Confined Electroconvective and Flexoelectric Instabilities Deep in the Freedericksz State of Nematic CB7CB.

Autor: Krishnamurthy KS; Centre for Nano and Soft Matter Sciences , P.O. Box 1329, Jalahalli, Bangalore 560013, India., Palakurthy NB; Centre for Nano and Soft Matter Sciences , P.O. Box 1329, Jalahalli, Bangalore 560013, India., Yelamaggad CV; Centre for Nano and Soft Matter Sciences , P.O. Box 1329, Jalahalli, Bangalore 560013, India.
Jazyk: angličtina
Zdroj: The journal of physical chemistry. B [J Phys Chem B] 2017 Jun 01; Vol. 121 (21), pp. 5447-5454. Date of Electronic Publication: 2017 May 19.
DOI: 10.1021/acs.jpcb.7b03072
Abstrakt: We report wormlike flexoelectric structures evolving deep in the Freedericksz state of a nematic layer of the liquid crystal cyanobiphenyl-(CH2) 7 -cyanobiphenyl. They form in the predominantly splay-bend thin boundary layers and are built up of solitary flexoelectric domains of the Bobylev-Pikin type. Their formation is possibly triggered by the gradient flexoelectric surface instability that remains optically discernible up to unusually high frequencies. The threshold voltage at which the worms form scales as square root of the frequency; in their extended state, worms often appear as labyrinthine structures on a section of loops that separate regions of opposite director deviation. Such asymmetric loops are also derived through pincement-like dissociation of ring-shaped walls. Formation of isolated domains of bulk electroconvection precedes the onset of surface instabilities. In essence, far above the Freedericksz threshold, the twisted nematic layer behaves as a combination of two orthogonally oriented planar half-layers destabilized by localized flexoelectric distortion.
Databáze: MEDLINE
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