Lyotropic Liquid Crystal Formed in Aqueous Lecithin Solutions with IPM and AEO20 Additives

Abstract

Abstract The phase behavior and rheological properties of a lyotropic liquid crystal formed in the lecithin/AEO20/IPM/H2O system were investigated by means of phase diagram, polarized optical microscopy and rheology techniques at 37°C. After adding polyoxyethylene-20-oleyl ether (AEO20) and isopropyl myristate (IPM) to lecithin solutions, an isotropic liquid phase and an anisotropic liquid crystal phase were found. By analyzing the shear viscosity (η γ=0.1) and yield stress (σ 0), with increase in water content, the η γ=0.1 and σ 0 increase firstly and then decrease; with increasing IPM content, a decrease in the η γ=0.1 and σ 0 is observed. Notably, at the relatively higher water content area, the water content has little effect on the η γ=0.1 and critical stress. When the lecithin/AEO20 mass ratio is 1:2, the liquid crystal phase displays a stronger shear resistance and more stable network structure.