Critical length of nanowires for hydrophobic behavior

This Letter investigates the wetting behavior on surface with well-controlled nanoscale structure. Water and water–alcohol droplets were brought to contact the surface electroplated by Ag nanowires. It is found that hydrophobic behavior becomes more pronounced as the length of the nanowires increases. A critical length of approximately 100 nm is observed, beyond which the contact angle approaches a steady value of 130°. In addition, the contact angle of water levels off around 160° when the length of the fluorine-coated Ag nanowires exceeds the critical value of 100 nm. The mechanism of the hydrophobic behavior on surface with nanoscale structure is proposed.