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Sakamoto M, Hanasaki I. Analytical model of critical buckling transition for smectic liquid crystal based on the viscoelastic scaling of coarse-grained molecular dynamics. Phys Rev E 2023; 107:014703. [PMID: 36797970 DOI: 10.1103/physreve.107.014703] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Accepted: 12/19/2022] [Indexed: 06/18/2023]
Abstract
The buckling transition of smectic liquid crystals (LCs) is important not only as fundamental physics but also for the rational design of devices to make use of their optical and mechanical properties. However, there exists a huge gap between the specific knowledge and universal analytical formulation. We have conducted coarse-grained molecular dynamics (CGMD) simulations with the force field optimized for the description of buckling phenomena including topological defects to link the molecular nature and continuum formulation. The simulations reveal the viscoelastic characteristics where the critical strain and the compression modulus highly depend on the strain rate as well as the number of layers. Therefore, we formulate the scaling model whose coupling constants depend on both strain rate and domain size. The model reproduces the CGMD results as well as experimental and theoretical values in existing literature. Furthermore, we elucidate from this model that the critical buckling behavior is determined by the competition between the suppression of compression-induced flow and the undulation fluctuation of layers. The framework consisting of the CGMD simulation and the scaling model enables us to estimate the buckling characteristics of smectic LCs reflecting their molecular structures in a wide range from the low-frequency regime that can be verified by experiments to the high-frequency regime beyond the reach of it.
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Affiliation(s)
- Michiaki Sakamoto
- Institute of Engineering, Tokyo University of Agriculture and Technology, Naka-cho 2-24-16, Koganei, Tokyo 184-8588, Japan
| | - Itsuo Hanasaki
- Institute of Engineering, Tokyo University of Agriculture and Technology, Naka-cho 2-24-16, Koganei, Tokyo 184-8588, Japan
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2
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Joshi SY, Deshmukh SA. A review of advancements in coarse-grained molecular dynamics simulations. MOLECULAR SIMULATION 2020. [DOI: 10.1080/08927022.2020.1828583] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Soumil Y. Joshi
- Department of Chemical Engineering, Virginia Tech, Blacksburg, VA, USA
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3
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Chacón E, Tarazona P, Bresme F. A computer simulation approach to quantify thetruearea andtruearea compressibility modulus of biological membranes. J Chem Phys 2015. [DOI: 10.1063/1.4926938] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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4
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Sethuraman V, Nguyen BH, Ganesan V. Coarse-graining in simulations of multicomponent polymer systems. J Chem Phys 2014; 141:244904. [DOI: 10.1063/1.4904390] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
| | - Bryan H. Nguyen
- Department of Chemical Engineering, University of Texas at Austin, Austin, Texas 78712, USA
| | - Venkat Ganesan
- Department of Chemical Engineering, University of Texas at Austin, Austin, Texas 78712, USA
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5
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Schmid F, Dolezel S, Lenz O, Meinhardt S. On ripples and rafts: Curvature induced nanoscale structures in lipid membranes. ACTA ACUST UNITED AC 2014. [DOI: 10.1088/1742-6596/487/1/012004] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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6
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Tarazona P, Chacón E, Bresme F. Thermal fluctuations and bending rigidity of bilayer membranes. J Chem Phys 2013; 139:094902. [DOI: 10.1063/1.4818421] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
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7
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Abstract
We review recent computer simulation studies of undulating lipid bilayers. Theoretical interpretations of such fluctuating membranes are most commonly based on generalized Helfrich-type elastic models, with additional contributions of local "protrusions" and/or density fluctuations. Such models provide an excellent basis for describing the fluctuations of tensionless bilayers in the fluid Lαphase at a quantitative level.However, this description is found to fail for membranes in the gel phase and for membranes subject to high tensions. The fluctuations of tilted gel membranes (Lβ′phase) show a signature of the modulated ripple structure Pβ′, which is a nearby phase observed in the pretransition regime between the Lαand Lβ′state. This complicates a quantitative analysis on mesoscopic length scales. In the case of fluid membranes under tension, the large-wavelength fluctuation modes are found to be significantly softer than predicted by theory.In the latter context, we also address the general problem of the relation between frame tension and the fluctuation tension, which has been discussed somewhat controversially in recent years. Simulations of very simple model membranes with fixed area show that the fluctuations should be controlled by the frame tension, and not by the internal tension.
