Bio-inspired isotropic and anisotropic wettability on a Janus free-standing polypyrrole film fabricated by interfacial electro-polymerization

A Janus free-standing polypyrrole (PPy) film was successfully fabricated by a facile one-step aqueous/organic interfacial electro-polymerization. The Janus film showed isotropic hierarchical micro/nanostructures resembling the surface of a lotus-leaf on the side facing the aqueous phase, and an anisotropic butterfly scale-like ordered porous microstructure on the other side facing the organic phase. The unique topographic nature of the Janus PPy film result in isotropic and anisotropic underwater superoleophobicity behavior. The controlled surface wettability will find broader applications in micro-fluidic devices, liquid transfer, and bio-inspired systems.