Nanoscale structures of polarisation-modulated bent-core materials in thin films

We present small angle X-ray and cryogenic transmission electron microscopy (cryo-TEM) studies of three nitro-substituted (n-OPIMB-NO 2 , n = 7, 9 and16) bent-core liquid crystals (LCs) that form peculiar optical patterns known as B7 textures. Small angle X-ray scattering studies show two periodicit...

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Bibliographic Details
Published inLiquid crystals Vol. 42; no. 11; pp. 1621 - 1626
Main Authors Zhang, Cuiyu, Salili, Seyyed Muhammad, Diorio, Nicholaus, Weissflog, Wolfgang, Jákli, Antal
Format Journal Article
LanguageEnglish
Published Abingdon Taylor & Francis 02.11.2015
Taylor & Francis Ltd
Subjects
bent-core liquid crystal
Crystal structure
Molecules
Nanocrystals
nanostructure
TEM
Thin films
X-ray
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Summary:We present small angle X-ray and cryogenic transmission electron microscopy (cryo-TEM) studies of three nitro-substituted (n-OPIMB-NO 2 , n = 7, 9 and16) bent-core liquid crystals (LCs) that form peculiar optical patterns known as B7 textures. Small angle X-ray scattering studies show two periodicities between a ~ 3.4-4.7 nm and b X   ~ 9-16 nm. Cryo-TEM images of about 100 nm thick films do not show the a-periodicity, but only periodicities b T that are about 1 nm smaller than b X measured in bulk by X-ray. Additionally, an intensity modulation with a period c ~ 100-200 nm is observed. These observations can be explained by a B1-type structure, where there are half-layer step discontinuities at the boundaries of the splay domains, and where the molecules are everywhere normal to the substrate.
ISSN:0267-8292
1366-5855
DOI:10.1080/02678292.2015.1081297