Summary: Hexagonal patterns have been designed and fabricated using
photolithography with hydrophobic and hydrophilic zones. The hydrophilic
zones are SiO2 while the hydrophobic zone is made from Teflon«. The
pattern size d was typically between 40 and 60% of the pitch p between
patterns. We varied p from 50 to 200 Ám, as well as the connectivity of the
hydrophobic and hydrophilic patterns. The total height of the patterns was
less than 100 nm. Hydrophilic surfaces with hydrophobic islands were called
hydrophilic networks + (a), meaning that any two hydrophilic zones could be
joined without passing over a hydrophobic zone. Hydrophobic surfaces with
hydrophilic islands were called hydrophobic networks - (b). The bubble
nucleation on the pattern can also be seen in (c). The performance of these
surfaces are plotted in the boiling curves on the right. They are denoted by
their pitch p, their network (+/-) and an optional HF treatment.
Drastic Enhancement of Boiling Heat Transfer with Micro- and
Nano- Engineering of Surface Wettability
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