ABSTRACT
Surface wettability plays an important role in nature and numerous industrial applications such as coatings, paintings, adhesives, microuidic technology, microelectronics, textiles, and so on. Many examples of super-hydrophobicity are found in nature, especially in plants and insects. For example, lotus leaves (Barthlott and Neinhuis 1997) are super-hydrophobic because of their rough-surface microstructure and presence of wax coating. Self-cleaning occurs as water droplets remove surface particles as they roll off the leaves. Super-hydrophobicity also helps many plants and insects oat on water because of the buoyancy force provided by the trapped air in their rough surface (Kim et al. 2010). Lady’s mantle leaf, water strider feet, rice leaves, and sher spiders are the most common examples present in the nature. Super-hydrophobicity mainly results from a combination of low surface energy and high surface roughness. Numerous methods to attain these two requirements have been reported experimentally (Heslot et al. 1990; Modaressi and
7.1 Introduction .......................................................................................................................... 219 7.2 Thermodynamics of Liquid Drop on a Surface ....................................................................220 7.3 Contact Angle Measurement ................................................................................................ 222
7.3.1 Fitting Method ......................................................................................................... 222 7.3.2 Center of Mass Method ............................................................................................ 222 7.3.3 GC-TMMC Approach ............................................................................................... 223
7.4 Phase Transition on Surfaces ................................................................................................225 7.4.1 Prewetting Transition ................................................................................................225 7.4.2 Wetting on Smooth Surface ......................................................................................228
