1
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Silva P, Silva GMC, Morgado P, Fauré MC, Goldmann M, Filipe EJM. Origin of the central pit in hemimicelles of semifluorinated alkanes: How molecular dipoles and substrate deformation can determine supra-molecular morphology. J Colloid Interface Sci 2024; 655:576-583. [PMID: 37956545 DOI: 10.1016/j.jcis.2023.11.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2023] [Revised: 10/26/2023] [Accepted: 11/01/2023] [Indexed: 11/15/2023]
Abstract
HYPOTHESIS Semifluorinated alkanes amphiphiles spontaneously form highly monodispersed hemimicelles at the surface of water. The origin of the formation and complex structure of these surprising supramolecular aggregates were only recently clarified using molecular dynamics simulations (MD). The existence of a pit at the center of these aggregates made up of almost 3000 molecules was indeed reproduced by the MD simulations, but not understood. METHOD A careful strategy of atomistic MD simulations comparing non-electrostatic force fields with force fields that include electrostatic forces, thus bearing an implicit or explicit dipole, allowed demonstrating the roles of dipolar interactions and interactions with the liquid subphase on the morphology of the aggregates. FINDINGS The simulation results clearly show that within the hemimicelles the strong molecular dipoles located at the CH2-CF2 junctions tend to align, leading to a collective shift of the PFAA molecules relatively to each other. This shift is responsible for the curvature of the hemimicelles and originates the central pit, provided the possibility of deforming the surface of the water sub-phase. Comparisons with non-electrostatic force field results further contribute to understand the origin of the self-assembling process. The results directly connect for the first time a molecular property with a mesoscopic structural feature. Given the molecular simplicity of these "primitive" amphiphiles compared to the common hydrophilic/hydrophobic surfactants, the results contribute to understand self-assembly in general.
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Affiliation(s)
- Pedro Silva
- Centro de Química Estrutural, Institute of Molecular Sciences, Departamento de Engenharia Química, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal; Sorbonne Université, Institut des NanoSciences de Paris, CNRS-UMR 7588, 4 place Jussieu, 75005 Paris, France
| | - Gonçalo M C Silva
- Centro de Química Estrutural, Institute of Molecular Sciences, Departamento de Engenharia Química, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal
| | - Pedro Morgado
- Centro de Química Estrutural, Institute of Molecular Sciences, Departamento de Engenharia Química, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal
| | - Marie-Claude Fauré
- Sorbonne Université, Institut des NanoSciences de Paris, CNRS-UMR 7588, 4 place Jussieu, 75005 Paris, France; Université Paris Cité, UFR des Sciences Fondamentales et Biomédicales, 45 Rue de Saints-Pères, 75006 Paris, France
| | - Michel Goldmann
- Sorbonne Université, Institut des NanoSciences de Paris, CNRS-UMR 7588, 4 place Jussieu, 75005 Paris, France; Université Paris Cité, UFR des Sciences Fondamentales et Biomédicales, 45 Rue de Saints-Pères, 75006 Paris, France; Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin BP48, 91192 Gif-Sur-Yvette, France
| | - Eduardo J M Filipe
- Centro de Química Estrutural, Institute of Molecular Sciences, Departamento de Engenharia Química, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal.
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2
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Hrahsheh F, Wilemski G. Effects of molecular size and orientation on the interfacial properties and wetting behavior of water/ n-alkane systems: a molecular-dynamics study. Phys Chem Chem Phys 2023; 25:5808-5816. [PMID: 36744733 DOI: 10.1039/d2cp05735b] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Molecular dynamics simulations (MD) are performed to study the interfacial structure/tension and wetting behavior of water/n-alkane systems (water/nC5 to water/nC16 where nCx = CxH(2x + 2)). In particular, we study complete-to-partial wetting transitions by changing the n-alkane chain length (NC) at a constant temperature, T = 295 K. Simulations are carried out with a united-atom TraPPE model for n-alkanes and the TIP4P-2005 model of water. Simulation results are in excellent agreement with the initial spreading coefficients and contact angles calculated using experimental values of the surface and interfacial tensions. In addition, it has been determined that water/(nC5-nC7) and water/(nC8-nC16), respectively, exhibit complete and partial initial wetting modes. Simulations show that the interfacial structures of water/(nC5-nC7) are different from water/(nC8-nC16) systems. In the latter, water preferentially orients near the interface to increase the number of hydrogen bonds and the charge and mass densities. Moreover, the orientation of n-alkane molecules at water/(nC8-nC16) interfaces has a long-range persistence, resulting in layered structures that increase with NC. In addition, simulation results of the orientational order parameter Sz show alignment behavior of the n-alkane molecules with respect to the interfaces. Simulations predict that the central segments of n-alkane are strongly packed in the interfaces while the end segments (methyl groups) form smaller peaks in the outer edge of the layer. This observation confirms the "horseshoe" or "C-shaped" structure of n-alkane molecules in the water/n-alkane interfaces. At constant temperature, the interface widths of both water and the n-alkanes decrease with increasing n-alkane molecular length. These results suggest that increasing the n-alkane chain length affects the water/n-alkane interfacial properties in a manner similar to that of cooling.
