“…When the surface of the copper foil is rice-grain copper nanoparticles, the contact angle of diiodomethane on RG-VLP is 88.3°, while the contact angle on the VLP surface is 63.2°. According to the Cassie–Baxter model, 22–24 the contact angle can be defined as the angle between the tangent of a boundary droplet and the plane of a solid surface. The droplet–gas–solid interface relationship can be obtained as solid surface wettability using the following formula.cos θ CA = f s (cos θ flat + 1) − 1where θ CA and cos θ flat denote the contact angle between a rough solid surface and an ideal smooth surface droplet, respectively, and f s denotes the ratio of the solid surface vs. the droplet contact.…”