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Mihai LA, Wang H, Guilleminot J, Goriely A. Nematic liquid crystalline elastomers are aeolotropic materials. Proc Math Phys Eng Sci 2021; 477:20210259. [PMID: 35153581 PMCID: PMC8424302 DOI: 10.1098/rspa.2021.0259] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Accepted: 08/04/2021] [Indexed: 11/12/2022] Open
Abstract
Continuum models describing ideal nematic solids are widely used in theoretical studies of liquid crystal elastomers. However, experiments on nematic elastomers show a type of anisotropic response that is not predicted by the ideal models. Therefore, their description requires an additional term coupling elastic and nematic responses, to account for aeolotropic effects. In order to better understand the observed elastic response of liquid crystal elastomers, we analyse theoretically and computationally different stretch and shear deformations. We then compare the elastic moduli in the infinitesimal elastic strain limit obtained from the molecular dynamics simulations with the ones derived theoretically, and show that they are better explained by including nematic order effects within the continuum framework.
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Affiliation(s)
- L Angela Mihai
- School of Mathematics, Cardiff University, Senghennydd Road, Cardiff CF24 4AG, UK
| | - Haoran Wang
- Department of Mechanical and Aerospace Engineering,Utah State University, Logan, UT 84322-4130, USA
| | - Johann Guilleminot
- Department of Civil and Environmental Engineering, Duke University, Durham, NC 27708-0287, USA
| | - Alain Goriely
- Mathematical Institute, University of Oxford, Woodstock Road, Oxford OX2 6GG, UK
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Chen W, Zhu Y, Cui F, Liu L, Sun Z, Chen J, Li Y. GPU-Accelerated Molecular Dynamics Simulation to Study Liquid Crystal Phase Transition Using Coarse-Grained Gay-Berne Anisotropic Potential. PLoS One 2016; 11:e0151704. [PMID: 26986851 PMCID: PMC4795799 DOI: 10.1371/journal.pone.0151704] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2015] [Accepted: 03/02/2016] [Indexed: 12/26/2022] Open
Abstract
Gay-Berne (GB) potential is regarded as an accurate model in the simulation of anisotropic particles, especially for liquid crystal (LC) mesogens. However, its computational complexity leads to an extremely time-consuming process for large systems. Here, we developed a GPU-accelerated molecular dynamics (MD) simulation with coarse-grained GB potential implemented in GALAMOST package to investigate the LC phase transitions for mesogens in small molecules, main-chain or side-chain polymers. For identical mesogens in three different molecules, on cooling from fully isotropic melts, the small molecules form a single-domain smectic-B phase, while the main-chain LC polymers prefer a single-domain nematic phase as a result of connective restraints in neighboring mesogens. The phase transition of side-chain LC polymers undergoes a two-step process: nucleation of nematic islands and formation of multi-domain nematic texture. The particular behavior originates in the fact that the rotational orientation of the mesogenes is hindered by the polymer backbones. Both the global distribution and the local orientation of mesogens are critical for the phase transition of anisotropic particles. Furthermore, compared with the MD simulation in LAMMPS, our GPU-accelerated code is about 4 times faster than the GPU version of LAMMPS and at least 200 times faster than the CPU version of LAMMPS. This study clearly shows that GPU-accelerated MD simulation with GB potential in GALAMOST can efficiently handle systems with anisotropic particles and interactions, and accurately explore phase differences originated from molecular structures.
