Low frequency dielectric relaxation in liquid crystal-polymer composites

Year: 2004

Authors: Dolgov L., Yaroshchuk O., Kovalchuk A., Wiersma D.

Autors Affiliation: Institute of Physics, NASU, pr. Nauki 46, 03028 Kyiv, Ukraine; LENS, University of Florence, via Nello Carrara 1, 50019 Florence, Italy

Abstract: The dielectric constants epsilon\’ and epsilon\” of a series of \”liquid crystal (LC) – polymer\” composites in the frequency region 10(-3)- 10(5) Hz are measured. The composites are prepared by a photo-separation method with the variation of polymer content from 0 to 50 weight %. For all samples, a relaxation effect with a low relaxation frequency (10(-1)-20 Hz) is observed. This effect is assigned to dielectric relaxation in the near-electrode layers. The experimentally observed increase of the relaxation frequency and the electric conductivity with polymer concentration is explained by incomplete phase separation occurred in \”liquid crystal – pre-polymer\” mixture under irradiation.

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KeyWords: Dielectric relaxation; Irradiation; Liquid crystal polymers; Mixtures; Natural frequencies; Permittivity; Phase separation; Scanning electron microscopy, Isotropic transitions; Polarizers; Polymer network liquid crystals (PNLC); Polymer networks, Composite materials
DOI: 10.1117/12.569819