Nematic liquid crystals doped with nanoparticles : phase behavior and dielectric properties

Osipov, Mikhail A. and Gorkounov, Maxim V.; Lagerwall, Jan P F and Scalia, Giusy, eds. (2016) Nematic liquid crystals doped with nanoparticles : phase behavior and dielectric properties. In: Liquid Crystals with Nano and Microparticles. Series in Soft Condensed Matter . World Scientific Publishing Company, Singapore. ISBN 9789814619257 (https://doi.org/10.1142/9280)

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Abstract

Thermodynamics and dielectric properties of nematic liquid crystals doped with various nanoparticles have been studied in the framework of a molecular mean-field theory. It is shown that spherically isotropic nanoparticles efectively dilute the liquid crystal material and cause a de- crease of the nematic-isotropic transition temperature, while anisotropic nanoparticles are aligned by the nematic host and, in turn, may sig- nifcantly improve the liquid crystal alignment. In the case of strong interaction between spherical nanoparticles and mesogenic molecules, the nanocomposite possesses a number of unexpected properties: The nematic-isotropic co-existence region appears to be very broad, and the system either undergoes a direct transition from the isotropic phase into the phase-separated state, or undergoes first a transition into the ho- mogeneous nematic phase and then phase-separates at a lower tempera- ture. The phase separation does not occur for sufficiently low nanopar- ticle concentrations, and, in certain cases, the separation takes place only within a finite region of the nanoparticle concentration. For ne- matics doped with strongly polar nanoparticles, the theory predicts the nanoparticle aggregation in linear chains that make a substantial contri- bution to the static dielectric anisotropy and optical birefringence of the nematic composite. The theory clarifies the microscopic origin of im- portant phenomena observed in nematic composites including a shift of the isotropic-nematic phase transition and improvement of the nematic order; a considerable softening of the first order nematic-isotropic tran- sition; a complex phase-separation behavior; and a significant increase of the dielectric anisotropy and the birefringence.

  • Item type:Book Section
    ID code:55879
    Dates:
    Date
    Event
    31 October 2016
    Published
    3 August 2016
    Accepted
    Notes:Electronic version of an article published asOsipov, M. A., & Gorkounov, M. V. (2016). Nematic liquid crystals doped with nanoparticles: phase behavior and dielectric properties. In J. P. F. Lagerwall, & G. Scalia (Eds.), Liquid Crystals with Nano and Microparticles (Series in Soft Condensed Matter; Vol. 7). Singapore: World Scientific Publishing Company. DOI: 10.1142/9280 - © World Scientific Publishing Company.
    Subjects:Science > Chemistry
    Department:Faculty of Science > Mathematics and Statistics
    Depositing user: Pure Administrator
    Date deposited:14 Mar 2016 14:23
    Last modified:19 Apr 2024 00:04
    Related URLs:
    URI:https://strathprints.strath.ac.uk/id/eprint/55879
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