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- Liquid crystalline phases and demixing in binary mixtures of shape-anisometric colloids
- Extending the Maier-Saupe theory to cybotactic nematics
- Two-Dimensional Ordered Porous Patterns by Molecular Design
- Symmetries and allignement of biaxial nematic liquid crystals.
- Biaxial Nematics: symmetries, order domains and field-induced phase transitions
- Thermotropic biaxial liquid crystals: Spontaneous or field stabilized?
- Molecular Modeling of Liquid Crystalline Self-Organization of Fullerodendrimers: Columnar to Lamellar Phase Transitions Driven by Temperature and/or Concentration Changes
- Self-organisation of fullerene-containing conical supermesogens
- Helix formation in linear achiral dendronized polymers: A computer simulation study
- Self-Organization and Pattern Formation of Janus Particles in Two Dimensions by Computer Simulations
- A simple theory of molecular organization in fullerene containing liquid crystals
- On the molecular theory of dimer liquid crystals
- Molecular Theory of Dendritic Liquid Crystals: Self-Organization and Phase Transitions
- Structure and Nanomechanics of Linear Dendronised Polymers: A Molecular Simulation Study
- Polar Molecular Organisation in Liquid Crystals
- Theory and simulation of biaxial nematic and orthogonal smectic phases formed by mixtures of board-like molecules
- The phase behavior of a binary mixture of rodlike and disclike mesogens: Monte Carlo simulation, theory, and experiment
- Dipole Strength Effects on the Polymorphism in Smectic-A Mesophases
- Tilt Order Parameters, Polarity and Inversion Phenomena in Smectic Liquid Crystals
Category Archives: Paper
S. Droulias, A.G. Vanakaras, D.J. Photinos, Liquid Crystals, 37:6, 969-976, (2010).
Abstract: The possible symmetries of the biaxial nematic phase are examined against the implications of the presently available experimental results. Contrary to the widespread notion that biaxial nematics have orthorhombic symmetry, our study shows that a monoclinic C2h symmetry is more likely to be the case for the recently observed phase biaxiality in thermotropic bent-core and calamitc tetrapode nematic systems. The methodology for differentiating between the possible symmetries of the biaxial nematic phase by NMR and by IR spectroscopy measurements is presented in detail. The manifestations of the different symmetries on the alignment of the biaxial phase are identified and their implications on the measurement and quantification of biaxiality as well as on the potential use of biaxial nematic liquid crystals in electro-optic applications are discussed. ©2009 American Institute of Physics
Abstract: We studied the symmetry and spatial uniformity of the orientational order of the biaxial nematic phase in the light of recent experimental observations of phase biaxiality in thermotropic bent-core and calamitic-tetramer nematics. Evidence is presented supporting monoclinic symmetry, instead of the usually assumed orthorhombic symmetry. The use of deuterium nuclear magnetic resonance to differentiate between the possible symmetries is described. The spatial aspects of biaxial order are presented in the context of the cluster model, wherein macroscopic biaxiality can result from the field-induced alignment of biaxial and possibly polar domains. The implications of different symmetries on the alignment of biaxial nematics and on the measurements of biaxial order are discussed in conjunction with the microdomain structure of the biaxial phase.
Abstract: An intermediate nematic phase is proposed for the interpretation of recent experimental results on phase biaxiality in bent-core nematic liquid crystals. The phase is macroscopically uniaxial but has microscopic biaxial, and possibly polar, domains. Under the action of an electric field, the phase acquires macroscopic biaxial ordering resulting from the collective alignment of the domains. A phenomenological theory is developed for the molecular order in this phase and for its transitions to purely uniaxial and to spontaneously biaxial nematic phases.
- Theory and simulation of biaxial nematic and orthogonal smectic phases formed by mixtures of board-like molecules, A. G. Vanakaras, M. A. Bates and D. J. Photinos, Phys. Chem. Chem. Phys. 5(17), 3700 (2003).
- The phase behavior of a binary mixture of rodlike and disclike mesogens: Monte Carlo simulation, theory, and experiment, A. Galindo, A. J. Haslam, S. Varga, G. Jackson, A. G. Vanakaras, D. J. Photinos and D. A. Dunmur, J. Chem. Phys. 119(10), 5216 (2003).
- On the Molecular requirements for the stabilization of thermotropic Biaxial ordering in Rod-Plate nematics, A. G. Vanakaras, A. F. Terzis and D.J. Photinos, Molec.Cryst. Liq. Cryst., 362, 67-78 (2001).
- Theory of biaxial nematic ordering in rod-disc mixtures revisited, A. G. Vanakaras and D.J. Photinos, Molec.Cryst. Liq. Cryst., 299, 65-71 (1997).
- Hydrogen bonding and phase biaxiality in nematic rod-plate mixtures, A. G. Vanakaras, S. C. McGrother, G. Jackson and D. J. Photinos, Molec.Cryst. Liq. Cryst., 323, 199 (1998).
Molecular Modeling of Liquid Crystalline Self-Organization of Fullerodendrimers: Columnar to Lamellar Phase Transitions Driven by Temperature and/or Concentration Changes
S.D. Peroukidis, A.G. Vanakaras and D.J. Photinos, J. Phys. Chem. B , 112(40), 12761-12767 (2008). (e-print)
Abstract: The molecular cubic-block model [J. Chem. Phys. 2005, 123, 164904] is used to study a class of poly(benzyl ether) fullerodendrimers that have recently been reported to form columnar liquid crystal phases. In agreement with experiment, the model-molecules are found to self-assemble into columns which form hexagonal or rectangular lattices. The columnar cross sections are elongated in the rectangular phase. Transitions to the isotropic phase, either directly or through the intermediate formation of smectic phases, have been found. The effects of dissolving small amounts of nonbonded fullerene molecules have been explored. The results predict that the fullerene solutes restrict the range of stability of the columnar phase and may induce transitions from the columnar to the smectic or the isotropic phase. ©2008 American Chemical Society
A simple theory of molecular organization in fullerene containing liquid crystals, S. D. Peroukidis, A. G. Vanakaras and D. J. Photinos, J. Chem. Phys., 123, 164904 (2005).
Self-organisation of fullerene-containing conical supermesogens, S. D. Peroukidis , A. G. Vanakaras and D. J. Photinos, Soft Matter, 4, 493-499 (2008).
Molecular Theory of Dendritic Liquid Crystals: Self-Organization and Phase Transitions, A. G. Vanakaras and D. J. Photinos, J. Mater. Chem. 15, 2002-2012 (2005).