Impact-induced hole growth and liquid film dewetting on superhydrophobic surfaces

Wetting and dewetting phenomena occur widely in the fields of coating, anti-icing, and microfluidics. While liquid wetting via hole collapse has been intensively researched, liquid film dewetting, especially that induced by hole growth, has rarely been studied. This paper describes a combined experimental and theoretical investigation of metastable liquid film dewetting on superhydrophobic surfaces induced by dry hole growth. Experiments show that dry holes can form upon droplet impact, and these holes mainly exhibit growth, stability, or collapse depending on their initial size. Only the growth behavior can induce liquid film dewetting. Theoretical analysis further clarifies that the hole behavior is a result of competition between the capillary force and hydrostatic pressure, and the scale of the dewetting area is controlled by the Young-Laplace equation and affected by the shape of the superhydrophobic surface. The quantitative relationship between the dewetting velocity and the liquid film thickness is also established. These results deepen our understanding of liquid film dewetting on superhydrophobic surfaces and present fresh insights into related engineering applications.