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Affiliation(s)
- Fawaz Hrahsheh
- Higher Colleges of Technology, ETS, MZWC, Abu Dhabi, 58855, United Arab Emirates.
| | - Gerald Wilemski
- Department of Physics, Missouri University of Science and Technology, Rolla, MO 65409, USA.
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3
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Stovbun SV, Skoblin AA, Shilkina NG, Lomakin SM, Zlenko DV. A gel lattice alters the phase state of a solvent. SOFT MATTER 2022; 18:5815-5822. [PMID: 35899804 DOI: 10.1039/d2sm00767c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Some low-molecular-weight substances are able to self-assemble into fiber-like structures (strings) to form gels. One of the examples of such substances is trifluoroacetylated alpha-aminoalcohols (TFAAAs) able to gelate in many organic solvents. Here we report the formation and describe the properties of a layer of an altered solvent covering the strings' surface. The altered solvent layer has a different refractive index and melts at a temperature about several degrees lower than that of the bulk solvent. Moreover, the bulk solvent's melting temperature was also decreased by values far beyond the one expected according to Raoult's law. Based on the Gibbs-Thomson equation it is possible to derive the thickness of the special layer as well as the average gel lattice parameters, which were very stable across the variety of systems investigated.
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Affiliation(s)
- Sergey V Stovbun
- N.N. Semenov Institute of Chemical Physics, RAS, 119334, Kosygina 4/1, Moscow, Russia.
| | - Aleksey A Skoblin
- N.N. Semenov Institute of Chemical Physics, RAS, 119334, Kosygina 4/1, Moscow, Russia.
| | - Natalia G Shilkina
- N.N. Semenov Institute of Chemical Physics, RAS, 119334, Kosygina 4/1, Moscow, Russia.
| | - Sergey M Lomakin
- N.N. Semenov Institute of Chemical Physics, RAS, 119334, Kosygina 4/1, Moscow, Russia.
- N.M. Emanuel Institute of Biochemical Physics, RAS, 119334, Kosygina 4, Moscow, Russia
| | - Dmitry V Zlenko
- N.N. Semenov Institute of Chemical Physics, RAS, 119334, Kosygina 4/1, Moscow, Russia.
- M.V. Lomonosov Moscow State University, Faculty of Biology, 119234, Lenin Hills 1/24, Moscow, Russia
- A.N. Severtson Institute of Ecology and Evolution, 119071, Lenin Avenue, 33, Moscow, Russia
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4
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Bui T, Frampton H, Huang S, Collins IR, Striolo A, Michaelides A. Water/oil interfacial tension reduction - an interfacial entropy driven process. Phys Chem Chem Phys 2021; 23:25075-25085. [PMID: 34738605 DOI: 10.1039/d1cp03971g] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The interfacial tension (IFT) of a fluid-fluid interface plays an important role in a wide range of applications and processes. When low IFT is desired, surface active compounds (e.g. surfactants) can be added to the system. Numerous attempts have been made to relate changes in IFT arising from such compounds to the specific nature of the interface. However, the IFT is controlled by an interplay of factors such as temperature and molecular structure of surface-active compounds, which make it difficult to predict IFT as those conditions change. In this study, we present the results from molecular dynamics simulations revealing the specific role surfactants play in IFT. We find that, in addition to reducing direct contact between the two fluids, surfactants serve to increase the disorder at the interface (related to interfacial entropy) and consequently reduce the water/oil IFT, especially when surfactants are present at high surface density. Our results suggest that surfactants that yield more disordered interfacial films (e.g. with flexible and/or unsaturated tails) reduce the water/oil IFT more effectively than surfactants which yield highly ordered interfacial films. Our results shed light on some of the factors that control IFT and could have important practical implications in industrial applications such as the design of cosmetics, food products, and detergents.
