Monolithic and Hierarhical(micro/nano) surface strcuture and its effect on hydrophobicity of polymer films

초록

Inspired by self-cleaning lotus leaves, super-hydrophobic surface with water contact angles larger than 150° have attracted great interest over the last few years for both fundamental research and practical applications. Since a combination of a hierarchical micro/nanostructure and low surface energy materials are suggested to be essential for super-hydrophobicity, many studies have been focused on the micro, nano structure on polymer film to acquire the super-hydrophobic properties. Polymer surface treated with various physical and chemical processes may exhibit super-hydrophobic properties many objects in nature show. The hydrophobicity of a polymer surface can be used for many applications such as environmentally resistant coatings, water proof fabrics, low-friction device. Also, hydrophobic structure can be accompanied with other properties such as dust-free, self-cleaning. We have developed new process to fabricate the surface nano/micro structure using nano/micro template. The surface of the polymeric film was modified by forming various nano/micro structures using the new technique developed in this laboratory and the effect of the surface nano/micro structure on the hydrophobicity was studied. It was found that by forming the nano brushes on polystyrene film, the contact angle could be increased up to about 120°. The thin mono-layer coating with the hydrophobic material was also carried out to further enhance the hydrophobicity of nanostructure polymer film. The hydrophobicity could be further increased to about 145° by modifying surface chemical structure with CF4 plasma treatment. In nature, lotus effect is thought to be caused by the complex surface structure of the leaf. We tried to fabricate nano-structures on micro-structure like lotus leaf and the effect of the nano/micro structure on the hydrophobic properties will be discussed.