Capillary-Driven Liquid Transport of Low-Surface-Tension Liquids

There has been extensive research on capillary-driven transport of high surface tension liquids (e.g. water, glycerol, etc.), but only limited attention has been given to contact-line confined transport of liquids with low surface tension (e.g. oils, alcohols, etc.). When the fluid surface tension drops below 40 mN/m, repellency becomes extremely difficult. This situation is encountered in many engineering applications and thus is of high technological importance. In this work, we use a fluorinated nanocomposite coating deposited on a surface textured by laser etching, a scalable technique that requires no lithography implementation. The approach results in the repellency of liquid hydrocarbons with surface tensions as low as 21mN/m. The repellency of several liquids with surface tensions in the range 21-72mN/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 wettable track. Finally, travel distance and velocities of low-surface tension liquids transported on inclined ramps against gravity on similar wedge-shaped wettability-patterned tracks are compared.