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Wilding NB, Evans R, Turci F. What is the best simulation approach for measuring local density fluctuations near solvo-/hydrophobes? J Chem Phys 2024; 160:164103. [PMID: 38651807 DOI: 10.1063/5.0203088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2024] [Accepted: 03/20/2024] [Indexed: 04/25/2024] Open
Abstract
Measurements of local density fluctuations are crucial to characterizing the interfacial properties of equilibrium fluids. A specific case that has been well-explored involves the heightened compressibility of water near hydrophobic entities. Commonly, a spatial profile of local fluctuation strength is constructed from the measurements of the mean and variance of solvent particle number fluctuations in a set of contiguous subvolumes of the system adjacent to the solvo-/hydrophobe. An alternative measure proposed by Evans and Stewart [J. Phys.: Condens. Matter 27, 194111 (2015)] defines a local compressibility profile in terms of the chemical potential derivative of the spatial number density profile. Using Grand canonical Monte Carlo simulation, we compare and contrast the efficacy of these two approaches for a Lennard-Jones solvent at spherical and planar solvophobic interfaces and SPC/E water at a hydrophobic spherical solute. Our principal findings are as follows: (i) the local compressibility profile χ(r) of Evans and Stewart is considerably more sensitive to variations in the strength of local density fluctuations than the spatial fluctuation profile F(r) and can resolve much more detailed structure; and (ii) while the local compressibility profile is essentially independent of the choice of spatial discretization used to construct the profile, the spatial fluctuation profile exhibits a strong systematic dependence on the size of the subvolumes on which the profile is defined. We clarify the origin and nature of this finite-size effect.
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Affiliation(s)
- Nigel B Wilding
- H.H. Wills Physics Laboratory, University of Bristol, Royal Fort, Bristol BS8 1TL, United Kingdom
| | - Robert Evans
- H.H. Wills Physics Laboratory, University of Bristol, Royal Fort, Bristol BS8 1TL, United Kingdom
| | - Francesco Turci
- H.H. Wills Physics Laboratory, University of Bristol, Royal Fort, Bristol BS8 1TL, United Kingdom
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2
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Turci F, Jack RL, Wilding NB. Partial and complete wetting of droplets of active Brownian particles. SOFT MATTER 2024; 20:2060-2074. [PMID: 38345308 DOI: 10.1039/d3sm01493b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/29/2024]
Abstract
We study wetting droplets formed of active Brownian particles in contact with a repulsive potential barrier, in a wedge geometry. Our numerical results demonstrate a transition between partially wet and completely wet states, as a function of the barrier height, analogous to the corresponding surface phase transition in passive fluids. We analyse partially wet configurations characterised by a nonzero contact angle θ between the droplet surface and the barrier including the average density profile and its fluctuations. These findings are compared with two equilibrium systems: a Lennard-Jones fluid and a simple contour model for a liquid-vapour interface. We locate the wetting transition where cos(θ) = 1, and the neutral state where cos(θ) = 0. We discuss the implications of these results for possible definitions of surface tensions in active fluids.
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Affiliation(s)
- Francesco Turci
- H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL, UK.
| | - Robert L Jack
- Department of Applied Mathematics and Theoretical Physics, Centre for Mathematical Sciences, University of Cambridge, Wilberforce Road, Cambridge CB3 0WA, UK
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK
| | - Nigel B Wilding
- H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL, UK.
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3
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Eckert T, Stuhlmüller NCX, Sammüller F, Schmidt M. Local measures of fluctuations in inhomogeneous liquids: statistical mechanics and illustrative applications. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2023; 35:425102. [PMID: 37414000 DOI: 10.1088/1361-648x/ace50c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2023] [Accepted: 07/06/2023] [Indexed: 07/08/2023]
Abstract
We show in detail how three one-body fluctuation profiles, namely the local compressibility, the local thermal susceptibility, and the reduced density, can be obtained from a statistical mechanical many-body description of classical particle-based systems. We present several different and equivalent routes to the definition of each fluctuation profile, facilitating their explicit numerical calculation in inhomogeneous equilibrium systems. This underlying framework is used for the derivation of further properties such as hard wall contact theorems and novel types of inhomogeneous one-body Ornstein-Zernike equations. The practical accessibility of all three fluctuation profiles is exemplified by grand canonical Monte Carlo simulations that we present for hard sphere, Gaussian core and Lennard-Jones fluids in confinement.
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Affiliation(s)
- Tobias Eckert
- Theoretische Physik II, Physikalisches Institut, Universität Bayreuth, D-95440 Bayreuth, Germany
| | - Nico C X Stuhlmüller
- Theoretische Physik II, Physikalisches Institut, Universität Bayreuth, D-95440 Bayreuth, Germany
| | - Florian Sammüller
- Theoretische Physik II, Physikalisches Institut, Universität Bayreuth, D-95440 Bayreuth, Germany
| | - Matthias Schmidt
- Theoretische Physik II, Physikalisches Institut, Universität Bayreuth, D-95440 Bayreuth, Germany
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4
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Coe MK, Evans R, Wilding NB. Understanding the physics of hydrophobic solvation. J Chem Phys 2023; 158:034508. [PMID: 36681639 DOI: 10.1063/5.0134060] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Simulations of water near extended hydrophobic spherical solutes have revealed the presence of a region of depleted density and accompanying enhanced density fluctuations. The physical origin of both phenomena has remained somewhat obscure. We investigate these effects employing a mesoscopic binding potential analysis, classical density functional theory (DFT) calculations for a simple Lennard-Jones solvent, and Grand Canonical Monte Carlo (GCMC) simulations of a monatomic water (mw) model. We argue that the density depletion and enhanced fluctuations are near-critical phenomena. Specifically, we show that they can be viewed as remnants of the critical drying surface phase transition that occurs at bulk liquid-vapor coexistence in the macroscopic planar limit, i.e., as the solute radius Rs → ∞. Focusing on the radial density profile ρ(r) and a sensitive spatial measure of fluctuations, the local compressibility profile χ(r), our binding potential analysis provides explicit predictions for the manner in which the key features of ρ(r) and χ(r) scale with Rs, the strength of solute-water attraction ɛsf, and the deviation from liquid-vapor coexistence of the chemical potential, δμ. These scaling predictions are confirmed by our DFT calculations and GCMC simulations. As such, our theory provides a firm basis for understanding the physics of hydrophobic solvation.
