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

HR Ren and SY Zhu and Y Xiao and C Li, ACS APPLIED NANO MATERIALS (2021).

DOI: 10.1021/acsanm.1c03533

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 nano-droplets 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 degrees. 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 similar to 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

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