the method to evaluate the equilibrium chemical potentials of confined nitrogen in carbon slit pores and silica cylindrical pores at 77 K, and show that the results are in good agreement with those obtained by two conventional thermodynamic integration methods. Moreover, we also show that the proposed method can be particularly useful for determining vapor-liquid and vapor-solid coexistence curves and the triple point of the confined system.
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Affiliation(s)
- Minoru T Miyahara
- Department of Chemical Engineering, Kyoto University, Katsura, Nishikyo, Kyoto 615-8510, Japan.
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19
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Ghosh S, Ghosh SK. Spherical seed mediated vapor condensation of Lennard-Jones fluid: a density functional theory approach. J Chem Phys 2013; 139:054702. [PMID: 23927276 DOI: 10.1063/1.4817197] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Vapor to liquid condensation in presence of spherical seed particle of any arbitrary radius ranging from zero to infinity has been investigated using density functional theory, by modeling the local Helmholtz free energy density functional as well as the density profile at the vapor-liquid interface. A general theory is, thus, obtained which provides the different modes of nucleation based on the size of the seed ranging from zero (corresponding to the homogeneous mode of nucleation) to infinity (corresponding to the heterogeneous nucleation on flat surface). The theory is applied to the Lennard-Jones fluid and the optimized shape (i.e., contact angle) and formation free energy of droplets of any arbitrary size have been obtained in this work. The change of the shape (optimized) with the variation of the size of the liquid droplet as well as with the size of the solid substrate has been studied, thus predicting the shape-size relationship in the course of vapor to liquid heterogeneous nucleation on a spherical solid substrate of any particular size. The spinodal decomposition of vapor has also been observed at higher strength of the solid-fluid interaction. The results have been compared with the results of the conventional classical nucleation theory.
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Affiliation(s)
- Satinath Ghosh
- Research Reactor Services Division, Bhabha Atomic Research Centre, Mumbai 400085, India
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20
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Ghosh S, Ghosh SK. Density functional theory of vapor to liquid heterogeneous nucleation: Lennard–Jones fluid on solid substrate. Mol Phys 2013. [DOI: 10.1080/00268976.2012.750765] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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21
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Rasmussen CJ, Vishnyakov A, Neimark AV. Translocation dynamics of freely jointed Lennard-Jones chains into adsorbing pores. J Chem Phys 2013; 137:144903. [PMID: 23061861 DOI: 10.1063/1.4754632] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Polymer translocation into adsorbing nanopores is studied by using the Fokker-Planck equation of chain diffusion along the energy landscape calculated with Monte Carlo simulations using the incremental gauge cell method. The free energy profile of a translocating chain was found by combining two independent sub-chains, one free but tethered to a hard wall, and the other tethered inside an adsorbing pore. Translocation dynamics were revealed by application of the Fokker-Planck equation for normal diffusion. Adsorption of polymer chains into nanopores involves a competition of attractive adsorption and repulsive steric hindrance contributions to the free energy. Translocation times fell into two regimes depending on the strength of the adsorbing pore. In addition, we found a non-monotonic dependence of translocation times with increasing adsorption strength, with sharp peak associated with local free energy minima along the translocation coordinate.
