Wetting behaviours of a-C:H:Si:O film coated nano-scale dual rough surface

By combining nano-scale surface roughening with a hydrophobic a-C:H:Si:O coating, we generated the super-hydrophobic surface with very low wetting angle hysteresis. We focused on the effect of the dual structure of the surface on the static and the dynamic wetting behaviours. It was observed that the dual rough surface is super-hydrophobic with a wetting angle around 160° and a wetting angle hysteresis (difference between forwarding and receding angle) less than 5°. On the other hand, mono rough surfaces in any scale appeared sticky and the wetting angle hysteresis ranged from 30° to 60° depending on the dimension of the surface roughness.