Extreme Non-Wetting of Condensation-Induced Droplets on Smooth Monolayer Suspended Graphene

Abstract Superhydrophobicity has only ever been achieved by a combination of chemical hydrophobicity and surface topography due to our inability to attain complete non-wetting on the smooth surface of any known material. Here, we report extreme non-wetting of condensation-induced droplets with contact angles approaching 180° on a smooth surface using suspended monolayers of graphene experimentally. Such extreme non-wetting droplets are reported exclusively on suspended monolayer graphene open to the water vapour saturated environment on both sides. Simultaneous observations of droplets condensing on monolayer and multilayer supported and suspended graphene demonstrates that this extreme non-wetting behaviour is unique to suspended monolayer graphene. These results anticipate that interactions between liquid molecules across a suspended monolayer isolated from a bulk substrate may induce extreme non-wetting beyond that possible on smooth hydrophobic or atomically flat supported monolayer surfaces.