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Krott LB, Puccinelli T, Bordin JR. Core-softened colloid under extreme geometrical confinement. SOFT MATTER 2024; 20:4681-4691. [PMID: 38739368 DOI: 10.1039/d4sm00339j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2024]
Abstract
Geometrical constraints offer a promising strategy for assembling colloidal crystal structures that are not typically observed in bulk or under 2D conditions. Core-softened colloids, in particular, have emerged as versatile chemical building blocks with applications across various scientific and technological areas. In this study, we investigate the behavior of a core-softened model confined between two parallel walls. Employing molecular dynamics simulations, we analyze the system's response under extreme confinement, where only one or two layers of colloids are permitted. The system comprises particles modeled by a ramp-like potential confined within slit nanoslits created by two flat, purely repulsive walls with a lateral side L separated by a distance Lz. Through a systematic analysis of the phase behavior as Lz increases, or as the system undergoes decompression, for different values of L, we identified a mono-to-bilayer transition associated with changes in the colloidal structure. In the monolayer regime, we observed solid phases at lower densities than those observed in the 2D case. Importantly, we demonstrated that confinement at specific Lz values, allowing particle arrangement into two layers, can lead to the emergence of the square phase, which was not observed under monolayer or 2D conditions. By correlating thermodynamic, translational, and orientational ordering, as well as the dynamics of this confined colloidal system, our findings offer valuable insights into the utilization of geometrical constraints to induce and manipulate structural changes.
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Affiliation(s)
- Leandro B Krott
- Centro de Ciências, Tecnologias e Saúde, Campus Araranguá, Universidade Federal de Santa Catarina. Rua Pedro João Pereira, 150, CEP 88905120, Araranguá, SC, Brazil.
| | - Thiago Puccinelli
- Departamento de Física, Instituto de Física e Matemática, Universidade Federal de Pelotas. Caixa Postal 354, CEP 96001-970, Pelotas, RS, Brazil.
| | - José Rafael Bordin
- Departamento de Física, Instituto de Física e Matemática, Universidade Federal de Pelotas. Caixa Postal 354, CEP 96001-970, Pelotas, RS, Brazil.
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2
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Medos G, Urbic T. Computer simulations and integral equation study of a two length scale core-softened fluid. J Mol Liq 2022; 345:116982. [PMID: 37727780 PMCID: PMC10508876 DOI: 10.1016/j.molliq.2021.116982] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Monte Carlo simulations, molecular dynamics and integral equation theory were used to study the thermodynamics and structure of particles interacting through the core softened interaction. Core-softened disks have two length scales of interaction, a hard core with one diameter and a soft corona with a larger diameter. We checked the possibility that a fluid with a core-softened potential reproduces anomalies of liquid water and attempted to determine the critical points which we did not observe nor with computer simulations nor with integral equations. We showed that some versions of the integral equation theory completely fail to predict structure and thermodynamics of such system, while others predict it quite well depending on the position in phase space.
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Affiliation(s)
- Gregor Medos
- Faculty of Chemistry and Chemical Technology, University of Ljubljana, Vecna pot 113, Ljubljana SI-1000, Slovenia
| | - Tomaz Urbic
- Faculty of Chemistry and Chemical Technology, University of Ljubljana, Vecna pot 113, Ljubljana SI-1000, Slovenia
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3
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Leoni F, Calero C, Franzese G. Nanoconfined Fluids: Uniqueness of Water Compared to Other Liquids. ACS NANO 2021; 15:19864-19876. [PMID: 34807577 PMCID: PMC8717635 DOI: 10.1021/acsnano.1c07381] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Accepted: 11/18/2021] [Indexed: 05/27/2023]
Abstract
Nanoconfinement can drastically change the behavior of liquids, puzzling us with counterintuitive properties. It is relevant in applications, including decontamination and crystallization control. However, it still lacks a systematic analysis for fluids with different bulk properties. Here we address this gap. We compare, by molecular dynamics simulations, three different liquids in a graphene slit pore: (1) A simple fluid, such as argon, described by a Lennard-Jones potential; (2) an anomalous fluid, such as a liquid metal, modeled with an isotropic core-softened potential; and (3) water, the prototypical anomalous liquid, with directional HBs. We study how the slit-pore width affects the structure, thermodynamics, and dynamics of the fluids. All the fluids show similar oscillating properties by changing the pore size. However, their free-energy minima are quite different in nature: (i) are energy-driven for the simple liquid; (ii) are entropy-driven for the isotropic core-softened potential; and (iii) have a changing nature for water. Indeed, for water, the monolayer minimum is entropy driven, at variance with the simple liquid, while the bilayer minimum is energy driven, at variance with the other anomalous liquid. Also, water has a large increase in diffusion for subnm slit pores, becoming faster than bulk. Instead, the other two fluids have diffusion oscillations much smaller than water, slowing down for decreasing slit-pore width. Our results, clarifying that water confined at the subnm scale behaves differently from other (simple or anomalous) fluids under similar confinement, are possibly relevant in nanopores applications, for example, in water purification from contaminants.
