Spreading Behavior of Oil on Hierarchical Microstructured PET Surfaces Fabricated Using Hot‐Embossing Combined with Laser‐Based Methods

In this study, the wetting behavior of microstructured polyethylene terephthalate (PET) foils for polar and nonpolar liquids produced by plate-to-plate hot embossing is investigated. For the embossing step, stainless steel plates are used as stamps, which are microstructured with single-scaled and hierarchical textures using direct laser writing and two-beam direct laser interference patterning. The imprinted microstructures, containing pillar- and line-like textures, show increased water contact angles combined with a superoleophilic behavior. Time-resolved measurements reveal that oil droplets spread rapidly on the hierarchical textures with velocities of up to 1.4 mm2 s-1. This functionalization of PET foils creates new opportunities for a wide range of industrial applications, such as the use of oil-based instead of solvent-based paints, an improved distribution of lubricants in mechanical components or for oil-water separation in maritime surroundings.