Folding surfaces: Capillary Origami
It seems obvious that something which is "hydro" - "phobic" would fear water, but what happens when a thin sheet of Teflon - the most hydrophobic material that chemistry can create - touches a droplet of water?
|A droplet of water coming into contact with a thin sheet of Teflon.|
Even Teflon prefers to cling to the surface of water rather than remain in contact with air unless we make that surface superhydrophobic (see lower image sequence below). Spontaneous wrapping of a droplet of water by Teflon is a form of Capillary Origami.
Teflon is Hydrophilic. Comments on Definitions of Hydrophobic, Shear versus Tensile Hydrophobicity, and Wettability Characterization,
Langmuir 24 (17) (2009) 9183-9188. View abstract
All solids, including teflon, are hydrophilic (to some extent), but some have roughness induced hydrophobic tendencies,
Langmuir 25 (13) (2009) 7185-7187. Via ACS server
Capillary origami and superhydrophobic membrane surfaces,
Appl. Phys. Lett. 102 (21) (2013) art. 214104. View reprint