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Materials 2011, 4(10), 1632-1647; doi:10.3390/ma4101632
Article

Effect of Molecular Flexibility on the Nematic-to-Isotropic Phase Transition for Highly Biaxial Molecular Non-Symmetric Liquid Crystal Dimers

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Received: 22 August 2011 / Revised: 2 September 2011 / Accepted: 19 September 2011 / Published: 27 September 2011
(This article belongs to the Special Issue Liquid Crystals 2011)
Download PDF [1102 KB, 28 September 2011; original version 27 September 2011]

Abstract

In this work, a study of the nematic (N)–isotropic (I) phase transition has been made in a series of odd non-symmetric liquid crystal dimers, the α-(4-cyanobiphenyl-4’-yloxy)-ω-(1-pyrenimine-benzylidene-4’-oxy) alkanes, by means of accurate calorimetric and dielectric measurements. These materials are potential candidates to present the elusive biaxial nematic (NB) phase, as they exhibit both molecular biaxiality and flexibility. According to the theory, the uniaxial nematic (NU)–isotropic (I) phase transition is first-order in nature, whereas the NB–I phase transition is second-order. Thus, a fine analysis of the critical behavior of the N–I phase transition would allow us to determine the presence or not of the biaxial nematic phase and understand how the molecular biaxiality and flexibility of these compounds influences the critical behavior of the N–I phase transition.
Keywords: liquid crystal dimers; phase transitions; critical exponents; calorimetry; dielectric spectroscopy liquid crystal dimers; phase transitions; critical exponents; calorimetry; dielectric spectroscopy
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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Sebastián, N.; López, D.O.; Diez-Berart, S.; de la Fuente, M.R.; Salud, J.; Pérez-Jubindo, M.A.; Ros, M.B. Effect of Molecular Flexibility on the Nematic-to-Isotropic Phase Transition for Highly Biaxial Molecular Non-Symmetric Liquid Crystal Dimers. Materials 2011, 4, 1632-1647.

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