Characterization and Development of Polymer Surfaces with Excellent Water Transport

Abstract

Recently, research has been conducted to mimic the unique structures that are found in nature. This includes the fabrication of anti-fouling/anti-bacterial surfaces, controlling the flow, and improving the water capturing performance. However, these structures have limitations that are too small and complex to be applied for industry. To solve this problem, this study investigated the microstructure size that can be used with the injection and blowing method that applies a mold so it can be widely used throughout industry. 200 and 400 m structures were built to simplify the shape of these existing microstructures and to make it easier to make the molds by increasing them in size. However, as the size of the structure increases, the fabrication becomes simple and easy; however, a decrease in water-repellency occurs. In order to solve these issues, this study focused on the relationship between the shape of the structure and the water droplet behavior. In particular, the behavior of the water droplets is highly influenced by the shape of the microstructure. Even with the similar contact angle, the behavior of the water droplets on the surface may vary. In addition, the geometric factors that do not differ much on the superhydrophobic surface can have a significant impact. To confirm this, the contact angles, repellency, and flowability were measured for a variety of structures, and the anti-fouling test was conducted to verify the performance. The experiments have shown that the microstructure has a good performance in comparison to the planar. In addition, in the case of the one-way structure, the water repellency is slightly inferior to that of the two-way structure, whereas the water transport ability shows better results. Through this, it was found that the structural design of the microstructure suitable for the purpose is very important. Next, in order to investigate the applicability to the actual application by utilizing the structural characteristics of the micro-scale structure, a micropattern design and performance experiment were conducted to increase the water collection efficiency. A new surface structure was devised by combining the cactus conical structures with a high water collection performance and the microchannel structures found on insect plant surfaces with an excellent water transport performance. The two structures were fabricated with a size that was along the order of hundreds of microns, which are capable of molding to confirm the performance improvement. As a result, it was confirmed that the performance improvement effect was very good not only for low-speed flow, which was carried out in a previous study, but also for high-speed flow. This means that it is applicable in industry. For a more accurate verification, the newly designed surface was applied to the surface of the structures that are modeled after the mist-eliminator. The results of the improvement were determined to be excellent, which confirms that the application to the various forms is not problematic.