Table 2: Experiment results of immersed surfaces.

From: Sustaining dry surfaces under water

MaterialSpacing between structuresLiquid pressureObservation: Dry/Wet (duration of experiment)
Aging Experiments
Polymer/HFS (NC1)53O(10 nm) - O(10 μm)AmbientDry (127 days)
Polymer/HFS (NC1)53O(10 nm) - O(10 μm)AmbientDry (50 days)
Polymer/PTFE (NC2)53O(260 nm) - O(10 μm)AmbientWet (3 days)
Degassing in Vacuum Desiccator
Polymer/PTFE (NC2)53O(260 nm) - O(10 μm)All samples: 21.33–26.34 kPa in the daytime, and 47.37 kPa in the nighttimeWet (30 hours)
Zinc oxide nanorods90–410 nm Dry (3 days)
Zinc oxide nanorods20–480 nm Dry (3 days)
Silicon nanograss51,54,55<300 nm Dry (5 days)
Silicon microposts545 μm Wet (3 days)
Silicon microposts5425 μm Wet (3 days)
Silicon microgrooves3 μm Wet (3 days)
Silicon microgrooves12 μm Wet (3 days)
Degassing in Vacuum Oven
Polymer/HFS (NC1)53O(10 nm) - O(10 μm)2.0 kPaWet (5 days)
Zinc oxide nanorods90–410 nm2.0 kPaDry (1.5 hours)
Zinc oxide nanorods20–480 nm2.0 kPaDry (1.5 hours)
Silicon nanograss51,54,55<300 nm2.0 kPaDry (1.5 hours)
Silicon microposts545 μm2.0 kPaWet (1.5 hours)
Silicon microposts5425 μm2.0 kPaWet (1.5 hours)
Silicon microgrooves3 μm2.0 kPaWet (1.5 hours)
Silicon microgrooves12 μm2.0 kPaWet (1.5 hours)
Imaging the water-solid interface
Silicon nanowire forest44,56100–400 nmA few TorrDry (1 minute of degassing)
Silicon microposts545 μmA few TorrWet (1 minute of degassing)
Silicon microposts5425 μmA few TorrWet (1 minute of degassing)
  1. Aging, degassing, and imaging experiments were conducted on various samples of rough hydrophobic solids immersed in water. Observations for each sample reflect the state of the surface at the conclusion of the experiment, even if non-wetting behavior is initially exhibited. Surfaces with sub-micron or less spacing tended to remain dry, whereas, surfaces with micron spacing became wet, as predicted.