Efficient spreading and controllable penetration of high-speed drops on superhydrophobic surface by vesicles

Abstract

Droplet spreading and penetration are essential steps to improve the utilization rate of pesticides spraying on superhydrophobic foliage. However, due to the low surface energy and high roughness of the superhydrophobic surface, high-speed sprayed drops always bounce off surfaces quickly. Strong deposition and even penetration to the surface are necessary to enhance the control effect for pesticides. To address these problems, here, we demonstrate efficient spreading and controllable penetration of high-speed impacting water drops on superhydrophobic surfaces by changing the stability and rigidity of surfactant vesicles. The supple and easily deformed vesicles achieve complete spreading but without penetration after the impact. In contrast, the unstable vesicles rapidly disassociate into single molecules during the impact and the drop achieves complete spreading and effective penetration. Significantly, without changing dynamic surface tension, the vesicle makes droplets completely spread on superhydrophobic surfaces, opening a door for droplet spreading on superhydrophobic surfaces to escape the assistance of dynamic surface tension.