Orientational order in liquid crystals exhibited by some binary mixtures of rod-like and bent-core molecules

Kundu, B. ; Pratibha, R. ; Madhusudana, N. V. (2010) Orientational order in liquid crystals exhibited by some binary mixtures of rod-like and bent-core molecules European Physical Journal E: Soft Matter, 31 (2). pp. 145-152. ISSN 1292-8941

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Official URL: http://www.springerlink.com/content/q278g27k243104...

Related URL: http://dx.doi.org/10.1140/epje/i2010-10556-8

Abstract

We report measurements of the temperature variations of the optical birefringence in the nematic (N) and partial bilayer SmA (SmAd) phases in 4-n-octyloxy 4' -cyanobiphenyl made of rod-like (R) molecules and five mixtures of this compound with 1,3-phenylene bis[4-(3-methylbenzoyloxy)] 4' -n- dodecylbiphenyl 4' -carboxylate, made of bent-core (BC) molecules. The birefringence decreases with the concentration x of the BC molecules but the macroscopic order parameter initially decreases upto 11mol% of BC molecules and subsequently increases with x . This is attributed to the possible formation of polar clusters of BC molecules. Orientation of BC molecules changes between the N and SmAd phases and the birefringence data in the two phases imply that the kink angle of the BC molecules is ~90° rather than ~110° as obtained from calculations which minimize the energy of the molecule. IR spectroscopic measurements on the mixture with 11mol% of BC molecules have been used to estimate the molecular order parameter S of the R molecules, and to provide additional support for a relatively small kink angle of BC molecules.

Item Type:Article
Source:Copyright of this article belongs to EDP Sciences.
ID Code:21041
Deposited On:20 Nov 2010 09:19
Last Modified:07 Jun 2011 04:51

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