Wetting transition of nanodroplets of water on textured surfaces: a molecular dynamics study

The crossover behaviour of water droplet's state from the Wenzel state to the Cassie state with varying pillar height and surface fraction is examined critically using molecular dynamics. We report the effect of the system size on the wetting behaviour of water droplets by examining the contact angle for both regimes. We observe that when the droplet size is comparable to the pillar dimension, the contact angle of droplets fluctuates with increasing droplet size because of the contact line pinning, which is more pronounced in the Wenzel regime. We further demonstrate the phantom-wall method to evaluate free energy of intermediate wetting states.