Underwater Anisotropic 3D Superoleophobic Tracks Applied for the Directional Movement of Oil Droplets and the Microdroplets Reaction

Abstract In this paper, a simple way to fabricate underwater anisotropic superoleophobic tracks is reported for manipulating underwater oil droplets by the femtosecond laser etching and the oxygen plasma treatment. Laser ablation is able to generate micro/nanoscale hierarchical structures on the poly(dimethylsiloxane) (PDMS) surface. The textured PDMS surface is further turned from superhydrophobicity to hydrophilicity and underwater superoleophobicity by subsequent oxygen plasma irradiation. Underwater anisotropic 3D superoleophobic tracks can also be fabricated on the PDMS surface by the laser etching method. The width of the tracks depends on the laser‐treated area, while the depth of the tracks increases with increasing the laser power and the scanning number and with decreasing the laser scanning speed/space. The underwater superoleophobic 3D tracks show ultralow adhesion and anisotropic sliding property to oil droplets, thereby allow the underwater oil droplets to move just along the track. A microdroplets reaction is proposed based on the underwater superoleophobic tracks. There is no loss of the reactants during the whole reaction process. The anisotropic sliding property of underwater organic droplets will potentially have enormous applications in droplet manipulation, microfluidics system, surface lab‐chip devices, and chemical engineering.