ISSN:
1435-1536
Keywords:
Key words Oil penetration
;
Phase behavior
;
Small-angle X-ray scattering
;
Lamellar liquid crystal
;
Cationic surfactant
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
,
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
Abstract The mixing fraction of didodecyldimethylammonium bromide (DDAB) in dodecyltrimethylammonium bromide + DDAB to produce a lamellar liquid crystal (L α) abruptly decreases upon addition of a small amount of m-xylene, whereas the mixing fraction becomes constant at high m-xylene content. Similar results were obtained in saturated hydrocarbon systems. It is considered that oil molecules in the surfactant palisade layer increases the effective cross-sectional area per surfactant head group, as, whereas as is constant if the oil molecules are solubilized in the core of the liquid crystal. The volume fraction of penetrating oil in the total solubilized oil is defined as a penetration parameter, Pe, which is calculated from small-angle X-ray scattering data. Pe is high in the m-xylene system, whereas it is low in the n-decane system. Even in the same oil system, Pe decreases dramatically with increasing solubilization. Hence, most of the oil added penetrates into a palisade layer at an early stage of oil addition. This causes a change in the mixing fraction of surfactant in the L α phase. Thereafter the oil is solubilized in the core of the bilayer with further addition of oil.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/s003960050364
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