3D-Printed Repeating Re-Entrant Topography to Achieve On-Demand Wettability and Separation.

While it is difficult and expensive to fabricate a complicated surface structure via conventional techniques, three-dimensional (3D) printing serves as a time-efficient and cost-efficient alternative. In the current study, a novel repeating re-entrant topography is fabricated by two-photon polymerization 3D printing. The experimental results show that the repeating re-entrant surface enhances the desired on-demand surface wettability. Moreover, the 3D-printed membranes with the repeating re-entrant structures enable the efficient on-demand separation of liquid mixtures with high flux, which is critical for the wastewater treatment in the chemical industry.