Fluorinated Nanocomposite Coatings for Confinement and Pumpless Transport of Low‐Surface‐Tension Liquids

Preparing surfaces that repel low-surface-tension liquids, such as oils and hydrocarbon fuels with surface tensions below 30 mN m(-1), poses more challenges than attaining water repellency. Oleophobic surfaces are needed when organic fluids must be contained to avoid pollutant spreading. A composite material system is presented comprised of fluorinated silica (filler), a perfluoroalkyl methacrylate copolymer (binder), and fluorinated polyhedral oligomeric silsesquioxane (additive; considered the lowest surface-energy material to date), which can be applied as a thin coating onto any substrate. The coating is shown to repel liquids with surface tension as low as 23.8 mN m(-1). Regions of the coatings are made superoleophilic (high affinity to oils and other hydrocarbons) through laser processing, thus generating wettability-patterned surfaces that can passively manage and transport low-surface-tension liquids by harnessing forces arising from the spatial confinement of the fluid. The rapid (>20 cm s(-1)) pumpless transport of several liquid hydrocarbons on open-air, wettability-engineered surfaces is demonstrated, and the respective transport rates are compared to those of water. The sprayable coating formulation and post-processing steps used in this work offer a tractable approach to rapidly fabricate and test wettability-engineered devices that can effectively contain, manage, and pumplessly transport low-surface-tension liquids on open surfaces.