Phase Behavior, Formation, and Rheology of Cubic Phase and Related Gel Emulsion in Tween80/Water/Oil Systems

抄録

We investigated the phase behavior, formation, and rheology of the cubic phase (I₁) and related O/I₁ gel emulsion in water/Tween 80/oil systems using squalane, liquid paraffin (LP), and decane as oil components. In the phase behavior study, the phase sequences were similar for squalane and LP systems, while a lamellar liquid crystal (L_α) was observed for decane system. In all the systems the addition of oil to W_m or H₁ phase induced the I₁ phase, which can solubilize some amounts of oil followed by the appearance of I₁+O phase. The formation of the O/I₁ gel emulsion has been studied at a fixed w/s (50/50) and we found that 30 wt% decane, 70 wt% squalane, and 60 wt% LP can form the gel emulsion. The water/Tween 80/squalane system has been taken as a model system to study viscoelastic properties of the I₁ phase and O/I₁ gel emulsion. The I₁ phase shows a typical hard gel cubic structure under the frequency and the values of the complex viscosity, ¦η*¦ and the elastic modulus, G ′ increase with the addition of squalane, which could be due to the neighboring micellar interaction. On the other hand, the decreasing values of the viscoelastic parameters in the O/I₁ gel emulsion simply relate to the volume fraction of the I₁ phase in the system.