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Abstract
Dormancy is an evolutionarily conserved protective mechanism widely observed in nature. A pathological example is found during cancer metastasis, where cancer cells disseminate from the primary tumor, home to secondary organs, and enter a growth-arrested state, which could last for decades. Recent studies have pointed toward the microenvironment being heavily involved in inducing, preserving, or ceasing this dormant state, with a strong focus on identifying specific molecular mechanisms and signaling pathways. Increasing evidence now suggests the existence of an interplay between intracellular as well as extracellular biochemical and mechanical cues in guiding such processes. Despite the inherent complexities associated with dormancy, proliferation, and growth of cancer cells and tumor tissues, viewing these phenomena from a physical perspective allows for a more global description, independent from many details of the systems. Building on the analogies between tissues and fluids and thermodynamic phase separation concepts, we classify a number of proposed mechanisms in terms of a thermodynamic metastability of the tumor with respect to growth. This can be governed by interaction with the microenvironment in the form of adherence (wetting) to a substrate or by mechanical confinement of the surrounding extracellular matrix. By drawing parallels with clinical and experimental data, we advance the notion that the local energy minima, or metastable states, emerging in the tissue droplet growth kinetics can be associated with a dormant state. Despite its simplicity, the provided framework captures several aspects associated with cancer dormancy and tumor growth.
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Ghaffari S, Chan PK, Mehrvar M. Computational analysis of short‐range surface‐directed polymerization‐induced phase separation. CAN J CHEM ENG 2021. [DOI: 10.1002/cjce.23954] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Shima Ghaffari
- Department of Chemical Engineering Ryerson University Toronto Ontario Canada
| | - Philip K. Chan
- Department of Chemical Engineering Ryerson University Toronto Ontario Canada
| | - Mehrab Mehrvar
- Department of Chemical Engineering Ryerson University Toronto Ontario Canada
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Ghaffari S, Chan PK, Mehrvar M. Long-Range Surface-Directed Polymerization-Induced Phase Separation: A Computational Study. Polymers (Basel) 2021; 13:256. [PMID: 33466703 PMCID: PMC7828815 DOI: 10.3390/polym13020256] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Revised: 01/05/2021] [Accepted: 01/08/2021] [Indexed: 11/16/2022] Open
Abstract
The presence of a surface preferably attracting one component of a polymer mixture by the long-range van der Waals surface potential while the mixture undergoes phase separation by spinodal decomposition is called long-range surface-directed spinodal decomposition (SDSD). The morphology achieved under SDSD is an enrichment layer(s) close to the wall surface and a droplet-type structure in the bulk. In the current study of the long-range surface-directed polymerization-induced phase separation, the surface-directed spinodal decomposition of a monomer-solvent mixture undergoing self-condensation polymerization was theoretically simulated. The nonlinear Cahn-Hilliard and Flory-Huggins free energy theories were applied to investigate the phase separation phenomenon. The long-range surface potential led to the formation of a wetting layer on the surface. The thickness of the wetting layer was found proportional to time t*1/5 and surface potential parameter h 1 1/5. A larger diffusion coefficient led to the formation of smaller droplets in the bulk and a thinner depletion layer, while it did not affect the thickness of the enrichment layer close to the wall. A temperature gradient imposed in the same direction of long-range surface potential led to the formation of a stripe morphology near the wall, while imposing it in the opposite direction of surface potential led to the formation of large particles at the high-temperature side, the opposite side of the interacting wall.
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Affiliation(s)
| | - Philip K. Chan
- Department of Chemical Engineering, Ryerson University, 350 Victoria Street, Toronto, ON M5B 2K3, Canada; (S.G.); (M.M.)
