Biomimetic Superhydrophobic Surface Fabrication by Plasma Processing - Biomimetic Architectures by Plasma Processing - page 162

perhydrophobic surface fabricated by the plasma processing can be
categori sed into three main strategies: (i) etching, (ii) functionali-
sation, and (iii) polymerisation. Descriptions of these reactions are
discussed below.

5.4.1 Etching

In general, plasma etching is a chemical etching in which a chemical
reaction takes place. It is a selective removal of material surface after
the surface is reacted with plasma species. Adsorption of species
will occur depending on the affinity between chemicals as well as
surface temperature. Reaction products are volatile compounds
which will be desorbed into the plasma phase and eliminated
through pumping. They will be rejected off from the surface as
gaseous compounds and thus, cause etching of the material [32]. In
plasma etching, a resistant etching mask can be used to protect parts
of the surface from exposure to the etching medium [33,34]. Thus, it
is a well-mastered technique for patterning features (Fig. 5.6).

Figure 5.6 Plasma etching treatment.

5.4.2 Functionalisation

Plasma functionalisation is a chemically modification of the surface
by some functions. After the plasma species interact with the sample,
it will form a thin film at the surface of the material if the product is
not volatile [32]. Specifically, the plasma species and the material
surface should preferably be covalently bonded rather than just
like a physically adsorbed coating [35]. In some cases, the addition
of functionality and surface roughening occurs simultaneously.
Additionally, deposition of hydrophobic particulates on the material
surface can also occur [36]. This particulate formation is known to
occur at relatively high density of reactive radicals and ions in the