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Affiliation(s)
- FRIEDERIKE SCHMID
- Institute of Physics, Johannes-Gutenberg University of Mainz, D-55099 Mainz, Germany
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8
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Slimani MZ, Moreno AJ, Rossi G, Colmenero J. Dynamic Heterogeneity in Random and Gradient Copolymers: A Computational Investigation. Macromolecules 2013. [DOI: 10.1021/ma400577d] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
| | - Angel J. Moreno
- Centro de Física de Materiales (CSIC, UPV/EHU) and Materials Physics Center MPC, Paseo Manuel de Lardizabal 5, 20018 San Sebastián, Spain
| | - Giulia Rossi
- INSERM UMR-S 665, DSIMB 6, rue Alexandre Cabanel, 75739 Paris Cedex 15, France
| | - Juan Colmenero
- Donostia International Physics Center, Paseo Manuel de Lardizabal 4, 20018
San Sebastián, Spain
- Centro de Física de Materiales (CSIC, UPV/EHU) and Materials Physics Center MPC, Paseo Manuel de Lardizabal 5, 20018 San Sebastián, Spain
- Departamento de Física
de Materiales, Universidad del País Vasco (UPV/EHU), Apartado 1072, 20080 San Sebastián, Spain
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9
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Slimani MZ, Moreno AJ, Colmenero J. Heterogeneity of the Segmental Dynamics in Cylindrical and Spherical Phases of Diblock Copolymers. Macromolecules 2012. [DOI: 10.1021/ma301388j] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
| | - Angel J. Moreno
- Centro de Física de Materiales (CSIC, UPV/EHU) and Materials Physics Center MPC, Paseo Manuel de Lardizabal 5, 20018 San Sebastián, Spain
| | - Juan Colmenero
- Donostia International Physics Center, Paseo Manuel de Lardizabal 4, 20018
San Sebastián, Spain
- Centro de Física de Materiales (CSIC, UPV/EHU) and Materials Physics Center MPC, Paseo Manuel de Lardizabal 5, 20018 San Sebastián, Spain
- Departamento de Física
de Materiales, Universidad del País Vasco (UPV/EHU), Apartado 1072, 20080 San Sebastián, Spain
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10
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Slimani MZ, Moreno AJ, Colmenero J. Heterogeneity of the Segmental Dynamics in Lamellar Phases of Diblock Copolymers. Macromolecules 2011. [DOI: 10.1021/ma200470a] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Mohammed Zakaria Slimani
- Donostia International Physics Center, Paseo Manuel de Lardizabal 4, E-20018 San Sebastián, Spain
| | - Angel J. Moreno
- Centro de Física de Materiales (CSIC, UPV-EHU) and Materials Physics Center MPC, Paseo Manuel de Lardizabal 5, E-20018 San Sebastián, Spain
| | - Juan Colmenero
- Donostia International Physics Center, Paseo Manuel de Lardizabal 4, E-20018 San Sebastián, Spain
- Centro de Física de Materiales (CSIC, UPV-EHU) and Materials Physics Center MPC, Paseo Manuel de Lardizabal 5, E-20018 San Sebastián, Spain
- Departamento de Física de Materiales, Universidad del País Vasco (UPV-EHU), Apartado 1072, E-20080 San Sebastián, Spain
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11
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Martínez H, Chacón E, Tarazona P, Bresme F. The intrinsic interfacial structure of ionic surfactant monolayers at water–oil and water–vapour interfaces. Proc Math Phys Eng Sci 2011. [DOI: 10.1098/rspa.2010.0516] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Using computer simulations, we investigate the interfacial structure of sodium dodecyl sulphate (SDS) monolayers adsorbed at the water surface and water–oil interfaces. Using an algorithm that removes the averaging effect of the capillary waves, we obtain a detailed view of the solvation structure of water around the monolayer. We investigate surface concentrations between 45 and 33 Å