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Affiliation(s)
- Christopher J Rasmussen
- Department of Chemical and Biochemical Engineering, Rutgers, The State University of New Jersey, 98 Brett Road, Piscataway, New Jersey 08854, USA
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On the hysteresis and equilibrium phase transition of argon and benzene adsorption in finite slit pores: Monte Carlo vs. Bin-Monte Carlo. Chem Eng Sci 2013. [DOI: 10.1016/j.ces.2012.11.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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23
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Liu Y, Men Y, Zhang X. Nucleation mechanism for vapor-to-liquid transition from substrates with nanoscale pores opened at one end. J Chem Phys 2012; 137:104701. [DOI: 10.1063/1.4749319] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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24
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Gommes CJ. Adsorption, capillary bridge formation, and cavitation in SBA-15 corrugated mesopores: a Derjaguin-Broekhoff-de Boer analysis. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:5101-5115. [PMID: 22324828 DOI: 10.1021/la2051228] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
A Derjaguin-Broekhoff-de Boer analysis of adsorption and desorption in SBA-15 mesoporous silica is presented, using realistic geometrical models that account for the pore corrugation in these materials. The model parameters are derived from independent electron tomography and small-angle scattering characterization. A geometrical characteristic of the pore that is found to be important for adsorption is the corrugation length, l(C), which describes the longitudinal size of the geometrical defects along a given pore. Capillary bridges are possible only for large values of l(C). The results are explained in terms of two spinodal and two equilibrium pressures, characterizing the wide and the narrow sections of the pores. Simplified analytical expressions are obtained, which provide necessary conditions for bridge formation and for cavitation in terms of the radii of the narrow and wide sections of the pores, as well as of l(C). Quite generally, the results show that the deviation of the pore shape from that of ideal cylinders is key to understanding adsorption and desorption in corrugated mesopores, notably in SBA-15.
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Affiliation(s)
- Cedric J Gommes
- Department of Chemical Engineering, University of Liège, Liège, Belgium.
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25
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Liu Z, Do DD, Nicholson D. A thermodynamic study of the mid-density scheme to determine the equilibrium phase transition in cylindrical pores. MOLECULAR SIMULATION 2012. [DOI: 10.1080/08927022.2011.613383] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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26
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Rasmussen CJ, Vishnyakov A, Neimark AV. Calculation of chemical potentials of chain molecules by the incremental gauge cell method. J Chem Phys 2011; 135:214109. [DOI: 10.1063/1.3657438] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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27
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Liu Y, Men Y, Zhang X. How nanoscale seed particles affect vapor-liquid nucleation. J Chem Phys 2011; 135:184701. [DOI: 10.1063/1.3658502] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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28
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Liu Z, Herrera L, Nguyen VT, Do DD, Nicholson D. A Monte Carlo scheme based on mid-density in a hysteresis loop to determine equilibrium phase transition. MOLECULAR SIMULATION 2011. [DOI: 10.1080/08927022.2011.578135] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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29
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Nguyen VT, Do DD, Nicholson D. Monte Carlo Simulation of the Gas-Phase Volumetric Adsorption System: Effects of Dosing Volume Size, Incremental Dosing Amount, Pore Shape and Size, and Temperature. J Phys Chem B 2011; 115:7862-71. [DOI: 10.1021/jp202073r] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Van T. Nguyen
- School of Chemical Engineering, University of Queensland, St. Lucia, Qld 4072, Australia
| | - D. D. Do
- School of Chemical Engineering, University of Queensland, St. Lucia, Qld 4072, Australia
| | - D. Nicholson
- School of Chemical Engineering, University of Queensland, St. Lucia, Qld 4072, Australia
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Berim GO, Ruckenstein E. Size dependence of the contact angle of a nanodrop in a nanocavity: density functional theory considerations. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2011; 83:021603. [PMID: 21405850 DOI: 10.1103/physreve.83.021603] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2010] [Revised: 12/22/2010] [Indexed: 05/30/2023]
Abstract
The dependence of the contact angles of nanodrops of Lennard-Jones type fluids in nanocavities on their sizes are calculated using a nonlocal density functional theory in a canonical ensemble. Cavities of various radii and depths, various temperatures, as well as various values of the energy parameter of the fluid-solid interactions were considered. It is argued that this dependence might affect strongly, for instance, the rate of heterogeneous nucleation on rough surfaces, which is usually calculated under the assumption of constant contact angle.
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Affiliation(s)
- Gersh O Berim
- Department of Chemical and Biological Engineering, State University of New York at Buffalo, Buffalo, New York 14260, USA.