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Affiliation(s)
- Mary K Coe
- H. H. Wills Physics Laboratory, Royal Fort, University of Bristol, Bristol BS8 1TL, United Kingdom
| | - Robert Evans
- H. H. Wills Physics Laboratory, Royal Fort, University of Bristol, Bristol BS8 1TL, United Kingdom
| | - Nigel B Wilding
- H. H. Wills Physics Laboratory, Royal Fort, University of Bristol, Bristol BS8 1TL, United Kingdom
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5
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Tschopp SM, Sammüller F, Hermann S, Schmidt M, Brader JM. Force density functional theory in- and out-of-equilibrium. Phys Rev E 2022; 106:014115. [PMID: 35974621 DOI: 10.1103/physreve.106.014115] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Accepted: 06/06/2022] [Indexed: 06/15/2023]
Abstract
When a fluid is subject to an external field, as is the case near an interface or under spatial confinement, then the density becomes spatially inhomogeneous. Although the one-body density provides much useful information, a higher level of resolution is provided by the two-body correlations. These give a statistical description of the internal microstructure of the fluid and enable calculation of the average interparticle force, which plays an essential role in determining both the equilibrium and dynamic properties of interacting fluids. We present a theoretical framework for the description of inhomogeneous (classical) many-body systems, based explicitly on the two-body correlation functions. By consideration of local Noether-invariance against spatial distortion of the system we demonstrate the fundamental status of the Yvon-Born-Green (YBG) equation as a local force-balance within the fluid. Using the inhomogeneous Ornstein-Zernike equation we show that the two-body correlations are density functionals and, thus, that the average interparticle force entering the YBG equation is also a functional of the one-body density. The force-based theory we develop provides an alternative to standard density functional theory for the study of inhomogeneous systems both in- and out-of-equilibrium. We compare force-based density profiles to the results of the standard potential-based (dynamical) density functional theory. In-equilibrium, we confirm both analytically and numerically that the standard approach yields profiles that are consistent with the compressibility pressure, whereas the force-density functional gives profiles consistent with the virial pressure. For both approaches we explicitly prove the hard-wall contact theorem that connects the value of the density profile at the hard-wall with the bulk pressure. The structure of the theory offers deep insights into the nature of correlation in dense and inhomogeneous systems.
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Affiliation(s)
- Salomée M Tschopp
- Department of Physics, University of Fribourg, CH-1700 Fribourg, Switzerland
| | - Florian Sammüller
- Theoretische Physik II, Physikalisches Institut, Universität Bayreuth, D-95447 Bayreuth, Germany
| | - Sophie Hermann
- Theoretische Physik II, Physikalisches Institut, Universität Bayreuth, D-95447 Bayreuth, Germany
| | - Matthias Schmidt
- Theoretische Physik II, Physikalisches Institut, Universität Bayreuth, D-95447 Bayreuth, Germany
| | - Joseph M Brader
- Department of Physics, University of Fribourg, CH-1700 Fribourg, Switzerland
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6
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Feng D, Chen Z, Wu K, Li J, Dong X, Peng Y, Jia X, Li X, Wang D. A comprehensive review on the flow behaviour in shale gas reservoirs: Multi‐scale, multi‐phase, and multi‐physics. CAN J CHEM ENG 2022. [DOI: 10.1002/cjce.24439] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Dong Feng
- State Key Laboratory of Petroleum Resources and Prospecting China University of Petroleum (Beijing) Beijing P. R. China
| | - Zhangxin Chen
- State Key Laboratory of Petroleum Resources and Prospecting China University of Petroleum (Beijing) Beijing P. R. China
- Department of Chemical and Petroleum Engineering University of Calgary Calgary Canada
| | - Keliu Wu
- State Key Laboratory of Petroleum Resources and Prospecting China University of Petroleum (Beijing) Beijing P. R. China
| | - Jing Li
- State Key Laboratory of Petroleum Resources and Prospecting China University of Petroleum (Beijing) Beijing P. R. China
| | - Xiaohu Dong
- State Key Laboratory of Petroleum Resources and Prospecting China University of Petroleum (Beijing) Beijing P. R. China
| | - Yan Peng
- State Key Laboratory of Petroleum Resources and Prospecting China University of Petroleum (Beijing) Beijing P. R. China
| | - Xinfeng Jia
- State Key Laboratory of Petroleum Resources and Prospecting China University of Petroleum (Beijing) Beijing P. R. China
| | - Xiangfang Li
- State Key Laboratory of Petroleum Resources and Prospecting China University of Petroleum (Beijing) Beijing P. R. China
| | - Dinghan Wang
- State Key Laboratory of Petroleum Resources and Prospecting China University of Petroleum (Beijing) Beijing P. R. China
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7
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Hermann S, Schmidt M. Why Noether's theorem applies to statistical mechanics. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2022; 34:213001. [PMID: 35255482 DOI: 10.1088/1361-648x/ac5b47] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Accepted: 03/07/2022] [Indexed: 06/14/2023]
Abstract
Noether's theorem is familiar to most physicists due its fundamental role in linking the existence of conservation laws to the underlying symmetries of a physical system. Typically the systems are described in the particle-based context of classical mechanics or on the basis of field theory. We have recently shown (2021Commun. Phys.4176) that Noether's reasoning also applies to thermal systems, where fluctuations are paramount and one aims for a statistical mechanical description. Here we give a pedagogical introduction based on the canonical ensemble and apply it explicitly to ideal sedimentation. The relevant mathematical objects, such as the free energy, are viewed as functionals. This vantage point allows for systematic functional differentiation and the resulting identities express properties of both macroscopic average forces and molecularly resolved correlations in many-body systems, both in and out-of-equilibrium, and for active Brownian particles. To provide further background, we briefly describe the variational principles of classical density functional theory, of power functional theory, and of classical mechanics.
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Affiliation(s)
- Sophie Hermann
- Theoretische Physik II, Physikalisches Institut, Universität Bayreuth, D-95447 Bayreuth, Germany
| | - Matthias Schmidt
- Theoretische Physik II, Physikalisches Institut, Universität Bayreuth, D-95447 Bayreuth, Germany
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8
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Coe MK, Evans R, Wilding NB. The coexistence curve and surface tension of a monatomic water model. J Chem Phys 2022; 156:154505. [PMID: 35459314 DOI: 10.1063/5.0085252] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We study the monatomic water model of Molinero and Moore the grand canonical ensemble Monte Carlo simulation. Measurements of the probability distribution of the number density obtained via multicanonical sampling and histogram reweighting provide accurate estimates of the temperature dependence of both the liquid-vapor coexistence densities and the surface tension. Using finite-size scaling methods, we locate the liquid-vapor critical point at Tc = 917.6 K, ρc = 0.311 g cm-3. When plotted in scaled variables, in order to test the law of corresponding states, the coexistence curve of monatomic water is close to that of real water. In this respect, it performs better than extended simple point charge (SPC/E), TIP4P, and TIP4P/2005 water.
