Mass-producible replication of highly hydrophobic surfaces from plant leaves

Many plant leaves found in nature are known to exhibit a characteristic of superhydrophobicity ('lotus leaf effect'). The present study proposes a mass-production method of highly hydrophobic surfaces by simply replicating the highly hydrophobic plant leaf surfaces in two steps: the first step of making a nickel mould via electroforming and the second step of replication via a UV-nanoimprint lithography. Making a nickel mould, either a plant leaf or its negative polymer replica is used as a mandrel in electroforming, and final products become positive or negative polymer replicas of a plant leaf, respectively. It is found that the nickel-mould making using the plant leaf as a mandrel is quite successful and the final products in the form of a positive replica are better than those in the form of a negative replica in terms of replication quality and hydrophobicity. Contact angle values of the positive replicas are less than those of the natural leaves' surfaces by only 2 degrees-5 degrees.