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

Abstract

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.