Wettability and dynamics of water droplet on a snail shell

Abstract

Hypothesis: There are many natural surfaces with special wettabilities. Snail shells have unique rough structures, which indicates a specific wettability. In this study, the surface of a snail shell was simulated using epoxy resins, and water droplet dynamics on original and simulated snail shells were investigated to understand its special wettability.

Experiments: The shell of the Euhadra sandai species of snails was used. The surface structure of the snail shell was simulated using epoxy resins. The surface of this EP resin was treated with UV-O₃ for different periods of time. Wettabilities and dynamics of water droplet on the samples were characterized.

Findings: The surface of the snail shell with a water contact angle of approximately 85° caused the droplet to spread, which is the first report of water droplet dynamics on the shell surface. The behavior of a water droplet on the shell transformed from the Cassie state into the Wenzel state. Changes in the contact angle and diameter of the droplet base on the snail shell were larger than those on the epoxy resins. The surface roughness and chemical heterogeneity of the snail shell led to distortion of the three-phase contact line and enhancement of the spreading of the water droplet.

Keywords: Snail shell; Spreading; Surface roughness; Wettability.