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Affiliation(s)
- Tai Bui
- Thomas Young Centre and London Centre for Nanotechnology, and Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, UK. .,BP Exploration Operating Co. Ltd, Chertsey Road, Sunbury-on-Thames TW16 7LN, UK.,Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK
| | - Harry Frampton
- BP Exploration Operating Co. Ltd, Chertsey Road, Sunbury-on-Thames TW16 7LN, UK
| | - Shanshan Huang
- BP Exploration Operating Co. Ltd, Chertsey Road, Sunbury-on-Thames TW16 7LN, UK
| | - Ian R Collins
- BP Exploration Operating Co. Ltd, Chertsey Road, Sunbury-on-Thames TW16 7LN, UK
| | - Alberto Striolo
- Department of Chemical Engineering, University College London, Gower Street, London WC1E 6BT, UK.,School of Chemical, Biological and Materials Engineering, University of Oklahoma, Norman, OK 73019, USA
| | - Angelos Michaelides
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK
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5
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Neupane P, Wilemski G. Molecular dynamics study of wetting of alkanes on water: from high temperature to the supercooled region and the influence of second inflection points of interfacial tensions. Phys Chem Chem Phys 2021; 23:14465-14476. [PMID: 34184020 DOI: 10.1039/d1cp01108a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
To explore the wetting behavior of alkanes on bulk water interfaces, molecular dynamics (MD) simulations were carried out for united-atom PYS alkane models, and for SPC/E and TIP4P/2005 water models over a wide temperature range. The MD results at each temperature were used to find (1) the surface tension of the alkanes (octane, nonane) and water, and (2) the interfacial tensions of the alkane-water systems. These quantities were then used to calculate the spreading coefficient (S) and contact angle (θc) for each alkane on water. At higher temperatures, the contact angle of octane and nonane on water is found to behave in accord with conventional expectations, i.e., it decreases with increasing temperature for both water models as each system approaches the usual high-temperature transition to perfect wetting. At lower temperatures, we found an unusual temperature dependence of S and θc for each PYS alkane on SPC/E water. In contrast to conventional expectations, θc decreases with a decrease in the temperature. For octane-SPC/E water, this unusual behavior of θc occurs due to the presence of second inflection points (SIP) in the vapor-water and the octane-water interfacial tensions, whereas the SIP effect is much less important for the nonane-water system. The unusual temperature dependence of θc observed for nonane on SPC/E water is also found for nonane on TIP4P/2005 water. On the other hand, such unusual wetting behavior has not been observed in the PYS octane-TIP4P/2005 water system, except possibly for the two lowest temperatures studied.
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Affiliation(s)
- Pauf Neupane
- Department of Physics, Missouri University of Science and Technology, Rolla, MO 65409, USA.
| | - Gerald Wilemski
- Department of Physics, Missouri University of Science and Technology, Rolla, MO 65409, USA.
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6
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Coalescence dynamics in oil-in-water emulsions at elevated temperatures. Sci Rep 2021; 11:10990. [PMID: 34040010 PMCID: PMC8155042 DOI: 10.1038/s41598-021-89919-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Accepted: 04/23/2021] [Indexed: 11/23/2022] Open
Abstract
Emulsion stability in a flow field is an extremely important issue relevant for many daily-life applications such as separation processes, food manufacturing, oil recovery etc. Microfluidic studies can provide micro-scale insight of the emulsion behavior but have primarily focussed on droplet breakup rather than on droplet coalescence. The crucial impact of certain conditions such as increased pressure or elevated temperature frequently used in industrial processes is completely overlooked in such micro-scale studies. In this work, we investigate droplet coalescence in flowing oil-in-water emulsions subjected to higher than room temperatures namely between 20 to 70 \documentclass[12pt]{minimal}
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\begin{document}$$^{\circ }$$\end{document}∘C. We use a specifically designed lab-on-a-chip application for this purpose. Coalescence frequency is observed to increase with increasing temperature. We associate with this observation the change in viscosity at higher temperatures triggering a stronger perturbation in the thin aqueous film separating the droplets. Using the scaling law for rupture time of such a thin film, we establish a mechanism leading to a higher coalescence frequency at elevated temperatures.
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7
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Metya AK, Molinero V. Is Ice Nucleation by Organic Crystals Nonclassical? An Assessment of the Monolayer Hypothesis of Ice Nucleation. J Am Chem Soc 2021; 143:4607-4624. [PMID: 33729789 DOI: 10.1021/jacs.0c12012] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Potent ice nucleating organic crystals display an increase in nucleation efficiency with pressure and memory effect after pressurization that set them apart from inorganic nucleants. These characteristics were proposed to arise from an ordered water monolayer at the organic-water interface. It was interpreted that ordering of the monolayer is the limiting step for ice nucleation on organic crystals, rendering their mechanism of nucleation nonclassical. Despite the importance of organics in atmospheric ice nucleation, that explanation has never been investigated. Here we elucidate the structure of interfacial water and its role in ice nucleation at ambient pressure on phloroglucinol dihydrate, the paradigmatic example of outstanding ice nucleating organic crystal, using molecular simulations. The simulations confirm the existence of an interfacial monolayer that orders on cooling and becomes fully ordered upon ice formation. The monolayer does not resemble any ice face but seamlessly connects the distinct hydrogen-bonding orders of ice and the organic surface. Although large ordered patches develop in the monolayer before ice nucleates, we find that the critical step is the formation of the ice crystallite, indicating that the mechanism is classical. We predict that the fully ordered, crystalline monolayer nucleates ice above -2 °C and could be responsible for the exceptional ice nucleation by the organic crystal at high pressures. The lifetime of the fully ordered monolayer around 0 °C, however, is too short to account for the memory effect reported in the experiments. The latter could arise from an increase in the melting temperature of ice confined by strongly ice-binding surfaces.
