Colloid and Polymer Science

, Volume 286, Issue 1, pp 31–46 | Cite as

Liquid crystal and solution phases of sodium dodecyl-p-benzene sulphonate (NaLAS) and octa-oxyethylene glycol hexadecyl ether (C16E8): 1:1 mixtures in water

  • Claire Richards
  • Gordon J. T. Tiddy
  • Siobhan Casey
Original Contribution
First Online:
Received:
Accepted:

Abstract

The liquid crystals and other phases formed when the mixed surfactant system sodium dodecyl-p-benzene sulphonate (NaLAS) and octa-oxyethylene glycol hexadecyl ether (C16E8, 1:1 by weight) is dispersed in water have been investigated using optical microscopy, X-ray diffraction and differential scanning calorimetry. Despite the fact that neat LAS is a multi-phase solid and C16E8 is a crystalline solid, when the two are mixed at temperatures above the melting temperature of the C16E8 with no water present, what appears to be a metastable gel phase formed containing only a small volume fraction of un-dissolved LAS (ca. 5%). Moreover, when water is added to the system, the phase behaviour of the mixture considerably differs to that of either of the individual components. We report a detailed phase study on this mixture here particularly focussing on the ‘neat’ mixture. The phase behaviour when water is added is also discussed. Particularly interesting is the presence of a micellar phase between the hexagonal and lamellar phases thought to be due to weak interactions between micelles during the transition from rods to discs. In addition, the presence of a low temperature intermediate phase is discussed.

Keywords

Surfactant Liquid crystal Dissolution Mixed anionic non-ionic 
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Notes

Acknowledgment

It is a pleasure to thank EPSRC and Unilever Research for financial support, together with CLRC Daresbury for the X-ray facilities.

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Copyright information

© Springer-Verlag 2007

Authors and Affiliations

  • Claire Richards
    • 1
  • Gordon J. T. Tiddy
    • 1
  • Siobhan Casey
    • 2
  1. 1.School of Chemical Engineering & Analytical ScienceUniversity of ManchesterManchesterUK
  2. 2.Unilever Research Port Sunlight LaboratoryMerseysideUK

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