LAUSR

Underoil adhesives are intensively needed in case of oil spill caused by pipeline rupture, but remain a challenge owing to the obstruction of oil layer or their swelling in oil. Herein, a general solvent diffusion principle is demonstrated by introducing dual‐soluble “mediator” solvents to develop a new type of interfacial instability‐induced (3I) adhesives, achieving effective underoil adhesion on various substrates and blocking the oil leakage within seconds. Microscopic characterization reveals a fast and dynamic solvent exchange process that destroys the oil layer by liquid–liquid interfacial diffusion between the “mediator” solvent and oil, enabling 3I adhesives to contact the solid surfaces directly. The principle of interfacial instability‐induced liquid replacement is quite different from typical immiscible liquid replacement and is not restricted by the surface tension of solvents, surface energy, and roughness of solid surfaces, successfully directing the construction of a series of effective 3I adhesives with commercially available feedstocks. This study provides a unique clue for the design of next‐generation adhesives in complex environments.