3D-Printed Robust Dual Superlyophobic Ti-Based Porous Structure for Switchable Oil/Water Emulsion Separations

Smart surfaces with responsive wettability are unstable, and depend upon continuous external stimuli, which limits their widespread application in switchable oil/water emulsions separations. In this study, a Ti-based 3D porous structure (SLM-3DTi) is printed using advanced selective laser melting (SLM) technology for the switchable separation of oil/water emulsion. With the assistance of the computer program, porous structure and re-entrant texture can be easily designed and printed in one step. Without any continuous external stimulus, the wettability of SLM-3DTi can be reversibly switched between underwater superoleophobicity and underoil superhydrophobicity simply by drying and washing cycles. The SLM-3DTi achieves switchable surfactant-stabilized oil-in-water emulsion (SSE(o/w)) and surfactants-stabilized water-in-oil emulsion (SSE(w/o)) separation with purity above 99.8% at a flux of more than 2000 L m⁻² h⁻¹. In addition, the re-entrant texture of the SLM-3DTi surface is formed with the partially melting powder particles on the part contour, which has much stronger mechanical durability than any binder. Furthermore, SLM-3DTi has excellent corrosion resistance due to the material properties of Ti. More importantly, based on the visualization analysis of the simulation, the mechanism of SLM-3DTi emulsion separation is further elucidated. Therefore, SLM-3DTi has broad practical application potential for high-flux, high-purity, and switchable oil/water emulsion separation.