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Affiliation(s)
- Mary K Coe
- H.H. Wills Physics Laboratory, University of Bristol, Bristol BS8 1TL, United Kingdom
| | - Robert Evans
- H.H. Wills Physics Laboratory, University of Bristol, Bristol BS8 1TL, United Kingdom
| | - Nigel B Wilding
- H.H. Wills Physics Laboratory, University of Bristol, Bristol BS8 1TL, United Kingdom
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9
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Leoni F, Calero C, Franzese G. Nanoconfined Fluids: Uniqueness of Water Compared to Other Liquids. ACS NANO 2021; 15:19864-19876. [PMID: 34807577 PMCID: PMC8717635 DOI: 10.1021/acsnano.1c07381] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Accepted: 11/18/2021] [Indexed: 05/27/2023]
Abstract
Nanoconfinement can drastically change the behavior of liquids, puzzling us with counterintuitive properties. It is relevant in applications, including decontamination and crystallization control. However, it still lacks a systematic analysis for fluids with different bulk properties. Here we address this gap. We compare, by molecular dynamics simulations, three different liquids in a graphene slit pore: (1) A simple fluid, such as argon, described by a Lennard-Jones potential; (2) an anomalous fluid, such as a liquid metal, modeled with an isotropic core-softened potential; and (3) water, the prototypical anomalous liquid, with directional HBs. We study how the slit-pore width affects the structure, thermodynamics, and dynamics of the fluids. All the fluids show similar oscillating properties by changing the pore size. However, their free-energy minima are quite different in nature: (i) are energy-driven for the simple liquid; (ii) are entropy-driven for the isotropic core-softened potential; and (iii) have a changing nature for water. Indeed, for water, the monolayer minimum is entropy driven, at variance with the simple liquid, while the bilayer minimum is energy driven, at variance with the other anomalous liquid. Also, water has a large increase in diffusion for subnm slit pores, becoming faster than bulk. Instead, the other two fluids have diffusion oscillations much smaller than water, slowing down for decreasing slit-pore width. Our results, clarifying that water confined at the subnm scale behaves differently from other (simple or anomalous) fluids under similar confinement, are possibly relevant in nanopores applications, for example, in water purification from contaminants.
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Affiliation(s)
- Fabio Leoni
- Department
of Physics, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185 Rome, Italy
| | - Carles Calero
- Secció
de Física Estadística i Interdisciplinària-Departament
de Física de la Matèria Condensada, Institut de Nanociència i Nanotecnologia (IN2UB), Universitat
de Barcelona, Carrer Martí i Franquès 1, 08028 Barcelona, Spain
| | - Giancarlo Franzese
- Secció
de Física Estadística i Interdisciplinària-Departament
de Física de la Matèria Condensada, Institut de Nanociència i Nanotecnologia (IN2UB), Universitat
de Barcelona, Carrer Martí i Franquès 1, 08028 Barcelona, Spain
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10
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Bryk P, Terzyk AP. Chasing the Critical Wetting Transition. An Effective Interface Potential Method. MATERIALS 2021; 14:ma14237138. [PMID: 34885293 PMCID: PMC8658170 DOI: 10.3390/ma14237138] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Revised: 11/15/2021] [Accepted: 11/16/2021] [Indexed: 11/30/2022]
Abstract
Wettablity is one of the important characteristics defining a given surface. Here we show that the effective interface potential method of determining the wetting temperature, originally proposed by MacDowell and Müller for the surfaces exhibiting the first order wetting transition, can also be used to estimate the wetting temperature of the second order (continuous) wetting transition. Some selected other methods of determination of the wetting temperature are also discussed.
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Affiliation(s)
- Paweł Bryk
- Faculty of Chemistry, Maria Curie Skłodowska University, 20-031 Lublin, Poland;
| | - Artur P. Terzyk
- Physicochemistry of Carbon Materials Research Group, Faculty of Chemistry, Nicolaus Copernicus University, 87-100 Toruń, Poland
- Correspondence:
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11
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Tang W, Yu H, Zhao T, Qing L, Xu X, Zhao S. A dynamic reaction density functional theory for interfacial reaction-diffusion coupling at nanoscale. Chem Eng Sci 2021. [DOI: 10.1016/j.ces.2021.116513] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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12
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Eckert T, Stuhlmüller NCX, Sammüller F, Schmidt M. Fluctuation Profiles in Inhomogeneous Fluids. PHYSICAL REVIEW LETTERS 2020; 125:268004. [PMID: 33449757 DOI: 10.1103/physrevlett.125.268004] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Accepted: 12/09/2020] [Indexed: 06/12/2023]
Abstract
Three one-body profiles that correspond to local fluctuations in energy, in entropy, and in particle number are used to describe the equilibrium properties of inhomogeneous classical many-body systems. Local fluctuations are obtained from thermodynamic differentiation of the density profile or equivalently from average microscopic covariances. The fluctuation profiles follow from functional generators and they satisfy Ornstein-Zernike relations. Computer simulations reveal markedly different fluctuations in confined fluids with Lennard-Jones, hard sphere, and Gaussian core interactions.
