Multifunctional epoxy/ZnO/GO superhydrophobic coatings for integrated marine protection and hydrodynamic drag reduction.

Marine biofouling limits the efficacy of epoxy (EP) based marine coatings due to their inherent hydrophilic properties and easy bio-adaptability, leading to loss of barrier performance and increased hydrodynamic drag. To overcome these constraints, the present work demonstrates a multifunctional EP-based antibiofouling coating modified with acetic acid (AA) and stearic acid (SA), containing functionally active zinc oxide (ZnO) and graphene oxide (GO) additives. Three coatings were fabricated, namely EP, EP/ZnO (EPZ), and EPZ/GO (EPZG). Surface chemical modification showed a shift in water contact angle (WCA) of hydrophilic EP coatings from 72.58° ± 1.03 to superhydrophobic EPZG coatings with a WCA of 153.17° ± 1.16. Furthermore, the superhydrophobic EPZG coating showed corrosion protection with |Z|0.01 Hz 1.67 × 1010 Ω cm2 in 3.5 wt% NaCl. Additionally, biocorrosion performance was tested by exposing the coated samples to Escherichia (E.) coli and Staphylococcus (S.) aureus for 7 days and found that the superhydrophobic EPZG coating retained corrosion inhibition efficiencies of 91.5% and 98.7% with bacterial inhibition rates of 88.84% and 65.86% against E. coli and S. aureus, respectively. Additionally, the superhydrophobic EPZG coating demonstrated a remarkable drag reduction of 29.37% at a velocity of 6.85 m s-1, favouring the overall potential of this multifunctional coating for total marine protection.