Contrasting water adhesion strengths of hydrophobic surfaces engraved with hierarchical grooves: lotus leaf and rose petal effects.

The (de)wetting transitions of hierarchical grooves periodically engraved on a hydrophobic surface were investigated using a fully atomistic molecular dynamics simulation. The (meta) stable and transition states with sagging or depinning liquid surfaces were identified by calculating the free energy profiles of the (de)wetting transitions. The dewetting transitions for wide and narrow minor grooves have large and small activation free energies, respectively, exhibiting contrasting water adhesion forces as found for rose petals and lotus leaves.