Inspired undesired in their use as cloths

Inspired from the lotus phenomenon
1 construction of such special superhydrophobic (water
contact angle is greater than 1500)
surfaces are increasingly attractive in various potential
application fields both in academic research and practical application such
as self-cleaning, anti-contamination and anti-sticking. Superhydrophobicity
is
an extraordinary wettability with high water contact
angle and low sliding angle. Neinhuis
et al have
elaborated that water drops rolling off on the
lotus leave surfaces is due to the
presence of a combination of rough micro-nanostructure and low surface energy
waxy materials on their surfaces. Based on
the principle, scientists and researchers have endeavored various
methods to fabricate such special hydrophobic and superhydrophobic surfaces by
constructing hierarchical micro/nanostructures with low surface energy
materials 2. Cotton, a soft
fluffy fiber has low production cost, low density, and
good strength in both wet and in dry condition and other unique properties such as
comfortability; breathability makes them
even more attractive for future applications. It is extremely used raw material
to make garments for many years. Cotton is composed of almost pure
cellulose which contains hydroxyl groups.
In spite of the many advantages of cotton, the hydroxyl groups make
them tremendous water loving adsorbent i.e.
hydrophilic. The excessive water absorbability allows the cotton
textile to be easily stained and dirtied. Sometimes the cotton textiles are
also wetted and contaminated by blood, oily appearance and even bacteria which
are undesired in their use as cloths particularly in hospitality. Thus in
recent years, nonwettable cotton textile
with high water contact angle value and dirt resistant cotton textile has long
been an interesting subject in research. Modifying textile with hydrophobic
chemicals to make surface hydrophobicity is a well-established
technology developed in early 1940 (Roach
et al. 2008). For example, a patent published by Gao and McCarthy
et al (2006) on the basis of
hydrophobization with silane 3. They were successfully fabricated artificial
lotus leaf-like polyester fabric. Two
factors (1) surface chemical composition and (2) surface structure (roughness)
promotes the special nonwettable effects
on fabrics. A variety of approaches are reported to enhance the surface
roughness such as introduction of
nanotechnology through electrospinning 4, plasma treatment 5,6 and
sol-gel technology 7-9, chemical vapor deposition 10. Silicone compound is also reported to coat on fabric surfaces for
many years. Beside nanotechnology, polymer technology 11,12 plays
also an important role to create a surface thin
film with high hydrophobic character. Among known chemical methods,
?uorine is the best element to be used to lower the surface free energy and
make fabric hydrophobic 13. Fluorine has a small radius and a high
electronegativity, thus the covalent bond between ?uorine and carbon is
extremely stable. When ?uorine is replaced by other H and C, the surface free
energy is increased in the order –CF3