Category Archives: 2008

Thermotropic biaxial liquid crystals: Spontaneous or field stabilized?

A.G. Vanakaras and D.J. Photinos, J. Chem. Phys., 128, 154512 (2008). e-Reprint

biaxial clusters 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.

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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)

biaxial clusters

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

Related Works:
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).

Self-organisation of fullerene-containing conical supermesogens

S.D. Peroukidis, A.G. Vanakaras and D. J. Photinos, Soft Matter, 4, 493-499 (2008). (e-print)

Conical_SupermesogensAbstract: A molecular model of cubic building blocks is used to describe the mesomorphism of conical fullerenomesogens. Calculations based on density functional molecular theory and on Monte Carlo computer simulations give qualitatively similar results that are also in good agreement with the experimentally observed mesomorphic behaviour. The columnar and lamellar mesophases obtained are non-polar, and their relative stability is controlled by a single model parameter representing the softness of the repulsive interactions among the building blocks of the conical molecules.