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Affiliation(s)
- Atanu K Metya
- Department of Chemistry, The University of Utah, Salt Lake City, Utah 84112-0850, United States
| | - Valeria Molinero
- Department of Chemistry, The University of Utah, Salt Lake City, Utah 84112-0850, United States
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8
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Modak VP, Wyslouzil BE, Singer SJ. Mechanism of surface freezing of alkanes. J Chem Phys 2020; 153:224501. [PMID: 33317286 DOI: 10.1063/5.0031761] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Using molecular dynamics simulation of octane (C8) and nonadecane (C19), we probe the mechanism of n-alkane surface freezing, the appearance of a crystalline monolayer above the liquid at a temperature Tsf above the bulk freezing point Tf. Formation of a crystalline monolayer occurs robustly in these systems. When Tf > Tsf, the surface frozen phase is metastable with respect to the solid but persists for long periods for study in simulations. Surface freezing of both C8 and C19 is driven by significant energy-lowering when alkane chains become ordered along the surface normal, and we elucidate the origins of this phenomenon. The degree of configurational disorder in the surface frozen layer relative to the solid is much larger for C8 compared to C19. From the Gibbsian viewpoint, we extract the excess energy and entropy of the liquid and surface frozen phases. We also consider the surface frozen layer as an intervening third phase, the viewpoint taken in previous theoretical analyses. Here, we find significantly increased entropy of the surface frozen phase of C8 associated with configurational disorder, while the energy and entropy of the surface frozen phase of C19 are marginally different from the bulk solid. Finally, by combining our previously determined solid-vapor surface free energies of C8 and C19 with liquid-vapor surface tensions from this work, we eliminate wetting as a possible mechanism for C8 surface freezing, but it remains a possibility for C19. We analyze the molecular structure of the liquid, surface frozen, and solid surfaces and discuss its relevance to thermodynamic properties.
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Affiliation(s)
- Viraj P Modak
- William G. Lowrie Department of Chemical and Biomolecular Engineering, Columbus, Ohio 43210, USA
| | - Barbara E Wyslouzil
- William G. Lowrie Department of Chemical and Biomolecular Engineering, Columbus, Ohio 43210, USA
| | - Sherwin J Singer
- Department of Chemistry and Biochemistry, Columbus, Ohio 43210, USA
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9
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Naullage PM, Metya AK, Molinero V. Computationally efficient approach for the identification of ice-binding surfaces and how they bind ice. J Chem Phys 2020; 153:174106. [DOI: 10.1063/5.0021631] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Pavithra M. Naullage
- Department of Chemistry, The University of Utah, Salt Lake City, Utah 84112-0850, USA
| | - Atanu K. Metya
- Department of Chemistry, The University of Utah, Salt Lake City, Utah 84112-0850, USA
| | - Valeria Molinero
- Department of Chemistry, The University of Utah, Salt Lake City, Utah 84112-0850, USA
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10
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Xu D, Lu Y, Luo C. Pathway of orientational symmetry breaking in crystallization of short n-alkane droplets: A molecular dynamics study. J Chem Phys 2020; 153:084903. [PMID: 32872849 DOI: 10.1063/5.0016350] [Citation(s) in RCA: 2] [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 carry out molecular dynamics simulations by using an all-atom model to study the nucleation and crystallization of n-alkane droplets under three-dimensional and quasi-two-dimensional conditions. We focus on the development of orientational order of chains from a random state to a neatly ordered one. Two new methods, the map of symmetry breaking and the information entropy of chain orientations, are introduced to characterize the emerge and remelting phenomena of a primary nucleus at the early stage of crystallization. Stepwise nucleation, as well as the surface induced nucleation, of large droplets is observed. We elucidate the kinetic process of the formation of a primary nucleus and the rearrangement of every single molecule involved in a primary nucleus. We found that density fluctuation and orientational preordering are coupled together and occur simultaneously in nucleation. Our results show the pathway of orientational symmetry breaking in the crystallization of n-alkane droplets that are heuristic for the deeper understanding of the crystallization in more complex molecules such as polymers.
