1
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Venkatareddy N, Mandal J, Maiti PK. Effect of confinement and topology: 2-TIPS vs. MIPS. SOFT MATTER 2023; 19:8561-8576. [PMID: 37905347 DOI: 10.1039/d3sm00796k] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/02/2023]
Abstract
2-TIPS (two temperature induced phase separation) refers to the phase separation phenomenon observed in mixtures of active and passive particles which are modelled using scalar activity. The active particles are connected to a thermostat at high temperature while the passive particles are connected to the thermostat at low temperature and the relative temperature difference between "hot" and "cold" particles is taken as the measure of the activity χ of the non-equilibrium system. The study of such binary mixtures of hot and cold particles under various kinds of confinement is an important problem in many physical and biological processes. The nature and extent of phase separation are heavily influenced by the geometry of confinement, activity, and density of the non-equilibrium binary mixture. Investigating such 3D binary mixtures confined by parallel walls, we observe that the active and passive particles phase separate, but the extent of phase separation is reduced compared to bulk phase separation at high densities and enhanced at low densities. However, when the binary mixture of active and passive particles is confined inside a spherical cavity, the phase separation is radial for small radii of the confining sphere and the extent of phase separation is higher compared to their bulk counterparts. Confinement leads to interesting properties in the passive (cold) region like enhanced layering and high compression in the direction parallel to the confining wall. In 2D, both the bulk and confined systems of the binary mixture show a significant decrement in the extent of phase separation at higher densities. This observation is attributed to the trapping of active particles inside the passive cluster, which increases with density. Thus the 2D systems show structures more akin to dense-dilute phase co-existence, which is observed in motility induced phase separation in 2D active systems. The binary mixture constrained on the spherical surface also shows similar phase co-existence. Our analyses reveal that the coexistent densities observed in 2-TIPS on the spherical surface agree with the findings of previous studies on MIPS in active systems on a sphere.
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Affiliation(s)
- Nayana Venkatareddy
- Centre for Condensed Matter Theory, Department of Physics, Indian Institute of Science, Bangalore 560012, India.
| | - Jaydeep Mandal
- Centre for Condensed Matter Theory, Department of Physics, Indian Institute of Science, Bangalore 560012, India.
| | - Prabal K Maiti
- Centre for Condensed Matter Theory, Department of Physics, Indian Institute of Science, Bangalore 560012, India.
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2
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Patel M, Shimizu S, Bates MA, Fernandez-Nieves A, Guldin S. Long term phase separation dynamics in liquid crystal-enriched microdroplets obtained from binary fluid mixtures. SOFT MATTER 2023; 19:1017-1024. [PMID: 36647716 DOI: 10.1039/d2sm01348g] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
The dynamics of long term phase separation in binary liquid mixtures remains a subject of fundamental interest. Here, we study a binary liquid mixture, where the minority phase is confined to a liquid crystal (LC)-rich droplet, by investigating the evolution of size, defect and mesogen alignment over time. We track the binary liquid mixture evolving towards equilibrium by visualising the configuration of the liquid crystal droplet through polarisation microscopy. We compare our experimental findings with computational simulations and elucidate differences between bulk phases and confined droplets based on the respective thermodynamics of phase separation. Our work provides insights on how phase transitions on the microscale can deviate from bulk phase diagrams with relevance to other material systems, such as the liquid-liquid phase separation of polymer and protein solutions.
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Affiliation(s)
- Mehzabin Patel
- Department of Chemical Engineering, University College London, Torrington Place, London, WC1E 7JE, UK.
| | - Seishi Shimizu
- Department of Chemistry, University of York, Heslington, York YO10 5DD, UK
| | - Martin A Bates
- Department of Chemistry, University of York, Heslington, York YO10 5DD, UK
| | - Alberto Fernandez-Nieves
- Department of Condensed Matter Physics, University of Barcelona, 08028 Barcelona, Spain
- ICREA-Institució Catalana de Recerca i Estudis Avançats, 08010 Barcelona, Spain
- Institute for Complex Systems (UBICS), University of Barcelona, 08028, Barcelona, Spain
| | - Stefan Guldin
- Department of Chemical Engineering, University College London, Torrington Place, London, WC1E 7JE, UK.
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3
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Horstmann R, Hecht L, Kloth S, Vogel M. Structural and Dynamical Properties of Liquids in Confinements: A Review of Molecular Dynamics Simulation Studies. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:6506-6522. [PMID: 35580166 DOI: 10.1021/acs.langmuir.2c00521] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Molecular dynamics (MD) simulations are a powerful tool for detailed studies of altered properties of liquids in confinement, in particular, of changed structures and dynamics. They allow, on one hand, for perfect control and systematic variation of the geometries and interactions inherent in confinement situations and, on the other hand, for type-selective and position-resolved analyses of a huge variety of structural and dynamical parameters. Here, we review MD simulation studies on various types of liquids and confinements. The main focus is confined aqueous systems, but also ionic liquids and polymer and silica melts are discussed. Results for confinements featuring different interactions, sizes, shapes, and rigidity will be presented. Special attention will be given to situations in which the confined liquid and the confining matrix consist of the same type of particles and, hence, disparate liquid-matrix interactions are absent. Findings for the magnitude and the range of wall effects on molecular positions and orientations and on molecular dynamics, including vibrational motion and structural relaxation, are reviewed. Moreover, their dependence on the parameters of the confinement and their relevance to theoretical approaches to the glass transition are addressed.
