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(a)
Si
N
O
Si
N
O
Silica nanoparticles
deposition
N
Br -
N
Grafting block copolymer
Br
b
O
Si
m
Silanization
n
Si
N
MeO
OMe
OMe
(b)
(c)
10 µm
10 µm
50 µm
50 µm
FIGURE 7.3
(See color insert.) Preparation and characterization of a surface with switchable superoleophilicity and super-
oleophobicity on a nonwoven textile substrate. (a) Diagram showing the preparation strategy for a surface with
switchable superoleophilicity and superoleophobicity on a nonwoven textile using a pyridine contain polymer
that changes charge state as a function of pH. (b) Scanning electron microscope (SEM) image of the raw tex-
tile. Inset: enlarged view of the surface of a single iber. (c) SEM image of the textile after deposition of silica
nanoparticles and block copolymer grafting. Inset: enlarged view of the surface of a single iber.
mesh was subsequently reported by Kota and coworkers, with a mixture of a hydrophilic
polymer, cross-linked polyethylene glycol diacrylate, and an oleophilic luorinated poly-
hedral silsesquioxane. 44 An oil-water mixture or emulsion can be separated since the
microcrystalline regions of the polymer ilm reconigure upon exposure to form a smooth,
noncrystalline surface that hydrogen bonds with the water. The water can subsequently
low through the mesh while the oil is retained. The low cost of the mesh substrate makes
the approach commercially interesting.
Recent developments in the nanostructuring and functionalization of nonwoven sur-
faces indicate that such technology may be useful for bilge water treatment where the
primary goal is removal of free or dispersed oil. Several other hydrophobic mesh materi-
als have been reported for the separation of oil and water. 45,46 Removal of dissolved com-
pounds has not been demonstrated with mesh systems; however, there is no regulatory
necessity to remove dissolved organics. Further studies will need to encompass separation
of emulsions. If successful, mesh-based systems may be very attractive for use in bilge
water treatment as the energy requirements would be much less in the physical separation
by high-lux membranes as compared with centrifugation or UF. Overall, the area will be
interesting to follow in the coming years.
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