Dielectric relaxation in a novel tapered chiral photochromatic liquid crystalline dendrimer

ABSTRACT

Temperature-dependent dielectric spectroscopic measurements of newly synthesised ribbon-shaped chiral liquid crystalline dendrimer with photochromic azobenzene mesogens and an isosorbide chiral centre on planar anchoring cell have been performed in the frequency range of 1.0 Hz to 5.5 MHz. Three dielectric dispersions in the relaxation frequency range of 10–80 Hz, 80–130 kHz and ~3.5 MHz have been observed not only in chiral smectic phase but also in isotropic phase in which two lower-frequency processes are retarded while the other one remained at same relaxation rate from isotropic to chiral smectic phase. Based on the dielectric and optical polarising microscopic results, the chiral smectic phase has been identified as SmC* phase. The relaxation mode observed at low-frequency region in the SmC* phase followed the dielectric characteristics of pinned Goldstone mode. Whereas the dielectric dispersions observed at high-frequency region have been analysed in the framework of the model given by Maier and Meier.

GRAPHICAL ABSTRACT

KEYWORDS:

• Dendrimer
• chiral smectic liquid crystal
• dielectric relaxation
• photochromatic

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This research was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the ministry of Science, ICT & Future Planning [NRF-2013R1A1A1058681]. This research was also supported by the Ministry of Trade, Industry & Energy [MOTIE, 10051334] and Korea Display Research Corporation (KDRC). This work was partially supported by BRL (2015042417) and IDEC.