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31
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Monson P. Fluids Confined in Porous Materials: Towards a Unified Understanding of Thermodynamics and Dynamics. CHEM-ING-TECH 2011. [DOI: 10.1002/cite.201000181] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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32
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Microscopic description of a drop on a solid surface. Adv Colloid Interface Sci 2010; 157:1-33. [PMID: 20362270 DOI: 10.1016/j.cis.2010.02.011] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2009] [Accepted: 02/20/2010] [Indexed: 11/22/2022]
Abstract
Two approaches recently suggested for the treatment of macro- or nanodrops on smooth or rough, planar or curved, solid surfaces, based on fluid-fluid and fluid-solid interaction potentials are reviewed. The first one employs the minimization of the total potential energy of a drop by assuming that the drop has a well defined profile and a constant liquid density in its entire volume with the exception of the monolayer nearest to the surface where the density has a different value. As a result, a differential equation for the drop profile as well as the necessary boundary conditions are derived which involve the parameters of the interaction potentials and do not contain such macroscopic characteristics as the surface tensions. As a consequence, the macroscopic and microscopic contact angles which the drop profile makes with the surface can be calculated. The macroscopic angle is obtained via the extrapolation of the circular part of the drop profile valid at some distance from the surface up to the solid surface. The microscopic angle is formed at the intersection of the real profile (which is not circular near the surface) with the surface. The theory provides a relation between these two angles. The ranges of the microscopic parameters of the interaction potentials for which (i) the drop can have any height (volume), (ii) the drop can have a restricted height but unrestricted volume, and (iii) a drop cannot be formed on the surface were identified. The theory was also extended to the description of a drop on a rough surface. The second approach is based on a nonlocal density functional theory (DFT), which accounts for the inhomogeneity of the liquid density and temperature effects, features which are missing in the first approach. Although the computational difficulties restrict its application to drops of only several nanometers, the theory can be applied indirectly to macrodrops by calculating the surface tensions and using the Young equation to determine the contact angle. Employing the canonical ensemble version of the DFT, nanodrops on smooth and rough solid surfaces could be investigated and their characteristics, such as the drop profile, contact angle, as well as the fluid density distribution inside the drop can be determined as functions of the parameters of the interaction potentials and temperature. It was found that the contact angle of the drop has a simple (quasi)universal dependence on the energy parameter epsilon(fs) of the fluid-solid interaction potential and temperature. The main feature of this dependence is the existence of a fixed value theta(0) of the contact angle theta which separates the solid substrates (characterized by the energy parameter epsilon(fs) of the fluid-solid interaction potential) into two classes with respect to their temperature dependence. For theta>theta(0) the contact angle monotonously increases and for theta<theta(0) monotonously decreases with increasing temperature. For theta=theta(0) the contact angle is independent of temperature. The results obtained via DFT were also applied to check the validity of the macroscopic phenomenological equations (Cassie-Baxter and Wenzel equations) for drops on rough surfaces, and of the equation for the sticking force of a drop on an inclined surface.