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Das P, Jaiswal PK, Puri S. Surface-directed spinodal decomposition on morphologically patterned substrates. Phys Rev E 2020; 102:032801. [PMID: 33076022 DOI: 10.1103/physreve.102.032801] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Accepted: 08/23/2020] [Indexed: 06/11/2023]
Abstract
This paper is the second in a two-part exposition on surface-directed spinodal decomposition (SDSD), i.e., the interplay of kinetics of wetting and phase separation at a surface which is wetted by one of the components of a binary mixture. In our first paper [P. Das, P. K. Jaiswal, and S. Puri, Phys. Rev. E 102, 012803 (2020)2470-004510.1103/PhysRevE.102.012803], we studied SDSD on chemically heterogeneous and physically flat substrates. In this paper, we study SDSD on a chemically homogeneous but morphologically patterned substrate. Such substrates arise in a vast variety of technological applications. Our goal is to provide a theoretical understanding of SDSD in this context. We present detailed numerical results for domain growth both inside and above the grooves in the substrate. The morphological evolution can be understood in terms of the interference of SDSD waves originating from the different surfaces comprising the substrate.
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Affiliation(s)
- Prasenjit Das
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot 76100, Israel
- School of Physical Sciences, Jawaharlal Nehru University, New Delhi 110067, India
| | - Prabhat K Jaiswal
- Department of Physics, Indian Institute of Technology Jodhpur, Karwar 342037, India
| | - Sanjay Puri
- School of Physical Sciences, Jawaharlal Nehru University, New Delhi 110067, India
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5
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Das P, Jaiswal PK, Puri S. Surface-directed spinodal decomposition on chemically patterned substrates. Phys Rev E 2020; 102:012803. [PMID: 32794988 DOI: 10.1103/physreve.102.012803] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Accepted: 06/19/2020] [Indexed: 11/07/2022]
Abstract
Surface-directed spinodal decomposition (SDSD) is the kinetic interplay of phase separation and wetting at a surface. This process is of great scientific and technological importance. In this paper, we report results from a numerical study of SDSD on a chemically patterned substrate. We consider simple surface patterns for our simulations, but most of the results apply for arbitrary patterns. In layers near the surface, we observe a dynamical crossover from a surface-registry regime to a phase-separation regime. We study this crossover using layerwise correlation functions and structure factors and domain length scales.
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Affiliation(s)
- Prasenjit Das
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot 76100, Israel.,School of Physical Sciences, Jawaharlal Nehru University, New Delhi 110067, India
| | - Prabhat K Jaiswal
- Department of Physics, Indian Institute of Technology Jodhpur, Karwar 342037, India
| | - Sanjay Puri
- School of Physical Sciences, Jawaharlal Nehru University, New Delhi 110067, India
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Mukherjee B, Chakrabarti B. Gelation Impairs Phase Separation and Small Molecule Migration in Polymer Mixtures. Polymers (Basel) 2020; 12:E1576. [PMID: 32708547 PMCID: PMC7407309 DOI: 10.3390/polym12071576] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Revised: 07/06/2020] [Accepted: 07/10/2020] [Indexed: 11/16/2022] Open
Abstract
Surface segregation of the low molecular weight component of a polymeric mixture is a ubiquitous phenomenon that leads to degradation of industrial formulations. We report a simultaneous phase separation and surface migration phenomena in oligomer-polymer ( O P ) and oligomer-gel ( O G ) systems following a temperature quench that induces demixing of components. We compute equilibrium and time varying migrant (oligomer) density profiles and wetting layer thickness in these systems using coarse grained molecular dynamics (CGMD) and mesoscale hydrodynamics (MH) simulations. Such multiscale methods quantitatively describe the phenomena over a wide range of length and time scales. We show that surface migration in gel-oligomer systems is significantly reduced on account of network elasticity. Furthermore, the phase separation processes are significantly slowed in gels leading to the modification of the well known Lifshitz-Slyozov-Wagner (LSW) law ℓ ( τ ) ∼ τ 1 / 3 . Our work allows for rational design of polymer/gel-oligomer mixtures with predictable surface segregation characteristics that can be compared against experiments.
