Non-wetting of condensation-induced droplets on smooth monolayer suspended graphene with contact angle approaching 180 degrees

Superhydrophobicity is usually achieved by a combination of chemical hydrophobicity and surface topography due to an inability to attain complete non-wetting on the smooth surface of existing materials. Here, we experimentally report high non-wetting of condensation-induced droplets with contact angles approaching 180° on a smooth surface of suspended monolayer of graphene. Such highly non-wetting droplets are found 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 non-wetting behaviour may be unique to suspended monolayer graphene. These results anticipate that interactions between liquid molecules across a suspended monolayer isolated from a bulk substrate may induce high non-wetting beyond that possible on smooth hydrophobic or atomically flat supported monolayer surfaces.