Pyridinium salt liquid crystals Effect of mesogen extension and alkyl chain length
作者:
Maryam Tabrizian,
Armand Soldera,
Michel Couturier,
C.Geraldine Bazuin,
期刊:
Liquid Crystals
(Taylor Available online 1995)
卷期:
Volume 18,
issue 3
页码: 475-482
ISSN:0267-8292
年代: 1995
DOI:10.1080/02678299508036647
出版商: Taylor & Francis Group
数据来源: Taylor
摘要:
The thermotropism of 1-n-alkyl-(4-methyl and 4-tolyl)pyridinium bromides were compared for alkyl chain lengths ranging fromn= 12 to 22 carbons. A smectic A mesophase is present in both series for the longer chain compounds,n≥ 16, with the clearing temperature being similar for both series but increasing rapidly with chain length. The series with the elongated mesogen also possesses an ordered mesophase identified as smectic G. The transition between this mesophase and the SAor isotropic phase in the 4-tolyl series, and the transition to and from the crystalline phase in both series, are affected relatively little by the alkyl chain length. It seems that the SAmesophase is governed primarily by the amphiphilic character of the substances, whereas elongation of the ionic head group is responsible for the appearance of a more ordered mesophase at intermediate temperatures.
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