(a), the water contact angle of the PMMA-
sprayed specimen, which was sprayed for 10 seconds, var-
ied with the position significantly. At the center point,
5 mm outward, and 10 mm outward, the water contact
angles were about 138, 112, and 82 degrees, respectively.
However, in the case of a 20-second spraying, the water
contact angles at the center point and at 5 mm outward
converged to about 145 degrees. Moreover, in the case
of a 30-second spraying, the water contact angles at the
center point and at 5 mm outward were almost same
as those for the 20-second spraying. In addition, at the
position of 10 mm outward, the water contact angle in-
creased with increasing spraying time which means that
the stacked amount of sprayed PMMA is related to the
increase in the water contact angle.