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Affiliation(s)
- Robin Horstmann
- Institute of Condensed Matter Physics, Technische Universität Darmstadt, Hochschulstr. 6, 64289 Darmstadt, Germany
| | - Lukas Hecht
- Institute of Condensed Matter Physics, Technische Universität Darmstadt, Hochschulstr. 6, 64289 Darmstadt, Germany
| | - Sebastian Kloth
- Institute of Condensed Matter Physics, Technische Universität Darmstadt, Hochschulstr. 6, 64289 Darmstadt, Germany
| | - Michael Vogel
- Institute of Condensed Matter Physics, Technische Universität Darmstadt, Hochschulstr. 6, 64289 Darmstadt, Germany
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4
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Reuhl M, Monnard P, Vogel M. Confinement effects on glass-forming mixtures: Insights from a combined experimental approach to aqueous ethylene glycol solutions in silica pores. J Chem Phys 2022; 156:084506. [DOI: 10.1063/5.0082406] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We perform nuclear magnetic resonance, broadband dielectric spectroscopy, and differential scanning calorimetry studies to ascertain the dynamical behaviors of aqueous ethylene glycol (EG) solutions in silica pores over broad temperature ranges. Both translational and rotational motions are analyzed, and the pore diameter (2.4–9.2 nm) and the EG concentration (12–57 mol. %) are varied, leading to fully liquid or partially crystalline systems. It is found that the translational diffusion coefficient strongly decreases when the diameter is reduced, resulting in a slowdown of nearly three orders of magnitude in the narrowest pores, while the confinement effects on the rotational correlation times are moderate. For the fully liquid solutions, we attribute bulk-like and slowed down reorientation processes to the central and interfacial pore regions, respectively. This coexistence is found in all the studied pores, and, hence, the range of the wall effects on the solution dynamics does not exceed ∼1 nm. Compared to the situation in the bulk, the concentration dependence is reduced in confinements, implying that the specific interactions of the molecular species with the silica walls lead to preferential adsorption. On the other hand, bulk-like structural relaxation is not observed in the partially frozen samples, where the liquid is sandwiched between the silica walls and the ice crystallites. Under such circumstances, there is another relaxation process with a weaker temperature dependence, which is observed in various kinds of partially frozen aqueous systems and denoted as the x process.
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Affiliation(s)
- Melanie Reuhl
- Institute of Condensed Matter Physics, Technische Universität Darmstadt, Hochschulstr. 6, 64289 Darmstadt, Germany
| | - Philipp Monnard
- Institute of Condensed Matter Physics, Technische Universität Darmstadt, Hochschulstr. 6, 64289 Darmstadt, Germany
| | - Michael Vogel
- Institute of Condensed Matter Physics, Technische Universität Darmstadt, Hochschulstr. 6, 64289 Darmstadt, Germany
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5
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Köster R, Vogel M. Slow liquid dynamics near solid surfaces: Insights from site-resolved studies of ionic liquids in silica confinement. J Chem Phys 2022; 156:074501. [DOI: 10.1063/5.0079722] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
| | - Michael Vogel
- Institute of Condensed Matter Physics, TU Darmstadt, Germany
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6
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Qin Y, You Y, Jin G, Zhu W, Zhu Y, Wang Q, Lu X, Shi Y. Atomistic insight into the lubrication of glycerol aqueous solution: The role of the solid interface‐induced microstructure of fluid molecules. AIChE J 2022. [DOI: 10.1002/aic.17581] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- Yao Qin
- College of Chemical Engineering, State Key Laboratory of Materials‐Oriented Chemical Engineering Nanjing Tech University Nanjing People's Republic of China
| | - Yajing You
- College of Chemical Engineering, State Key Laboratory of Materials‐Oriented Chemical Engineering Nanjing Tech University Nanjing People's Republic of China
| | - Guangzheng Jin
- College of Chemical Engineering, State Key Laboratory of Materials‐Oriented Chemical Engineering Nanjing Tech University Nanjing People's Republic of China
| | - Wei Zhu
- College of Chemical Engineering, State Key Laboratory of Materials‐Oriented Chemical Engineering Nanjing Tech University Nanjing People's Republic of China
| | - Yudan Zhu
- College of Chemical Engineering, State Key Laboratory of Materials‐Oriented Chemical Engineering Nanjing Tech University Nanjing People's Republic of China
| | - Qiutian Wang
- College of Chemical Engineering, State Key Laboratory of Materials‐Oriented Chemical Engineering Nanjing Tech University Nanjing People's Republic of China
| | - Xiaohua Lu
- College of Chemical Engineering, State Key Laboratory of Materials‐Oriented Chemical Engineering Nanjing Tech University Nanjing People's Republic of China
| | - Yijun Shi
- Division of Machine Elements Luleå University of Technology Luleå Sweden
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7
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Buntkowsky G, Döller S, Haro-Mares N, Gutmann T, Hoffmann M. Solid-state NMR studies of non-ionic surfactants confined in mesoporous silica. Z PHYS CHEM 2021. [DOI: 10.1515/zpch-2021-3132] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Abstract
This review gives an overview of current trends in the investigation of confined molecules such as higher alcohols, ethylene glycol and polyethylene glycol as guest molecules in neat and functionalized mesoporous silica materials. All these molecules have both hydrophobic and hydrophilic parts. They are characteristic role-models for the investigation of confined surfactants. Their properties are studied by a combination of solid-state NMR and relaxometry with other physicochemical techniques and molecular dynamics techniques. It is shown that this combination delivers unique insights into the structure, arrangement, dynamical properties and the guest-host interactions inside the confinement.
