Omniphobic Surfaces for Low-Surface-Tension Liquids*

There has been substantial research on superhydrophobic (water-repellent) surfaces, but only limited research on superoleophobic (oil-repellent) surfaces that can repel liquids with low surface tension. Water has a high surface tension 72 mN/m, which makes it simpler to repel, but when the fluid surface tension drops below 40 mN/m, repellency becomes more difficult. This situation is encountered in certain engineering applications and thus is of technological importance. In this work, we report a fluorinated nanocomposite coating deposited on a surface textured by femtosecond laser surface processing (FLSP), a scalable technique that requires no lithography implementation. The approach resulted in the repellency of liquids with surface tensions as low as 21 mN/m. The repellency of liquids with surface tensions from 72mN/m to 21mN/m is experimentally investigated. Comparisons are performed between the velocities acquired by fluids transported pumplessly on a wedge-shaped wettability-patterned track, due to confinement imposed by the superomniphobic background surrounding the superphilic track. Finally, transport length and velocities of low-surface tension liquids transported on inclined ramps against gravity on similar wedge-shaped wettability-patterned tracks are being exhibited.