Superhydrophobic nano-wire entanglement structures

Abstract

Superhydrophobic nano-wire entanglement structures (NWES) were fabricated by the dipping method, based on an anodization process in oxalic acid. The pore diameter and the depth were influenced by the applied voltage and the anodizing time. To obtain the NWES, polytetrafluoroethylene (PTFT, Teflon®: DuPont™) replication based on the dipping method was used, with a PTFT solution (0.3 wt%). During replication, the polymer sticking phenomenon due to van der Waals interactions creates microscale bunch structures on the nanoscale wire-entanglement structures. This process provides a hierarchical structure with nanostructures on microstructures and enables commercialization. The diameter of the replicated wires was about 40 nm, and their lengths were 22–75 µm according to the anodizing time. The fabricated surface has superhydrophobicity; the apparent contact angle of the PTFT micro and nanostructures is about 160°–170° and the sliding angle is less than 1°.