Effective and Reversible Switching of Emulsions by an Acid/Base-Mediated Redox Reaction

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• 作者：Yuandi Zhang ; Hui Chen ; Xuefeng LiuYongmin Zhang ; Yun Fang ; Zhirong Qin
• 刊名：Langmuir
• 出版年：2016
• 出版时间：December 27, 2016
• 年：2016
• 卷：32
• 期：51
• 页码：13728-13735
• 全文大小：506K
• ISSN：1520-5827

文摘

To develop a fast, effective, and reversible strategy for phase separation and re-emulsification of the surfactant-based emulsions, a strategy for using acid/base-mediated redox reactions was established to switch the emulsions formed from a redox-responsive anionic surfactant of potassium dodecyl seleninate (C₁₂SeO₂K). Upon acidification, C₁₂SeO₂K was reduced by KI to give didodecyl diselenide (C₁₂Se)₂, a state of almost no surface or interfacial activity; upon basification, (C₁₂Se)₂ was oxidized by I₂ to give C₁₂SeO₂K again. The fractional conversion of C₁₂SeO₂K in the reversible switching processes was close to 100%. Consequently, an unusually large change in interfacial tension (ΔIFT) as high as ∼27.1 mN m^–1 was obtained at a wider concentration range starting from the critical micelle concentration of C₁₂SeO₂K; the highest IFT at the oil–water interface was obtained after an almost complete switch-off, giving an oil–aqueous solution interface very similar to that without any emulsifiers, which leads to the effective and fast phase separation of the C₁₂SeO₂K-based switchable emulsions.