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33
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Chen L, Ozisik R, Schadler LS. The influence of carbon nanotube aspect ratio on the foam morphology of MWNT/PMMA nanocomposite foams. POLYMER 2010. [DOI: 10.1016/j.polymer.2010.03.042] [Citation(s) in RCA: 142] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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34
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Kowalczyk P, Gauden PA, Terzyk AP. Nanoporous Quantum Filters: Inside Vapor−Liquid Transitions of Quantum Fluids in Nanopores. J Phys Chem B 2010; 114:5047-52. [DOI: 10.1021/jp911189j] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Piotr Kowalczyk
- Applied Physics, RMIT University, GPO Box 2476 V, Victoria 3001, Australia, and Department of Chemistry, Physicochemistry of Carbon Materials Research Group, N. Copernicus University, Gagarin St. 7, 87-100 Torun, Poland
| | - Piotr A. Gauden
- Applied Physics, RMIT University, GPO Box 2476 V, Victoria 3001, Australia, and Department of Chemistry, Physicochemistry of Carbon Materials Research Group, N. Copernicus University, Gagarin St. 7, 87-100 Torun, Poland
| | - Artur P. Terzyk
- Applied Physics, RMIT University, GPO Box 2476 V, Victoria 3001, Australia, and Department of Chemistry, Physicochemistry of Carbon Materials Research Group, N. Copernicus University, Gagarin St. 7, 87-100 Torun, Poland
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35
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Ruckenstein E, Berim GO. Symmetry breaking in confined fluids. Adv Colloid Interface Sci 2010; 154:56-76. [PMID: 20170894 DOI: 10.1016/j.cis.2010.01.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2009] [Accepted: 01/20/2010] [Indexed: 11/16/2022]
Abstract
The recent progress in the theoretical investigation of the symmetry breaking (the existence of a stable state of a system, in which the symmetry is lower than the symmetry of the system itself) for classical and quantum fluids is reviewed. The emphasis is on the conditions which cause symmetry breaking in the density distribution for one component fluids and binary mixtures confined in a closed nanoslit between identical solid walls. The existing studies have revealed that two kinds of symmetry breaking can occur in such systems. First, a one-dimensional symmetry breaking occurs only in the direction normal to the walls as a fluid density profile asymmetric with respect of the middle of the slit and uniform in any direction parallel to the walls. Second, a two-dimensional symmetry breaking occurs in the fluid density distribution which is nonuniform in one of the directions parallel to the walls and asymmetrical in the direction normal to the walls. It manifests through liquid bumps and bridges in the fluid density distribution. For one component fluids, conditions of existence of symmetry breaking are provided in terms of the average fluid density, strength of fluid-solid interactions, distance at which the solid wall generates a hard core repulsion, and temperature. In the case of binary mixtures, the occurrence of symmetry breaking also depends on the composition of the confined mixtures.
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Affiliation(s)
- Eli Ruckenstein
- Department of Chemical and Biological Engineering, State University of New York at Buffalo, Buffalo, New York 14260, USA.
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36
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Edison JR, Monson PA. Dynamic mean field theory of condensation and evaporation processes for fluids in porous materials: Application to partial drying and drying. Faraday Discuss 2010; 146:167-84; discussion 195-215, 395-403. [DOI: 10.1039/b925672e] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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37
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Puibasset J, Kierlik E, Tarjus G. Influence of reservoir size on the adsorption path in an ideal pore. J Chem Phys 2009; 131:124123. [DOI: 10.1063/1.3236510] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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38
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Dzubiella J, Chakrabarti J, Löwen H. Tuning colloidal interactions in subcritical solvents by solvophobicity: explicit versus implicit modeling. J Chem Phys 2009; 131:044513. [PMID: 19655900 DOI: 10.1063/1.3193557] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
The distance-resolved effective interaction between two colloidal particles in a subcritical solvent is explored both by an explicit and implicit modeling. An implicit solvent approach based on a simple thermodynamic interface model is tested against grand-canonical Monte Carlo computer simulations using explicit Lennard-Jones solvent molecules. Close to liquid-gas coexistence, a joint gas bubble surrounding the colloidal particle pair yields an effective attraction between the colloidal particles, the strength of which can be vastly tuned by the solvophobicity of the colloids. The implicit model is in good agreement with our explicit computer simulations, thus enabling an efficient modeling and evaluation of colloidal interactions and self-assembly in subcritical solvent environments.
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Affiliation(s)
- J Dzubiella
- Department of Physics, Technical University Munich, 85748 Garching, Germany.