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Affiliation(s)
- Tobias Eckert
- Theoretische Physik II, Physikalisches Institut, Universität Bayreuth, D-95447 Bayreuth, Germany
| | - Nico C X Stuhlmüller
- Theoretische Physik II, Physikalisches Institut, Universität Bayreuth, D-95447 Bayreuth, Germany
| | - Florian Sammüller
- Theoretische Physik II, Physikalisches Institut, Universität Bayreuth, D-95447 Bayreuth, Germany
| | - Matthias Schmidt
- Theoretische Physik II, Physikalisches Institut, Universität Bayreuth, D-95447 Bayreuth, Germany
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13
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Can liquid density-fluctuations near solid surface drive the motion of nanoscale droplets? Chem Phys Lett 2020. [DOI: 10.1016/j.cplett.2020.138066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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14
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Zhang T, Javadpour F, Li X, Wu K, Li J, Yin Y. Mesoscopic method to study water flow in nanochannels with different wettability. Phys Rev E 2020; 102:013306. [PMID: 32794987 DOI: 10.1103/physreve.102.013306] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Accepted: 06/15/2020] [Indexed: 12/19/2022]
Abstract
Molecular dynamics (MD) simulations is currently the most popular and credible tool to model water flow in nanoscale where the conventional continuum equations break down due to the dominance of fluid-surface interactions. However, current MD simulations are computationally challenging for the water flow in complex tube geometries or a network of nanopores, e.g., membrane, shale matrix, and aquaporins. We present a novel mesoscopic lattice Boltzmann method (LBM) for capturing fluctuated density distribution and a nonparabolic velocity profile of water flow through nanochannels. We incorporated molecular interactions between water and the solid inner wall into LBM formulations. Details of the molecular interactions were translated into true and apparent slippage, which were both correlated to the surface wettability, e.g., contact angle. Our proposed LBM was tested against 47 published cases of water flow through infinite-length nanochannels made of different materials and dimensions-flow rates as high as seven orders of magnitude when compared with predictions of the classical no-slip Hagen-Poiseuille (HP) flow. Using the developed LBM model, we also studied water flow through finite-length nanochannels with tube entrance and exit effects. Results were found to be in good agreement with 44 published finite-length cases in the literature. The proposed LBM model is nearly as accurate as MD simulations for a nanochannel, while being computationally efficient enough to allow implications for much larger and more complex geometrical nanostructures.
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Affiliation(s)
- Tao Zhang
- Key Laboratory for Petroleum Engineering of the Ministry of Education, China University of Petroleum, Beijing 102249, China.,Bureau of Economic Geology, Jackson School of Geosciences, The University of Texas at Austin, University Station, Box X, Austin, Texas 78713, USA
| | - Farzam Javadpour
- Bureau of Economic Geology, Jackson School of Geosciences, The University of Texas at Austin, University Station, Box X, Austin, Texas 78713, USA
| | - Xiangfang Li
- Key Laboratory for Petroleum Engineering of the Ministry of Education, China University of Petroleum, Beijing 102249, China
| | - Keliu Wu
- Key Laboratory for Petroleum Engineering of the Ministry of Education, China University of Petroleum, Beijing 102249, China.,The Department of Chemical and Petroleum Engineering, University of Calgary, Alberta, Canada T2N1N4
| | - Jing Li
- The Department of Chemical and Petroleum Engineering, University of Calgary, Alberta, Canada T2N1N4
| | - Ying Yin
- MOE Key Laboratory of Thermo-Fluid Science and Engineering, School of Energy and Power Engineering, Xi'an Jiaotong University, Xi'an 710049, China
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15
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Saxena U, Chouksey S, Rane K. Spontaneous translation of nanodroplet over a heterogeneous surface due to thermal cycles: role of solid–liquid interfacial fluctuations. Mol Phys 2020. [DOI: 10.1080/00268976.2019.1657191] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Affiliation(s)
- Utkarsh Saxena
- Indian Institute of Technology, Gandhinagar, Gujarat, India
| | | | - Kaustubh Rane
- Indian Institute of Technology, Gandhinagar, Gujarat, India
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16
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Monroe J, Barry M, DeStefano A, Aydogan Gokturk P, Jiao S, Robinson-Brown D, Webber T, Crumlin EJ, Han S, Shell MS. Water Structure and Properties at Hydrophilic and Hydrophobic Surfaces. Annu Rev Chem Biomol Eng 2020; 11:523-557. [PMID: 32169001 DOI: 10.1146/annurev-chembioeng-120919-114657] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The properties of water on both molecular and macroscopic surfaces critically influence a wide range of physical behaviors, with applications spanning from membrane science to catalysis to protein engineering. Yet, our current understanding of water interfacing molecular and material surfaces is incomplete, in part because measurement of water structure and molecular-scale properties challenges even the most advanced experimental characterization techniques and computational approaches. This review highlights progress in the ongoing development of tools working to answer fundamental questions on the principles that govern the interactions between water and surfaces. One outstanding and critical question is what universal molecular signatures capture the hydrophobicity of different surfaces in an operationally meaningful way, since traditional macroscopic hydrophobicity measures like contact angles fail to capture even basic properties of molecular or extended surfaces with any heterogeneity at the nanometer length scale. Resolving this grand challenge will require close interactions between state-of-the-art experiments, simulations, and theory, spanning research groups and using agreed-upon model systems, to synthesize an integrated knowledge of solvation water structure, dynamics, and thermodynamics.
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Affiliation(s)
- Jacob Monroe
- Department of Chemical Engineering, University of California, Santa Barbara, California 93106, USA;
| | - Mikayla Barry
- Department of Materials, University of California, Santa Barbara, California 93106, USA
| | - Audra DeStefano
- Department of Chemical Engineering, University of California, Santa Barbara, California 93106, USA;
| | - Pinar Aydogan Gokturk
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Sally Jiao
- Department of Chemical Engineering, University of California, Santa Barbara, California 93106, USA;
| | - Dennis Robinson-Brown
- Department of Chemical Engineering, University of California, Santa Barbara, California 93106, USA;
| | - Thomas Webber
- Department of Chemical Engineering, University of California, Santa Barbara, California 93106, USA;
| | - Ethan J Crumlin
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.,Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Songi Han
- Department of Chemical Engineering, University of California, Santa Barbara, California 93106, USA; .,Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, USA
| | - M Scott Shell
- Department of Chemical Engineering, University of California, Santa Barbara, California 93106, USA;
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17
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Guo Z, Zhang X. Enhanced fluctuation for pinned surface nanobubbles. Phys Rev E 2019; 100:052803. [PMID: 31869961 DOI: 10.1103/physreve.100.052803] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2019] [Indexed: 11/07/2022]
Abstract
By employing molecular dynamics simulations we investigate the fluctuation of surface nanobubbles immersed in liquid phase. Our simulation results indicate that in comparison with the surrounding liquid and nanobubble interior, the vapor-liquid or gas-liquid interface of nanobubbles always exhibits the largest compressibility, demonstrating the enhanced fluctuation for nanobubble interfaces. We also find that vapor surface nanobubbles and gas surface nanobubbles exhibit different fluctuation behaviors. For vapor nanobubbles that appear in overheated pure liquid, both density fluctuation and interface fluctuation are independent on the external pressure since the internal pressure remains constant at a given temperature. For gas nanobubbles that appear in gas supersaturated solution, the density fluctuation monotonously decreases with the increase of gas concentration, while the interface fluctuation shows a nonmonotonic variation. Departure from the intermediate gas concentration with the minimal interface fluctuation would enhance the fluctuation, which may finally lead to nanobubble destabilization. Finally, our simulation results indicate that the complicated interface fluctuation of surface nanobubbles comprises two different modes: interface deformation and interface oscillation, both of which display similar trends as that of the combined interface fluctuation.