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Affiliation(s)
- Fabio Leoni
- Department
of Physics, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185 Rome, Italy
| | - Carles Calero
- Secció
de Física Estadística i Interdisciplinària-Departament
de Física de la Matèria Condensada, Institut de Nanociència i Nanotecnologia (IN2UB), Universitat
de Barcelona, Carrer Martí i Franquès 1, 08028 Barcelona, Spain
| | - Giancarlo Franzese
- Secció
de Física Estadística i Interdisciplinària-Departament
de Física de la Matèria Condensada, Institut de Nanociència i Nanotecnologia (IN2UB), Universitat
de Barcelona, Carrer Martí i Franquès 1, 08028 Barcelona, Spain
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Hernandes VF, Marques MS, Bordin JR. Phase classification using neural networks: application to supercooled, polymorphic core-softened mixtures. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 34:024002. [PMID: 34638114 DOI: 10.1088/1361-648x/ac2f0f] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Accepted: 10/12/2021] [Indexed: 06/13/2023]
Abstract
Characterization of phases of soft matter systems is a challenge faced in many physical chemical problems. For polymorphic fluids it is an even greater challenge. Specifically, glass forming fluids, as water, can have, besides solid polymorphism, more than one liquid and glassy phases, and even a liquid-liquid critical point. In this sense, we apply a neural network algorithm to analyze the phase behavior of a mixture of core-softened fluids that interact through the continuous-shouldered well (CSW) potential, which have liquid polymorphism and liquid-liquid critical points, similar to water. We also apply the neural network to mixtures of CSW fluids and core-softened alcohols models. We combine and expand methods based on bond-orientational order parameters to study mixtures, applied to mixtures of hardcore fluids and to supercooled water, to include longer range coordination shells. With this, the trained neural network was able to properly predict the crystalline solid phases, the fluid phases and the amorphous phase for the pure CSW and CSW-alcohols mixtures with high efficiency. More than this, information about the phase populations, obtained from the network approach, can help verify if the phase transition is continuous or discontinuous, and also to interpret how the metastable amorphous region spreads along the stable high density fluid phase. These findings help to understand the behavior of supercooled polymorphic fluids and extend the comprehension of how amphiphilic solutes affect the phases behavior.
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Affiliation(s)
- V F Hernandes
- Programa de Pós-Graduação em Física, Departamento de Física, Instituto de Física e Matemática, Universidade Federal de Pelotas, Caixa Postal 354, 96001-970, Pelotas-RS, Brazil
| | - M S Marques
- Centro das Ciências Exatas e das Tecnologias, Universidade Federal do Oeste da Bahia Rua Bertioga, 892, Morada Nobre, CEP 47810-059, Barreiras-BA, Brazil
| | - José Rafael Bordin
- Departamento de Física, Instituto de Física e Matemática, Universidade Federal de Pelotas, Caixa Postal 354, 96001-970, Pelotas-RS, Brazil
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Tsiok EN, Fomin YD, Gaiduk EA, Ryzhov VN. Structural transition in two-dimensional Hertzian spheres in the presence of random pinning. Phys Rev E 2021; 103:062612. [PMID: 34271643 DOI: 10.1103/physreve.103.062612] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Accepted: 06/03/2021] [Indexed: 11/07/2022]
Abstract
Using molecular dynamics simulation we have investigated the influence of random pinning on the phase diagram and melting scenarios of a two-dimensional system with the Hertz potential for α=5/2. It has been shown that random pinning can cardinally change the mechanism of first-order transition between the different crystalline phases (triangular and square) by virtue of generating hexatic and tetratic phases: a triangular crystal to hexatic transition is of the continuous Berezinskii-Kosterlitz-Thouless (BKT) type, a hexatic to tetratic transition is of first order, and finally, there is a continuous BKT-type transition from tetratic to the square crystal.
