1
|
Kaur J, Deb D. Pressure-tensor method evaluation of the interfacial tension between Gay-Berne isotropic fluid and a smooth repulsive wall. SOFT MATTER 2021; 17:10566-10579. [PMID: 34779475 DOI: 10.1039/d1sm01293b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The interfacial properties of a confined thermotropic liquid crystalline material are investigated using a molecular dynamics simulation technique. The pairwise interaction among the soft ellipsoidal particles is modeled by the Gay-Berne (GB) potential. The GB ellipsoids are confined by two soft, smooth, repulsive walls defined by the Weeks-Chandler-Andersen (WCA) potential. The aperiodic confinement due to walls makes the system mechanically anisotropic. Hence using the pressure-tensor method, the interfacial tension of an interface between the bulk isotropic (I) phase and WCA wall at various number densities (ρ) is calculated. From the pressure tensor and orientational order profiles, the arrangement of ellipsoids in the bulk and the vicinity of the wall is determined. The effect of system size and the wall-particle interaction strength (εW) on is also analyzed by varying the system size and εW.
Collapse
Affiliation(s)
- Jagroop Kaur
- School of Physics and Materials Science, Thapar Institute of Engineering and Technology, Bhadson Road, Patiala, Punjab - 147004, India.
| | - Debabrata Deb
- School of Physics and Materials Science, Thapar Institute of Engineering and Technology, Bhadson Road, Patiala, Punjab - 147004, India.
| |
Collapse
|
2
|
Affiliation(s)
- Michael P. Allen
- Department of Physics, University of Warwick, Coventry, UK
- H. H. Wills Physics Laboratory, Royal Fort, Bristol, UK
| |
Collapse
|
3
|
Salgado-Blanco D, Díaz-Herrera E, Mendoza CI. Effect of the anchoring strength on the phase behaviour of discotic liquid crystals under face-on confinement. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2019; 31:105101. [PMID: 30540979 DOI: 10.1088/1361-648x/aaf843] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
In this study we have performed molecular dynamics simulations to study a Gay-Berne discotic fluid confined in a slab geometry for a fixed confinement length. Four different anchoring strengths with a homeotropic (face-on) configuration were studied. We found that changing the anchoring strength changes the normal component of the stress tensor, which in turn changes the density of the system's bulk. This phenomenon leads to a shift in the isotropic-nematic transition temperature. We observe that the temperature regions where the nematic phase is present diminishes as the anchoring strength increases. The anchoring strength also affects the nematic-columnar coexistence temperature-region: it spans over more temperatures at higher anchoring strengths.
Collapse
Affiliation(s)
- Daniel Salgado-Blanco
- Cátedras CONACyT-Centro Nacional de Supercómputo, Instituto Potosino de Investigación Científica y Tecnológica, Camino a la Presa San José 2055, 78216, San Luis Potosí, Mexico
| | | | | |
Collapse
|
4
|
|
5
|
Brumby PE, Wensink HH, Haslam AJ, Jackson G. Structure and Interfacial Tension of a Hard-Rod Fluid in Planar Confinement. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:11754-11770. [PMID: 28885848 DOI: 10.1021/acs.langmuir.7b02254] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The structural properties and interfacial tension of a fluid of rodlike hard-spherocylinder particles in contact with hard structureless flat walls are studied by means of Monte Carlo simulation. The calculated surface tension between the rod fluid and the substrate is characterized by a nonmonotonic trend as a function of the bulk concentration (density) over the range of isotropic bulk concentrations. As suggested by earlier theoretical studies, a surface-ordering scenario is confirmed by our simulations: the local orientational order close to the wall changes from uniaxial to biaxial nematic when the bulk concentration reaches about 85% of the value at the onset of the isotropic-nematic phase transition. The surface ordering coincides with a wetting transition whereby the hard wall is wetted by a nematic film. Accurate values of the fluid-solid surface tension, the adsorption, and the average particle-wall contact distance are reported (over a broad range of densities into the dense nematic region for the first time), which can serve as a useful benchmark for future theoretical and experimental studies on confined rod fluids. The simulation data are supplemented with predictions from second-virial density functional theory, which are in good qualitative agreement with the simulation results.
