Superhydrophobic surfaces raised a great deal of attention in recent years due to their numerous potential applications. In this work, a method which can manufacture "large" superhydrophobic surfaces using very fine stainless steel mesh to "hot-emboss" hydrophobic polytetrafluoroethylene (PTFE) surfaces is provided. A high static contact angle and low contact angle hysteresis for these "xPTFE" superhydrophobic surfaces were measured being around 150° and 15° respectively. The surfaces' structures were investigated via scanning electron microscopy (SEM). Otherwise, the "slip-length" was measured using rheometer as ∼30 μm which indicates a great potential drag-reduction. This easy and inexpensive method could be a great step to bring superhydrophobic surfaces into real-world.
On a rainy day, the rain drops hit and stick on the glass window making your vision fuzzy, but when you look through the window, the leaves of trees and other plants are still clean and without water attached. This phenomenon is the well-known "lotus-effect" ((Neinhuis and Barthlott, 1997)). Some plant leaves, like lotus and rice leaves, are highly water-repellent, small water drops can stand on such surfaces in an almost perfect spherical shape and very easily roll off. Inspired from nature, these kind of surfaces, also called "superhydrophobic" surfaces have attracted a great deal of attention in recent decades because of their numerous potential applications such as "self-cleaning" surfaces (Cheng and Rodak (2005) and Neinhuis and Barthlott (1997)), friction-reduced surfaces for drag reduction (e.g., for hydrodynamically efficient ship design and "drag-reducing" pipe flows) and icephobic ((Nosonovsky and Hejazi, 2012)) surfaces for wind turbine blades.
Superhydrophobic surfaces can be characterized using several wetting properties. The most convenient one is the static contact angle. The contact angle is the angle which is measured through the liquid, where a liquid-vapor interface meets a solid surface. For a surface having a contact angle lower than 90°, the surface is called a hydrophilic surface, otherwise it is a hydrophobic surface. Superhydrophobic surfaces can be simply defined as a surface which has a very high contact angle (typically > 150°) and low contact angle hysteresis, (Tian, Verho and Ras, 2016)).