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Affiliation(s)
- Gerd Buntkowsky
- Eduard-Zintl-Institut für Anorganische und Physikalische Chemie , Technische Universität Darmstadt , Alarich-Weiss-Str. 8 , D-64287 Darmstadt , Germany
| | - Sonja Döller
- Eduard-Zintl-Institut für Anorganische und Physikalische Chemie , Technische Universität Darmstadt , Alarich-Weiss-Str. 8 , D-64287 Darmstadt , Germany
| | - Nadia Haro-Mares
- Eduard-Zintl-Institut für Anorganische und Physikalische Chemie , Technische Universität Darmstadt , Alarich-Weiss-Str. 8 , D-64287 Darmstadt , Germany
| | - Torsten Gutmann
- Eduard-Zintl-Institut für Anorganische und Physikalische Chemie , Technische Universität Darmstadt , Alarich-Weiss-Str. 8 , D-64287 Darmstadt , Germany
| | - Markus Hoffmann
- Department of Chemistry and Biochemistry , State University of New York College at Brockport , Brockport , NY , 14420 , USA
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8
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Abstract
Prepeak in the structure factor of alcohols is known for a half century and was attributed to one of two mechanisms (i) self-assembly in aggregates and (ii) existence of spatial heterogeneity. Although both explnations are often argued the molecular origin is yet unclear. In this work, molecular dynamics simulation of neat alcohols and their mixtures in the presence of an apolar liquid in bulk and in confined phases is performed to unveil and to clarify the origin of the prepeak at the molecular scale. Unambiguously, we show that the existence of the prepeak is the result of the self-assembly in clusters leading to long-range correlations rather than the spatial heterogeneity. We also establish that the confinement of neat liquids at the nanoscale does not erase the clustering and the prepeak but strongly reduce the spatial heterogeneity. Regarding the binary alcohol/toluene mixtures, we highlight the possibility to erase the clustering and the spatial heterogeneity from nanoconfinement inducing the formation of a core-shell structure. By tuning the interfacial chemistry and pore size, we shed light on the possibility to control the spatial heterogeneity, the self-assembly, and the microphase separation.
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Affiliation(s)
- Aziz Ghoufi
- Institut de Physique de Rennes, IPR, CNRS-Université de Rennes 1, UMR CNRS 6251, 35042 Rennes, France
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9
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Demuth D, Reuhl M, Hopfenmüller M, Karabas N, Schoner S, Vogel M. Confinement Effects on Glass-Forming Aqueous Dimethyl Sulfoxide Solutions. Molecules 2020; 25:E4127. [PMID: 32917011 PMCID: PMC7570821 DOI: 10.3390/molecules25184127] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Revised: 09/04/2020] [Accepted: 09/05/2020] [Indexed: 11/17/2022] Open
Abstract
Combining broadband dielectric spectroscopy and nuclear magnetic resonance studies, we analyze the reorientation dynamics and the translational diffusion associated with the glassy slowdown of the eutectic aqueous dimethyl sulfoxide solution in nano-sized confinements, explicitly, in silica pores with different diameters and in ficoll and lysozyme matrices at different concentrations. We observe that both rotational and diffusive dynamics are slower and more heterogeneous in the confinements than in the bulk but the degree of these effects depends on the properties of the confinement and differs for the components of the solution. For the hard and the soft matrices, the slowdown and the heterogeneity become more prominent when the size of the confinement is reduced. In addition, the dynamics are more retarded for dimethyl sulfoxide than for water, implying specific guest-host interactions. Moreover, we find that the temperature dependence of the reorientation dynamics and of the translational diffusion differs in severe confinements, indicating a breakdown of the Stokes-Einstein-Debye relation. It is discussed to what extent these confinement effects can be rationalized in the framework of core-shell models, which assume bulk-like and slowed-down motions in central and interfacial confinement regions, respectively.