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Affiliation(s)
- Zhenjiang Guo
- State Key Laboratory of Organic-Inorganic Composites, Beijing University of Chemical Technology, Beijing 100029, China
| | - Xianren Zhang
- State Key Laboratory of Organic-Inorganic Composites, Beijing University of Chemical Technology, Beijing 100029, China
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18
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A unified description of hydrophilic and superhydrophobic surfaces in terms of the wetting and drying transitions of liquids. Proc Natl Acad Sci U S A 2019; 116:23901-23908. [PMID: 31611388 DOI: 10.1073/pnas.1913587116] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Clarifying the factors that control the contact angle of a liquid on a solid substrate is a long-standing scientific problem pertinent across physics, chemistry, and materials science. Progress has been hampered by the lack of a comprehensive and unified understanding of the physics of wetting and drying phase transitions. Using various theoretical and simulational techniques applied to realistic fluid models, we elucidate how the character of these transitions depends sensitively on both the range of fluid-fluid and substrate-fluid interactions and the temperature. Our calculations uncover previously unrecognized classes of surface phase diagram which differ from that established for simple lattice models and often assumed to be universal. The differences relate both to the topology of the phase diagram and to the nature of the transitions, with a remarkable feature being a difference between drying and wetting transitions which persists even in the approach to the bulk critical point. Most experimental and simulational studies of liquids at a substrate belong to one of these previously unrecognized classes. We predict that while there appears to be nothing particularly special about water with regard to its wetting and drying behavior, superhydrophobic behavior should be more readily observable in experiments conducted at high temperatures than at room temperature.
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19
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Playing the long game wins the cohesion-adhesion rivalry. Proc Natl Acad Sci U S A 2019; 116:23874-23876. [PMID: 31659047 DOI: 10.1073/pnas.1916911116] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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20
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Yadav HOS, Kuo AT, Urata S, Shinoda W. Effects of Packing Density and Chain Length on the Surface Hydrophobicity of Thin Films Composed of Perfluoroalkyl Acrylate Chains: A Molecular Dynamics Study. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:14316-14323. [PMID: 31596100 DOI: 10.1021/acs.langmuir.9b02656] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
A good understanding of the surface hydrophobicity of fluorinated materials is useful for their application as coating materials. The present study investigates the surface hydrophobicity of perfluoroalkyl acrylate (PFA) thin films using molecular dynamics simulations. Surface hydrophobicity is characterized by examining the contact angle of a water droplet on PFA surfaces and the cavity formation free energy in the vicinity of the surface. It is found that the calculated microscopic contact angles are in good agreement with the experimental results and partially capture the difference in the hydrophobicity of the surface arising from the variation of packing density and side chain length of PFA. The variations of cavity formation free energy in the vicinity of the surface elucidate that the surface hydrophobicity is mainly governed by the packing density rather than the chain length of PFA. The hydrophobicity generally increases with decreasing the packing density to some extent and then turns to decrease as further reducing the packing density. At higher packing density, the surface hydrophobicity slightly decreases with increasing the chain length, while at the lower packing density, the surface hydrophobicity is increased when chain length of PFA is longer than six carbons. Furthermore, we found that the influence of packing density on the surface hydrophobicity is directly related to the variation of the surface roughness and chain flexibility, that is, the surface hydrophobicity increases with increase in the surface roughness, while the chain flexibility plays a secondary role in the enhancement by affecting the stability of water staying near the interface. The study provides a significant insight into the local hydrophobicity and microscopic structure of the PFA surfaces, which would be useful for the application of surface modification.
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Affiliation(s)
- Hari O S Yadav
- Department of Materials Chemistry , Nagoya University , Furo-cho, Chikusa-ku, Nagoya 464-8603 , Japan
| | - An-Tsung Kuo
- Innovative Technology Laboratories , AGC Inc. , Yokohama , Kanagawa 230-0045 , Japan
| | - Shingo Urata
- Innovative Technology Laboratories , AGC Inc. , Yokohama , Kanagawa 230-0045 , Japan
| | - Wataru Shinoda
- Department of Materials Chemistry , Nagoya University , Furo-cho, Chikusa-ku, Nagoya 464-8603 , Japan
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21
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Ramos-Alvarado B. Water wettability of graphene and graphite, optimization of solid-liquid interaction force fields, and insights from mean-field modeling. J Chem Phys 2019; 151:114701. [DOI: 10.1063/1.5118888] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Bladimir Ramos-Alvarado
- Department of Mechanical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
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22
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Yin H, Sibley DN, Archer AJ. Binding potentials for vapour nanobubbles on surfaces using density functional theory. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2019; 31:315102. [PMID: 30978706 DOI: 10.1088/1361-648x/ab18e8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
We calculate density profiles of a simple model fluid in contact with a planar surface using density functional theory (DFT), in particular for the case where there is a vapour layer intruding between the wall and the bulk liquid. We apply the method of Hughes et al (2015 J. Chem. Phys. 142 074702) to calculate the density profiles for varying (specified) amounts of the vapour adsorbed at the wall. This is equivalent to varying the thickness h of the vapour at the surface. From the resulting sequence of density profiles we calculate the thermodynamic grand potential as h is varied and thereby determine the binding potential as a function of h. The binding potential obtained via this coarse-graining approach allows us to determine the disjoining pressure in the film and also to predict the shape of vapour nano-bubbles on the surface. Our microscopic DFT based approach captures information from length scales much smaller than some commonly used models in continuum mechanics.