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39
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40
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Men Y, Yan Q, Jiang G, Zhang X, Wang W. Nucleation and hysteresis of vapor-liquid phase transitions in confined spaces: effects of fluid-wall interaction. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2009; 79:051602. [PMID: 19518462 DOI: 10.1103/physreve.79.051602] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2008] [Revised: 02/24/2009] [Indexed: 05/27/2023]
Abstract
In this work, we propose a method to stabilize a nucleus in the framework of lattice density-functional theory (LDFT) by imposing a suitable constraint. Using this method, the shape of critical nucleus and height of the nucleation barrier can be determined without using a predefined nucleus as input. As an application of this method, we study the nucleation behavior of vapor-liquid transition in nanosquare pores with infinite length and relate the observed hysteresis loop on an adsorption isotherm to the nucleation mechanism. According to the dependence of hysteresis and the nucleation mechanism on the fluid-wall interaction, w , in this work, we have classified w into three regions ( w>0.9 , 0.1< or =w< or =0.9 , and w<0.1 ), which are denoted as strongly, moderately, and weakly attractive fluid-wall interaction, respectively. The dependence of hysteresis on the fluid-wall interaction is interpreted by the different nucleation mechanisms. Our constrained LDFT calculations also show that the different transition paths may induce different nucleation behaviors. The transition path dependence should be considered if morphological transition of nuclei exists during a nucleation process.
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Affiliation(s)
- Yumei Men
- Division of Molecular and Materials Simulation, Key Laboratory for Nanomaterials, Ministry of Education, Beijing University of Chemical Technology, Beijing 100029, China
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41
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Berim GO, Ruckenstein E. Simple expression for the dependence of the nanodrop contact angle on liquid-solid interactions and temperature. J Chem Phys 2009; 130:044709. [DOI: 10.1063/1.3068406] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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42
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Ustinov EA. The special features of equilibrium adsorption of argon on homogeneous and inhomogeneous surfaces. RUSSIAN JOURNAL OF PHYSICAL CHEMISTRY A 2008. [DOI: 10.1134/s0036024408120285] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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43
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Berim GO, Ruckenstein E. Nanodrop on a nanorough solid surface: density functional theory considerations. J Chem Phys 2008; 129:014708. [PMID: 18624497 DOI: 10.1063/1.2951453] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The density distributions and contact angles of liquid nanodrops on nanorough solid surfaces are determined on the basis of a nonlocal density functional theory. Two kinds of roughness, chemical and physical, are examined. The former considers the substrate as a sequence of two kinds of semi-infinite vertical plates of equal thicknesses but of different natures with different strengths for the liquid-solid interactions. The physical roughness involves an ordered set of pillars on a flat homogeneous surface. Both hydrophobic and hydrophilic surfaces were considered. For the chemical roughness, the contact angle which the drop makes with the flat surface increases when the strength of the liquid-solid interaction for one kind of plates decreases with respect to the fixed value of the other kind of plates. Such a behavior is in agreement with the Cassie-Baxter expression derived from macroscopic considerations. For the physical roughness on a hydrophobic surface, the contact angle which a drop makes with the plane containing the tops of the pillars increases with increasing roughness. Such a behavior is consistent with the Wenzel formula developed for macroscopic drops. For hydrophilic surfaces, as the roughness increases the contact angle first increases, in contradiction with the Wenzel formula, which predicts for hydrophilic surfaces a decrease of the contact angle with increasing roughness. However, a further increase in roughness changes nonmonotonously the contact angle, and at some roughness, the drop disappears and only a liquid film is present on the surface. It was also found that the contact angle has a periodic dependence on the volume of the drop.
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Affiliation(s)
- Gersh O Berim
- Department of Chemical and Biological Engineering, State University of New York at Buffalo, Buffalo, New York 14260, USA
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44
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Berim GO, Ruckenstein E. Microscopic calculation of the sticking force for nanodrops on an inclined surface. J Chem Phys 2008; 129:114709. [DOI: 10.1063/1.2978238] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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45
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Zheng F, Zhang X, Wang W. Macrophase and microphase separations for surfactants adsorbed on solid surfaces: a gauge cell monte carlo study in the lattice model. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2008; 24:4661-4669. [PMID: 18380512 DOI: 10.1021/la800046s] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
By combining the gauge cell method and lattice model, we study the surface phase transition and adsorption behaviors of surfactants on a solid surface. Two different cases are considered in this work: macrophase transition and adsorption in a single-phase region. For the case of macrophase transition, where two phases coexist, we investigate the shape and size of the critical nuclei and determine the height of the nucleation barrier. It is found that the nucleation depends on the bulk surfactant concentration. Our simulations show that there exist a critical temperature and critical adsorption energy, below which the transition from low-affinity adsorption to the bilayer structure shows the characteristic of a typical first-order phase transition. Such a surface phase transition in the adsorption isotherm is featured by a hysteresis loop. The hysteresis loop becomes narrower at higher temperature and weaker adsorption energy and finally disappears at the critical value. For the case where no macrophase transition occurs, we study the adsorption isotherm and microphase separation in a single-phase region. The simulation results indicate that the adsorption isotherm in adsorption processes is divided into four regions in a log-log plot, being in agreement with experimental observations. In this work, the four regions are called the low-affinity adsorption region, the hemimicelle region, the morphological transition region, and the plateau region. Simulation results reveal that in the second region the adsorbed monomers aggregate and nucleate hemimicelles, while adsorption in the third region is accompanied by morphological transitions.
