The Study of Effect of the Distribution of Microstructures on Surface Wettability
| Autor: | Zi-Ying Wu, 吳姿瑩 |
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| Rok vydání: | 2016 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 104 Controlling wettability of solid surface plays an important role for applications in water-repellent, anti-fouling, microfluidics, and so on. Modification of surface wettability is achieved through either chemical or physical means; however, chemical means suffer the drawback of a short-lived effect. Therefore, physical means of modifying surface wettability are typically achieved through surface roughening, which caused many researchers began to fabricate a variety of surface microstructure to modification of hydrophobic material surface. Polydimethylsiloxane, a silicon-based polymer, is a transparent, plastic and flexible material. Besides, the properties of low surface free energy makes it be hydrophobic. Accordingly, the use of PDMS with high plasticity to transfer the microstructure patterns to PDMS surfaces by soft lithography, and the production process is simple and efficient. In this study, replica molding method is involved to produce the anisotropic and isotropic microstructures of hydrophobic leaves which are transferred to PDMS surfaces. After twice replica molding process, we duplicate the surface microtextures of the original leaves, enhancing the hydrophobicity of flat PDMS. Then we will observe surface morphology, contact angle and surface free energy to analyze microstructure distribution and surface wettability of PDMS samples. And we find that the anisotropic distribution of surface free energy will be caused by the anisotropic arrangement of PDMS surface microtextures. Accordingly, the length of the droplet is stretched since it is subjected to a capillary force parallel to the veins; however, due to the existence of the energy barrier in the direction perpendicular to the veins, the width of the droplet is shortened. The PDMS surface microstructures of Panicum maximum Jacq. with anisotropic wettability and hydrophobicity is the most significant among all leaves which can be applied to directional self-cleaning. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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