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Affiliation(s)
- Hanyu Yin
- Department of Mathematical Sciences, Loughborough University, Loughborough, LE11 3TU, United Kingdom
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23
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Sun Z, Kang Y, Kang Y. Density Functional Study on Enhancement of Modulus of Confined Fluid in Nanopores. Ind Eng Chem Res 2019. [DOI: 10.1021/acs.iecr.9b02437] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Zongli Sun
- Science and Technology College, North China Electric Power University, Baoding 071051, P. R. China
| | - Yanshuang Kang
- College of Science, Hebei Agricultural University, Baoding 071001, P. R. China
| | - Yanmei Kang
- University of International Relations, Beijing 100091, P. R. China
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24
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Jain K, Schultz AJ, Errington JR. Construction of the interface potential from a series of canonical ensemble simulations. J Chem Phys 2019; 151:044103. [DOI: 10.1063/1.5110922] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Affiliation(s)
- Karnesh Jain
- Department of Chemical and Biological Engineering, University at Buffalo, Buffalo, New York 14260-4200, USA
| | - Andrew J. Schultz
- Department of Chemical and Biological Engineering, University at Buffalo, Buffalo, New York 14260-4200, USA
| | - Jeffrey R. Errington
- Department of Chemical and Biological Engineering, University at Buffalo, Buffalo, New York 14260-4200, USA
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25
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Lippmann M, Seeck OH, Ehnes A, Nygård K, Bertram F, Ciobanu A. Experimental Observation of Crystal-Liquid Coexistence in Slit-Confined Nonpolar Fluids. J Phys Chem Lett 2019; 10:1634-1638. [PMID: 30900899 DOI: 10.1021/acs.jpclett.9b00331] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Films of carbon tetrachloride (CCl4) confined in slit geometry between two flat diamond substrates down to a few tens of Angstroms are studied by combining X-ray reflectivity with in-plane and out-of-plane X-ray scattering. The confined films form a heterogeneous structure with coexisting regions of liquid and crystalline phases. The liquid phase shows short-range ordering normal to the surfaces of the substrates. The experiments directly show the ability of the confinement to induce crystal objects, which is a long-discussed issue in the literature. The surface structure and morphology of the substrates may influence the actual realization of the crystalline phase in confinement.
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Affiliation(s)
- Milena Lippmann
- Deutsches Elektronen-Synchrotron DESY , Notkestraße 85 , 22607 Hamburg , Germany
| | - Oliver H Seeck
- Deutsches Elektronen-Synchrotron DESY , Notkestraße 85 , 22607 Hamburg , Germany
| | - Anita Ehnes
- Deutsches Elektronen-Synchrotron DESY , Notkestraße 85 , 22607 Hamburg , Germany
| | - Kim Nygård
- MAX IV Laboratory , Lund University , Fontongatan 2 , 22484 Lund , Sweden
| | - Florian Bertram
- Deutsches Elektronen-Synchrotron DESY , Notkestraße 85 , 22607 Hamburg , Germany
| | - Anca Ciobanu
- Deutsches Elektronen-Synchrotron DESY , Notkestraße 85 , 22607 Hamburg , Germany
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26
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27
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Lam J, Lutsko JF. Solvent-mediated interactions between nanostructures: From water to Lennard-Jones liquid. J Chem Phys 2018; 149:134703. [PMID: 30292194 DOI: 10.1063/1.5037571] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Solvent-mediated interactions emerge from complex mechanisms that depend on the solute structure, its wetting properties, and the nature of the liquid. While numerous studies have focused on the first two influences, here, we compare the results from water and Lennard-Jones liquid in order to reveal to what extent solvent-mediated interactions are universal with respect to the nature of the liquid. Besides the influence of the liquid, the results were obtained with classical density functional theory and brute-force molecular dynamics simulations which allow us to contrast these two numerical techniques.
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Affiliation(s)
- Julien Lam
- Center for Nonlinear Phenomena and Complex Systems, Universite Libre de Bruxelles, Code Postal 231, Boulevard du Triomphe, 1050 Brussels, Belgium
| | - James F Lutsko
- Center for Nonlinear Phenomena and Complex Systems, Universite Libre de Bruxelles, Code Postal 231, Boulevard du Triomphe, 1050 Brussels, Belgium
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28
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Affiliation(s)
- Filip Persson
- Division of Biophysical Chemistry, Department of Chemistry, Lund University, P.O. Box 124, SE-22100 Lund, Sweden
| | - Bertil Halle
- Division of Biophysical Chemistry, Department of Chemistry, Lund University, P.O. Box 124, SE-22100 Lund, Sweden
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29
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Remsing RC, Weeks JD. Alchemical free energy calculations and umbrella sampling with local molecular field theory. JOURNAL OF THEORETICAL & COMPUTATIONAL CHEMISTRY 2018. [DOI: 10.1142/s0219633618400035] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Understanding the thermodynamic driving forces underlying any chemical process requires a description of the underlying free energy surface. However, computation of free energies is difficult, often requiring advanced sampling techniques. Moreover, these computations can be further complicated by the evaluation of any long-ranged interactions in the system of interest, such as Coulomb interactions in charged and polar media. Local molecular field theory is a promising approach to avoid many of the conceptual and computational difficulties associated with long-ranged interactions. We present frameworks for performing alchemical free energy calculations and non-Boltzmann sampling with local molecular field theory. We demonstrate that local molecular field theory can be used to perform these free energy calculations with accuracy comparable to traditional methodologies while eliminating the need for explicit treatment of long-ranged interactions in simulations.
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Affiliation(s)
- Richard C. Remsing
- Institute for Computational Molecular Science, Department of Chemistry, Temple University, Philadelphia, PA 19122, USA
| | - John D. Weeks
- Institute for Physical Science and Technology, Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20742, USA
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30
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Shrivastav G, Remsing RC, Kashyap HK. Capillary evaporation of the ionic liquid [EMIM][BF4] in nanoscale solvophobic confinement. J Chem Phys 2018; 148:193810. [PMID: 30307173 DOI: 10.1063/1.5010259] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Affiliation(s)
- Gourav Shrivastav
- Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Richard C. Remsing
- Institute for Computational Molecular Science and Department of Chemistry, Temple University, Philadelphia, Pennsylvania 19122, USA
| | - Hemant K. Kashyap
- Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
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31
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MacDowell LG. Capillary wave theory of adsorbed liquid films and the structure of the liquid-vapor interface. Phys Rev E 2017; 96:022801. [PMID: 28950477 DOI: 10.1103/physreve.96.022801] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2017] [Indexed: 11/07/2022]
Abstract
In this paper we try to work out in detail the implications of a microscopic theory for capillary waves under the assumption that the density is given along lines normal to the interface. Within this approximation, which may be justified in terms of symmetry arguments, the Fisk-Widom scaling of the density profile holds for frozen realizations of the interface profile. Upon thermal averaging of capillary wave fluctuations, the resulting density profile yields results consistent with renormalization group calculations in the one-loop approximation. The thermal average over capillary waves may be expressed in terms of a modified convolution approximation where normals to the interface are Gaussian distributed. In the absence of an external field we show that the phenomenological density profile applied to the square-gradient free energy functional recovers the capillary wave Hamiltonian exactly. We extend the theory to the case of liquid films adsorbed on a substrate. For systems with short-range forces, we recover an effective interface Hamiltonian with a film height dependent surface tension that stems from the distortion of the liquid-vapor interface by the substrate, in agreement with the Fisher-Jin theory of short-range wetting. In the presence of long-range interactions, the surface tension picks up an explicit dependence on the external field and recovers the wave vector dependent logarithmic contribution observed by Napiorkowski and Dietrich. Using an error function for the intrinsic density profile, we obtain closed expressions for the surface tension and the interface width. We show the external field contribution to the surface tension may be given in terms of the film's disjoining pressure. From literature values of the Hamaker constant, it is found that the fluid-substrate forces may be able to double the surface tension for films in the nanometer range. The film height dependence of the surface tension described here is in full agreement with results of the capillary wave spectrum obtained recently in computer simulations, and the predicted translation mode of surface fluctuations reproduces to linear order in field strength an exact solution of the density correlation function for the Landau-Ginzburg-Wilson Hamiltonian in an external field.
