Surface wettability analysis and preparation of hydrophobic microcylindrical arrays by μ-SLA 3D printing

Hydrophobic surface preparation is always complicated because of the different microstructures requirements with specific functions. This paper describes a Stereo Lithography Appearance (SLA) 3D printing method for creating hydrophobic surfaces. In this work, four different shapes of microstructures were prepared to observe the molding effect of the SLA process for the determination of the best printing structures. The contact angles of water droplet on the microarray surface were also measured through a contact angle meter with high-definition camera. The results show that the contact angles of different microarray surfaces were much better than the flat surfaces with chemical coating. Moreover, the cylindrical array shows the most stable hydrophobic effect with a maximum contact angle of 143.6°. The theoretical design and construction of surface wetting microstructures were also explored by calculating the minimum percentage of solid based on the Cassie-Baxter's wetting model. It is believed that the micro-cylindrical array could be adopted to promote the hydrophobic properties of material surfaces, which also indicates that the μ-SLA method could provide a new idea for the preparation of wettability surfaces.