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Ghosh S, Mukherjee A, Arroyave R, Douglas JF. Impact of particle arrays on phase separation composition patterns. J Chem Phys 2020; 152:224902. [PMID: 32534548 DOI: 10.1063/5.0007859] [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 examine the symmetry-breaking effect of fixed constellations of particles on the surface-directed spinodal decomposition of binary blends in the presence of particles whose surfaces have a preferential affinity for one of the components. Our phase-field simulations indicate that the phase separation morphology in the presence of particle arrays can be tuned to have a continuous, droplet, lamellar, or hybrid morphology depending on the interparticle spacing, blend composition, and time. In particular, when the interparticle spacing is large compared to the spinodal wavelength, a transient target pattern composed of alternate rings of preferred and non-preferred phases emerges at early times, tending to adopt the symmetry of the particle configuration. We reveal that such target patterns stabilize for certain characteristic length, time, and composition scales characteristic of the pure phase-separating mixture. To illustrate the general range of phenomena exhibited by mixture-particle systems, we simulate the effects of single-particle, multi-particle, and cluster-particle systems having multiple geometrical configurations of the particle characteristic of pattern substrates on phase separation. Our simulations show that tailoring the particle configuration, or substrate pattern configuration, a relative fluid-particle composition should allow the desirable control of the phase separation morphology as in block copolymer materials, but where the scales accessible to this approach of organizing phase-separated fluids usually are significantly larger. Limited experiments confirm the trends observed in our simulations, which should provide some guidance in engineering patterned blend and other mixtures of technological interest.
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Affiliation(s)
- Supriyo Ghosh
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - Arnab Mukherjee
- Center for Hierarchical Materials Design, Northwestern University, Evanston, Illinois 60208, USA
| | - Raymundo Arroyave
- Materials Science and Engineering Department, Texas A&M University, College Station, Texas 77843, USA
| | - Jack F Douglas
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
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Hennessy MG, Münch A, Wagner B. Phase separation in swelling and deswelling hydrogels with a free boundary. Phys Rev E 2020; 101:032501. [PMID: 32289983 DOI: 10.1103/physreve.101.032501] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Accepted: 02/27/2020] [Indexed: 06/11/2023]
Abstract
We present a full kinetic model of a hydrogel that undergoes phase separation during swelling and deswelling. The model accounts for the interfacial energy of coexisting phases, finite strain of the polymer network, and solvent transport across free boundaries. For the geometry of an initially dry layer bonded to a rigid substrate, the model predicts that forcing solvent into the gel at a fixed rate can induce a volume phase transition, which gives rise to coexisting phases with different degrees of swelling, in systems where this cannot occur in the free-swelling case. While a nonzero shear modulus assists in the propagation of the transition front separating these phases in the driven-swelling case, increasing it beyond a critical threshold suppresses its formation. Quenching a swollen hydrogel induces spinodal decomposition, which produces several highly localized, highly swollen phases which coarsen and are then ejected from free boundary. The wealth of dynamic scenarios of this system is discussed using phase-plane analysis and numerical solutions in a one-dimensional setting.
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Affiliation(s)
- Matthew G Hennessy
- Mathematical Institute, University of Oxford, Andrew Wiles Building, Woodstock Road, Oxford OX2 6GG, United Kingdom
| | - Andreas Münch
- Mathematical Institute, University of Oxford, Andrew Wiles Building, Woodstock Road, Oxford OX2 6GG, United Kingdom
| | - Barbara Wagner
- Weierstrass Institute, Mohrenstrasse 39, 10117 Berlin, Germany
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Krishnan R, Jaiswal PK, Puri S. Phase separation in antisymmetric films: a molecular dynamics study. J Chem Phys 2013; 139:174705. [PMID: 24206320 DOI: 10.1063/1.4827882] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We have used molecular dynamics (MD) simulations to study phase-separation kinetics in a binary fluid mixture (AB) confined in an antisymmetric thin film. One surface of the film (located at z = 0) attracts the A-atoms, and the other surface (located at z = D) attracts the B-atoms. We study the kinetic processes which lead to the formation of equilibrium morphologies subsequent to a deep quench below the miscibility gap. In the initial stages, one observes the formation of a layered structure, consisting of an A-rich layer followed by a B-rich layer at z = 0; and an analogous structure at z = D. This multi-layered morphology is time-dependent and propagates into the bulk, though it may break up into a laterally inhomogeneous structure at a later stage. We characterize the evolution morphologies via laterally averaged order parameter profiles; the growth laws for wetting-layer kinetics and layer-wise length scales; and the scaling properties of layer-wise correlation functions.
