Lyotropic mesomorphism of alkyl esters of acyl-L-carnitines
作者:
Paolo De Maria,
Sara Frascari,
Paolo Mariani,
Letizia Saturni,
GianPiero Spada,
MariaOrnella Tinti,
期刊:
Liquid Crystals
(Taylor Available online 1995)
卷期:
Volume 19,
issue 3
页码: 353-365
ISSN:0267-8292
年代: 1995
DOI:10.1080/02678299508031992
出版商: Taylor & Francis Group
数据来源: Taylor
摘要:
The lyotropic polymorphism of a series of alkyl esters of acyl-L-carnitine has been studied by optical polarizing microscopy and X-ray diffraction. The different structures observed as a function of concentration and temperature have been characterized and their topology determined. As a result, two different phase sequence patterns have been detected: esters of normal alcohols bearing an alkyl chain of 6 or more carbon atoms in the acyl substituent display only a lamellar phase, while compounds which bear a relatively short alkyl chain (4 or less carbon atoms) show in addition non-lamellar type I hexagonal and cubic Q230phases. From the analysis of the areas-per-molecule at the polar/apolar interface, the ability of the compounds investigated to form not only non-lamellar phases, but also direct micelles in isotropic solution has been related to the structural characteristics of the molecules. Curved, convex interfaces (in micelles and in non-lamellar phases) are possible only for the most polar acylcarnitines which have a relatively short alkyl chain, so that they behave like single chain surfactants; the most paraffinic derivatives, which have a relatively long alkyl chain, are effective double chain surfactants and then generate only quasi-planar interfaces.
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