2
per surfactant, which are near experimental conditions corresponding to the critical micellar concentration and the formation of Newton black films. The surfactants induce a layering structure in water, which disappears at approximately 1 nm from the monolayer plane. The water molecules exhibit a preferred orientation with the dipoles pointing towards the monolayer. The orientational order decays slowly, but it does not influence the hydrogen bond structure of water, which is significantly disrupted in the interfacial region only. These structural changes are qualitatively the same in SDS–water and oil–SDS–water interfaces. In the latter case, we find a small degree of penetration of oil in the monolayer (between 0.2 and 0.25 molecules per SDS). This small penetration has a measurable effect on the monolayer, which increases its thickness by approximately 10 per cent. The bending modulus of the SDS monolayers is of the order of the thermal energy,
k
B
T
.
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Affiliation(s)
- Hector Martínez
- Departamento de Física Teórica de la Materia Condensada, CSIC, 28049 Madrid, Spain
| | - Enrique Chacón
- Instituto de Ciencia de Materiales de Madrid, CSIC, 28049 Madrid, Spain
- Instituto de Ciencia de Materiales Nicolás Cabrera, Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - Pedro Tarazona
- Departamento de Física Teórica de la Materia Condensada, CSIC, 28049 Madrid, Spain
- Instituto de Ciencia de Materiales Nicolás Cabrera, Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - Fernando Bresme
- Department of Chemistry, Imperial College London, London SW7 2AZ, UK
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12
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Neder J, West B, Nielaba P, Schmid F. Coarse-grained simulations of membranes under tension. J Chem Phys 2010; 132:115101. [PMID: 20331316 DOI: 10.1063/1.3352583] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
We investigate the properties of membranes under tension by Monte Carlo simulations of a generic coarse-grained model for lipid bilayers. We give a comprising overview of the behavior of several membrane characteristics, such as the area per lipid, the monolayer overlap, the nematic order, and pressure profiles. Both the low-temperature regime, where the membranes are in a gel L(beta(')) phase, and the high-temperature regime, where they are in the fluid L(alpha) phase, are considered. In the L(beta(')) state, the membrane is hardly influenced by tension. In the fluid state, high tensions lead to structural changes in the membrane, which result in different compressibility regimes. The ripple state P(beta(')), which is found at tension zero in the transition regime between L(alpha) and L(beta(')), disappears under tension and gives way to an interdigitated phase. We also study the membrane fluctuations in the fluid phase. In the low-tension regime the data can be fitted nicely to a suitably extended elastic theory. At higher tensions the elastic fit consistently underestimates the strength of long-wavelength fluctuations. Finally, we investigate the influence of tension on the effective interaction between simple transmembrane inclusions and show that tension can be used to tune the hydrophobic mismatch interaction between membrane proteins.
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Affiliation(s)
- Jörg Neder
- Department of Physics, University of Konstanz, 78457 Konstanz, Germany.
