Gas film transportation on asymmetric superhydrophobic mesh surfaces for excellent drag reduction and anti-scaling properties

Manipulation of gas in an aqueous environment is fundamental to both academic research and industrial applications. Especially, the gas film on a superhydrophobic surface, referred to as a plastron, has fascinated scientists due to its potential applications including drag reduction, antifouling, gas-involving reactions and gas transport. However, most gas manipulation strategies mainly focus on the transportation of bubbles. Effective method of facile manipulation of plastron still has to be explored. In this paper, we propose a high-performance manipulation strategy for plastrons, utilizing the capillary pressure difference generated by connected sparse and dense superhydrophobic mesh surfaces (S-D-SHM). Plastrons can be transported directionally, spontaneously, repeatedly and counterbuoyantly (up to 30° tilt angle) between the asymmetric superhydrophobic mesh surfaces. This method, which requires no external energy input or human intervention, can provide on-demand plastron replenishment for superhydrophobic mesh surfaces (8 times), significantly enhancing the plastron stability. Furthermore, S-D-SHM achieves an 142% improvement in water impact resistance due to the automatic adjustment of the plastron pressure. With the long-term isolation effect of the plastron, the S-D-SHM shows excellent drag reduction effect (23.7% drag-reduction rate) and anti-scaling performance (93.3% anti-scaling rate). This facile and effective strategy simplifies plastron manipulation and can advance the development of stable superhydrophobicity under complex wetting conditions.