Effects of the distribution of micropapillae with nanofolds on the adhesive property of artificial red rose petals

Many biological organism surfaces exhibit amazing characters. An intriguing example is the red rose petal, which is famous of its "petal effect"(i.e. the water droplet adhesion effect). Numerous studies have revealed that these interesting characters of the biological surfaces are attributed to their special wettabilities with the combination of unusual micro- and nano-hierarchical structures and chemical composition. In this article, the "petal effect" was reproduced on an "artificial red rose petal" - a superhydrophobic PDMS film with the same hierarchical rough structures of red rose petals. The surface adhesive effect was characterized by the high-sensitivity microelectromechanical balance system, and the effects of micro- and nano-structure on the adhesive property of "artificial red rose petal" was investigated by altering the stretch stage. The morphology of the "artificial red rose petal" at different stages were observed by environmental scanning electron microscope(ESEM), and the wettability was characterized by the apparent contact angle. The experimental results show that surface hydrophobicity can be enhanced by the nano-scaled structure and the high adhesive force is mainly caused by the micro- and nano-scaled structure. It is believed that this work will provide us a new avenue to further understand the wettablilty of solid surface and to design novel microfluidic devices in a wide range of applications.