Gelation at oil–water interface by using dimethylcyclohexylamine/fatty acid-based surface-active ionic liquids

Organogelators and hydrogelators which belong to low-molecular-weight gelators (LMWGs) have attracted considerable attention due to various practical applications. Whether organogelators or hydrogelators, they can congeal single oil or water phase. However, gelators capable of gelation at oil/water interface have thus far remained unexplored. Herein, we report a class of surface-active ionic liquids (SAILs) based on dimethylcyclohexylamine and fatty acids. They can form high-strength gels at the oil/water interface instead of in single oil or water phase. These molecules spontaneously aggregate at oil/water interface, and then self-assemble into lamellar liquid crystalline structure, as evident from POM and SAXS analysis. Rheology analysis shows that these gels are of very high viscosity, strength and stability. These unique characters make these SAILs can effectively block the oil–water interface, which has potential application in oilfield development or oil leaks from underwater tubes.