Biomedical Engineering Reference
In-Depth Information
antenna comparing with non-superhydrophobic coating sample. Superhydrophobic
surfaces have been found to be candidate of anti-biofouling coatings materials,
which can remove the undesirable adherence of microorganisms, plants, algae,
and animals on submerged surfaces, for example, ships' hulls. Traditional anti-
biofouling coatings on the hulls of ships and other marine-based architectures
contain poisons to kill the adhered marine organisms. And this solution is not
environment-friendly. Zhang et al. [
215
] have investigated superhydrophobic ma-
terials as anti-biofouling coating. Compared with non-treated substrates exhibiting
fouling within a day, the superhydrophobic one can keep the surface clean in the
first weeks of immersion. Then the superhydrophobic surface lost its function
due to gradually deterioration of the coating. This study indicates that robust
superhydrophobic surfaces that can sustain in real marine environment are desired
in marine technology. Another related research is that optimizing superhydrophobic
coatings on metal surface to moderate corrosion process. Liu et al. [
216
]have
fabricated copper cluster superhydrophobic surfaces by immersing polished fresh
copper surfaces into
n
-tetradecanoic acid ethanol solution. The strong bound
between copper and
n
-tetradecanoic acid makes the superhydrophobic-modified
copper remain intact in seawater for 1 month.
9.6
Outlook
We have tried our best to provide a balanced review of the combination of surface
roughness and low-surface-energy coatings for superhydrophobicity. Although the
superhydrophobic coating is the focus of many practical applications, and some
commercial products have appeared, for example, non-stick pans, superhydrophobic
textiles, and self-cleaning coatings, there are still lots of questions that need to be
addressed. For example, the contact angle hysteresis is a key factor for the applica-
tion of superhydrophobic coatings; however, its origin is still not fully understood.
There is a need to establish the relationship between contact angle hysteresis and the
surface structures and compositions. Many types of methods have been developed
to fabricate superhydrophobic surfaces, but most of them are limited to laboratory
research and are not suitable for industrial scale production. One-step fabrication
or other simple techniques are greatly needed to easily fabricate superhydrophobic
surfaces of large scale and good homogeneity. Stability is another important issue
we need to be concerned with in view of practical applications. Superhydrophobic
coatings cannot find practical use without sufficient stability including mechanical
and thermal stability. The stimuli-responsive superhydrophobic surfaces have been
discussed, and these studies are certainly a new direction in this field and may
provide interesting functional surfaces. In summary, the study of superhydrophobic
surfaces originates from mimicking nature, but it has been extended to create new
surface materials beyond those found in nature. Therefore, it is a multidisciplinary
field interfacing with surface chemistry and physics, nanomaterials, biosurface,
mechanics, and so on, where researchers can make full use of their imagination.
