Abstract: The plant leaf surface is generally characterized by microscopic or macroscopic non-smooth appearance, and is mostly water-repellent. From the engineering point of view, applying the method of multi-contrast experiment and the typical analysis in combination, selecting some plants in Changchun area as samples to study their non-smooth appearance of the functional leaf surface, their wettability (characterized by the surface contact angle) by means of a stereoscopic microscope, a scanning electron microscope, and the interface contact angle measurement. It was found that the relationship between the nonsmooth appearance of leaf surface and its wettability is very strong, and the shape and distribution of the non-smooth elements are the decisive factors. The surface with regular distribution of convex elements presents large contact angle, strong water repellence, and good self-clearing ability, and that of hairy non-smooth elements takes the nextplace. The study is beneficial to the surface bionic engineering and the surface design of composite materials.

Key words: engineering bionics, non-smoothness, wettability, water repellence, contact angle, leaf surface