Biomimetic Superhydrophobic Surface Fabrication by Plasma Processing - Biomimetic Architectures by Plasma Processing - page 163

plasma [37]. However, the hydrophobicity is not always due to the
higher extent of roughness but to the lower surface energy caused
by the coated functional groups (Fig. 5.7).

Figure 5.7 Plasma functionalisation.

5.4.3 Polymerisation

Plasma polymerisation, also known as deposition, is referred to the
deposition of polymer films on the material surface. Monomers are
introduced into the plasma chamber as a plasma gas where they
are excited and subsequently deposited and polymerised on the
surface. Plasma polymerisation is different from functionalisation
in which the plasma species and the material surface are not
necessarily bonded covalently [38] (Fig. 5.8). Advantages of the
plasma polymerisation over other conventional surface treatment
methods are its ability to produce ultra-thin, pinhole-free polymer
layers [39] and its potential to polymerise monomers that cannot
be polymerised under normal conditions because such processes
involve electron impact dissociation and ionisation for chemical
reactions [40]. Possible mechanisms of the plasma polymerisation
are: (i) plasma-induced radical chain-growth polymerisation
mechanism, (ii) ion-molecule reactions mechanism, and (iii)
fragmentation-(poly) recombination mechanism [39].