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Affiliation(s)
- Dan Xu
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, People's Republic of China
| | - Yuyuan Lu
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, People's Republic of China
| | - Chuanfu Luo
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, People's Republic of China
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11
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Shamloo A, Rodrigue D, Soldera A. Melting of alkane nanocrystals: towards a representation of polyethylene. MOLECULAR SIMULATION 2020. [DOI: 10.1080/08927022.2020.1797020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- Azar Shamloo
- Laboratory of Physical Chemistry of Matters, Department of chemistry, Université de Sherbrooke, Sherbrooke, Canada
| | - Denis Rodrigue
- Department of chemical engineering, Université Laval, Quebec City, Canada
| | - Armand Soldera
- Laboratory of Physical Chemistry of Matters, Department of chemistry, Université de Sherbrooke, Sherbrooke, Canada
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12
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Cafolla C, Voïtchovsky K. Impact of water on the lubricating properties of hexadecane at the nanoscale. NANOSCALE 2020; 12:14504-14513. [PMID: 32613214 DOI: 10.1039/d0nr03642k] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Fluid lubricants are routinely used to reduce friction in a wide range of applications, from car engines to machinery and hard-disk drives. However, their efficiency can be significantly influenced by the ambient conditions they are exposed to, in particular humidity. Our understanding of the molecular mechanisms responsible for the well-documented impact of water on lubrication remains limited, hindering the improvement of tribological formulations. Here, we use Atomic Force Microscopy (AFM) and shear force spectroscopy to investigate the structural and dynamical behaviour of a model lubricant, hexadecane, confined between an AFM probe and a hydrophilic mica surface at different temperatures and humidities. We show that both the nanoscale structure and the tribological behaviour of the system are dominated by the nucleation of water nanodroplets at the interface. The process is favoured at higher temperature and can be explained with classical nucleation theory whereby the droplets become stable when larger than 20 nm to 50 nm size, depending on the ambient conditions. Below this threshold, a molecularly thin film of water molecules coats the surface uniformly. Highly localised shear measurements demonstrate a detrimental impact of the nanodroplets on shear with a twofold increase in the lubricated friction force. However, this can be mitigated by the adjunction of an amphiphilic additive, here oleic acid.
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Perez Sirkin YA, Gadea ED, Scherlis DA, Molinero V. Mechanisms of Nucleation and Stationary States of Electrochemically Generated Nanobubbles. J Am Chem Soc 2019; 141:10801-10811. [DOI: 10.1021/jacs.9b04479] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Yamila A. Perez Sirkin
- Department of Chemistry, The University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112-0850, United States
- Departamento de Química Inorgánica, Analítica y Química Física/INQUIMAE, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pab. II, Buenos Aires C1428EHA, Argentina
| | - Esteban D. Gadea
- Departamento de Química Inorgánica, Analítica y Química Física/INQUIMAE, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pab. II, Buenos Aires C1428EHA, Argentina
| | - Damian A. Scherlis
- Departamento de Química Inorgánica, Analítica y Química Física/INQUIMAE, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pab. II, Buenos Aires C1428EHA, Argentina
| | - Valeria Molinero
- Department of Chemistry, The University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112-0850, United States
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14
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Naullage P, Bertolazzo AA, Molinero V. How Do Surfactants Control the Agglomeration of Clathrate Hydrates? ACS CENTRAL SCIENCE 2019; 5:428-439. [PMID: 30937370 PMCID: PMC6439454 DOI: 10.1021/acscentsci.8b00755] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Indexed: 05/14/2023]
Abstract
Clathrate hydrates can spontaneously form under typical conditions found in oil and gas pipelines. The agglomeration of clathrates into large solid masses plugs the pipelines, posing adverse safety, economic, and environmental threats. Surfactants are customarily used to prevent the aggregation of clathrate particles and their coalescence with water droplets. It is generally assumed that a large contact angle between the surfactant-covered clathrate and water is a key predictor of the antiagglomerant performance of the surfactant. Here we use molecular dynamic simulations to investigate the structure and dynamics of surfactant films at the clathrate-oil interface, and their impact on the contact angle and coalescence between water droplets and hydrate particles. In agreement with the experiments, the simulations predict that surfactant-covered clathrate-oil interfaces are oil wet but super-hydrophobic to water. Although the water contact angle determines the driving force for coalescence, we find that a large contact angle is not sufficient to predict good antiagglomerant performance of a surfactant. We conclude that the length of the surfactant molecules, the density of the interfacial film, and the strength of binding of its molecules to the clathrate surface are the main factors in preventing the coalescence and agglomeration of clathrate particles with water droplets in oil. Our analysis provides a molecular foundation to guide the molecular design of effective clathrate antiagglomerants.