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Affiliation(s)
- E N Tsiok
- Institute of High Pressure Physics RAS, Kaluzhskoe shosse, 14, Troitsk, 108840 Moscow, Russia
| | - Yu D Fomin
- Institute of High Pressure Physics RAS, Kaluzhskoe shosse, 14, Troitsk, 108840 Moscow, Russia
| | - E A Gaiduk
- Institute of High Pressure Physics RAS, Kaluzhskoe shosse, 14, Troitsk, 108840 Moscow, Russia
| | - V N Ryzhov
- Institute of High Pressure Physics RAS, Kaluzhskoe shosse, 14, Troitsk, 108840 Moscow, Russia
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Nogueira TPO, Frota HO, Piazza F, Bordin JR. Tracer diffusion in crowded solutions of sticky polymers. Phys Rev E 2020; 102:032618. [PMID: 33075900 DOI: 10.1103/physreve.102.032618] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Accepted: 09/14/2020] [Indexed: 06/11/2023]
Abstract
Macromolecular diffusion in strongly confined geometries and crowded environments is still to a large extent an open subject in soft matter physics and biology. In this paper, we employ large-scale Langevin dynamics simulations to investigate how the diffusion of a tracer is influenced by the combined action of excluded-volume and weak attractive crowder-tracer interactions. We consider two species of tracers, standard hard-core particles described by the Weeks-Chandler-Andersen (WCA) repulsive potential and core-softened (CS) particles, which model, e.g., globular proteins, charged colloids, and nanoparticles covered by polymeric brushes. These systems are characterized by the presence of two length scales in the interaction and can show waterlike anomalies in their diffusion, stemming from the inherent competition between different length scales. Here we report a comprehensive study of both diffusion and structure of these two tracer species in an environment crowded by quenched configurations of polymers at increasing density. We analyze in detail how the tracer-polymer affinity and the system density affect transport as compared to the emergence of specific static spatial correlations. In particular, we find that, while hardly any differences emerge in the diffusion properties of WCA and CS particles, the propensity to develop structural order for large crowding is strongly frustrated for CS particles. Surprisingly, for large enough affinity for the crowding matrix, the diffusion coefficient of WCA tracers display a nonmonotonic trend as their density is increased when compared to the zero affinity scenario. This waterlike anomaly turns out to be even larger than what observed for CS particle and appears to be rooted in a similar competition between excluded-volume and affinity effects.
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Affiliation(s)
- T P O Nogueira
- Departamento de Física, Instituto de Física e Matemática, Universidade Federal de Pelotas. Caixa Postal 354, 96001-970, Pelotas, Brazil
| | - H O Frota
- Department of Physics, Federal University of Amazonas, 69077-000 Manaus, AM, Brazil
| | - Francesco Piazza
- Université d'Orléans, Centre de Biophysique Moléculaire (CBM), CNRS UPR4301, Rue C. Sadron, 45071 Orléans, France
| | - José Rafael Bordin
- Departamento de Física, Instituto de Física e Matemática, Universidade Federal de Pelotas. Caixa Postal 354, 96001-970, Pelotas, Brazil
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Trejos VM, Gámez F, Torres-Carbajal A, Martínez-Borquez A. Monte Carlo simulations and perturbation theory for highly correlated fluids: The Lennard-Jones core softened potential case. J Mol Liq 2020. [DOI: 10.1016/j.molliq.2019.112201] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Fijan D, Wilson M. The interactions between thermodynamic anomalies. J Chem Phys 2019; 151:024502. [DOI: 10.1063/1.5103242] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Domagoj Fijan
- Physical and Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QZ, United Kingdom
- Institute of Industrial Science, University of Tokyo, 4 Chome-6-1 Komaba, Meguro City, Tokyo 153-8508, Japan
| | - Mark Wilson
- Physical and Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QZ, United Kingdom
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Fomin YD, Gaiduk EA, Tsiok EN, Ryzhov VN. The phase diagram and melting scenarios of two-dimensional Hertzian spheres. Mol Phys 2018. [DOI: 10.1080/00268976.2018.1464676] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- Yu. D. Fomin
- Institute for High Pressure Physics RAS, Moscow, Russia
| | - E. A. Gaiduk
- Institute for High Pressure Physics RAS, Moscow, Russia
| | - E. N. Tsiok
- Institute for High Pressure Physics RAS, Moscow, Russia
| | - V. N. Ryzhov
- Institute for High Pressure Physics RAS, Moscow, Russia
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