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Affiliation(s)
| | | | | | | | | | - Michael Vogel
- Institute of Condensed Matter Physics, Technische Universität Darmstadt, 64289 Darmstadt, Germany; (D.D.); (M.R.); (M.H.); (N.K.); (S.S.)
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10
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Buntkowsky G, Vogel M. Small Molecules, Non-Covalent Interactions, and Confinement. Molecules 2020; 25:E3311. [PMID: 32708283 PMCID: PMC7397022 DOI: 10.3390/molecules25143311] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Revised: 07/07/2020] [Accepted: 07/15/2020] [Indexed: 11/27/2022] Open
Abstract
This review gives an overview of current trends in the investigation of small guest molecules, confined in neat and functionalized mesoporous silica materials by a combination of solid-state NMR and relaxometry with other physico-chemical techniques. The reported guest molecules are water, small alcohols, and carbonic acids, small aromatic and heteroaromatic molecules, ionic liquids, and surfactants. They are taken as characteristic role-models, which are representatives for the typical classes of organic molecules. It is shown that this combination delivers unique insights into the structure, arrangement, dynamics, guest-host interactions, and the binding sites in these confined systems, and is probably the most powerful analytical technique to probe these systems.
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Affiliation(s)
- Gerd Buntkowsky
- Institut für Physikalische Chemie, Technische Universität Darmstadt, 64287 Darmstadt, Germany
| | - Michael Vogel
- Institut für Festkörperphysik, Technische Universität Darmstadt, 64295 Darmstadt, Germany
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11
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Mhanna R, Catrou P, Dutta S, Lefort R, Essafri I, Ghoufi A, Muthmann M, Zamponi M, Frick B, Morineau D. Dynamic Heterogeneities in Liquid Mixtures Confined in Nanopores. J Phys Chem B 2020; 124:3152-3162. [DOI: 10.1021/acs.jpcb.0c01035] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Ramona Mhanna
- Institute of Physics of Rennes, CNRS−University of Rennes 1, UMR 6251, F-35042 Rennes, France
- Institut Laue-Langevin, 71 avenue des Martyrs, F-38000 Grenoble, France
| | - Pierre Catrou
- Institute of Physics of Rennes, CNRS−University of Rennes 1, UMR 6251, F-35042 Rennes, France
| | - Sujeet Dutta
- Institute of Physics of Rennes, CNRS−University of Rennes 1, UMR 6251, F-35042 Rennes, France
| | - Ronan Lefort
- Institute of Physics of Rennes, CNRS−University of Rennes 1, UMR 6251, F-35042 Rennes, France
| | - Ilham Essafri
- Institute of Physics of Rennes, CNRS−University of Rennes 1, UMR 6251, F-35042 Rennes, France
| | - Aziz Ghoufi
- Institute of Physics of Rennes, CNRS−University of Rennes 1, UMR 6251, F-35042 Rennes, France
| | - Matthias Muthmann
- Forschungszentrum Jülich GmbH, Jülich Centre for Neutron Science at MLZ Lichtenbergstrasse 1, 85748 Garching, Germany
| | - Michaela Zamponi
- Forschungszentrum Jülich GmbH, Jülich Centre for Neutron Science at MLZ Lichtenbergstrasse 1, 85748 Garching, Germany
| | - Bernhard Frick
- Institut Laue-Langevin, 71 avenue des Martyrs, F-38000 Grenoble, France
| | - Denis Morineau
- Institute of Physics of Rennes, CNRS−University of Rennes 1, UMR 6251, F-35042 Rennes, France
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12
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Chen X, Zhu J, Xu C, Peng Q, Li X, Su J. Simulation study on the structural and dynamic properties of ethanol confined in nanochannels. NEW J CHEM 2020. [DOI: 10.1039/d0nj01427c] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
The structural and dynamic properties of ethanol molecules in nanochannels of various diameters have been studied using molecular dynamics simulations.
