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Pospíšil M, Malijevský A. Phase behavior of fluids in undulated nanopores. Phys Rev E 2022; 106:024801. [PMID: 36109889 DOI: 10.1103/physreve.106.024801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Accepted: 07/20/2022] [Indexed: 06/15/2023]
Abstract
The geometry of walls forming a narrow pore may qualitatively affect the phase behavior of the confined fluid. Specifically, the nature of condensation in nanopores formed of sinusoidally shaped walls (with amplitude A and period P) is governed by the wall mean separation L as follows. For L>L_{t}, where L_{t} increases with A, the pores exhibit standard capillary condensation similar to planar slits. In contrast, for L<L_{t}, the condensation occurs in two steps, such that the fluid first condenses locally via bridging transition connecting adjacent crests of the walls, before it condenses globally. For the marginal value of L=L_{t}, all the three phases (gaslike, bridge, and liquidlike) may coexist. We show that the locations of the phase transitions can be described using geometric arguments leading to modified Kelvin equations. However, for completely wet walls, to which we focus on, the phase boundaries are shifted significantly due to the presence of wetting layers. In order to take this into account, mesoscopic corrections to the macroscopic theory are proposed. The resulting predictions are shown to be in a very good agreement with a density-functional theory even for molecularly narrow pores. The limits of stability of the bridge phase, controlled by the pore geometry, is also discussed in some detail.
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Affiliation(s)
- Martin Pospíšil
- Department of Physical Chemistry, University of Chemical Technology Prague, Praha 6, 166 28, Czech Republic and The Czech Academy of Sciences, Institute of Chemical Process Fundamentals, Department of Molecular Modelling, 165 02 Prague, Czech Republic
| | - Alexandr Malijevský
- Department of Physical Chemistry, University of Chemical Technology Prague, Praha 6, 166 28, Czech Republic and The Czech Academy of Sciences, Institute of Chemical Process Fundamentals, Department of Molecular Modelling, 165 02 Prague, Czech Republic
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Malijevský A. Height of a liquid drop on a wetting stripe. Phys Rev E 2020; 102:052802. [PMID: 33327112 DOI: 10.1103/physreve.102.052802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Accepted: 11/10/2020] [Indexed: 11/07/2022]
Abstract
Adsorption of liquid on a planar wall decorated by a hydrophilic stripe of width L is considered. Under the condition that the wall is only partially wet (or dry) while the stripe tends to be wet completely, a liquid drop is formed above the stripe. The maximum height ℓ_{m}(δμ) of the drop depends on the stripe width L and the chemical potential departure from saturation δμ where it adopts the value ℓ_{0}=ℓ_{m}(0). Assuming a long-range potential of van der Waals type exerted by the stripe, the interfacial Hamiltonian model is used to show that ℓ_{0} is approached linearly with δμ with a slope which scales as L^{2} over the region satisfying L≲ξ_{∥}, where ξ_{∥} is the parallel correlation function pertinent to the stripe. This suggests that near the saturation there exists a universal curve ℓ_{m}(δμ) to which the adsorption isotherms corresponding to different values of L all collapse when appropriately rescaled. Although the series expansion based on the interfacial Hamiltonian model can be formed by considering higher order terms, a more appropriate approximation in the form of a rational function based on scaling arguments is proposed. The approximation is based on exact asymptotic results, namely, that ℓ_{m}∼δμ^{-1/3} for L→∞ and that ℓ_{m} obeys the correct δμ→0 behavior in line with the results of the interfacial Hamiltonian model. All the predictions are verified by the comparison with a microscopic density functional theory (DFT) and, in particular, the rational function approximation-even in its simplest form-is shown to be in a very reasonable agreement with DFT for a broad range of both δμ and L.
