pH-Induced\nReversible Wetting Transition between the Underwater Superoleophilicity\nand Superoleophobicity

Abstract

Surfaces with controlled oil wettability\nin water have great potential for numerous underwater applications.\nIn this work, we report a smart surface with pH-responsive oil wettability.\nThe surface shows superoleophilicity in acidic water and superoleophobicity\nin basic water. Reversible transition between the two states can be\nachieved through alteration of the water pH. Such smart ability of\nthe surface is due to the cooperation between the surface chemistry\nvariation and hierarchical structures on the surface. Furthermore,\nwe also extended this strategy to the copper mesh substrate and realized\nthe selective oil/water separation on the as-prepared film. This paper\nreports a new surface with excellently controllable underwater oil\nwettability, and we believe such a surface has a lot of applications,\nfor instance, microfluidic devices, bioadhesion, and antifouling materials.