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Affiliation(s)
- Xiuting Chen
- State Key Laboratory of Metastable Materials Science and Technology and Key Laboratory for Microstructural Material Physics of Hebei Province
- Yanshan University
- Qinhuangdao 066004
- China
| | - Jianzhuo Zhu
- State Key Laboratory of Metastable Materials Science and Technology and Key Laboratory for Microstructural Material Physics of Hebei Province
- Yanshan University
- Qinhuangdao 066004
- China
| | - Chao Xu
- State Key Laboratory of Metastable Materials Science and Technology and Key Laboratory for Microstructural Material Physics of Hebei Province
- Yanshan University
- Qinhuangdao 066004
- China
| | - Qiuming Peng
- State Key Laboratory of Metastable Materials Science and Technology and Key Laboratory for Microstructural Material Physics of Hebei Province
- Yanshan University
- Qinhuangdao 066004
- China
| | - Xingyuan Li
- State Key Laboratory of Metastable Materials Science and Technology and Key Laboratory for Microstructural Material Physics of Hebei Province
- Yanshan University
- Qinhuangdao 066004
- China
| | - Jiguo Su
- State Key Laboratory of Metastable Materials Science and Technology and Key Laboratory for Microstructural Material Physics of Hebei Province
- Yanshan University
- Qinhuangdao 066004
- China
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13
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Geske J, Harrach M, Heckmann L, Horstmann R, Klameth F, Müller N, Pafong E, Wohlfromm T, Drossel B, Vogel M. Molecular Dynamics Simulations of Water, Silica, and Aqueous Mixtures in Bulk and Confinement. ACTA ACUST UNITED AC 2018. [DOI: 10.1515/zpch-2017-1042] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Abstract
Aqueous systems are omnipresent in nature and technology. They show complex behaviors, which often originate in the existence of hydrogen-bond networks. Prominent examples are the anomalies of water and the non-ideal behaviors of aqueous solutions. The phenomenology becomes even richer when aqueous liquids are subject to confinement. To this day, many properties of water and its mixtures, in particular, under confinement, are not understood. In recent years, molecular dynamics simulations developed into a powerful tool to improve our knowledge in this field. Here, our simulation results for water and aqueous mixtures in the bulk and in various confinements are reviewed and some new simulation data are added to improve our knowledge about the role of interfaces. Moreover, findings for water are compared with results for silica, exploiting that both systems form tetrahedral networks.
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Affiliation(s)
- Julian Geske
- Institut für Festkörperphysik , Technische Universität Darmstadt, Hochschulstr. 6 , 64289 Darmstadt , Germany
| | - Michael Harrach
- Institut für Festkörperphysik , Technische Universität Darmstadt, Hochschulstr. 6 , 64289 Darmstadt , Germany
| | - Lotta Heckmann
- Institut für Festkörperphysik , Technische Universität Darmstadt, Hochschulstr. 6 , 64289 Darmstadt , Germany
| | - Robin Horstmann
- Institut für Festkörperphysik , Technische Universität Darmstadt, Hochschulstr. 6 , 64289 Darmstadt , Germany
| | - Felix Klameth
- Institut für Festkörperphysik , Technische Universität Darmstadt, Hochschulstr. 6 , 64289 Darmstadt , Germany
| | - Niels Müller
- Institut für Festkörperphysik , Technische Universität Darmstadt, Hochschulstr. 6 , 64289 Darmstadt , Germany
| | - Elvira Pafong
- Institut für Festkörperphysik , Technische Universität Darmstadt, Hochschulstr. 6 , 64289 Darmstadt , Germany
| | - Timothy Wohlfromm
- Institut für Festkörperphysik , Technische Universität Darmstadt, Hochschulstr. 6 , 64289 Darmstadt , Germany
| | - Barbara Drossel
- Institut für Festkörperphysik , Technische Universität Darmstadt, Hochschulstr. 6 , 64289 Darmstadt , Germany
| | - Michael Vogel
- Institut für Festkörperphysik , Technische Universität Darmstadt, Hochschulstr. 6 , 64289 Darmstadt , Germany
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14
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Abstract
Empty spaces are abhorred by nature, which immediately rushes in to fill the void. Humans have learnt pretty well how to make ordered empty nanocontainers, and to get useful products out of them. When such an order is imparted to molecules, new properties may appear, often yielding advanced applications. This review illustrates how the organized void space inherently present in various materials: zeolites, clathrates, mesoporous silica/organosilica, and metal organic frameworks (MOF), for example, can be exploited to create confined, organized, and self-assembled supramolecular structures of low dimensionality. Features of the confining matrices relevant to organization are presented with special focus on molecular-level aspects. Selected examples of confined supramolecular assemblies - from small molecules to quantum dots or luminescent species - are aimed to show the complexity and potential of this approach. Natural confinement (minerals) and hyperconfinement (high pressure) provide further opportunities to understand and master the atomistic-level interactions governing supramolecular organization under nanospace restrictions.
