Emulsions are important in numerous fields, including cosmetics, coatings, and biomedical applications. A subset of these structures, oil-in-oil emulsions, are especially intriguing for water sensitive reactions such as polymerizations and catalysis. Widespread use and application of oil-in-oil emulsions is currently limited by the lack of facile and simple methods for preparing suitable surfactants. Herein, we report the ready preparation of oil-in-oil emulsions using 2D nanomaterials as surfactants at the interface of polar and nonpolar organic solvents. Both the edges and basal plane of graphene oxide nanosheets were functionalized with primary alkyl amines and we demonstrated that the length of the alkyl chain dictates the continuous phase of the oil-in-oil emulsions (i.e., nonpolar-in-polar or polar-in-nonpolar). The prepared emulsions are stable at least 5 weeks and we demonstrate they can be used to compartmentalize reagents such that reaction occurs only upon physical agitation. The simplicity and scalability of these oil-in-oil emulsions render them ideal for applications impossible with traditional oil-in-water emulsions, and provide a new interfacial area to explore and exploit.

中文翻译：

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使用二维材料作为表面活性剂控制油包油 Pickering 型乳液

乳液在许多领域都很重要，包括化妆品、涂料和生物医学应用。这些结构的一个子集，油包油乳液，对于聚合和催化等水敏感反应特别有吸引力。油包油乳液的广泛使用和应用目前受到缺乏制备合适表面活性剂的简便方法的限制。在此，我们报告了在极性和非极性有机溶剂界面使用二维纳米材料作为表面活性剂制备油包油乳液的现成方法。氧化石墨烯纳米片的边缘和基面都用伯烷基胺进行了功能化，我们证明了烷基链的长度决定了油包油乳液的连续相（即极性中的非极性或极性中的-非极性）。制备的乳液至少可稳定 5 周，我们证明它们可用于分隔试剂，以便仅在物理搅拌时发生反应。这些油包油乳液的简单性和可扩展性使其成为传统水包油乳液无法实现的应用的理想选择，并为探索和开发提供了一个新的界面领域。