Lyotropic Liquid Crystal Formed in Oleyl Polyoxyethylene Solutions by Adding Different Additives: NaDC, Tween 80, Alkyl Esters

Abstract

Lyotropic liquid crystalline of oleylpolyoxyethylene(20)(AEO₂₀)/oil/water system was investigated at 25°C. The phase behavior, microstructure, and rheological properties of liquid crystalline were investigated by rheological techniques and polarizingoptical microscopy in the presence of various additives including Tween 80, sodium deoxycholate (NaDC), isoamylacetate, butyl acetate, isopropyl myristate. Diagrams show that cubic phase transforms to hexagonal phase when a shorter chain length oil is applied or NaDC or Tween 80 is added to the system.Flow experiments indicate the shear-thinning properties and a plastic behavior. The turning points of flow curves of the system AEO₂₀ and system AEO₂₀/NaDC were found. The dynamic modulus increase with increase in water content however the tendency is weaken by adding NaDC. Frequency dependence of experimental G ′ and G ′ were fitted using the multiple Maxwell model the cubic LLCs described by three relaxation times while hexagonal LLCs described by 5–8 elements. When AEO₂₀ mixes with Tween 80, the hexagonal have a monotonic decrease distribution of relaxation times without valleys.

Keywords:

• Lytropic liquid crystalline
• oleylpolyoxyethylene
• phase behavior
• rheological properties

Acknowledgments

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