Figure 7. Evolution of WCA of the samples produced in the ambient air
and aged up to 30 days in air. HP is the polarization direction of laser
field perpendicular to direction of scanning, VP is the direction of
laser field parallel to direction of scanning and CP is circularly
polarized laser beam.
Strongly irradiated surface at initial periods of air ageing
demonstrates hydrophilic properties, but for later times
(>2 days) the pace of changing is increasing and
outperforms initial WCA. Final result of ageing in Fig. 7 demonstrates
no noticeable dependence on the morphology generated by applying
different laser polarizations.
Figure 8 shows relation of the presence of the C (black bars) and O
(cyan bars) for mesh samples after 30 days of ageing. For all samples we
see the increase of the relative amount of carbon C on the textured
surface. This amount lower than in case of samples stored inside Chamber
#2 (Fig. 5), that can explain lower WCA in the case of air aged
samples.