Anomalies of periodicity in TGB structures in new liquid crystal dimers

Autor:	F. Hardouin, Jung-Il Jin, Marie-France Achard, Soon Wook Cha
Rok vydání:	2002
Předmět:	chemistry.chemical_classification Materials science Mesogen General Chemistry Condensed Matter Physics Crystallography chemistry Polymorphism (materials science) Liquid crystal Alkoxy group Moiety Organic chemistry Molecule General Materials Science Alkyl
Zdroj:	Liquid Crystals. 29:755-763
ISSN:	1366-5855 0267-8292
DOI:	10.1080/02678290210129902
Popis:	Non-symmetric liquid crystal dimers consist of two different mesogenic units linked through a polymethylene flexible spacer. Our previous studies have shown that dimers containing a cholesteryl moiety as one of the mesogenic groups and a Schiff's base unit as the second, exhibit a rich polymorphism and that several types of smectic packing are obtained depending on the molecular parameters: specifically, a smectic periodicity similar to the molecular length and an intercalated structure with a smectic parameter lower than half the molecular length can be obtained. The competition between these two incommensurate lengths can induce two-dimensional phases and/or an incommensurate smectic phase in which the two smectic periodicities coexist over a long range. Small modifications of the molecular structure can significantly influence the phase sequence. Here we have replaced the Schiff's base by a tolan unit and the terminal alkyl chains by alkoxy chains. As a result, anomalies of periodicity are also observe...
Databáze:	OpenAIRE
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