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Affiliation(s)
- Raishma Krishnan
- School of Physical Sciences, Jawaharlal Nehru University, New Delhi 110067, India
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Jamie EAG, Dullens RPA, Aarts DGAL. Fluid-fluid demixing of off-critical colloid-polymer systems confined between parallel plates. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2012; 24:284120. [PMID: 22739489 DOI: 10.1088/0953-8984/24/28/284120] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We investigate the off-critical demixing of colloid-polymer systems confined between two parallel plates, where the surface potential is short ranged. We study the case where the minority phase completely wets the surfaces. We find that initially the sample separates as in bulk, until the size of the domains becomes sufficiently large such that further growth is restricted by the plate spacing. The behaviour of the droplets is then determined by the wettability of the walls. We furthermore explore a sample where the loss of wetting phase material to the surfaces causes a shift from a morphology associated with an unstable sample, showing spinodal decomposition, to that associated with a metastable sample. This underlines the importance of the rich interplay between the viscosity contrast and the local volume fraction on the observed morphologies.
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Affiliation(s)
- E A G Jamie
- Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QZ, UK
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11
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Jaiswal PK, Puri S, Das SK. Surface-directed spinodal decomposition: a molecular dynamics study. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2012; 85:051137. [PMID: 23004733 DOI: 10.1103/physreve.85.051137] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2012] [Indexed: 06/01/2023]
Abstract
We use molecular dynamics simulations to study surface-directed spinodal decomposition in unstable binary AB fluid mixtures at wetting surfaces. The thickness of the wetting layer R1 grows with time t as a power law (R1∼tθ). We find that hydrodynamic effects result in a crossover of the growth exponent from θ≃1/3 to 1. We also present results for the layerwise correlation functions and domain length scales.
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Affiliation(s)
- Prabhat K Jaiswal
- School of Physical Sciences, Jawaharlal Nehru University, New Delhi 110 067, India
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12
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Jaiswal PK, Binder K, Puri S. Phase separation of binary mixtures in thin films: Effects of an initial concentration gradient across the film. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2012; 85:041602. [PMID: 22680483 DOI: 10.1103/physreve.85.041602] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2011] [Revised: 01/20/2012] [Indexed: 06/01/2023]
Abstract
We study the kinetics of phase separation of a binary (A,B) mixture confined in a thin film of thickness D by numerical simulations of the corresponding Cahn-Hilliard-Cook (CHC) model. The initial state consisted of 50% A:50% B with a concentration gradient across the film, i.e., the average order parameter profile is Ψav(z,t=0)=(2z/D-1)Ψg,0≤z≤D, for various choices of Ψg and D. The equilibrium state (for time t→∞) consists of coexisting A-rich and B-rich domains separated by interfaces oriented perpendicular to the surfaces. However, for sufficiently large Ψg, a (metastable) layered state is formed with a single interface parallel to the surfaces. This phenomenon is explained in terms of a competition between domain growth in the bulk and surface-directed spinodal decomposition (SDSD) that is caused by the gradient. Thus, gradients in the initial state can stabilize thin-film morphologies which are not stable in full equilibrium. This offers interesting possibilities as a method for preparing novel materials.
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Affiliation(s)
- Prabhat K Jaiswal
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudinger Weg 7, D-55099 Mainz, Germany
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13
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Jamie EAG, Dullens RPA, Aarts DGAL. Surface Effects on the Demixing of Colloid–Polymer Systems. J Phys Chem B 2011; 115:13168-74. [DOI: 10.1021/jp207250q] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- E. A. G. Jamie
- Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QZ, United Kingdom
| | - R. P. A. Dullens
- Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QZ, United Kingdom
| | - D. G. A. L. Aarts
- Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QZ, United Kingdom
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14
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Jaiswal PK, Puri S, Das SK. Kinetics of surface enrichment: A molecular dynamics study. J Chem Phys 2010; 133:154901. [DOI: 10.1063/1.3491833] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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15
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Wang CH, Chen P, Lu CYD. Phase separation of thin-film polymer mixtures under in-plane electric fields. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2010; 81:061501. [PMID: 20866419 DOI: 10.1103/physreve.81.061501] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2010] [Indexed: 05/29/2023]
Abstract
Phase-separation dynamics of polymer thin-film mixtures of polystyrene (PS) and poly(methyl methacrylate) (PMMA) are observed while an in-plane electric field is applied, instead of the out-of-plane fields usually employed previously. The phase separation is accompanied by the formation of PS dewetting holes at zero or weak fields. The dewetting velocity at 0.25 μm/min is a few times slower than that seen in regular bilayer dewetting. With the increasing of the field strength, we observe the formation of PS droplets in PMMA matrix, a reversal from zero- or low-field conditions. The PS dewetting holes are also suppressed. At further increased fields, PS droplets quickly penetrate up to the top of the PMMA matrix, leading to smaller and more irregular final PS droplets. This is manifested in the dramatic decrease in the growth exponent of the droplet size L from L∼t1.5 to L∼t0.1. These morphology changes are explained by the electrostatic energy resulted from the PS and PMMA dielectric contrast.