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Affiliation(s)
- Alexandr Malijevský
- Department of Physical Chemistry, University of Chemical Technology Prague, Praha 6, 166 28, Czech Republic; The Czech Academy of Sciences, Institute of Chemical Process Fundamentals, Department of Molecular Modelling, 165 02 Prague, Czech Republic
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Láska M, Parry AO, Malijevský A. Three-Phase Fluid Coexistence in Heterogenous Slits. PHYSICAL REVIEW LETTERS 2020; 124:115701. [PMID: 32242718 DOI: 10.1103/physrevlett.124.115701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Revised: 02/19/2020] [Accepted: 02/28/2020] [Indexed: 06/11/2023]
Abstract
We study the competition between local (bridging) and global condensation of fluid in a chemically heterogeneous capillary slit made from two parallel adjacent walls each patterned with a single stripe. Using a mesoscopic modified Kelvin equation, which determines the shape of the menisci pinned at the stripe edges in the bridge phase, we determine the conditions under which the local bridging transition precedes capillary condensation as the pressure (or chemical potential) is increased. Provided the contact angle of the stripe is less than that of the outer wall we show that triple points, where evaporated, locally condensed, and globally condensed states all coexist are possible depending on the value of the aspect ratio a=L/H, where H is the stripe width and L the wall separation. In particular, for a capillary made from completely dry walls patterned with completely wet stripes the condition for the triple point occurs when the aspect ratio takes its maximum possible value 8/π. These predictions are tested using a fully microscopic classical density functional theory and shown to be remarkably accurate even for molecularly narrow slits. The qualitative differences with local and global condensation in heterogeneous cylindrical pores are also highlighted.
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Affiliation(s)
- Martin Láska
- Department of Physical Chemistry, University of Chemical Technology Prague, Praha 6, 166 28, Czech Republic and Department of Molecular and Mesoscopic Modelling, ICPF of the Czech Academy Sciences, Prague, Czech Republic
| | - Andrew O Parry
- Department of Mathematics, Imperial College London, London SW7 2BZ, United Kingdom
| | - Alexandr Malijevský
- Department of Physical Chemistry, University of Chemical Technology Prague, Praha 6, 166 28, Czech Republic and Department of Molecular and Mesoscopic Modelling, ICPF of the Czech Academy Sciences, Prague, Czech Republic
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Höft N, Horbach J. Condensation of Methane in the Metal–Organic Framework IRMOF-1: Evidence for Two Critical Points. J Am Chem Soc 2015. [DOI: 10.1021/jacs.5b04077] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Nicolas Höft
- Institute for Theoretical
Physics II, University of Düsseldorf, Universitätsstraße 1, 40225 Düsseldorf, Germany
| | - Jürgen Horbach
- Institute for Theoretical
Physics II, University of Düsseldorf, Universitätsstraße 1, 40225 Düsseldorf, Germany
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Broesch DJ, Frechette J. From concave to convex: capillary bridges in slit pore geometry. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:15548-15554. [PMID: 23061424 DOI: 10.1021/la302942k] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We investigate the morphological evolution of nonaxisymmetric capillary bridges in slit-pore geometry as the height of the pore and aspect ratio of the bridge are varied. The liquid bridges are formed between two hydrophobic surfaces patterned with hydrophilic strips. The aspect ratio of the capillary bridges (length/width) is varied from 2.5 to 120 by changing the separation between the surfaces, the width of the strips, or the fluid volume. As the bridge height is increased, the aspect ratio decreases and we observe a large increase in the mean curvature of the bridge. More specifically, the following counterintuitive result is observed: the mean curvature of the bridges changes sign and goes from negative (concave bridge) to positive (convex bridge) when the height is increased at constant volume. These experimental observations are in quantitative agreement with Surface Evolver simulations. Scaling shows a collapse of the data indicating that this transition in the sign of the Laplace pressure is universal for capillary bridges with high aspect ratios. Finally, we show that the morphology diagrams obtained from our 3D analysis are considerably different from those expected from a 2D analysis.
