Emulsification through Surfactant Hydration: The PIC Process Revisited

详细信息    查看全文

• 作者：Kevin Roger ; Bernard Cabane ; Ulf Olsson
• 刊名：Langmuir
• 出版年：2011
• 出版时间：January 18, 2011
• 年：2011
• 卷：27
• 期：2
• 页码：604-611
• 全文大小：963K
• 年卷期：v.27,no.2(January 18, 2011)
• ISSN：1520-5827

文摘

We have performed sudden composition changes on a (surfactant + oil + water) system by adding water to a (surfactant + oil) solution. This composition change quenches the system into a metastable oil-in-water emulsion with a population in the 100 nm range. The conditions for a successful quench are as follows: the initial water content should be below a boundary called the 鈥渃learing boundary鈥?(<b>CBb>), the final water content should be sufficiently beyond <b>CBb>, and the quench should be fast. We have used high purity components to avoid the complex phase separation patterns that occur with low purity ingredients: the surfactant is octaethylenehexadecyl ether (Cb>16b>Eb>8b>) and the oil is hexadecane (Cb>16b>). Under these conditions, we show that the pathway for this type of quench proceeds through the swelling of the reverse micellar phase by the added water and the formation of a sponge phase. Then, further water addition causes the nucleation of oil droplets in this sponge phase, with a size that matches the spontaneous curvature of the sponge phase. Part of the surfactant remains adsorbed on these droplets, and the rest is expelled as micelles that coexist with the droplets. It is concluded that a PIC emulsification will always lead to a bimodal size distribution with surfactant 鈥渨asted鈥?in small micelles. This is in contrast with the more efficient PIT emulsification.