Formation and development of nanometer-sized cybotactic clusters in bent-core nematic liquid crystalline compounds

Yuri P. Panarin, Sithara P. Sreenilayam, Jagdish K. Vij, Anne Lehmann, Carsten Tschierske

    Research output: Contribution to journalArticlepeer-review

    Abstract

    Two homologue achiral bent-core liquid crystals (LCs), BCN66 and BCN84, in their nematic phases are studied by dielectric spectroscopy in the frequency range 10 Hz-10 MHz. In each of these compounds, two relaxation processes are identified and assigned to (i) collective dynamics of molecules in nanometer-sized cybotactic clusters and (ii) individual molecular relaxations, in the ascending order of frequency of the probe field. The temperature and the bias electric field dependence of the dielectric strength and relaxation frequency for these processes are shown to give rise to sharpness in cluster boundaries, increased size and volume fraction in the LC nematic phase. The effect of the bias field on the LC cell is similar to reducing its temperature; both variables increase the cluster size and volume fraction and give rise to sharp cluster boundaries. The findings confirm that dielectric spectroscopy is a powerful and an extremely useful technique to provide a deeper understanding of the mechanism of cybotactic cluster formation in the isotropic liquid and the nematic phase of LCs as a function of temperature and the bias field.

    Original languageEnglish
    Pages (from-to)1288-1296
    Number of pages9
    JournalBeilstein Journal of Nanotechnology
    Volume9
    Issue number1
    DOIs
    Publication statusPublished - 2018

    Keywords

    • Bent-core liquid crystals
    • Biaxiality
    • Clusters
    • Dielectric spectroscopy

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