Biomimetic Superhydrophobic Nanostructured Surface: Fabrication, Properties and Application in Evaporation
Date Issued
2011
Date
2011
Author(s)
Chiang, Cheng-Kun
Abstract
This thesis first studied the evaporation process of a sessile droplet on two topologically different surfaces, including smooth and nanostructured surfaces. The nanostructure was fabricated by electrodeposition copper (Cu) nanowires on smooth substrate. The porous anodic aluminum oxide (AAO) membrane was used as template to deposit nanowires of 200 nm in diameter and 25 μm in length. When the sessile droplets of deionized water and methanol-water binary mixtures evaporated on both smooth and nanostructured surfaces, they basically follow three stages：(I) constant baseline stage, (II) constant contact angle stage and (III) shrinking stage. In addition, the nanostructured surfaces, which possessed superhydrophobicity, changed sessile droplets’ contact angles, contact lines and therefore evaporation phase change behaviors.
The second part of the thesis further examined the nanowire distribution and related surface properties. The nanowires agglomerated differently when different releasing techniques, including drying techniques: evaporation drying, thermal drying and supercritical drying, were employed. It was found that the nanowires agglomeration resulted in different degrees of surface homogeneity, so the contact angle and hysteresis.
Subjects
contact angle
contact angle hysteresis
copper
nanowires
evaporation
binary mixture
superhydrophobic surface
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