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Affiliation(s)
- David J Broesch
- Chemical and Biomolecular Engineering Department, Johns Hopkins University, Baltimore, Maryland 21218, United States
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Adsorption of gas-like molecules to self-aligned square-well fluid channels under confinement of chemically patterned substrates. APPLIED NANOSCIENCE 2012. [DOI: 10.1007/s13204-012-0118-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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SINGH SATYAPAL, SINGH JAYANTK, SHARMA ASHUTOSH. INVESTIGATING BRIDGE-LIKE STRUCTURES IN A SQUARE-WELL BINARY MIXTURE USING NVT MONTE CARLO SIMULATION. INTERNATIONAL JOURNAL OF NANOSCIENCE 2012. [DOI: 10.1142/s0219581x11008034] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Bridge-like structures have been reported in recent studies for a binary mixture with square well fluids in 2D and 3D using different techniques. In this paper, we present our NVT simulation results in 3D with symmetric additive water and oil-like molecules. We use Dirac's delta function defined using theta step function for evaluating pressure components and surface tension values. Our investigation reveals that though 3D NVT MC results are in qualitative agreement with the published results showing all the structures as bridge-like, complete wetting of the walls by the preferred component and micelle structures but the critical parameters as surface attraction strength significantly alter to lower values for PW and CW cases in comparison to the 2D MD cases. We have studied cases with pore width as H = 6.0, 8.0, and 10.0 at T = 0.70, 0.80, and 0.90 for εAB = 0.0, 0.25, 0.50, and 1.0. For all of the bridge cases ε Wall -A = -0.50 and λ wall -A = 1.0. For fluid–fluid interaction λ ff = 1.2 and 1.5 are taken with εAA = εBB = -1.0. Our pressure and surface tension values show clear signature of confinement effect and dependence on other parameters for the bridge cases but it is concluded that different structural transitions depend only on the predefined energetically favorable and unfavorable interfaces which in turn comes from the separation of the two walls and average initial density. Our density profiles confirm the evolved structures.
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Affiliation(s)
- SATYA PAL SINGH
- Department of Applied Sciences, Madan Mohan Malviya Engineering College, Gorakhpur, 273010, India
- Department of Chemical Engineering, Indian Institute of Technology Kanpur, 208016, UP, India
| | - JAYANT K. SINGH
- Department of Chemical Engineering, Indian Institute of Technology Kanpur, 208016, UP, India
| | - ASHUTOSH SHARMA
- Department of Chemical Engineering, Indian Institute of Technology Kanpur, 208016, UP, India
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Structure and dynamics of reentrant nematics: any open questions after almost 40 years? Int J Mol Sci 2011; 12:5352-72. [PMID: 21954364 PMCID: PMC3179171 DOI: 10.3390/ijms12085352] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2011] [Revised: 08/09/2011] [Accepted: 08/11/2011] [Indexed: 11/17/2022] Open
Abstract
Liquid crystals have attracted enormous interest because of the variety of their phases and richness of their application. The interplay of general physical symmetries and specific molecular features generates a myriad of different phenomena. A surprising behavior of liquid crystals is the reentrancy of phases as temperature, pressure, or concentration are varied. Here, we review the main experimental facts and the different theoretical scenarios that have guided the understanding of bulk reentrant nematics. Recently, some computer simulations of a system confined to nanoscopic scales have found new dynamical features of the reentrant nematic phase. We discuss this prediction in relation with the available experimental evidence on reentrant nematics and with the dynamics of liquids in strongly confined environments.
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Schoen M, Günther G. Capillary condensation in deformable mesopores: wetting versus nanomechanics. Mol Phys 2011. [DOI: 10.1080/00268976.2010.513346] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Anquetil-Deck C, Cleaver DJ. Nematic liquid-crystal alignment on stripe-patterned substrates. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2010; 82:031709. [PMID: 21230093 DOI: 10.1103/physreve.82.031709] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2010] [Revised: 08/19/2010] [Indexed: 05/30/2023]
Abstract
Here, we use molecular simulation to consider the behavior of a thin nematic film confined between two identical nanopatterned substrates. Using patterns involving alternating stripes of homeotropic-favoring and homogeneous-favoring substrates, we investigate the influence of the relative stripe width and the film thickness. From this, we show that the polar anchoring angle can be varied continuously from planar to homeotropic by appropriate tuning of these parameters. For very thin films with equal stripe widths, we observe orientational bridging, the surface patterning being written in domains which traverse the nematic film. This dual-bridging-domain arrangement breaks down with increase in film thickness, however, being replaced by a single tilted monodomain. Strong azimuthal anchoring in the plane of the stripe boundaries is observed for all systems.
