Frustrated structure of an anticlinic-like smectic-C phase.

Full Abstract

We present a polarising optical microscopy study of the low-temperature anticlinic-like tilted mesophase of the liquid-crystal compound octylphenyl-2-chloro-4-(p-cyano-benzoyloxy) (DB8Cl). This mesophase has been described as a bilayer smectic structure in which the molecules within each layer are organised in an anticlinic way. The optical textures observed in samples with planar orientation show a double stripe pattern, with the lines aligned parallel to the rubbing direction, characteristic of a double periodic modulation of the refractive index of the material. The long-period modulation is temperature dependent and disappears for thin sample cells (< 5 microm). The short-period modulation is nearly independent of the thickness of the cells. The experimental results are analysed in terms of a model which considers that there is a special distribution of the principal optical axis which may be in or out of the polariser-analyser plane. The observed periodic variation of the principal optical axis could not be interpreted in terms of the original structure proposed for this phase. DB8Cl presents a structure formed by dimers that can be viewed as flexible bent-core-like molecules, showing similarities with phases found in banana-like systems, but exhibiting a much more complex structure.

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Author information

Author/s: Sebastião, P J (PJ); Simeão Carvalho, P (P); Chaves, M R (MR); Nguyen, H T (HT); Ribeiro, A C (AC);

Affiliation: Centro de Física da Matéria Condensada, Av. Prof. Gama Pinto 2, 1649-003, Lisboa Codex, Portugal. pedros(-atsign-)lince.cii.fc.ul.pt

Journal and publication information

Publication Type: Journal Article

Journal: The European physical journal. E, Soft matter (Eur Phys J E Soft Matter), published in France. (Language: eng)

Reference: 2006-May; vol 20 (issue 1) : pp 55-61

Dates: Created 2006/05/30; Completed 2006/09/05;

PMID: 16733639, status: MEDLINE (last retrieval date: 12/26/2008)

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MeSH headings (categories)

This article was linked to the MESH Headings shown below.

Phase Transition
Phenols - chemistry
Polymers - chemistry
Stress, Mechanical

Associated Chemicals: Phenols (0) ; Polymers (0) ; liquid crystal polymer (0) ; octylphenol (0)

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