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Affiliation(s)
- Fengxian Zheng
- Division of Molecular and Materials Simulation, Key Lab for Nanomaterials, Ministry of Education, Beijing University of Chemical Technology, Beijing 100029, China
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46
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Berim GO, Ruckenstein E. Symmetry breaking in binary mixtures in closed nanoslits. J Chem Phys 2008; 128:134713. [PMID: 18397100 DOI: 10.1063/1.2904880] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The symmetry breaking (SB) of the fluid density distribution (FDD) in closed nanoslits between two identical parallel solid walls described by Berim and Ruckenstein [J. Chem. Phys. 128, 024704 (2008)] for a single component fluid is examined for binary mixtures on the basis of a nonlocal canonical ensemble density functional theory. As in Monte Carlo simulations, the periodicity of the FDD in one of the lateral (parallel to the wall surfaces) directions, denoted as the x direction, was assumed. In the other lateral direction, y direction, the FDD was considered to be uniform. The molecules of the two components have different diameters and their Lennard-Jones interaction potentials have different energy parameters. It was found that depending on the average fluid density in the slit and mixture composition, SB can occur for both or none of the components but never for only one of them. In the direction perpendicular to the walls (h direction), the FDDs of both components can be asymmetrical about the middle plane between walls. In the x direction, the SB occurs as bumps and bridges enriched in one of the components, whereas the composition of the mixture between them is enriched in the other component. The dependence of the SB states on the length Lx of the FDD period at fixed average densities of the two components was examined for Lx in the range from 10 to 120 molecular diameters of the smaller size component. It was shown that for large Lx, the stable state of the system corresponds to a bridge. Because the free energy of that state decreases monotonically with increasing Lx, one can conclude that the real period is very large (infinite) and that a single bridge exists in the slit.
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Affiliation(s)
- Gersh O Berim
- Department of Chemical and Biological Engineering, State University of New York at Buffalo, Buffalo, New York 14260, USA
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47
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Monson PA. Mean field kinetic theory for a lattice gas model of fluids confined in porous materials. J Chem Phys 2008; 128:084701. [DOI: 10.1063/1.2837287] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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48
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Berim GO, Ruckenstein E. Two-dimensional symmetry breaking of fluid density distribution in closed nanoslits. J Chem Phys 2008; 128:024704. [PMID: 18205463 DOI: 10.1063/1.2816574] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Stable and metastable fluid density distributions (FDDs) in a closed nanoslit between two identical parallel solid walls have been identified on the basis of a nonlocal canonical ensemble density functional theory. Similar to Monte Carlo simulations, periodicity of the FDD in one of the lateral (parallel to the walls surfaces) directions, denoted as the x direction, was assumed. In the other lateral direction, y direction, the FDD was considered uniform. It was found that depending on the average fluid density in the slit, both uniform as well as nonuniform FDDs in the x direction can occur. The uniform FDDs are either symmetric or asymmetric about the middle plane between walls; the latter FDD being the consequence of a symmetry breaking across the slit. The nonuniform FDDs in the x direction occur either in the form of a bump on a thin liquid film covering the walls or as a liquid bridge between those walls and provide symmetry breaking in the x direction. For small and large average densities, the stable state is uniform in the x direction and is symmetric about the middle plane between walls. In the intermediate range of the average density and depending on the length L(x) of the FDD period, the stable state can be represented either by a FDD, which is uniform in the x direction and asymmetric about the middle of the slit (small values of L(x)), or by a bump- and bridgelike FDD for intermediate and large values of L(x), respectively. These results are in agreement with the Monte Carlo simulations performed earlier by other authors. Because the free energy of the stable state decreases monotonically with increasing L(x), one can conclude that the real period is very large (infinite) and that for the values of the parameters employed, a single bridge of finite length over the entire slit is generated.