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Affiliation(s)
- C Anquetil-Deck
- Laboratoire Chimie Provence, UMR 6264, University of Aix-Marseille I, Avenue Escadrille Normandie-Niemen, 13397 Marseille Cedex 20, France
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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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Schoen M, Paris O, Günther G, Müter D, Prass J, Fratzl P. Pore-lattice deformations in ordered mesoporous matrices: experimental studies and theoretical analysis. Phys Chem Chem Phys 2010; 12:11267-79. [DOI: 10.1039/c000782j] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Kuna JJ, Voïtchovsky K, Singh C, Jiang H, Mwenifumbo S, Ghorai PK, Stevens MM, Glotzer SC, Stellacci F. The effect of nanometre-scale structure on interfacial energy. NATURE MATERIALS 2009; 8:837-842. [PMID: 19749765 DOI: 10.1038/nmat2534] [Citation(s) in RCA: 106] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2009] [Accepted: 08/20/2009] [Indexed: 05/28/2023]
Abstract
Natural surfaces are often structured with nanometre-scale domains, yet a framework providing a quantitative understanding of how nanostructure affects interfacial energy, gamma(SL), is lacking. Conventional continuum thermodynamics treats gamma(SL) solely as a function of average composition, ignoring structure. Here we show that, when a surface has domains commensurate in size with solvent molecules, gamma(SL) is determined not only by its average composition but also by a structural component that causes gamma(SL) to deviate from the continuum prediction by a substantial amount, as much as 20% in our system. By contrasting surfaces coated with either molecular- (<2 nm) or larger-scale domains (>5 nm), we find that whereas the latter surfaces have the expected linear dependence of gamma(SL) on surface composition, the former show a markedly different non-monotonic trend. Molecular dynamics simulations show how the organization of the solvent molecules at the interface is controlled by the nanostructured surface, which in turn appreciably modifies gamma(SL).
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Affiliation(s)
- Jeffrey J Kuna
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139-4307, USA
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Günther G, Schoen M. Sorption strains and their consequences for capillary condensation in nanoconfinement. MOLECULAR SIMULATION 2009. [DOI: 10.1080/08927020802412370] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Feng Z, Zhang X, Wang W. Adsorption of fluids in a pore with chemical heterogeneities: the cooperative effect. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2008; 77:051603. [PMID: 18643075 DOI: 10.1103/physreve.77.051603] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2008] [Indexed: 05/26/2023]
Abstract
In this work, we study the cooperative adsorption of fluids in a heterogeneous pore, in which the pore walls are composed of homogeneous substrates with chemical groups (CGs) decorating them. The adsorption caused by the homogeneous substrates alone and that by CGs do not add up to the overall adsorption, indicating the existence of a cooperative effect. The cooperative effect is the source of cooperative adsorption, and is characterized in this work by the ratio of the overall adsorption to the sum of adsorption by the substrate only and that by CGs. It is found that the cooperative adsorption does not depend monotonically on the substrate or the CGs. Two different origins of the cooperative adsorption play different roles depending on which one dominates the overall adsorption. Our simulations reveal that, when the homogeneous substrate dominates the overall adsorption, weakening of the attractive fluid-substrate interaction or alternatively strengthening of the fluid-CGs interaction leads to a stronger cooperative effect and enhances the cooperative adsorption. However, when CGs dominate the overall adsorption, weakening of the attractive fluid-CG interaction or strengthening the fluid-substrate interaction results in strong cooperative adsorption. In order to investigate the effects of the distribution of CGs on cooperative adsorption, a design-test method is generalized and used in this work. Simulation results show that the overall adsorption can be significantly affected by the CG distribution.
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Affiliation(s)
- Zhikuan Feng
- 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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Messina GML, Satriano C, Marletta G. Confined protein adsorption into nanopore arrays fabricated by colloidal-assisted polymer patterning. Chem Commun (Camb) 2008:5031-3. [DOI: 10.1039/b809664c] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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