Biomimic from the superhydrophobic plant leaves in nature: Binary structure and unitary structure

The aim of this paper is to describe the superhydrophobicities of some plant leaves in nature by virtue of contact angle measurements and to analyze their corresponding microstructures by means of scanning electron microscopy (SEM). Water droplets easily slip or roll down on such surfaces, showing low hysteresis properties. The present study demonstrates that there are two main type kinds of surface structures in the natural plant leaves with superhydrophobicity. One is the micro-and nanostruture (so-called binary structure) and the other is micro-line structure (so-called unitary structure). According to the detailed surface structures of natural plant leaves, we have succeeded to mimic the superhydrophobic surfaces on various substrates, such as aluminum alloy and copper alloy.