X-ray microscopy study of chromonic liquid crystal dry film texture

Journal Article · Sat Dec 15 00:00:00 EST 2007 · Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics (Print)

DOI:https://doi.org/10.1103/PHYSREVE.76.061703· OSTI ID:21101958

Kaznatcheev, K V ^[1]; Dudin, P ^[1]; Lavrentovich, O D ^[2]; Hitchcock, A P ^[3]

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1. Canadian Light Source, University of Saskatchewan, Saskatoon, SK S7N 0X4 (Canada)
2. Liquid Crystal Institute, Kent State University, Kent, Ohio 44242 (United States)
3. BIMR, Department of Chemistry, McMaster University, Hamilton, Ontario, L8S 4M1 (Canada)

Soft x-ray spectromicroscopy has been used to investigate the degree of the molecular alignment of sulfonated benzo[de]benzo[4.5]imidazo[2,1-a]isoquinoline[7,1], a lyotropic chromonic liquid crystal (LCLC). LCLC thin films cast from concentrated aqua solution (20 % wt.), aligned by shear flow and dried, show strong linear dichroism in their C-, N-, O-, S-K edge near edge x-ray spectra (NEXAFS). The carbon K edge has been used for quantitative evaluation of the orientational texture of the films at a submicron spatial scale. This has verified there is predominantly in-plane alignment of the LC director. To highlight the role of hydrophobic-hydrophilic interactions, two stereoisomers of the same dye has been synthesized with different positioning of terminal sulfonate groups, in the form of a mixture of isomers with sulfonate groups in 2,10 and 2,11 positions (Y104 compound) and in a 5,10-disulfo arrangement (Y105). Both compounds develop characteristic herringbone-type texture with similar domain sizes. Polarized optical microscopy and higher resolution x-ray microscopy show sinusoidal-like undulations of the molecular director, with occasional crisscross appearance. Such behavior is found to be consistent with earlier observation of striations, characteristic of the columnar phase. The drastic difference in the degree of undulation ({+-}15 deg. in Y104 and {+-}7 deg. in Y105 films) and long period of undulation (approaching the film thickness) requires further analysis. It was also found that the degree of in-plane order within domains changes from 0.8 for Y104 to >0.9 in Y105 films.

• OSTI ID: 21101958
• Journal Information: Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics (Print), Vol. 76, Issue 6; Other Information: DOI: 10.1103/PhysRevE.76.061703; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 1539-3755
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ABSORPTION SPECTROSCOPY
AQUEOUS SOLUTIONS
CARBON
DICHROISM
DYES
EVALUATION
FINE STRUCTURE
ISOMERS
LIQUID CRYSTALS
OPTICAL MICROSCOPY
ORGANIC COMPOUNDS
POSITIONING
RESOLUTION
SOFT X RADIATION
STRIATIONS
TEXTURE
THIN FILMS
X-RAY SPECTRA
X-RAY SPECTROSCOPY