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13
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Schmid F. Toy amphiphiles on the computer: What can we learn from generic models? Macromol Rapid Commun 2009; 30:741-51. [DOI: 10.1002/marc.200800750] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2008] [Accepted: 01/20/2009] [Indexed: 11/08/2022]
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14
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West B, Brown FLH, Schmid F. Membrane-protein interactions in a generic coarse-grained model for lipid bilayers. Biophys J 2009; 96:101-15. [PMID: 18835907 PMCID: PMC2710048 DOI: 10.1529/biophysj.108.138677] [Citation(s) in RCA: 94] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2008] [Accepted: 09/04/2008] [Indexed: 11/18/2022] Open
Abstract
We study membrane-protein interactions and membrane-mediated protein-protein interactions by Monte Carlo simulations of a generic coarse-grained model for lipid bilayers with cylindrical hydrophobic inclusions. The strength of the hydrophobic force and the hydrophobic thickness of the proteins are systematically varied. The results are compared with analytical predictions of two popular analytical theories: The Landau-de Gennes theory and the elastic theory. The elastic theory provides an excellent description of the fluctuation spectra of pure membranes and successfully reproduces the deformation profiles of membranes around single proteins. However, its prediction for the potential of mean force between proteins is not compatible with the simulation data for large distances. The simulations show that the lipid-mediated interactions are governed by five competing factors: direct interactions; lipid-induced depletion interactions; lipid bridging; lipid packing; and a smooth long-range contribution. The mechanisms leading to hydrophobic mismatch interactions are critically analyzed.
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Affiliation(s)
- Beate West
- Fakultät für Physik, Universität Bielefeld, Bielefeld, Germany.
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15
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Davis JR, Panagiotopoulos AZ. Monte Carlo simulations of amphiphilic nanoparticle self-assembly. J Chem Phys 2008; 129:194706. [DOI: 10.1063/1.3009183] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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16
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Müller M, Daoulas KC. Calculating the free energy of self-assembled structures by thermodynamic integration. J Chem Phys 2008; 128:024903. [DOI: 10.1063/1.2818565] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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17
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Srinivas G, Swope WC, Pitera JW. Interfacial Fluctuations of Block Copolymers: A Coarse-Grain Molecular Dynamics Simulation Study. J Phys Chem B 2007; 111:13734-42. [DOI: 10.1021/jp073347y] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Goundla Srinivas
- IBM Almaden Research Center, 650 Harry Road, San Jose, California 95120
| | - William C. Swope
- IBM Almaden Research Center, 650 Harry Road, San Jose, California 95120
| | - Jed W. Pitera
- IBM Almaden Research Center, 650 Harry Road, San Jose, California 95120
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18
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Loison C, Mareschal M, Schmid F. Pores in bilayer membranes of amphiphilic molecules: coarse-grained molecular dynamics simulations compared with simple mesoscopic models. J Chem Phys 2006; 121:1890-900. [PMID: 15260741 DOI: 10.1063/1.1752884] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
We investigate pores in fluid membranes by molecular dynamics simulations of an amphiphile-solvent mixture, using a molecular coarse-grained model. The amphiphilic membranes self-assemble into a lamellar stack of amphiphilic bilayers separated by solvent layers. We focus on the particular case of tensionless membranes, in which pores spontaneously appear because of thermal fluctuations. Their spatial distribution is similar to that of a random set of repulsive hard disks. The size and shape distribution of individual pores can be described satisfactorily by a simple mesoscopic model, which accounts only for a pore independent core energy and a line tension penalty at the pore edges. In particular, the pores are not circular: their shapes are fractal and have the same characteristics as those of two-dimensional ring polymers. Finally, we study the size-fluctuation dynamics of the pores, and compare the time evolution of their contour length to a random walk in a linear potential.
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Affiliation(s)
- C Loison
- Max Planck Institut für Chemische Physik fester Stoffe, Nöthnitzer str. 40, D-01187 Dresden, Germany.