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Affiliation(s)
- Pavithra
M. Naullage
- Department
of Chemistry, The University of Utah, Salt Lake City, Utah 84112-0850, United States
| | - Andressa A. Bertolazzo
- Department
of Chemistry, The University of Utah, Salt Lake City, Utah 84112-0850, United States
- Departamento
de Ciências Exatas e Educação, Universidade Federal de Santa Catarina, Blumenau, Santa Catarina, Brazil
| | - Valeria Molinero
- Department
of Chemistry, The University of Utah, Salt Lake City, Utah 84112-0850, United States
- E-mail:
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15
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Park Y, Wyslouzil BE. CO 2 condensation onto alkanes: unconventional cases of heterogeneous nucleation. Phys Chem Chem Phys 2019; 21:8295-8313. [PMID: 30946401 DOI: 10.1039/c9cp00967a] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The classical picture invoked for heterogeneous nucleation is frequently that of a liquid condensing onto an immiscible solid particle. Here, we examine heterogeneous nucleation of CO2 onto particles comprised of n-pentane or n-hexane under conditions where CO2 should be a solid and the seed particles may be liquid or solid. Although CO2 condensed under all but one of the six conditions investigated, these experiments do not easily fit into the framework of standard heterogeneous nucleation experiments. Rather they explore unconventional regimes of heterogeneous nucleation in which the state of the seed particle may both affect whether deposition can proceed, and, in turn, be influenced by the presence of the condensing species. The work complements the earlier work of Tanimura et al. [RSC Adv., 2015, 5, 105537-105550] that investigated CO2 condensation onto ice nanoparticles, by using seed particles comprised of non-polar compounds that form and freeze under conditions where CO2 is already supersaturated with respect to the solid ice. In some cases, the conditions for seed formation approach the limit of homogeneous CO2 nucleation. Vibrational spectroscopy measurements help pinpoint where CO2 starts to condense. Furthermore, these IR measurements suggest that the n-alkanes never freeze in the presence of CO2, even if the temperatures are well below those required for them to freeze when CO2 is absent. Over the temperature range 65 < T/K < 140, the conditions corresponding to the onset of CO2 heterogeneous nucleation on pre-existing seed particle almost all lie very close to the extrapolated vapor-liquid equilibrium line of CO2 for a broad range of seed materials.
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Affiliation(s)
- Yensil Park
- William G. Lowrie Department of Chemical and Biomolecular Engineering, Ohio State University, Columbus, Ohio 43210, USA.
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16
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Huang H, Yarmush ML, Usta OB. Long-term deep-supercooling of large-volume water and red cell suspensions via surface sealing with immiscible liquids. Nat Commun 2018; 9:3201. [PMID: 30097570 PMCID: PMC6086840 DOI: 10.1038/s41467-018-05636-0] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Accepted: 07/17/2018] [Indexed: 11/12/2022] Open
Abstract
Supercooling of aqueous solutions is a fundamentally and practically important physical phenomenon with numerous applications in biopreservation and beyond. Under normal conditions, heterogeneous nucleation mechanisms critically prohibit the simultaneous long-term (> 1 week), large volume (> 1 ml), and low temperatures (< -10 °C) supercooling of aqueous solutions. Here, we report on the use of surface sealing of water by an oil phase to significantly diminish the primary heterogeneous nucleation at the water/air interface. We achieve deep supercooling (down to -20 °C) of large volumes of water (up to 100 ml) for long periods (up to 100 days) simultaneously via this approach. Since oils are mixtures of various hydrocarbons we also report on the use of pure alkanes and primary alcohols of various lengths to achieve the same. Furthermore, we demonstrate the utility of deep supercooling via preliminary studies on extended (100 days) preservation of human red blood cells.
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Affiliation(s)
- Haishui Huang
- Center for Engineering in Medicine, Massachusetts General Hospital, Harvard Medical School and Shriners Hospitals for Children, Boston, Massachusetts, 02114, United States
| | - Martin L Yarmush
- Center for Engineering in Medicine, Massachusetts General Hospital, Harvard Medical School and Shriners Hospitals for Children, Boston, Massachusetts, 02114, United States.
- Department of Biomedical Engineering, Rutgers University, Piscataway, New Jersey, 08854, United States.
| | - O Berk Usta
- Center for Engineering in Medicine, Massachusetts General Hospital, Harvard Medical School and Shriners Hospitals for Children, Boston, Massachusetts, 02114, United States.
