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Pickering emulsions are an excellent platform for interfacial catalysis. However, developing simple and efficient strategies to achieve product separation and catalyst and emulsifier recovery is still a challenge. Herein, we report the reversible transition between emulsification and demulsification of a light‐responsive Pickering emulsion, triggered by alternating between UV and visible light irradiation. The Pickering emulsion is fabricated from Pd‐supported silica nanoparticles, azobenzene ionic liquid surfactant, n‐octane, and water. This phase behavior is attributed to the adsorption of azobenzene ionic liquid surfactant on the surface of the nanoparticles and the light‐responsive activity of ionic liquid surfactant. The Pickering emulsion can be used as a microreactor that enables catalytic reaction, product separation as well as emulsifier and catalyst recycling. Catalytic hydrogenation of unsaturated hydrocarbons at room temperature and atmospheric pressure has been performed in this system to demonstrate product separation and emulsifier and catalyst re‐use. [ABSTRACT FROM AUTHOR]

It is known that traditional microemulsions are thermodynamically stable mixtures which are extensively applied in many fields. However, how to control emulsification and demulsification of microemulsions more flexibly in practical applications is still a challenge. In the present study, a new type of temperature-sensitive ionic liquid (IL) microemulsion [P 4444 ][CF 3 COO]/[C 12 mim]Br/H 2 O, composed of two ILs and water molecules, was designed. Compared with traditional microemulsions, this IL microemulsion was more sensitive to the small range of temperature. Thus, the reversible emulsification and demulsification process can easily be switched by using temperature as a trigger. To elucidate the demulsification mechanism of this temperature-sensitive IL microemulsion, a series of molecular simulations were performed at different temperatures. The simulation results indicate that the interaction between [CF 3 COO]− and H 2 O is the driving force of demulsification process. In addition, the effect of [P 4444 ][CF 3 COO] and [C 12 mim]Br concentration on the microstructure of microemulsion was investigated rigorously. The results demonstrate that contents of both the [P 4444 ][CF 3 COO] and [C 12 mim]Br have an important influence on the demulsification behavior of IL microemulsion. Unlabelled Image • A new type of temperature-sensitive ionic liquid microemulsion was designed. • The reversible emulsification and demulsification process can easily be switched by using temperature as a trigger. • Molecular dynamics simulations were used to study the demulsification mechanism of temperature-sensitive IL microemulsion. • The interaction between [CF 3 COO]- and H 2 O is the driving force of demulsification process. [ABSTRACT FROM AUTHOR]