One-Step Fabrication of Superhydrophobic Surfaces with Wettability Gradient Using Three-Dimensional Printing

Abstract

Polymer surfaces with wettability gradient were fabricated using three-dimensional (3D) printing technology to control the velocity of droplets on the surfaces. A microscale pattern of a semicircular casting mold was created layer-by-layer using a 3D printer based on fused deposition modeling. A surface with a wettability gradient was fabricated by replicating the semicircular mold with a continuously varying surface slope. Water contact angle measurements and droplet test results demonstrated the characterization of the wettability gradient. Droplets were released on a gradient surface inclined at 80°, and their movements were controlled; the locations of the droplets after collision on the ground were tracked. The distance of the main drop and splash drop was found to be reduced by 96.7% (from 6.1 to 0.2 cm) and 87.8% (from 18.8 to 2.3 cm), respectively, compared to that on a general superhydrophobic surface. This study demonstrates a simple, rapid, and inexpensive microfabrication method for functional polymer surfaces to control droplet movement using 3D printing technology.