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19
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Guo H. Shear-induced parallel-to-perpendicular orientation transition in the amphiphilic lamellar phase: A nonequilibrium molecular-dynamics simulation study. J Chem Phys 2006; 124:054902. [PMID: 16468913 DOI: 10.1063/1.2161198] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The present work is devoted to a study of the shear-induced parallel-to-perpendicular orientation transition in the lamellar system by the large-scale nonequilibrium molecular-dynamics (NEMD) simulation. An effective generic model-A2B2 tetramer for amphiphilies is used. The NEMD simulation produces unambiguous evidence that undulation instability along the vorticity direction sets in well above a critical shear rate and grows in magnitude as the shear rate is further increased. At a certain high shear rate, the coherent undulation instability grows so large that defects are nucleated and the global lamellar monodomain breaks into several aligned lamellar domains. Subsequently layers in these domains rotate into the perpendicular orientation with the rotation of chains towards the y direction, merge into a global perpendicular-aligned lamellar monodomain, and organize into a perfect well-aligned perpendicular lamellar phase by the migration and annihilation of edge dislocations and disclinations. The macroscopic observable viscosity as a function of time or shear rate is correlated with the structural response such as the mesoscopic domain morphology and the microscopic chain conformation. The onset of undulation instability concurs with the start-up of shear-thinning behavior. During the orientation transformation at the high shear rate, the complex time-dependent thixotropic behavior is observed. The smaller viscosity in the perpendicular lamellar phase gives an energetic reason for the shear-induced orientation transition.
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Affiliation(s)
- Hongxia Guo
- Department of Material Science and Engineering, Northwestern University, Evanston, Illinois 60208, USA.
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20
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Iacovella CR, Horsch MA, Zhang Z, Glotzer SC. Phase diagrams of self-assembled mono-tethered nanospheres from molecular simulation and comparison to surfactants. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2005; 21:9488-94. [PMID: 16207026 DOI: 10.1021/la051035l] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
We perform Brownian dynamics simulations on model 3-D systems of mono-tethered nanospheres (TNS) to study the equilibrium morphologies formed by their self-assembly in a selective solvent. We predict that in contrast to flexible amphiphiles the nanospheres are locally ordered and there is an increase in the local order with an increase in concentration or relative nanoparticle diameter. We present the temperature vs concentration phase diagram for a system of TNS and propose a dimensionless scaling factor F(v) (headgroup volume/tether volume) that allows a comparison between the morphologies formed from TNS and traditional surfactants.
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Affiliation(s)
- Christopher R Iacovella
- Departments of Chemical Engineering and Materials Science & Engineering, University of Michigan, Ann Arbor, MI 48109-2136, USA
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21
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Brannigan G, Lin LCL, Brown FLH. Implicit solvent simulation models for biomembranes. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2005; 35:104-24. [PMID: 16187129 DOI: 10.1007/s00249-005-0013-y] [Citation(s) in RCA: 124] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2005] [Revised: 08/03/2005] [Accepted: 08/12/2005] [Indexed: 11/25/2022]
Abstract
Fully atomic simulation strategies are infeasible for the study of many processes of interest to membrane biology, biophysics and biochemistry. We review various coarse-grained simulation methodologies with special emphasis on methods and models that do not require the explicit simulation of water. Examples from our own research demonstrate that such models have potential for simulating a variety of biologically relevant phenomena at the membrane surface.
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Affiliation(s)
- Grace Brannigan
- Department of Physics and Astronomy, University of California, Santa Barbara, CA 93106-9530, USA
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22
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Düchs D, Schmid F. Formation and structure of the microemulsion phase in two-dimensional ternary AB+A+B polymeric emulsions. J Chem Phys 2004; 121:2798-805. [PMID: 15281884 DOI: 10.1063/1.1768152] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
We present an analysis of the structure of the fluctuation-induced microemulsion phase in a ternary blend of balanced AB diblock copolymers with equal amounts of A and B homopolymers. To this end, graphical analysis methods are employed to characterize two-dimensional configuration snapshots obtained with the recently introduced field-theoretic Monte Carlo method. We find that a microemulsion forms when the mean curvature diameter of the lamellar phase coincides roughly with the periodicity of the lamellar phase. Further, we provide evidence to the effect of a subclassification of the microemulsion into a genuine and a defect-driven region.
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Affiliation(s)
- Dominik Düchs
- Fakultät für Physik, Universität Bielefeld, Universitatsstrasse 25, 33615 Bielefeld, Germany
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