Fabrication of superhydrophobic PLA surfaces by tailoring FDM 3D printing and chemical etching process

The present study describes a simple and robust method for fabricating superhydrophobic surfaces of Polylactic Acid (PLA) using the Fused Deposition Modelling (FDM) process without the need for nanoparticles. FDM 3D printing technology allows for replicating the surface topology of superhydrophobic surfaces. The resulting PLA samples show excellent non-wetting properties after chemical etching and coating with a low surface energy material. The water contact angles (WCA's) of the FDM printed PLA samples were found to be up to 142° at an optimized average roughness value of 148.6 nm on a 3D printed square pyramid structure with equal height and edges of base of 1.5 mm. Microstructural analyses suggest that the observed high WCA results from the hierarchical structures created by FDM 3D printing and chemical etching. The study found that increasing the distance between the peaks of two pyramids changes the wetting mechanism from the Cassie-Baxter state to the Wenzel wetting state, leading to a decrease in the WCA. This paper presents a detailed study of the impact of roughness created by 3D printing, surface topology, and chemical etching on the wetting properties of PLA. The vital outcome of this study is the fabrication of superhydrophobic surfaces using FDM 3D printing and low surface energy material without the use of nanoparticles.