Early stage of liquid drop spreading on tunable nanostructured surfaces

In this study, the early stage of liquid droplet spreading on tunable nanostructures was investigated through high resolved and fast imaging visualization. It is well-known that the early stage of water droplet spreading on a solid surface features an inertia dominance on resistive droplet motion in a short period (~0.01 sec). The spreading dynamic law of this stage differs greatly from those of the classical spreading stage, after the inertia regime, being determined by the balance between a spreading force and viscous friction. The effect of triple line physics associated with the surface properties is generally underestimated in the early inertial regime by a relatively short period and strong inertia momentum, and such physics result in the nature of the spreading (Dt^1/2). Here, we designed tunable nanostructures that can modify the nature law of the early droplet spreading. The results suggest that the increase of initial spreading momentum attribute to the capillary wicking effect controlled by the nanostructure morphology.