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Affiliation(s)
- Luis G MacDowell
- Departamento de Química Física, Facultad de Ciencias Químicas, Universidad Complutense, Madrid 28040, Spain
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32
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Ardham VR, Leroy F. Thermodynamics of atomistic and coarse-grained models of water on nonpolar surfaces. J Chem Phys 2017; 147:074702. [DOI: 10.1063/1.4999337] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Vikram Reddy Ardham
- Eduard-Zintl-Institut für Anorganische und Physikalische Chemie, Technische Universität Darmstadt, Alarich-Weiss-Strasse 8, 64287 Darmstadt, Germany
| | - Frédéric Leroy
- Eduard-Zintl-Institut für Anorganische und Physikalische Chemie, Technische Universität Darmstadt, Alarich-Weiss-Strasse 8, 64287 Darmstadt, Germany
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33
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Evans R, Stewart MC, Wilding NB. Drying and wetting transitions of a Lennard-Jones fluid: Simulations and density functional theory. J Chem Phys 2017; 147:044701. [DOI: 10.1063/1.4993515] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Affiliation(s)
- Robert Evans
- H. H. Wills Physics Laboratory, University of Bristol, Royal Fort, Bristol BS8 1TL, United Kingdom
| | - Maria C. Stewart
- H. H. Wills Physics Laboratory, University of Bristol, Royal Fort, Bristol BS8 1TL, United Kingdom
| | - Nigel B. Wilding
- Department of Physics, University of Bath, Bath BA2 7AY, United Kingdom
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34
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Chacko B, Evans R, Archer AJ. Solvent fluctuations around solvophobic, solvophilic, and patchy nanostructures and the accompanying solvent mediated interactions. J Chem Phys 2017; 146:124703. [DOI: 10.1063/1.4978352] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Blesson Chacko
- Department of Mathematical Sciences, Loughborough University, Loughborough LE11 3TU, United Kingdom
| | - Robert Evans
- H. H. Wills Physics Laboratory, University of Bristol, Bristol BS8 1TL, United Kingdom
| | - Andrew J. Archer
- Department of Mathematical Sciences, Loughborough University, Loughborough LE11 3TU, United Kingdom
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35
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Xu X, Dai Y. Stabilization and Antifouling of Polymer Films on a Planar Surface by CO 2 Pressurization. J Phys Chem B 2017; 121:314-321. [PMID: 27997192 DOI: 10.1021/acs.jpcb.6b11975] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In this article, we study the dewetting phenomenon of a polymer and carbon dioxide (CO2) mixture on a planar surface by combining density functional theory and the string method. It is found that dewetting is a first-order discontinuous phase transition. When the pressure is lower than the completely dewetting pressure (Pd), CO2 stabilizes the polymer films. The density fluctuation of the polymer decreases significantly with the inclusion of CO2. When the pressure is above Pd, the polymer film is depleted far away from the surface, leaving a thick layer of pure CO2 in the region near the surface. Pd is proportional to the surface energy strength. The CO2 molecules enhance the density fluctuation of the polymer during the dewetting process. The polymer-rich phase at the triple point dewets to a CO2-rich vapor film, as the CO2-rich liquid film near the surface is metastable. These results have promising application in the industry of fabricating polymer films and antifouling polymers on attractive surfaces.
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Affiliation(s)
- Xiaofei Xu
- Center for Soft Condensed Matter Physics and Interdisciplinary Research, and ‡College of Physics, Optoelectronics and Energy, Soochow University , Suzhou, Jiangsu 215006, China
| | - Yibing Dai
- Center for Soft Condensed Matter Physics and Interdisciplinary Research, and ‡College of Physics, Optoelectronics and Energy, Soochow University , Suzhou, Jiangsu 215006, China
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36
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Gor GY, Siderius DW, Shen VK, Bernstein N. Modulus-pressure equation for confined fluids. J Chem Phys 2016; 145:164505. [PMID: 27802643 PMCID: PMC5455990 DOI: 10.1063/1.4965916] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Ultrasonic experiments allow one to measure the elastic modulus of bulk solid or fluid samples. Recently such experiments have been carried out on fluid-saturated nanoporous glass to probe the modulus of a confined fluid. In our previous work [G. Y. Gor et al., J. Chem. Phys., 143, 194506 (2015)], using Monte Carlo simulations we showed that the elastic modulus K of a fluid confined in a mesopore is a function of the pore size. Here we focus on the modulus-pressure dependence K(P), which is linear for bulk materials, a relation known as the Tait-Murnaghan equation. Using transition-matrix Monte Carlo simulations we calculated the elastic modulus of bulk argon as a function of pressure and argon confined in silica mesopores as a function of Laplace pressure. Our calculations show that while the elastic modulus is strongly affected by confinement and temperature, the slope of the modulus versus pressure is not. Moreover, the calculated slope is in a good agreement with the reference data for bulk argon and experimental data for confined argon derived from ultrasonic experiments. We propose to use the value of the slope of K(P) to estimate the elastic moduli of an unknown porous medium.
