Plastron longevity of super-hydrophobic surfaces with micro-post structures

Superhydrophobic surfaces (SHS) have a wide range of applications including drag reduction, self-cleaning, anti-icing, and anti-biofouling. A critical parameter for their performance is the plastron longevity, the duration that SHSs can sustain a stable air layer (plastron) on their textured surfaces, typically influenced by gas diffusion. This work experimentally investigates how undersaturation levels and micro-texture dimensions affect the plastron longevity of SHSs. Seven different micro-post structures were fabricated using masked stereolithography 3D printing, varying texture’s gap, diameter, and height dimensions in the range of 200 to 600 μm. Hydrophobic nanoparticles were subsequently sprayed onto the samples to introduce nanoscale roughness and reduce surface energy. Plastron longevity tests were conducted for each surface in stationary DI water within a sealed chamber under three different undersaturation conditions. Two optical imaging setups were employed to visualize the decay of plastron and characterize wetting transitions. Results show that the transition from the Cassie-Baxter to Wenzel state was delayed with increased undersaturation levels. Additionally, reduced texture gaps and increased post heights further extended plastron stability. These findings offer valuable guidance for optimizing SHS designs in applications where enhanced plastron durability is essential.