Preparation And Applications Of Superhydrophobic Polymer Thin Films

It is more and more important to investigate the surface or interface problems, such as adherences, wettability, dyeing, anti-eroding, anti-abrasion and so on, with the great applications of polymer materials. Wettability is a vital property of solid, whatever from the aspect of fundamental research of theory or the aspect of applications. Therefore, the investigation on wettability has attracted great interest of researchers. Recently, superhydrophobic surfaces with a water contact angle (WCA) greater than 150°, has aroused significant attention of international researchers because of its excellent self-cleaning properties. There aren't chemical reactions between surface and water on it, for superhydrophobic surfaces has less contacting area with water. So various phenomena, such as snow or rainwater sticking, oxidation, and fiction, are expected to be decreased or inhibited on such a surface. That is why we think the superhydrophobic surfaces have self-cleaning properties. Generally, superhydrophobic surfaces have two great application fields: one is field of advanced biological technologies. The other is field of our daily life. An application of superhydrophobic surfaces in microfluidics is a common application in biological technologies. Researchers are interesting in controlling the movement of a liquid drop containing DNA and proteins and decreasing the external contamination on the liquid drop at full steam. The superhydrophobic surfaces can improve the ways and means of analyzing DNA and proteins by employing a superhyhydrophobic surface. In addition, superhydrophobic surfaces make it possible that a microfluidics system has a little drop as a transportation unit. Because there is a very small contacting area between superhyfrophobic substrate and drops, the little drops can move easily in external fields or only form a microfluidics on it. In order to control the location and movement of littile drops, many researchers and companies are commit themselves to microfludics systems like this. Superhydrophobic coatings have great practical application in areas where there is a great deal of snowfall. We can avoid signal interferences induced by snowfall through coating a layer of superhydrophobic coating on satellitic antennas. Super hydrophobic coatings have also potential practical applications in coating walls of building, signal surfaces, roof etc. replacing the present glasses in windows and doors will be the greatest potential application of superhydrophobic films. Because the cleaning expense for glasses in windows and doors is too expensive, particularly the glasses in skyscrapers, the applications of superhydrophobic coatings will bring out a significant economical benefit. In addition, the superhydrophobic surfaces have also been used for avoiding oxidation of solid surfaces. Because of these significant potential practical applications, preparations of superhydrophobic surfaces have been a most popular research issue. Therefore, we supposed to prepare superhydrophobic polymer coatings with self-cleaning properties by controlling the mirostructures of polymer thin films via investigating polmers'cystallization behaviours. Furthermore, we would like to develop a novel route for preparing polymer surfaces with a wttability gradient and smart surfaces with a responsive wettability to solvents, which have both been used in field of biology and life sciences, based on the superhydrophobic surfaces we prepared. In this thesis, we developed two novel methods for fabricating superhydrophobic surfaces with self-cleaning properties. Furthermore, we combined the fields of superhydrophobicity research, gradient surfaces research and smart surfaces and developed a new strategy for preparations of gradient surfaces and external stimuli-responsive surfaces. At the same time, we investigated the forming mechanism of the three functional thin films and discussed their potential practical applications. The conclusion as follows: 1.LDPE superhydrophobic surface with porous and floral structure of imperfect spherulites was prepared by controlling the crystallization behaviors of LDPE via increasing the crystallization time and nucleation rate. The cooperative porous microstructures and nanostructures of LDPE crystals were responsible for...