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Affiliation(s)
- Gloria Tabacchi
- Department of Science and High Technology, University of Insubria, Via Valleggio, 9 I-22100, Como, Italy
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15
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Abstract
Abstract
Effects of interfaces on hydrogen-bonded liquids play major roles in nature and technology. Despite their importance, a fundamental understanding of these effects is still lacking. In large parts, this shortcoming is due to the high complexity of these systems, leading to an interference of various interactions and effects. Therefore, it is advisable to take gradual approaches, which start from well designed and defined model systems and systematically increase the level of intricacy towards more complex mimetics. Moreover, it is necessary to combine insights from a multitude of methods, in particular, to link novel preparation strategies and comprehensive experimental characterization with inventive computational and theoretical modeling. Such concerted approach was taken by a group of preparative, experimentally, and theoretically working scientists in the framework of Research Unit FOR 1583 funded by the Deutsche Forschungsgemeinschaft (German Research Foundation). This special issue summarizes the outcome of this collaborative research. In this introductory article, we give an overview of the covered topics and the main results of the whole consortium. The following contributions are review articles or original works of individual research projects.
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Affiliation(s)
- Gerd Buntkowsky
- Institut für Physikalische Chemie , Technische Universität Darmstadt , 64287 Darmstadt , Germany
| | - Michael Vogel
- Institut für Festkörperphysik , Technische Universität Darmstadt , 64295 Darmstadt , Germany
| | - Roland Winter
- Fakultät für Chemie und Chemische Biologie , Technische Universität Dortmund , 44227 Dortmund , Germany
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16
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Essafri I, Courtin J, Ghoufi A. Numerical evidence of heterogeneity and nanophases in a binary liquid confined at the nanoscale. MOLECULAR SIMULATION 2018. [DOI: 10.1080/08927022.2018.1444762] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Affiliation(s)
- I. Essafri
- Institut de Physique de Rennes, UMR CNRS 6251, Université Rennes 1, Rennes, France
| | - J. Courtin
- Institut de Physique de Rennes, UMR CNRS 6251, Université Rennes 1, Rennes, France
| | - A. Ghoufi
- Institut de Physique de Rennes, UMR CNRS 6251, Université Rennes 1, Rennes, France
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17
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Muthulakshmi T, Dutta D, Maheshwari P, Pujari PK. Evidence for confinement induced phase separation in ethanol-water mixture: a positron annihilation study. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2018; 30:025001. [PMID: 29160241 DOI: 10.1088/1361-648x/aa9c12] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We report an experimental evidence for the phase separation of ethanol-water mixture confined in mesoporous silica with different pore size using positron annihilation lifetime spectroscopy (PALS). A bulk-like liquid in the core of the pore and a distinct interfacial region near the pore surface have been identified based on ortho-positronium lifetime components. The lifetime corresponding to the core liquid shows similar behavior to the bulk liquid mixture while the interfacial lifetime shows an abrupt rise within a particular range of ethanol concentration depending on the pore size. This abrupt increase is attributed to the appearance of excess free-volume near the interfacial region. The excess free-volume is originated due to microphase separation of confined ethanol-water primarily at the vicinity of the pore wall. We envisage that probing free-volume changes at the interface using PALS is a sensitive way to investigate microphase separation under nanoconfinement.
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Affiliation(s)
- T Muthulakshmi
- Radiochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India
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Demuth D, Sattig M, Steinrücken E, Weigler M, Vogel M. 2H NMR Studies on the Dynamics of Pure and Mixed Hydrogen-Bonded Liquids in Confinement. Z PHYS CHEM 2018. [DOI: 10.1515/zpch-2017-1027] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
2H NMR is used to ascertain dynamical behaviors of pure and mixed hydrogen-bonded liquids in bulk and in confinement. Detailed comparisons of previous and new results in broad dynamic and temperature ranges reveal that confinement effects differ for various liquids and confinements. For water, molecular reorientation strongly depends on the confinement size, with much slower and less fragile structural relaxation under more severe geometrical restriction. Moreover, a dynamical crossover occurs when a fraction of solid water forms so that the dynamics of the fraction of liquid water becomes even more restricted and, as a consequence, changes from bulk-like to interface-dominated. For glycerol, by contrast, confinement has weak effects on the reorientation dynamics. Mixed hydrogen-bonded liquids show even more complex dynamical behaviors. For aqueous solutions, the temperature dependence of the structural relaxation becomes discontinuous when the concentration changes due to a freezing of water fractions. This tendency for partial crystallization is enhanced rather than reduced by confinement, because different liquid-matrix interactions of the molecular species induce micro-phase segregation, which facilitates ice formation in water-rich regions. In addition, dynamical couplings at solvent-protein interfaces are discussed. It is shown that, on the one hand, solvent dynamics are substantially slowed down at protein surfaces and, on the other hand, protein dynamics significantly depend on the composition and, thus, the viscosity of the solvent. Furthermore, a protein dynamical transition occurs when the amplitude of water-coupled restricted backbone dynamics vanishes upon cooling.