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17
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Abstract
This special issue discusses recent advances in computer simulation studies of crystal growth. Crystal growth is a key to innovation in science and technology. Owing to recent progress in computer performance, computer simulation studies of crystal growth have become increasingly important. This special issue covers a variety of simulation methods, including the Monte Carlo, molecular dynamics, first-principles, multiscale, and continuum simulation methods, which are used for studies on the fundamentals and applications of crystal growth and related phenomena for different materials, such as hard-sphere systems, ice, organic crystals, semiconductors, and graphene.
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18
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Hudait A, Odendahl N, Qiu Y, Paesani F, Molinero V. Ice-Nucleating and Antifreeze Proteins Recognize Ice through a Diversity of Anchored Clathrate and Ice-like Motifs. J Am Chem Soc 2018; 140:4905-4912. [PMID: 29564892 DOI: 10.1021/jacs.8b01246] [Citation(s) in RCA: 90] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Cold-adapted organisms produce antifreeze and ice-nucleating proteins to prevent and promote ice formation. The crystal structure of hyperactive bacterial antifreeze protein (AFP) MpAFP suggests that this protein binds ice through an anchored clathrate motif. It is not known whether other hyperactive AFPs and ice-nucleating proteins (INPs) use the same motif to recognize or nucleate ice. Here we use molecular simulations to elucidate the ice-binding motifs of hyperactive insect AFPs and a model INP of Pseudomonas syringae. We find that insect AFPs recognize ice through anchored clathrate motifs distinct from that of MpAFP. By performing simulations of ice nucleation by PsINP, we identify two distinct ice-binding sites on opposite sides of the β-helix. The ice-nucleating sequences identified in the simulations agree with those previously proposed for the closely related INP of Pseudomonas borealis based on the structure of the protein. The simulations indicate that these sites have comparable ice-nucleating efficiency, but distinct binding motifs, controlled by the amino acid sequence: one is an anchored clathrate and the other ice-like. We conclude that anchored clathrate and ice-like motifs can be equally effective for binding proteins to ice and promoting ice nucleation.
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Affiliation(s)
- Arpa Hudait
- Department of Chemistry , 315 South 1400 East , The University of Utah , Salt Lake City , Utah 84112-0580 , United States
| | - Nathan Odendahl
- Department of Chemistry , 315 South 1400 East , The University of Utah , Salt Lake City , Utah 84112-0580 , United States
| | - Yuqing Qiu
- Department of Chemistry , 315 South 1400 East , The University of Utah , Salt Lake City , Utah 84112-0580 , United States
| | - Francesco Paesani
- Department of Chemistry and Biochemistry , University of California, San Diego , 9500 Gilman Drive , La Jolla , California 92093 , United States
| | - Valeria Molinero
- Department of Chemistry , 315 South 1400 East , The University of Utah , Salt Lake City , Utah 84112-0580 , United States
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19
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Fitzner M, Sosso GC, Pietrucci F, Pipolo S, Michaelides A. Pre-critical fluctuations and what they disclose about heterogeneous crystal nucleation. Nat Commun 2017; 8:2257. [PMID: 29273707 PMCID: PMC5741629 DOI: 10.1038/s41467-017-02300-x] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2017] [Accepted: 11/17/2017] [Indexed: 11/29/2022] Open
Abstract
Heterogeneous crystal nucleation is ubiquitous in nature and at the heart of many industrial applications. At the molecular scale, however, major gaps in understanding this phenomenon persist. Here we investigate through molecular dynamics simulations how the formation of precritical crystalline clusters is connected to the kinetics of nucleation. Considering heterogeneous water freezing as a prototypical scenario of practical relevance, we find that precritical fluctuations connote which crystalline polymorph will form. The emergence of metastable phases can thus be promoted by templating crystal faces characteristic of specific polymorphs. As a consequence, heterogeneous classical nucleation theory cannot describe our simulation results, because the different substrates lead to the formation of different ice polytypes. We discuss how the issue of polymorphism needs to be incorporated into analysis and comparison of heterogeneous and homogeneous nucleation. Our results will help to interpret and analyze the growing number of experiments and simulations dealing with crystal polymorph selection.
