Lamellar Liquid Crystals Formed in Ternary DEP/Oil/Water Systems

Abstract

Lamellar liquid crystals of the nonionic surfactant dodecyl polyoxyethylene (4) polyoxypropylene (5) ether (DEP) were investigated by means of phase diagram and rheological technique at 25°C in the presence of different solvents. The aqueous medium includes pure water, physiological saline and 20% sucrose solution, and the oil phase includes isopropyl myristate (IPM), oleic acid, and geraniol, which are all pharmaceutically accepted chemicals. The steady and dynamic rheological property analyses of the lamellar liquid crystals formed in DEP/H₂O/IPM system indicate that the lamellar samples constructed by this special surfactant behave as pseudo-plastic fluid with relatively high elasticity and possess defects in their assembled structure. Also in this system, the elastic character gets decreased with increase in the water content. Furthermore, the comparison investigations show that the relatively high polar oil component increases the network strength of the lamellar phase, while increase in the polarity of water phase enhances the structure defects.

Keywords:

• Dodecyl polyoxyethylene polyoxypropylene ether
• lamellar liquid crystal
• phase behavior
• rheological properties
• ternary surfactant system

Acknowledgments

Financial support of this work by the Natural Science Foundation of China (31071603 and 21073081) is gratefully acknowledged.