Location of Phase Boundaries of Lyotropic Liquid Crystal Employing Positron Lifetime Spectroscopy and Electrical Conductivity Measurement

Abstract:

Different compositions of surfactant systems give rise to a rich variety of structures of aggregates. At higher concentrations of surfactant in water, the surfactant molecules aggregate to form lyotropic liquid crystals [1]. In the present work we have prepared two surfactant systems consisting of (i) 20% of cetyl-trimethyl-ammonium-bromide (CTAB) in water, and (ii) 30% of tetra-decyl-trimethyl-ammonium-bromide (TTAB) in water. Both the systems exhibit various lyotropic liquid crystal structures when an increasing amount of co-surfactant is added as third component [2, 3]. These liquid crystalline structures are very sensitive to the solution conditions such as co-surfactant concentration, temperature, ionic strength, counter ion polarizability etc. In this study, positron life time spectroscopy and conductivity measurement have been employed to locate various phases exhibited by the lyotropic liquid crystals. In addition to delineating various phase boundaries of the systems, positron annihilation technique has also yielded new findings.

• Periodical: Materials Science Forum (Volume 733)
• Pages: 127-131
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.733.127
• Online since: November 2012
• Authors: Ramesh Yadav, K. Chandramani Singh, S.R. Choudhary, P.C. Jain
• Keywords: Aggregate, Conductivity, Micelle, Positron, Surfactant

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