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Affiliation(s)
- Wenduo Chen
- Key Laboratory of Synthetic Rubber & Laboratory of Advanced Power Sources, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 5625 Renmin Street, Changchun, PR China
| | - Youliang Zhu
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 5625 Renmin Street, Changchun, PR China
| | - Fengchao Cui
- Key Laboratory of Synthetic Rubber & Laboratory of Advanced Power Sources, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 5625 Renmin Street, Changchun, PR China
| | - Lunyang Liu
- Key Laboratory of Synthetic Rubber & Laboratory of Advanced Power Sources, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 5625 Renmin Street, Changchun, PR China
| | - Zhaoyan Sun
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 5625 Renmin Street, Changchun, PR China
| | - Jizhong Chen
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 5625 Renmin Street, Changchun, PR China
| | - Yunqi Li
- Key Laboratory of Synthetic Rubber & Laboratory of Advanced Power Sources, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 5625 Renmin Street, Changchun, PR China
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Lebar A, Cordoyiannis G, Kutnjak Z, Zalar B. The Isotropic-to-Nematic Conversion in Liquid Crystalline Elastomers. LIQUID CRYSTAL ELASTOMERS: MATERIALS AND APPLICATIONS 2010. [DOI: 10.1007/12_2010_103] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Ilnytskyi JM, Neher D. Structure and internal dynamics of a side chain liquid crystalline polymer in various phases by molecular dynamics simulations: a step towards coarse graining. J Chem Phys 2007; 126:174905. [PMID: 17492884 DOI: 10.1063/1.2712438] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Side chain liquid crystalline polymer with relatively long spacer was modeled on a semiatomistic level and studied in different liquid crystalline phases with the aid of molecular dynamics simulations. Well equilibrated isotropic, polydomain smectic and monodomain smectic phases were studied for their structural and dynamic properties. Particular emphasis was given to the analysis on a coarse-grained level, where backbones, side chains, and mesogens were considered in terms of their equivalent ellipsoids. The authors found that the liquid crystalline phase had a minor influence on the metrics of these objects but affected essentially their translational and orientational order. In the monodomain smectic phase, mesogens, backbones, and side chains are confined spatially. Their diffusion and shape dynamics are frozen along the mesogen director (the one-dimensional solidification) and the reorientation times increase by one to one-and-half orders of magnitude. In this phase, besides obvious orientational order of mesogens and side chains, a stable detectable order of the backbones was also observed. The backbone director is confined in the plane perpendicular to the mesogen director and constantly changes its orientation within this plane. The backbone diffusion in these planes is of the same range as in the polydomain smectic phase at the same temperature. A detailed analysis of the process of field-induced growth of the smectic phase was performed. The study revealed properties of liquid crystalline polymers that may enable their future fully coarse-grained modeling.
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Affiliation(s)
- Jaroslav M Ilnytskyi
- Institute for Physics, University of Potsdam, Am Neuen Palais 10, 14469 Potsdam, Germany.
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Giuseppone N, Lehn JM. Electric-Field Modulation of Component Exchange in Constitutional Dynamic Liquid Crystals. Angew Chem Int Ed Engl 2006; 45:4619-24. [PMID: 16789034 DOI: 10.1002/anie.200600430] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Nicolas Giuseppone
- Institut de Science et d'Ingénierie Supramoléculaires, 8 Allée Gaspard-Monge, BP 70028, 67083 Strasbourg, France
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Giuseppone N, Lehn JM. Electric-Field Modulation of Component Exchange in Constitutional Dynamic Liquid Crystals. Angew Chem Int Ed Engl 2006. [DOI: 10.1002/ange.200600430] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Gutman L, Cao J, Swager TM. Phase and orientational ordering of low molecular weight rod molecules in a quenched liquid crystalline polymer matrix with mobile side chains. J Chem Phys 2004; 120:11316-26. [PMID: 15268159 DOI: 10.1063/1.1739211] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
We study the phase diagram and orientational ordering of guest liquid crystalline (LC) rods immersed in a quenched host made of a liquid crystalline polymer (LCP) matrix with mobile side chains. The LCP matrix lies below the glass transition of the polymer backbone. The side chains are mobile and can align to the guest rod molecules in a plane normal to the local LCP chain contour. A field theoretic formulation for this system is proposed and the effects of the LCP matrix on LC ordering are determined numerically. We obtain simple analytical equations for the nematic/isotropic phase diagram boundaries. Our calculation show a nematic-nematic (N/N) first order transition from a guest stabilized to a guest-host stabilized region and the possibility of a reentrant transition from a guest stabilized nematic region to a host only stabilized regime separated by an isotropic phase. A detailed study of thermodynamic variables and interactions on orientational ordering and phases is carried out and the relevance of our predictions to experiments and computer simulations is presented.
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Affiliation(s)
- Lorin Gutman
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139-4307, USA
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