Self-Propelled Nanodroplet Jumping Enhanced by Nanocone Arrays: Implications for Self-Cleaning and Anti-Icing Surfaces

Abstract

Self-propelled jumping of droplets on solid surfaces is essential for many natural and engineering processes. Specifically, rational design based on micro-/nanostructures enables a merged droplet to jump spontaneously after the coalescence of two droplets. However, self-jumping is highly challenging for nanodroplets due to the significant energy dissipation. Herein, we show the enhancement of the nanodroplets’ self-propelled jumping with the properly designed nanocone arrays on hydrophobic surfaces using molecular dynamics simulation. The self-propulsion of nanodroplets could be triggered by the nanocone decoration on a graphene-like flat surface. With the reducing nanocone apex angle, the critical intrinsic contact angle that the merged droplet could successfully jump decreases to roughly 100°. Importantly, a strong droplet initial position dependence of the jumping velocity is revealed. As nanodroplets initially locate in the gap between the nanocones, an enhancement of ∼245% for the jumping velocity is obtained compared to that on the nanocone tip. Essentially, high-efficiency self-jumping dynamical behaviors are achieved by the small energy dissipation, which is strongly dependent on both the liquid–solid interaction area and time. This work confirms the crucial role of the nanostructure in boosting the self-propelled nanodroplet jumping and provides a feasible way to passively enhance the nanodroplets’ jumping, which has potential applications for controllable droplet movement on functional surfaces.