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Affiliation(s)
- Martin Fitzner
- Thomas Young Centre, London Centre for Nanotechnology and Department of Physics and Astronomy, University College London, Gower Street London, London, WC1E 6BT, UK
| | - Gabriele C Sosso
- Department of Chemistry and Centre for Scientific Computing, University of Warwick, Gibbet Hill Road, Coventry, CV4 7AL, UK
| | - Fabio Pietrucci
- Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, CNRS UMR 7590, IRD UMR 206, MNHN, Sorbonne Universités-Université Pierre et Marie Curie Paris 6, F-75005, Paris, France
| | - Silvio Pipolo
- Université de Lille, CNRS, Centrale Lille, ENSCL, Université d' Artois UMR 8181- UCCS Unité de Catalyse et Chimie du Solide, F-59000, Lille, France
| | - Angelos Michaelides
- Thomas Young Centre, London Centre for Nanotechnology and Department of Physics and Astronomy, University College London, Gower Street London, London, WC1E 6BT, UK.
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20
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Fitzner M, Joly L, Ma M, Sosso GC, Zen A, Michaelides A. Communication: Truncated non-bonded potentials can yield unphysical behavior in molecular dynamics simulations of interfaces. J Chem Phys 2017; 147:121102. [DOI: 10.1063/1.4997698] [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
Affiliation(s)
- Martin Fitzner
- Thomas Young Centre, London Centre for Nanotechnology and Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - Laurent Joly
- Univ. Lyon, Université Claude Bernard Lyon 1, CNRS, Institut Lumière Matière, F-69622 Villeurbanne,
France
| | - Ming Ma
- Department of Mechanical Engineering, State Key Laboratory of Tribology and Center for Nano and Micro Mechanics, Tsinghua University, Beijing 100084, China
| | - Gabriele C. Sosso
- Department of Chemistry and Centre for Scientific Computing, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL,
United Kingdom
| | - Andrea Zen
- Thomas Young Centre, London Centre for Nanotechnology and Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - Angelos Michaelides
- Thomas Young Centre, London Centre for Nanotechnology and Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom
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21
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Lupi L, Hanscam R, Qiu Y, Molinero V. Reaction Coordinate for Ice Crystallization on a Soft Surface. J Phys Chem Lett 2017; 8:4201-4205. [PMID: 28823159 DOI: 10.1021/acs.jpclett.7b01855] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The control of assembly and crystallization of molecules is becoming increasingly important in chemistry, engineering, and materials sciences. Crystallization is also central to understand natural processes that include the formation of atmospheric ice and biomineralization. Organic surfaces, biomolecules, and even liquid/vapor interfaces can promote the nucleation of crystals. These soft surfaces present significant structural fluctuations, which have been shown to strongly impact the rate of crystallization. This raises the question of whether degrees of freedom of soft surfaces play a role in the reaction coordinate for crystal nucleation. Here we use molecular simulations to investigate the mechanism of ice nucleation promoted by an alcohol monolayer. Our analysis indicates that while the flexibility of the surface strongly depresses its ice nucleation ability, it does not play a role in the coordinate that controls the transformation from liquid to ice. We find that the variable that drives the transformation is the size of the crystalline cluster, the same as that for the homogeneous crystallization. We argue that this is a general result that arises from the separation of time scales between surface fluctuations and the crossing of the transition state barrier for crystallization.
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Affiliation(s)
- Laura Lupi
- Department of Chemistry, The University of Utah , 315 South 1400 East, Salt Lake City, Utah 84112-0850, United States
| | - Rebecca Hanscam
- Department of Chemistry, The University of Utah , 315 South 1400 East, Salt Lake City, Utah 84112-0850, United States
| | - Yuqing Qiu
- Department of Chemistry, The University of Utah , 315 South 1400 East, Salt Lake City, Utah 84112-0850, United States
| | - Valeria Molinero
- Department of Chemistry, The University of Utah , 315 South 1400 East, Salt Lake City, Utah 84112-0850, United States
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22
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Haji-Akbari A, Debenedetti PG. Perspective: Surface freezing in water: A nexus of experiments and simulations. J Chem Phys 2017; 147:060901. [DOI: 10.1063/1.4985879] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Affiliation(s)
- Amir Haji-Akbari
- Department of Chemical and Environmental Engineering, Yale University, New Haven, Connecticut 06520, USA
| | - Pablo G. Debenedetti
- Department of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey 08540, USA
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23
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Gyawali G, Sternfield S, Kumar R, Rick SW. Coarse-Grained Models of Aqueous and Pure Liquid Alkanes. J Chem Theory Comput 2017. [DOI: 10.1021/acs.jctc.7b00389] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Gaurav Gyawali
- Department of Chemistry, University of New Orleans, New Orleans, Louisiana 70148, United States
| | - Samuel Sternfield
- Department of Chemistry, University of New Orleans, New Orleans, Louisiana 70148, United States
| | - Revati Kumar
- Department
of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70808, United States
| | - Steven W. Rick
- Department of Chemistry, University of New Orleans, New Orleans, Louisiana 70148, United States
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