Understanding the Role of Dynamic Wettability for Condensate Microdrop Self-Propelling Based on Designed Superhydrophobic TiO₂ Nanostructures

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• 作者：Songnan Zhang ; Jianying Huang ; Yuxin Tang ; Shuhui Li ; Mingzheng Ge ; Zhong Chen ; Keqin Zhang and Yuekun Lai
• 刊名：Small
• 出版年：2017
• 出版时间：January 25, 2017
• 年：2017
• 卷：13
• 期：4
• 全文大小：2159K
• ISSN：1613-6829

文摘

The ability to release the adhered drops on superhydrophobic surfaces is very important for self-cleaning, antifrosting/icing, microfluidic device, and heat transfer applications. In this paper, three types of in situ electrochemical anodizing TiO₂ nanostructure films are rationally designed and fabricated on titanium substrates with special superwettability, viz., TiO₂ nanotube arrays, irregular TiO₂ nanotube arrays, and hierarchical TiO₂ particle arrays (HTPA), and their corresponding behavior in condensate microdrop self-propelling (CMDSP) is investigated. Compared to the flat titanium counterpart, all three types of rough TiO₂ samples demonstrate a uniform distribution of smaller microscale droplets. Among the treated surfaces, the HTPA possesses the highest condensate density, and more than 80% of the droplets possess a diameter below 10 μm. Theoretical analysis indicates that the feature is mainly due to the morphology and structure induced extremely low droplet adhesion on super-antiwetting TiO₂ hierarchical surfaces, where the excess surface energy released from the migration leads to the self-propelling of merged microdrop. This work offers a way to rationally construct CMDSP surfaces with excellent self-cleaning, antifrosting/icing ability, and enhanced condensation heat transfer efficiency.