Contact: Michael Patrick Rutter
Caption: These are sequential images of ice layer removal from hydrophilic Al, fluorinated hydrophobic Si, and microstructured fluorinated Si (SHS). A group of droplets (Tdroplet = 20 °C) was impinged from a 10 cm height simultaneously onto three surfaces (Tsubstrate = −30 °C) tilted at 15°, freezing immediately upon contact (A). As the substrate temperature was raised above 0 °C, the droplets on the SHS that were not in contact with those pinned at the unpatterned hydrophobic region (see droplets located at the bottom of the imaged area) immediately slid off (B), followed by the removal of the droplets on SHS that were bridged with the droplets frozen on the unpatterned hydrophobic region (C) (shown with a dashed oval); while droplets on the unpatterned hydrophobic region (indicated with a white arrow) and the hydrophilic region remained pinned even upon fully melting (D). This indicates that even below the transition temperature, droplets are able to stay nonwetting on a SHS upon impact.
Credit: Courtesy of the laboratory of Joanna Aizenberg
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