Table 1: Material properties of surfaces used in the experiments.

From: Sustaining dry surfaces under water

MaterialSpacing between structuresStructure widthStructure heightMaterial contact angle§
Polymer/HFS (NC1)O(10 nm) - O(10 μm)10 nmHierarchicalN/A*
Polymer/PTFE (NC2)O(260 nm) - O(10 μm)260 nmHierarchicalN/A*
Zinc oxide nanorods90–410 nm40–80 nm1 μm110°
Zinc oxide nanorods20–480 nm100–150 nm2 μm110°
Silicon nanograss<300 nm5018 nm50,51100 nm110°
Silicon microposts5 μm10 μm10 μm110°
Silicon microposts25 μm10 μm10 μm110°
Silicon microgrooves3 μm3 μm5 μm110°
Silicon microgrooves12 μm3 μm5 μm110°
Silicon nanowire forest100–400 nm50–200 nm2.5 μm104°52
  1. Material samples consisted of either particle/polymer coatings or pillared-type micro/nano structures.
  2. §Contact angle observed on a flat surface (effect due to chemistry, not surface texture).
  3. Hierarchical structure consisting of both nanoscale and microscale surface roughness. The former is of the order of the nanoparticle size, while the latter is of the order of large clusters formed by these particles (as verified by surface profilometry). The nanoscale texture due to the nanoparticles is superimposed on the microscale texture of the coated dry material.
  4. Nominal diameter of single nanoparticles sprayed onto the surface. These particles may coalesce into larger structures.
  5. *The polymer/nanoparticle coatings consist of a composite of different materials, at least one of which is in particle phase. Thus, no smooth surface can be fabricated of the same constituents, making measurement of θe not possible.