Guangdong Provincial Key Laboratory of Industrial Surfactant , Guangdong Research Institute of Petrochemical and Fine Chemical Engineering , Guangzhou 510000 , Guangdong P. R. China.
Langmuir. 2018 Sep 25;34(38):11544-11552. doi: 10.1021/acs.langmuir.8b02456. Epub 2018 Sep 14.
Photoresponsive complex emulsions are prepared in a three-phase system consisting of two oils: hexane (H) and perfluorooctane (F). An aqueous solution of a mixed surfactant of fluorosurfactant, F(CF) (CHCHO) H (Zonyl FS-300), and a synthesized light-responsive surfactant, 2-(4-(4-butylphenyl)diazenylphenoxy)ethyltrimethylammonium bromide (CAZOCTAB) was employed as the continuous phase. Complex emulsions with various geometries were prepared by one-step vortex mixing and a temperature-induced phase-separation method. It was noticed that the topology of the complex emulsion was highly dependent on the mass ratio of Zonyl FS-300/CAZOCTAB. Light microscopy images showed that phase inversion from an H/F/W- to an F/H/W-type double emulsion via a Janus emulsion was achieved by gradually increasing the mass ratio of CAZOCTAB/Zonyl FS-300. Upon UV/blue light irradiation, the topology of complex emulsions was turned to switch from an F/H/W double emulsion to a Janus emulsion to an entirely inverted H/F/W double emulsion. Dynamic interfacial tension measurements showed that UV irradiation of the interface between an aqueous trans-CAZOCTAB solution and hexane brings about an increase in the interfacial tension, suggesting the nature of photoinduced morphological changes in complex emulsions. The reconfiguration process of complex emulsions was illustrated by the Marangoni effect based on heterogeneity in the interfacial tension at the complex emulsion surface induced by controlling the molecular conversion of CAZOCTAB using light irradiation. Finally, we used the complex emulsions structure to form an on-off switch to start and shut off the evaporation of one volatile phase to achieve process monitoring. This could be used to initiate and quench a reaction, which offers a novel idea for achieving switchable and reversible reaction control in multiple-phase reactions.
己烷（H）和全氟辛烷（F）组成的三相体系中制备的。氟表面活性剂 F(CF) (CHCHO) H (Zonyl FS-300) 和合成的光响应表面活性剂 2-(4-(4-丁基苯基)偶氮基苯氧基)乙基三甲基氯化铵 (CAZOCTAB) 的混合水溶液被用作连续相。通过一步涡旋混合和温度诱导相分离方法制备具有各种几何形状的复合乳液。人们注意到，复合乳液的拓扑结构高度依赖于 Zonyl FS-300/CAZOCTAB 的质量比。光镜图像显示，通过逐渐增加 CAZOCTAB/Zonyl FS-300 的质量比，可以实现从 H/F/W 型到 F/H/W 型双乳液再到 Janus 乳液的相反转。在紫外/蓝光照射下，复合乳液的拓扑结构从 F/H/W 双乳液转变为 Janus 乳液，再转变为完全倒置的 H/F/W 双乳液。动态界面张力测量表明，紫外光照射水相 trans-CAZOCTAB 溶液和己烷之间的界面会导致界面张力增加，这表明复合乳液中光诱导形态变化的性质。通过控制 CAZOCTAB 的光诱导分子转换，利用复合乳液表面的界面张力异质性基于马兰戈尼效应来阐明复合乳液的重构过程。最后，我们利用复合乳液的结构形成开/关开关，启动和关闭一种挥发性相的蒸发，以实现过程监测。这可用于引发和淬灭反应，为多相反应中实现可切换和可逆反应控制提供了新的思路。