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Affiliation(s)
- Chen-Hung Wang
- Department of Physics and Center for Complex Systems, National Central University, Chungli 320, Taiwan
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16
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Li JL, Yan LT, Xie XM. Phase dynamics and wetting layer formation mechanisms of pattern-directed phase separation in binary polymer mixture films with asymmetry compositions. POLYMER 2009. [DOI: 10.1016/j.polymer.2009.03.014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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17
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Das SK, Horbach J, Binder K. Kinetics of phase separation in thin films: lattice versus continuum models for solid binary mixtures. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2009; 79:021602. [PMID: 19391756 DOI: 10.1103/physreve.79.021602] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2008] [Indexed: 05/27/2023]
Abstract
A description of phase separation kinetics for solid binary (A,B) mixtures in thin film geometry based on the Kawasaki spin-exchange kinetic Ising model is presented in a discrete lattice molecular field formulation. It is shown that the model describes the interplay of wetting layer formation and lateral phase separation, which leads to a characteristic domain size l(t) in the directions parallel to the confining walls that grows according to the Lifshitz-Slyozov t;{13} law with time t after the quench. Near the critical point of the model, the description is shown to be equivalent to the standard treatments based on Ginzburg-Landau models. Unlike the latter, the present treatment is reliable also at temperatures far below criticality, where the correlation length in the bulk is only of the order of a lattice spacing, and steep concentration variations may occur near the walls, invalidating the gradient square approximation. A further merit is that the relation to the interaction parameters in the bulk and at the walls is always transparent, and the correct free energy at low temperatures is consistent with the time evolution by construction.
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Affiliation(s)
- Subir K Das
- Theoretical Sciences Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore 560064, India
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Yan LT, Li J, Zhang F, Xie XM. Surface-Directed Phase Separation via a Two-Step Quench Process in Binary Polymer Mixture Films with Asymmetry Compositions. J Phys Chem B 2008; 112:8499-506. [DOI: 10.1021/jp801648t] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Li-Tang Yan
- Advanced Materials Laboratory, Department of Chemical Engineering, Tsinghua University, Beijing 100084, People’s Republic of China
| | - Jialin Li
- Advanced Materials Laboratory, Department of Chemical Engineering, Tsinghua University, Beijing 100084, People’s Republic of China
| | - Fengbo Zhang
- Advanced Materials Laboratory, Department of Chemical Engineering, Tsinghua University, Beijing 100084, People’s Republic of China
| | - Xu-Ming Xie
- Advanced Materials Laboratory, Department of Chemical Engineering, Tsinghua University, Beijing 100084, People’s Republic of China
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Yan LT, Li J, Xie XM. Three-dimensional numerical simulations of lamellar structure via two-step surface-directed phase separation in polymer blend films. J Chem Phys 2008; 128:224906. [DOI: 10.1063/1.2938370] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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20
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Yan LT, Xie XM. The phase dynamics and wetting layer formation mechanisms in two-step surface-directed spinodal decomposition. J Chem Phys 2008; 128:154702. [DOI: 10.1063/1.2897974] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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21
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Hong S, Zhang X, Zhang R, Wang L, Zhao J, Han CC. Liquid–Liquid Phase Separation and Crystallization in Thin Films of a Polyolefin Blend. Macromolecules 2008. [DOI: 10.1021/ma7025379] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Song Hong
- State Key Laboratory of Polymer Physics and Chemistry, Joint Laboratory of Polymer Science and Materials, Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, CAS, Beijing 100080, China, and Graduate University of Chinese Academy of Sciences, Beijing 100080, China
| | - Xiaohua Zhang
- State Key Laboratory of Polymer Physics and Chemistry, Joint Laboratory of Polymer Science and Materials, Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, CAS, Beijing 100080, China, and Graduate University of Chinese Academy of Sciences, Beijing 100080, China
