Bioinspired superhydrophobic coatings: ZnO-based epoxy composites with the biomimetic structure of parrot feathers for anti-corrosion/anti-biofilm applications

In this study, superhydrophobic biomimetic ZnO-based epoxy thermoset (EP) composite coatings were fabricated through a nano-casting procedure to transfer the structural architecture of natural parrot feathers to the polymer surface for anti-corrosion and anti-biofilm applications. As-synthesized epoxy slurries without and with 5 wt% of ZnO were dispersed in ethanol and then dropped onto the negative soft PDMS biotemplate, resulting in the successful synthesis of a series of biomimetic epoxy coating surfaces (denoted by Bio-EP and Bio-EPMZ5–3). The surface morphology of biomimetic coatings exhibited micron-sized rachis adorned with many nano-scaled barbules, as observed under SEM. The contact angle (CA) was found to increase from 62° ± 0.57° for a non-biomimetic coating to 135° ± 1.32° and 152.4° ± 1.36° for Bio-EP and Bio- EPMZ5–3, respectively. The electrochemical corrosion potential (Ecorr)/impedance (Z') of EP coating was found to increase significantly from −649 mV/1.89 × 105 Ω to −178 mV/1.56 × 106 Ω for Bio-EPMZ5–3, indicating that the Bio-EP composite coating exhibited the best anti-corrosion performance. In anti-biofilm applications, short-term anti-bacterial and long-term anti-biofilm experiments were evaluated against Staphylococcus aureus and Escherichia coli) via SEM and crystal violet stain. The study findings revealed that the Bio-EPMZ5–3 surface coating effectively curtailed bacterial growth and significantly impeded biofilm development. This inhibition is primarily attributed to the surface's superhydrophobic properties, which prevent bacterial adhesion and, as a result, substantially hinder their proliferation.