Bilayer structures in cholesteric, cyclic-siloxane liquid crystals

Autor:	Edward T. Samulski, H. E. Klei, R. L. Crane, T. J. Bunning, R. J. Linville
Rok vydání:	1991
Předmět:	Biphenyl Diffraction Materials science business.industry Bilayer Mesophase General Chemistry Condensed Matter Physics Ring (chemistry) chemistry.chemical_compound Crystallography Optics chemistry Liquid crystal Siloxane General Materials Science Lamellar structure business
Zdroj:	Liquid Crystals. 10:445-456
ISSN:	1366-5855 0267-8292
DOI:	10.1080/02678299108036434
Popis:	X-ray diffraction has been used to investigate a series of commercially available liquid crystals based on a cyclic penta(methylsiloxane) with combinations of cholesteryl-4′-allyloxybenzoate and biphenyl-4′-allyloxybenzoate mesogens pendant on the siloxane ring. A lamellar, (smectic-like) structure is indicated in the mesophase and quenched glassy solid state. Extended molecular dimensions of the mesogens generally account for the observed d spacings. The mesogens may interdigitate within lamellae but the packing and extent of interdigitation is dependent on the ratio of cholesteryl to biphenyl mesogens. There is probably also a structural contribution from the nano-aggregated (nano-phase separated), immiscible, siloxane-rich layer delineating the lamellae interfaces as this mesophase shows unusually good definition; diffraction patterns exhibit high order reflections (up to 6th order). The lamellae have a macroscopic helicoidal twist about an axis lying in the plane of the lamellae, a cholesteri...
Databáze:	OpenAIRE
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