| | - Ruoyu Zhang
- State Key Laboratory of Polymer Physics and Chemistry, Joint Laboratory of Polymer Science and Materials, Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, CAS, Beijing 100080, China, and Graduate University of Chinese Academy of Sciences, Beijing 100080, China
| | - Li Wang
- State Key Laboratory of Polymer Physics and Chemistry, Joint Laboratory of Polymer Science and Materials, Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, CAS, Beijing 100080, China, and Graduate University of Chinese Academy of Sciences, Beijing 100080, China
| | - Jiang Zhao
- State Key Laboratory of Polymer Physics and Chemistry, Joint Laboratory of Polymer Science and Materials, Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, CAS, Beijing 100080, China, and Graduate University of Chinese Academy of Sciences, Beijing 100080, China
| | - Charles C. Han
- State Key Laboratory of Polymer Physics and Chemistry, Joint Laboratory of Polymer Science and Materials, Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, CAS, Beijing 100080, China, and Graduate University of Chinese Academy of Sciences, Beijing 100080, China
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Yan LT, Xie XM. Lamellar morphology induced by two-step surface-directed spinodal decomposition in binary polymer mixture films. J Chem Phys 2008; 128:034901. [DOI: 10.1063/1.2819676] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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23
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Náraigh LO, Thiffeault JL. Dynamical effects and phase separation in cooled binary fluid films. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2007; 76:035303. [PMID: 17930297 DOI: 10.1103/physreve.76.035303] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2007] [Revised: 07/26/2007] [Indexed: 05/25/2023]
Abstract
We study phase separation in thin films using a model based on the Navier-Stokes Cahn-Hilliard equations in the lubrication approximation, with a van der Waals potential to account for substrate-film interactions. We solve the resulting thin-film equations numerically and compare to experimental data. The model captures the qualitative features of real phase-separating fluids, in particular, how concentration gradients produce film thinning and surface roughening. The ultimate outcome of the phase separation depends strongly on the dynamical back reaction of concentration gradients on the flow, an effect we demonstrate by applying a shear stress at the film's surface. When the back reaction is small, the phase domain boundaries align with the direction of the imposed stress, while for larger back-reaction strengths, the domains align in the perpendicular direction.
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Affiliation(s)
- Lennon O Náraigh
- Department of Mathematics, Imperial College, London SW7 2AZ, United Kingdom
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24
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Yan LT, Xie XM. Wetting-layer formation mechanisms of surface-directed phase separation under different quench depths with off-critical compositions in polymer binary mixture. J Chem Phys 2007; 126:064908. [PMID: 17313245 DOI: 10.1063/1.2430526] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Focusing on the off-critical condition, the quench depth dependence of surface-directed phase separation in the polymer binary mixture is numerically investigated by combination of the Cahn-Hilliard-Cook theory and the Flory-Huggins-de Gennes theory. Two distinct situations, i.e., for the wetting, the minority component is preferred by the surface and the majority component is preferred by the surface, are discussed in detail. The simulated results show that the formation mechanism of the wetting layer is affected by both the quench depth and the off-critical extent. Moreover, a diagram, illustrating the formation mechanisms of the wetting layer with various quench depths and compositions, is obtained on the basis of the simulated results. It is found that, when the minority component is preferred by the surface, the growth of the wetting layer can exhibit pure diffusion limited growth law, logarithmic growth law, and Lifshitz-Slyozov growth law. However, when the majority component is preferred by the surface, the wetting layer always grows logarithmically, regardless of the quench depth and the off-critical extent. It is interesting that the surface-induced nucleation can be observed in this case. The simulated results demonstrate that the surface-induced nucleation only occurs below a certain value of the quench depth, and a detailed range about it is calculated and indicated. Furthermore, the formation mechanisms of the wetting layer are theoretically analyzed in depth by the chemical potential gradient.
