Complex Phase Behavior in the Transition Region Between Gel (L_β) and Lamellar (L_α) Phases for a Commercial Nonionic Surfactant System, C_12-14EO₃

Abstract

Surfactant formulators are faced with many challenges during product processing and manufacture, with increased problems from the use of commercial surfactants. Commercial surfactants have a distribution of EO sizes which can dramatically affect the product properties. The gel (L _β )/lamellar (L _α ) phase transition of a commercial surfactant C_12-14EO_2.9/water system is shown to split into two, with the sequence ↔ L _α being observed, where the region occurs over a ca. 10°C temperature range. In addition, both the gel and lamellar phases can incorporate at least 2–3 times more water than the pure surfactants before the formation of a separate aqueous phase. So while commerical surfactants could pose problems for formulators, they could also offer the possibility of enhanced solubilization of actives in the lamellar regions coupled with the enhanced emulsion stabilization by the gel phase.

Keywords:

• Formulation
• gel
• lamellar
• phase behavior
• surfactant

Acknowledgments

The authors would like to thank EPSRC and Unilever Research for their financial support, together with CLRC Daresbury for the x-ray facilities. The authors also thank Dr. Rob J. Nicol for help with the phase structures for this commercial surfactant.

Notes

From the Proceedings from Formula VI in Stockholm 2010.