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Affiliation(s)
- Dominik Demuth
- Institut für Festkörperphysik , Technische Universität Darmstadt , Hochschulstr. 6 , 64289 Darmstadt , Germany
| | - Matthias Sattig
- Institut für Festkörperphysik , Technische Universität Darmstadt , Hochschulstr. 6 , 64289 Darmstadt , Germany
| | - Elisa Steinrücken
- Institut für Festkörperphysik , Technische Universität Darmstadt , Hochschulstr. 6 , 64289 Darmstadt , Germany
| | - Max Weigler
- Institut für Festkörperphysik , Technische Universität Darmstadt , Hochschulstr. 6 , 64289 Darmstadt , Germany
| | - Michael Vogel
- Institut für Festkörperphysik , Technische Universität Darmstadt , Hochschulstr. 6 , 64289 Darmstadt , Germany
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Watermann T, Sebastiani D. Liquid Water Confined in Cellulose with Variable Interfacial Hydrophilicity. ACTA ACUST UNITED AC 2017. [DOI: 10.1515/zpch-2017-1011] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
We investigate liquid water confined within nanoscale cellulose slabs by means of molecular dynamics simulations. Depending on the construction of the cellulose–water interface, two different surface structures with distinct levels of hydrophilicity are exposed to the water. The different philicities are reflected in the response of the water phase to this geometric confinement, both in terms of the density profile and in the strength of the aqueous hydrogen bonding network. At the smooth surface cut along the (010) axis of the cellulose crystal, water shows typical properties of a hydrophilic confinement: the density shows fluctuations that disappear further away from the wall, the water molecules orient themselves and the coordination numbers increases at the interface. As a consequence, the water becomes “harder” at the interface, with a considerably increased local ordering. At the zigzag-shaped surface along the (111) axis, the degree of hydrophilicity is reduced, and only small effects can be seen: the density shows weak fluctuations, and the orientation of the water molecules is closer to that of bulk water than to the smooth surface. The local coordination numbers remains constant over the whole confinement. Our work shows that the nature of the exposed cellulose interface has a strong influence on how the structure of adjacent water is modified. The different ways of surface construction yield distinct degrees of hydrophilicity and spatial accessibility regarding the hydrogen bond network, resulting in a notably different interfacial water structure.
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Affiliation(s)
- Tobias Watermann
- Institute of Chemistry , Martin-Luther University Halle-Wittenberg , 06120 Halle , Germany
| | - Daniel Sebastiani
- Institute of Chemistry , Martin-Luther University Halle-Wittenberg , von-Danckelmann-Platz 4 , 06120 Halle , Germany
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Sebastiani D. Ab-Initio Molecular Dynamics Simulations and Calculations of Spectroscopic Parameters in Hydrogen-Bonding Liquids in Confinement (Project 8). Z PHYS CHEM 2017. [DOI: 10.1515/zpch-2017-1006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Abstract
We investigate the effect of several nanoscale confinements on structural and dynamical properties of liquid water and binary aqueous mixtures. By means of molecular dynamics simulations based on density functional theory and atomistic force fields. Our main focus is on the dependence on the structure and the hydrogen-bonding-network of the liquids near the confinement interface at atomistic resolution. As a complementary aspect, spatially resolved profiles of the proton NMR chemical shift values are used to quantify the local strength of the hydrogen-bond-network.
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Affiliation(s)
- Daniel Sebastiani
- Institute of Chemistry , Martin-Luther-Universität Halle-Wittenberg , von-Danckelmann-Platz 4 , 06120 Halle , Germany
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Mhanna R, Abdel Hamid AR, Dutta S, Lefort R, Noirez L, Frick B, Morineau D. More room for microphase separation: An extended study on binary liquids confined in SBA-15 cylindrical pores. J Chem Phys 2017; 146:024501. [DOI: 10.1063/1.4972126] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Dutta S, Lefort R, Morineau D, Mhanna R, Merdrignac-Conanec O, Saint-Jalmes A, Leclercq T. Thermodynamics of binary gas adsorption in nanopores. Phys Chem Chem Phys 2016; 18:24361-9. [PMID: 27532892 DOI: 10.1039/c6cp01587e] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
MCM-41 nanoporous silicas show a very high selectivity for monoalcohols over aprotic molecules during adsorption of a binary mixture in the gas phase. We present here an original use of gravimetric vapour sorption isotherms to characterize the role played by the alcohol hydrogen-bonding network in the adsorption process. Beyond simple selectivity, vapour sorption isotherms measured for various compositions help to completely unravel at the molecular level the step by step adsorption mechanism of the binary system in the nanoporous solid, from the first monolayers to the complete liquid condensation.
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Affiliation(s)
- Sujeet Dutta
- Institut de Physique de Rennes, University of Rennes 1, 263 Avenue du Général Leclerc, 35042 Rennes, France.