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Affiliation(s)
- Gennady Y Gor
- NRC Research Associate, Resident at Center for Materials Physics and Technology, Naval Research Laboratory, Washington, DC 20375, USA
| | - Daniel W Siderius
- Chemical Sciences Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
| | - Vincent K Shen
- Chemical Sciences Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
| | - Noam Bernstein
- Center for Materials Physics and Technology, Naval Research Laboratory, Washington, DC 20375, USA
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37
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Evans R, Stewart MC, Wilding NB. Critical Drying of Liquids. PHYSICAL REVIEW LETTERS 2016; 117:176102. [PMID: 27824478 DOI: 10.1103/physrevlett.117.176102] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Indexed: 06/06/2023]
Abstract
We report a detailed simulation and classical density functional theory study of the drying transition in a realistic model fluid at a smooth substrate. This transition (in which the contact angle θ→180°) is shown to be critical for both short-ranged and long-ranged substrate-fluid interaction potentials. In the latter case critical drying occurs at exactly zero attractive substrate strength. This observation permits the accurate elucidation of the character of the transition via a finite-size scaling analysis of the density probability function. We find that the critical exponent ν_{∥} that controls the parallel correlation length, i.e., the extent of vapor bubbles at the wall, is over twice as large as predicted by mean field and renormalization group calculations. We suggest a reason for the discrepancy. Our findings shed new light on fluctuation phenomena in fluids near hydrophobic and solvophobic interfaces.
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Affiliation(s)
- Robert Evans
- H. H. Wills Physics Laboratory, University of Bristol, Royal Fort, Bristol BS8 1TL, United Kingdom
| | - Maria C Stewart
- H. H. Wills Physics Laboratory, University of Bristol, Royal Fort, Bristol BS8 1TL, United Kingdom
| | - Nigel B Wilding
- Department of Physics, University of Bath, Bath BA2 7AY, United Kingdom
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38
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Parui S, Manna RN, Jana B. Destabilization of Hydrophobic Core of Chicken Villin Headpiece in Guanidinium Chloride Induced Denaturation: Hint of π-Cation Interaction. J Phys Chem B 2016; 120:9599-607. [DOI: 10.1021/acs.jpcb.6b06325] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Sridip Parui
- Department of Physical Chemistry, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700
032, India
| | - Rabindra Nath Manna
- Department of Physical Chemistry, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700
032, India
| | - Biman Jana
- Department of Physical Chemistry, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700
032, India
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39
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Li C, Huang J, Li Z. A Relation for Nanodroplet Diffusion on Smooth Surfaces. Sci Rep 2016; 6:26488. [PMID: 27215471 PMCID: PMC4877713 DOI: 10.1038/srep26488] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2016] [Accepted: 05/04/2016] [Indexed: 01/29/2023] Open
Abstract
In this work, we study the diffusion of nanodroplets on smooth surfaces through molecular dynamics (MD) simulations and theoretical analyses. Molecular dynamics simulations show that nanodroplet surface diffusion is different from that of single molecules and solid particles. The dependence of nanodroplet diffusion coefficient on temperature undergoes a transition from linear to nonlinear as the surface wettability is weakened due to the coupling of temperature and surface energy. We also develop a simple relation for the diffusion coefficient by using the contact angle and contact radius of the droplet. It works well for a wide range of surface wettabilities and different sized nanodroplets, as confirmed by MD simulations.
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Affiliation(s)
- Chu Li
- Department of Mechanical and Aerospace Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong
| | - Jizu Huang
- Institute of Computational Mathematics and Scientific/Engineering Computing, Academy of Mathematics and Systems Science, Chinese Academy of Sciences, Beijing 100190, China
| | - Zhigang Li
- Department of Mechanical and Aerospace Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong
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41
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Rane K, van der Vegt NFA. Understanding the influence of capillary waves on solvation at the liquid-vapor interface. J Chem Phys 2016; 144:114111. [DOI: 10.1063/1.4943781] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Kaustubh Rane
- Eduard-Zintl-Institut für Anorganische and Physikalische Chemie and Center of Smart Interfaces, Technische Universität Darmstadt, Alarich-Weiss-Strasse 10, 64287 Darmstadt, Germany
| | - Nico F. A. van der Vegt
- Eduard-Zintl-Institut für Anorganische and Physikalische Chemie and Center of Smart Interfaces, Technische Universität Darmstadt, Alarich-Weiss-Strasse 10, 64287 Darmstadt, Germany
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42
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Wu E, Garde S. Understanding n-Octane Behavior near Graphene with Scaled Solvent-Solute Attractions. J Phys Chem B 2016; 120:2033-42. [PMID: 26716462 DOI: 10.1021/acs.jpcb.5b10262] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We employ molecular dynamics simulations of n-octane near a layered graphene surface to study the related phenomena of solvation, density fluctuations, wettability, and structure and dynamics of n-octane molecules in the inhomogeneous interfacial environment. That solvation in bulk n-octane displays a lengthscale-dependent crossover similar to that of hydrophobic solvation in water is known. Here we show that, near an extended graphene interface having attractive interactions with n-octane, lengthscale-dependent solvation is similar to that in the bulk and displays a small to large crossover. However, as the n-octane-graphene interactions are reduced to make the surface increasingly solvophobic, the crossover behavior is modulated and essentially absent near the most solvophobic surfaces, similar to that in water near hydrophobic interfaces. We show that the macroscopic measure of wettability, namely, the contact angle, characterizes n-octane-graphene coupling over a limited range of attractions. In contrast, molecular measures such as the free energy of cavity formation or the local compressibility in the interfacial region provide an effective measure of this coupling over a broader range of attractions. Finally, as n-octane-graphene attractions are increased, the n-octane liquid displays a wetting transition and corresponding change from sigmoidal to layered density profile. Analysis of the local structure shows that n-octane molecules prefer approximately linear conformations and surface-parallel orientations near the graphene surface, and their translational dynamics slow down with increasing n-octane-graphene attractions. Our study highlights molecular scale behavior of n-octane molecules that is relevant to understanding nanoparticle-solvent coupling in composite materials with enhanced mechanical or thermal properties.
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Affiliation(s)
- Eugene Wu
- Howard P. Isermann Department of Chemical and Biological Engineering, Center for Biotechnology and Interdisciplinary Studies, and Center for Materials, Devices, and Integrated Systems, Rensselaer Polytechnic Institute , Troy, New York 12180, United States
| | - Shekhar Garde
- Howard P. Isermann Department of Chemical and Biological Engineering, Center for Biotechnology and Interdisciplinary Studies, and Center for Materials, Devices, and Integrated Systems, Rensselaer Polytechnic Institute , Troy, New York 12180, United States
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Xi E, Remsing RC, Patel AJ. Sparse Sampling of Water Density Fluctuations in Interfacial Environments. J Chem Theory Comput 2016; 12:706-13. [DOI: 10.1021/acs.jctc.5b01037] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Erte Xi
- Department of Chemical and
Biomolecular Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Richard C. Remsing
- Department of Chemical and
Biomolecular Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Amish J. Patel
- Department of Chemical and
Biomolecular Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
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