Collapse
Affiliation(s)
- Paul E Brumby
- Department of Mechanical Engineering, Keio University , 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan
| | - Henricus H Wensink
- Laboratoire de Physique des Solides, Université Paris Sud & CNRS , 91405 Orsay Cedex, France
| | - Andrew J Haslam
- Department of Chemical Engineering and Qatar Carbonates and Carbon Storage Research Centre, Imperial College London , South Kensington Campus, London SW7 2AZ, United Kingdom
| | - George Jackson
- Department of Chemical Engineering and Qatar Carbonates and Carbon Storage Research Centre, Imperial College London , South Kensington Campus, London SW7 2AZ, United Kingdom
| |
Collapse
|
6
|
Workineh ZG, Vanakaras AG. Homogeneous alignment of liquid crystalline dendrimers confined in a slit-pore. A simulation study. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2016; 28:115002. [PMID: 26903080 DOI: 10.1088/0953-8984/28/11/115002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
In this work we present results from isobaric-isothermal (NPT) Monte Carlo simulation studies of model liquid crystalline dendrimer (LCDr) systems confined in a slit-pore made of two parallel flat walls. The dendrimers are modelled as a collection of spherical and ellipsoidal particles corresponding to the junction points of the dendritic core and to the mesogenic units respectively. Assuming planar uniform (unidirectional) soft anchoring of the mesogenic units on the substrates we investigate the conformational and alignment properties of the LCDr system at different thermodynamic state points. Tractable coarse grained force fields have been used from our previous work. At low pressures the interior of the pore is almost empty, since almost all LCDrs are anchored to the substrates forming two-dimensional smectic-like structures with the mesogens aligned along the aligning direction of the substrates. As the pressure grows the LCDrs occupy the whole pore. However, even at low temperatures, the smectic organization does not transmit in the interior of the pore and is preserved for distances of 2-3 mesogenic diameters from the walls. For this reason, the global orientational order decreases with increasing pressure (density). In the vicinity (2-3 mesogenic diameters) of the pore walls, mesogenic units preserve the smectic structure whose layers are separated by layers of spherical beads. In this region individual LCDrs possess a rod like shape.
Collapse
Affiliation(s)
- Zerihun G Workineh
- Department of Materials Science and Engineering, Bahir Dar University, Bahir Dar, Ethiopia
| | | |
Collapse
|
7
|
Busselez R, Cerclier CV, Ndao M, Ghoufi A, Lefort R, Morineau D. Discotic columnar liquid crystal studied in the bulk and nanoconfined states by molecular dynamics simulation. J Chem Phys 2014; 141:134902. [DOI: 10.1063/1.4896052] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Rémi Busselez
- Institut de Physique de Rennes, CNRS UMR 6251, Université de Rennes 1, 35042 Rennes, France
- Institut des Molécules et des Matériaux du Mans, UMR-CNRS 6283 Université du Maine, Avenue Olivier Messiaen 72085 Le Mans Cedex 9, France
| | - Carole V. Cerclier
- Institut de Physique de Rennes, CNRS UMR 6251, Université de Rennes 1, 35042 Rennes, France
- Institut des Matériaux de Nantes (IMN), UMR-CNRS 6502, 2 rue de la Houssiniere, BP32229, 44322 Nantes cedex3, France
| | - Makha Ndao
- Institut de Physique de Rennes, CNRS UMR 6251, Université de Rennes 1, 35042 Rennes, France
- Institut de Chimie de Clermont-Ferrand (ICCF) - UMR-CNRS 6296, Université Blaise Pascal, Campus des Cézeaux, 63171 Aubiere cedex, France
| | - Aziz Ghoufi
- Institut de Physique de Rennes, CNRS UMR 6251, Université de Rennes 1, 35042 Rennes, France
| | - Ronan Lefort
- Institut de Physique de Rennes, CNRS UMR 6251, Université de Rennes 1, 35042 Rennes, France
| | - Denis Morineau
- Institut de Physique de Rennes, CNRS UMR 6251, Université de Rennes 1, 35042 Rennes, France
| |
Collapse
|
8
|
|
9
|
Cañeda-Guzmán E, Moreno-Razo J, Díaz-Herrera E, Sambriski E. Molecular aspect ratio and anchoring strength effects in a confined Gay–Berne liquid crystal. Mol Phys 2013. [DOI: 10.1080/00268976.2013.837206] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
|
10
|
Sakuma H. Potential energy surface of 4-hexyl-4′-cyanobiphenyl (6CB) on graphite surface: a DFT study with van der Waals corrections. MOLECULAR SIMULATION 2012. [DOI: 10.1080/08927022.2011.557833] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
|
11
|
Ji Q, Lefort R, Ghoufi A, Morineau D. Pore dimensionality effects on the dynamics of a nanoconfined liquid-crystal. Chem Phys Lett 2009. [DOI: 10.1016/j.cplett.2009.10.021] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
|
12
|
Ji Q, Lefort R, Busselez R, Morineau D. Structure and dynamics of a Gay–Berne liquid crystal confined in cylindrical nanopores. J Chem Phys 2009; 130:234501. [DOI: 10.1063/1.3148889] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
|
13
|
Mima T, Narumi T, Kameoka S, Yasuoka K. Cell size dependence of orientational order of uniaxial liquid crystals in flat slit. MOLECULAR SIMULATION 2008. [DOI: 10.1080/08927020802256058] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
|