Fabrication of superhydrophobic 3D objects by Digital Light Processing

The 3D printing process enables to print objects having various functionalities at pre-designed locations in the object. Hereby, we report on the printing of superhydrophobic objects composed of patterns of micropillars. Superhydrophobicity is an important property of surfaces that has applications in various fields such as self-cleaning, drag reduction, increased buoyancy, and air conditioning. Most existing methods for the fabrication of superhydrophobic surfaces are complicated and time-consuming. Here, we performed a simple and cost-effective process for the fabrication of superhydrophobic (SH) objects by Digital Light Processing (DLP) 3D printing. To the best of our knowledge, this is the first study that has used DLP 3D printing to fabricate SH 3D objects without further coating process. We designed a novel ink, which contained non-fluorinated acrylates and Hydrophobic Fumed Silica (HFS). We studied the effects of HFS concentration and pillar-array design for imparting the SH property, which was measured in terms of the contact and rolling angle of water droplets on the surface. As proof of the concept of increased buoyancy by superhydrophobicity, we demonstrated the floatation of the printed SH objects in comparison to their non-SH counterparts even after forcefully submerging them into water.