The as-prepared samples were characterized by high
resolution field-emission scanning electron microscopy
(FESEM; LEO 1530 FEG at 2-10 kV). Contact angle
measurements were performed with water droplets (4μl size)
formed using a 0.5 μl step on a microsyringe at a predefined
height and static images recorded; advancing contact angles
of the droplet on the solid surface were determined from these
images. Receding contact angles were measured by increasing
the volume of the 4 μl water droplet to 6 μl and subsequently
reducing the volume to 4 μl by extracting the extra water with
a volumetrically controlled pipette using the same 0.5 μl step
changes. Optical images were recorded with a Leica
Microscope at 50× magnification. For AFM force curve
measurement, a NanoScope IIIa/Dimension 3000 AFM
system was employed and a tipless probe (material: silicon
nitride) from Veeco was used.