Superhydrophobicity of post-like aligned carbon nanotube films

Abstract

Extreme water repellency is greatly desired for microfluidics and self-cleaning applications. Post-like aligned carbon nanotube (CNTs) films were grown on the Ni-coated Si substrates by a plasma enhanced chemical vapor deposition (PECVD) technique. The surface of morphologies of the pretreated Ni thin films were investigated using a non-contact mode of atomic force microscope (AFM) and the structural properties of as-grown CNTs films were characterized using scanning electron micrograph (SEM) and X-ray diffraction (XRD). The contact angles and the rolling angles on such films were measured through an optical contact angle meter. Wettability studies revealed the films exhibited a superhydrophobic behaviour with a higher contact angle (161.7°±1.5°) and lower rolling angle (less than 4°)-a water droplet moved easily on the surface. The post-like aligned CNTs showed discrete pillar composed of carbon nanatubes, these pillar formed nanostructure in the films, which made it easy for small water droplets to be suspended on a surface approaching that of a perfect air-water interface and strongly affected the contact angle and the rolling angle.