A study of the wetting characteristics of a nano-sized water droplet on heterogeneous striped surfaces

• Heterogeneous surfaces with different pillar and base surface energies were proposed.
• At high pillar heights the pillar surface energy has a large effect on the droplet.
• On highly heterogeneous surfaces the variation in droplet shape was large.
• Variation of molecule inflow percentage was large at high pillar heights.

Understanding hydrophobicity is important in many fields. The main purpose of this research is to investigate the wetting characteristics of a water droplet on a heterogeneous stripe patterned surface at the nano-scale including contact angle, molecule inflow percentage, contact length, diameter ratio and density fields of the water droplet. Molecular dynamics simulations were employed to analyze the wetting behavior of water droplets on surfaces with stripe pillar structures by considering the interacting forces between water molecules and the surface. The heterogeneous surfaces considered had stripe pillars with a different surface energy than the base surface. It was found that the difference in surface energy between the base surface and stripe pillar had a large effect on the hydrophobicity of the surface regardless of the stripe pillar height. As a result, there was a large variation in the characteristics of the water molecules such as the contact angle, molecule inflow percentage, contact length, diameter ratio and density fields. Also, there was a large variation in the contact angle of the droplet as the stripe pillar height increased when there was a large difference in the surface energies between the base and the stripe pillars.