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Schmitz R, Müller N, Ullmann S, Vogel M. A molecular dynamics simulations study on ethylene glycol-water mixtures in mesoporous silica. J Chem Phys 2016; 145:104703. [DOI: 10.1063/1.4962240] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Rebecca Schmitz
- Institut für Festkörperphysik, Technische Universität Darmstadt, 64289 Darmstadt, Germany
| | - Niels Müller
- Institut für Festkörperphysik, Technische Universität Darmstadt, 64289 Darmstadt, Germany
| | - Svenja Ullmann
- Institut für Festkörperphysik, Technische Universität Darmstadt, 64289 Darmstadt, Germany
| | - Michael Vogel
- Institut für Festkörperphysik, Technische Universität Darmstadt, 64289 Darmstadt, Germany
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Elamin K, Jansson H, Swenson J. Dynamics of aqueous binary glass-formers confined in MCM-41. Phys Chem Chem Phys 2015; 17:12978-87. [PMID: 25913915 DOI: 10.1039/c5cp00751h] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Dielectric permittivity measurements were performed on water solutions of propylene glycol (PG) and propylene glycol monomethyl ether (PGME) confined in 21 Å pores of the silica matrix MCM-41 C10 in wide frequency (10(-2)-10(6) Hz) and temperature (130-250 K) ranges. The aim was to elucidate how the formation of large hydrogen bonded structural entities, found in bulk solutions of PGME, was affected by the confined geometry, and to make comparisons with the dynamic behavior of the PG-water system. For all solutions the measurements revealed four almost concentration independent relaxation processes. The intensity of the fastest process is low compared to the other relaxation processes and might be caused by both hydroxyl groups of the pore surfaces and by local motions of water and solute molecules. The second fastest process contains contributions from both the main water relaxation as well as the intrinsic β-relaxation of the solute molecules. The third fastest process is the viscosity related α-relaxation. Its concentration independency is very different compared to the findings for the corresponding bulk systems, particularly for the PGME-water system. The experimental data suggests that the surface interactions induce a micro-phase separation of the two liquids, resulting in a full molecular layer of water molecules coordinating to the hydrophilic hydroxyl groups on the surfaces of the silica pores. This, in turn, increases the geometrical confinement effect for the remaining solution even more and prevents the building up of the same type of larger structural entities in the PGME-water system as in the corresponding bulk solutions. The slowest process is mainly hidden in the high conductivity contribution at low frequencies, but its temperature dependence can be extracted for the PGME-water system. However, its origin is not fully clear, as will be discussed.
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Affiliation(s)
- Khalid Elamin
- Department of Applied Physics, Chalmers University of Technology, SE-412 96 Göteborg, Sweden.
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Swenson J, Elamin K, Chen G, Lohstroh W, Garcia Sakai V. Anomalous dynamics of aqueous solutions of di-propylene glycol methylether confined in MCM-41 by quasielastic neutron scattering. J Chem Phys 2014; 141:214501. [PMID: 25481146 DOI: 10.1063/1.4902250] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The molecular dynamics of solutions of di-propylene glycol methylether (2PGME) and H2O (or D2O) confined in 28 Å pores of MCM-41 have been studied by quasielastic neutron scattering and differential scanning calorimetry over the concentration range 0-90 wt.% water. This system is of particular interest due to its pronounced non-monotonic concentration dependent dynamics of 2PGME in the corresponding bulk system, showing the important role of hydrogen bonding for the dynamics. In this study we have elucidated how this non-monotonic concentration dependence is affected by the confined geometry. The results show that this behaviour is maintained in the confinement, but the slowest diffusive dynamics of 2PGME is now observed at a considerably higher water concentration; at 75 wt.% water in MCM-41 compared to 30 wt.% water in the corresponding bulk system. This difference can be explained by an improper mixing of the two confined liquids. The results suggest that water up to a concentration of about 20 wt.% is used to hydrate the hydrophilic hydroxyl surface groups of the silica pores, and that it is only at higher water contents the water becomes partly mixed with 2PGME. Hence, due to this partial micro-phase separation of the two liquids larger, and thereby slower relaxing, structural entities of hydrogen bonded water and 2PGME molecules can only be formed at higher water contents than in the bulk system. However, the Q-dependence is unchanged with confinement, showing that the nature of the molecular motions is preserved. Thus, there is no indication of localization of the dynamics at length scales of less than 20 Å. The dynamics of both water and 2PGME is strongly dominated by translational diffusion at a temperature of 280 K.
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Affiliation(s)
- Jan Swenson
- Department of Applied Physics, Chalmers University of Technology, SE-412 96 Göteborg, Sweden
| | - Khalid Elamin
- Department of Applied Physics, Chalmers University of Technology, SE-412 96 Göteborg, Sweden
| | - Guo Chen
- Department of Applied Physics, Chalmers University of Technology, SE-412 96 Göteborg, Sweden
| | - Wiebke Lohstroh
- Heinz Maier-Leibnitz Zentrum (MLZ), Technische Universität München, Lichtenbergstr. 1, 85748 Garching, Germany
| | - Victoria Garcia Sakai
- ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot, OX11 0QX Oxfordshire, United Kingdom
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