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Affiliation(s)
- Li-Tang Yan
- Advanced Materials Laboratory, Department of Chemical Engineering, Tsinghua University, Beijing 100084, People's Republic of China
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Yan LT, Xie XM. Numerical simulation of substrate effects on spinodal decomposition in polymer binary mixture: Effects of the surface potential. POLYMER 2006. [DOI: 10.1016/j.polymer.2006.07.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Das SK, Puri S, Horbach J, Binder K. Spinodal decomposition in thin films: molecular-dynamics simulations of a binary Lennard-Jones fluid mixture. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2006; 73:031604. [PMID: 16605534 DOI: 10.1103/physreve.73.031604] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2005] [Revised: 02/03/2006] [Indexed: 05/08/2023]
Abstract
We use molecular dynamics (MD) to simulate an unstable homogeneous mixture of binary fluids (AB), confined in a slit pore of width D. The pore walls are assumed to be flat and structureless and attract one component of the mixture (A) with the same strength. The pairwise interactions between the particles are modeled by the Lennard-Jones potential, with symmetric parameters that lead to a miscibility gap in the bulk. In the thin-film geometry, an interesting interplay occurs between surface enrichment and phase separation. We study the evolution of a mixture with equal amounts of A and B, which is rendered unstable by a temperature quench. We find that A-rich surface enrichment layers form quickly during the early stages of the evolution, causing a depletion of A in the inner regions of the film. These surface-directed concentration profiles propagate from the walls towards the center of the film, resulting in a transient layered structure. This layered state breaks up into a columnar state, which is characterized by the lateral coarsening of cylindrical domains. The qualitative features of this process resemble results from previous studies of diffusive Ginzburg-Landau-type models [S. K. Das, S. Puri, J. Horbach, and K. Binder, Phys. Rev. E 72, 061603 (2005)], but quantitative aspects differ markedly. The relation to spinodal decomposition in a strictly two-dimensional geometry is also discussed.
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Affiliation(s)
- Subir K Das
- Institut für Physik, Johannes Gutenberg-Universität Mainz, D-55099 Mainz, Germany
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Yan LT, Xie XM. Numerical Simulation of Surface Effects on Spinodal Decomposition in Polymer Binary Mixture: Quench Depth Dependence. Macromolecules 2006. [DOI: 10.1021/ma0524878] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Li-Tang Yan
- Advanced Materials Laboratory, Department of Chemical Engineering, Tsinghua University, Beijing 100084, P. R. China
| | - Xu-Ming Xie
- Advanced Materials Laboratory, Department of Chemical Engineering, Tsinghua University, Beijing 100084, P. R. China
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He JH, Carosella CA, Hubler GK, Qadri SB, Sprague JA. Bombardment-induced tunable superlattices in the growth of Au-Ni films. PHYSICAL REVIEW LETTERS 2006; 96:056105. [PMID: 16486960 DOI: 10.1103/physrevlett.96.056105] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2005] [Indexed: 05/06/2023]
Abstract
Highly ordered superlattices are typically created through the sequential deposition of two different materials. Here, we report our experimental observation of spontaneous formation of superlattices in coevaporation of Au and Ni under energetic ion bombardment. The superlattice periodicities are on the order of a few nanometers and can be adjusted through the energy and flux of ion beams. Such a self-organization process is a consequence of the bombardment-induced segregation and uphill diffusion within the advancing nanoscale subsurface zone in the film growth. Our observations suggest that ion beams can be employed to make tunable natural superlattices in the deposition of phase-separated systems with strong bombardment-induced segregation.
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Affiliation(s)
- J H He
- Naval Research Laboratory, Washington, DC 20375, USA.
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Das SK, Puri S, Horbach J, Binder K. Molecular dynamics study of phase separation kinetics in thin films. PHYSICAL REVIEW LETTERS 2006; 96:016107. [PMID: 16486484 DOI: 10.1103/physrevlett.96.016107] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2005] [Indexed: 05/06/2023]
Abstract
We use molecular dynamics to simulate experiments where a symmetric binary fluid mixture (AB), confined between walls that preferentially attract one component (A), is quenched from the one-phase region into the miscibility gap. Surface enrichment occurs during the early stages, yielding a B-rich mixture in the film center with well-defined A-rich droplets. The droplet size grows with time as l(t) proportional t(2/3) after a transient regime. The present atomistic model is also compared to mesoscopic coarse-grained models for this problem.
