Stain-resistant, superomniphobic flexible optical plastics based on nano-enoki mushroom-like structures†
In this paper, we demonstrate the stain-resistance and high pressure stability of superomniphobic flexible optical plastics. A scalable method for creating nano-enoki mushroom-like structures in plastics is presented that provides the re-entrant geometry needed to prevent infiltration from a variety of liquids. The surface demonstrates static contact angles over 150° and low contact angle hysteresis under 20° for a wide variety of organic liquids. The re-entrant tops and fluorination of the nano-enoki as well as the few micron spacing between nanostructures provide robust metastable solid–liquid–air interfaces in the presence of Laplace pressures of at least 900 Pa. In addition, compared to the initial bare plastic, the nano-enoki structures demonstrate comparable transmission values (86.4% versus 88.4% at a wavelength of 550 nm) and ultrahigh haze values (96.4% versus 1.1%). The surfaces exhibit stain-resistance for a variety of liquids including mustard and blood, where mustard and dried blood both flake off the samples without any residue. We also performed durability experiments which demonstrate that nano-enoki plastics are robust to bending with similar transmission, haze, wetting contact angle, and hysteresis values after 5000 cycles of bending.