Phase diagram studies in two-surfactant ternary systems employing positron annihilation spectroscopy

Positron annihilation lifetime parameters in condensed media are sensitive to structural and conformational changes. This property has been exploited to study the phase diagrams of two ternary cationic surfactant systems. Positron lifetime measurements were performed in cetyltrimethylammonium bromid...

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Bibliographic Details
Published in:Journal of colloid and interface science 2005-02, Vol.282 (1), p.176-181
Main Authors: Chandramani Singh, K., Khani, P.H., Yadav, R., Jain, P.C.
Format: Article
Language:English
Subjects:
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Chemistry
Exact sciences and technology
General and physical chemistry
Lamellar structure
Phase transitions
Positron
Surfactant
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Summary:Positron annihilation lifetime parameters in condensed media are sensitive to structural and conformational changes. This property has been exploited to study the phase diagrams of two ternary cationic surfactant systems. Positron lifetime measurements were performed in cetyltrimethylammonium bromide (CTAB)/water/hexanol and tetradecyltrimethylammonium bromide (TTAB)/water/pentanol systems having varying concentrations of hexanol and pentanol respectively. For both the systems, changes were observed in the positron lifetime parameters whenever a phase transformation occurred. The various phase boundaries demarcated by this technique agrees well with those obtained by other conventional techniques. Besides this, the present work suggests the existence of two kinds of lamellar structures referred to as D I and D II phases in both the systems, which were otherwise considered to be a single D phase by other conventional techniques. The existence of such lamellar structures has been demonstrated by a change in the trend of o-Ps lifetime when the system passes from one type of lamellar structure to the other type. The results of these investigations are presented.
ISSN:0021-9797
1095-7103
DOI:10.1016/j.jcis.2004.08.112