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Affiliation(s)
- Subir K Das
- Institut für Physik, Johannes Gutenberg-Universität, D-55099 Mainz, Staudinger Weg 7, Germany
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Das SK, Puri S, Horbach J, Binder K. Kinetics of phase separation in thin films: simulations for the diffusive case. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2005; 72:061603. [PMID: 16485955 DOI: 10.1103/physreve.72.061603] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2005] [Indexed: 05/06/2023]
Abstract
We study the diffusion-driven kinetics of phase separation of a symmetric binary mixture (AB), confined in a thin-film geometry between two parallel walls. We consider cases where (i) both walls preferentially attract the same component (A), and (ii) one wall attracts and the other wall attracts (with the same strength). We focus on the interplay of phase separation and wetting at the walls, which is referred to as surface-directed spinodal decomposition (SDSD). The formation of SDSD waves at the two surfaces, with wave vectors oriented perpendicular to them, often results in a metastable layered state (also referred to as "stratified morphology"). This state is reminiscent of the situation where the thin film is still in the one-phase region but the surfaces are completely wet, and hence coated with thick wetting layers. This metastable state decays by spinodal fluctuations and crosses over to an asymptotic growth regime characterized by the lateral coarsening of pancakelike domains. These pancakes may or may not be coated by precursors of wetting layers. We use Langevin simulations to study this crossover and the growth kinetics in the asymptotic coarsening regime.
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Affiliation(s)
- Subir K Das
- Institut für Physik, Johannes Gutenberg-Universität, D-55099 Mainz, Staudinger Weg 7, Germany
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Yan LT, Xie XM. Numerical simulation of substrate effects on spinodal decomposition in polymer binary mixture: morphology and dynamics. POLYMER 2005. [DOI: 10.1016/j.polymer.2005.05.115] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Woywod D, Schemmel S, Rother G, Findenegg GH, Schoen M. Phase behavior and local structure of a binary mixture in pores: Mean-field lattice model calculations for analyzing neutron scattering data. J Chem Phys 2005; 122:124510. [PMID: 15836400 DOI: 10.1063/1.1867372] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We investigate the phase behavior of an asymmetric binary liquid A-W mixture confined between two planar homogenous substrates (slit pore). Molecules of species W interact preferentially with the solid walls via a long-range potential. Assuming nearest-neighbor attractions between the liquid molecules, we employ a lattice-gas model and a mean-field approximation for the grand potential. Minimization of this potential yields the density profiles of thermodynamically stable phases for fixed temperature, chemical potentials of both species, pore width and strengths of attraction. This model is used to analyze experimental small-angle neutron-scattering (SANS) data on the microscopic structure of the binary system isobutyric acid (iBA)+heavy water (D2O) inside a mesoscopic porous matrix (controlled-pore glass of about 10 nm mean pore width). Confinement-independent model parameters are adjusted so that the theoretical liquid-liquid coexistence curve in the bulk matches its experimental counterpart. By choosing appropriate values of the pore width and the attraction strength between substrates and water we analyze the effect of confinement on the phase diagram. In addition to a depression of the liquid-liquid critical point we observe surface induced phase transitions as well as water-film adsorption near the walls. The temperature dependence of the structure of water-rich and iBA-rich phases of constant composition are discussed in detail. The theoretical predictions are consistent with results of the SANS study and assist their interpretation.
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Affiliation(s)
- Dirk Woywod
- Stranski-Laboratorium für Physikalische und Theoretische Chemie, Fakultät für Mathematik und Naturwissenschaften, Technische Universität Berlin, Strasse des 17. Juni 124, D-10623 Berlin, Germany.
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Interfacial and bulk oscillatory instabilities in a binary fluid metal: the example of a Ga–Pb alloy. Chem Phys Lett 2004. [DOI: 10.1016/j.cplett.2004.01.110] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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