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Affiliation(s)
- Gersh O Berim
- Department of Chemical and Biological Engineering, State University of New York at Buffalo, Buffalo, New York 14260, USA
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49
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Berim GO, Ruckenstein E. Effect of fluid-solid interactions on symmetry breaking in closed nanoslits. J Phys Chem B 2007; 111:12823-8. [PMID: 17949027 DOI: 10.1021/jp071667b] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The possibility of symmetry breaking of the fluid (argon) density distribution across a long closed slit with identical walls composed of solid carbon dioxide was noted in previous papers by the authors. The main conclusion was that there is a range of average densities in which symmetry breaking occurs and that outside that range the fluid density profile is symmetrical. A critical temperature T(sb) was also identified below which symmetry breaking can occur. In this paper, symmetry breaking is examined for walls made of other materials and it is shown that it occurs only when the energy parameter epsilon(fw) of the fluid-wall interaction in the Lennard-Jones potential satisfies the inequalities epsilon(fw1) < or = epsilon(fw) < or = epsilon(fw2), where epsilon(fw1) and epsilon(fw2) are temperature-dependent critical values of epsilon(fw). The value of epsilon(fw1) increases and that of epsilon(fw2) decreases with increasing temperature. The comparison of the theory with Monte Carlo simulations confirms the existence of symmetry breaking across the slit. The possibility of symmetry breaking along the slit is also noted.
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Affiliation(s)
- Gersh O Berim
- Department of Chemical and Biological Engineering, State University of New York at Buffalo, Buffalo, New York 14260, USA
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50
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Morishige K, Ishino M. Lower closure point of adsorption hysteresis in ordered mesoporous silicas. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2007; 23:11021-6. [PMID: 17894507 DOI: 10.1021/la700904d] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
To examine the nature of the lower closure point of adsorption hysteresis in ordered mesoporous silicas, we measured the temperature dependence of the adsorption-desorption isotherm of nitrogen for three kinds of ordered silicas with cagelike pores and three kinds of ordered silicas with cylindrical pores. The lower closure point pressure of nitrogen in the cagelike pores with sufficiently small necks, that is, the cavitation pressure of a confined liquid, did not depend appreciably on the cage size in the temperature region far away from a hysteresis critical temperature (Tch) but its cage-size dependence was noticeable in the vicinity of Tch. The lower closure point in the cylindrical pores depended on the pore size, and its thermal behavior was totally different from that in the cagelike pores. Nevertheless, the hysteresis critical points of nitrogen in the ordered mesoporous silicas, which are defined as a threshold of temperatures (Tch) and pressure above which reversible capillary condensation takes place in a given size and shape of pores, fell on a common line in a temperature-pressure diagram regardless of the pore geometries. We consider this finding as evidence that capillary evaporation in the cylindrical pores follows a cavitation process in the vicinity of Tch in the same way as that in the cagelike pores and also that the low limit of the hysteresis loop that has been long recognized since 1965 is due to the occurrence of a vapor bubble in a stretched metastable liquid confined to the pores with decreasing pressure (cavitation).
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Affiliation(s)
- Kunimitsu Morishige
- Department of Chemistry, Okayama University of Science, 1-1 Ridai-cho, Okayama 700-0005, Japan
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