WCA, the lower surface energy materials and roughening agents
are selected and blended with a binder like PVC in THF as the
medium. On immersing the cotton into the suspension, a firm
coating of all ingredients over cotton was noticed. By examining
through a Scanning Electron Microscope, it is clear that the surface
texture of the plain cotton has been completely modified and takes
up the non-wettable character. The SEM image in Fig. 3(a) recorded
at 370 magnification and in 50.0 mm scale shows the morphology
of plain cotton fabric. They represent long pillar-like structures
which are actually the fibres present in cotton (cellulose). The SEM
image in Fig. 3(b) recorded at 400 magnification and in 50.0 mm
scale shows the fabric coated with PVC. The coating of PVC is
evident from the SEM image since the PVC covers the spongy
nature of the fabric, thus confirming the attachment of
PVC molecules all along the fabric. Thus, it can be seen that PVC
modifies the surface of cotton into a wax-like coating. Inset of
Fig. 3(b) is the image of a water droplet placed on the surfacemodified
cotton fabric with a WCA of 136.68.
Fig. 3(c) is the SEM image of cotton fabric after coating with
copper stearate. From the image of SEM, it is inferred that the low
surface energy material firmly covers the cotton fabrics. A drop of
water placed on this fabric shows hydrophobic character. The inset
is the image of a water droplet with a WCA of about 141.38.
The SEM image of the cotton fabric after being coated with the
additives consisting of copper stearate and PVC is represented in
Fig. 3(d). The SEM image was recorded at 750 magnification and
20.0 mm scale. This shows the covering of the spongy fabric into a
slightly roughened structure. The presence of stearate and PVC
over cotton has also been confirmed from their IR spectral studies.
PVC is added as a binder which may support the firm attachment of
nano particles onto the cotton, rather than being washed off.
Copper stearate and PVC blend change the cotton fabric into near
super hydrophobic type with a WCA of 145.68.
Fig. 3(e) represents the SEM image of iron oxide coated fabric
along with all additives. The presence of nano particles over the
cotton surface further influences the rough nature. Placing a drop
of water on this fabric has a rolling tendency with a contact angle of
147.58. The SEM image of chromia coated fabric with all other
additives is shown in Fig. 3(f) which has been recorded at 1000
magnification and 20.0 mm scale. The SEM image shows the
presence of chromia nanoparticles bound to it. The texture of
cotton appears like a roughened structure due to the inclusion of
nano chromia particles. Higher WCA (151.18) is noted for this fabric
since chromia blended additives show higher roughness. This
result was also confirmed from AFM studies.