Wetting Properties of Natural and Plasma-Processed Biomimetic Surfaces - Biomimetic Architectures by Plasma Processing - page 141

movement, is responsible for hysteresis [69]. A larger barrier would
resist the movement of the drop so that although the advancing angle is
increased, the receding angle will decrease creating the hysteresis. A
smaller contact line length, or smaller barrier, would allow the rolling
of the droplet so that neither the advancing nor the receding angle
would change much, thus keeping the hysteresis value to a minimum.
Water CA measurements revealed that the nanograss, nanopillar
and two-tier surfaces were all super-hydrophobic [65], but among
them the nanograss surface is the stickiest. Figure 4.19 shows the
advancing, receding, and sliding CAs for the three kinds of surfaces.

Figure 4.19 Influence of surface structure on hydrophobicity. Advancing,

receding and sliding CAs for samples possessing nanograss,
nanopillar and two-tier nanograss on-nanopillar topographies.
The sliding angle and the difference between advancing
and receding CAs are significantly smaller for the two-tier
structure. Reprinted with permission from Ref. [65], Copyright
© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

All three nanograsses displayed large CAH (the difference
between the advancing and receding CAs). The advancing CAs
were nearly the same for all the three different structures, but
for the nanograss sample the receding CA was much smaller