Structure and Percolation of Inverted Cylindrical Branched Micelles

There have been strong indications that lecithin with trace amounts of water in isooctane forms branched cylindrical micelles at relatively high water content. At a certain volume fraction these micelles percolate to form a connected network. Here this phenomenon is studied by viscometry and dielect...

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Bibliographic Details
Published inJournal of dispersion science and technology Vol. 22; no. 2-3; pp. 211 - 219
Main Authors Cirkel, P. A., Fontana, M., Koper, G. J. M.
Format Journal Article
LanguageEnglish
Published Philadelphia, PA Taylor & Francis Group 31.03.2001
Taylor & Francis
Subjects
Chemistry
Colloidal state and disperse state
Exact sciences and technology
General and physical chemistry
Micelles. Thin films
Branching
Cylindrical configuration
Volume fraction
Hydrocarbon
Molecular structure
Temperature effect
Micelle
Phospholipid
Composition effect
Lipids
Soybean
Experimental study
Isooctane
Free energy
Alkane
Water content
Phosphatidylcholine
Percolation
Aqueous solution
Thermodynamic properties
Phosphatidic acid
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Summary:There have been strong indications that lecithin with trace amounts of water in isooctane forms branched cylindrical micelles at relatively high water content. At a certain volume fraction these micelles percolate to form a connected network. Here this phenomenon is studied by viscometry and dielectric spectroscopy as a function of volume fraction and temperature. The observed percolation threshold is used to estimate the mean length between, and the size of, branch points. There is however a discrepancy with the theoretical model which can be explained by a water content dependent ratio of branch points and end-caps. It is argued that this is related to the water induced change from dynamic to static percolation, indicated by the observed scaling exponents. From the temperature dependence of the phase boundary the free energy of a branch point is estimated. As a function of the water content branch point formation changes from driven entirely by enthalpy towards more entropically driven.
ISSN:0193-2691
1532-2351
DOI:10.1081/DIS-100105208