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Understanding the Role of Dynamic Wettability for Condensate Microdrop Self‐Propelling Based on Designed Superhydrophobic TiO 2 Nanostructures

2016; Wiley; Volume: 13; Issue: 4 Linguagem: Inglês

10.1002/smll.201600687

1613-6829

Songnan Zhang, Jianying Huang, Yuxin Tang, Shuhui Li, Mingzheng Ge, Zhong Chen, Ke‐Qin Zhang, Yuekun Lai,

Micro and Nano Robotics

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 TiO 2 nanostructure films are rationally designed and fabricated on titanium substrates with special superwettability, viz., TiO 2 nanotube arrays, irregular TiO 2 nanotube arrays, and hierarchical TiO 2 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 TiO 2 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 TiO 2 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.