(524a) 3D-Printed Surface Topography to Achieve on-Demand Wettability and Separation

The biomimetic superhydrophobic and superoleophobic surfaces require the microscale and nanoscale hierarchical surface textures, combined with coatings with low surface energy. While it has always been difficult and expensive to fabricate the superwetting surfaces with well-controlled textures via conventional manufacturing techniques, 3D-printing serves as a time-efficient and cost-efficient alternative. In the current study, a novel microscale re-entrant surface topography is successfully fabricated by two-photon polymerization (2PP) 3D-printing. On-demand wettability of various liquids has been achieved on the single re-entrant surface. For a given liquid, the re-entrant angle can be precisely manipulated to be either smaller than the liquid contact angle (CA) on the flat surface to achieve dewetting, or larger than the liquid CA on the flat surface to achieve wetting. The 3D-printable microscopic repeating re-entrant surface, which is difficult to make by conventional techniques, has been demonstrated to further enhance the desired on-demand surface wettability. Moreover, efficient on-demand separations of liquid mixtures with high flux are enabled by the 3D-printed separation membranes with the repeating re-entrant structures, which is critical for the wastewater treatment in the chemical industry.