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

Abstract

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.