A Superamphiphobic Coating with an Ammonia‐Triggered Transition to Superhydrophilic and Superoleophobic for Oil–Water Separation

Abstract Superhydrophilic and superoleophobic materials are very attractive for efficient and cost‐effective oil–water separation, but also very challenging to prepare. Reported herein is a new superamphiphobic coating that turns superhydrophilic and superoleophobic upon ammonia exposure. The coating is prepared from a mixture of silica nanoparticles and heptadecafluorononanoic acid‐modified TiO 2 sol by a facile dip‐coating method. Commonly used materials, including polyester fabric and polyurethane sponge, modified with this coating show unusual capabilities for controllable filtration of an oil–water mixture and selective removal of water from bulk oil. We anticipate that this novel coating may lead to the development of advanced oil–water separation techniques.