Exceptional superhydrophobicity and low velocity impact icephobicity of acetone-functionalized carbon nanotube films.

We present a simple method to produce carbon nanotube-based films with exceptional superhydrophobicity and impact icephobicity by depositing acetone-treated single-walled carbon nanotubes on glass substrates. This method is scalable and can be adopted for any substrate, both flexible and rigid. These films have indicated a high contact angle, in the vicinity of 170°, proved both by static and dynamic analysis processes. The dynamic evaporation studies indicated that a droplet deposited on the treated films evaporated in the constant contact angle mode for more than 80% of the total evaporation time, which is definitely a characteristic of superhydrophobic surfaces. Furthermore, the acetone-functionalized films showed a strong ability to mitigate ice accretion from supercooled water droplets (-8 °C), when the droplets were found to bounce off the films tilted at 30°. The untreated nanotube films did not indicate similar behavior, and the supercooled water droplets remained attached to the films' surfaces. Such studies could be the foundation of highly versatile technologies for both water and ice mitigation.

Controlled growth of self-organized hexagonal arrays of metallic nanorods using template-assisted glancing angle deposition for superhydrophobic applications.

The fabrication of controlled, self-organized, highly ordered tungsten and aluminum nanorods was accomplished via the aluminum lattice template-assisted glancing angle sputtering technique. The typical growth mechanism of traditional glancing angle deposition technique was biased by self-organized aluminum lattice seeds resulting in superior quality nanorods in terms of size control, distribution, and long range order. The morphology, size, and distribution of the nanorods were highly controlled by the characteristics of the template seeds indicating the ability to obtain metallic nanorods with tunable distributions and morphologies that can be grown to suit a particular application. Water wettability of hexagonally arranged tungsten and aluminum nanorods was studied after modifying their surface with 5 nm of Teflon AF 2400, as an example, to exhibit the significance of such a controlled growth of metallic nanorods. This facile and scalable approach to generate nano seeds to guide GLAD, with nano seeds fabricated by anodic oxidization of aluminum followed by chemical etching, for the growth of highly ordered nanorods could have significant impact in a wide range of applications such as anti-icing coating, sensors, super capacitors, and solar cells.

Design and fabrication of teflon-coated tungsten nanorods for tunable hydrophobicity.

The nature of water interaction with tungsten nanorods (WNRs) fabricated by the glancing-angle deposition technique (GLAD)-using RF magnetron sputtering under various Ar pressures and substrate tilting angles and then subsequent coating with Teflon-has been studied and reported. Such nanostructured surfaces have shown strong water repellency properties with apparent water contact angles (AWCA) of as high as 160°, which were found to depend strongly upon the fabrication conditions. Variations in Ar pressure and the substrate tilting angle resulted in the generation of WNRs with different surface roughness and porosity properties. A theoretical model has been proposed to predict the observed high AWCAs measured at the nanostructure interfaces. The unique pyramidal tip geometry of WNRs generated at low Ar pressure with a high oblique angle reduced the solid fraction at the water interface, explaining the high AWCA measured on such surfaces. It was also found that the top geometrical morphologies controlling the total solid fraction of the WNRs are dependent upon and controlled by both the Ar pressure and substrate tilting angle. The water repellency of the tungsten nanorods with contact angles as high as 160° suggests that these coatings have enormous potential for robust superhydrophobic and anti-icing applications in harsh environments.

Catalytic hydrogenation of graphene films.

We developed a novel and facile method to hydrogenate graphene by using a conditioning catalyst upstream of the graphene sample to generate atomic hydrogen.