Multi-treatments based on polydimethylsiloxane and metal-organic framework wrapped with graphene oxide for achieving long-term corrosion and fouling protection: experimental and density functional theory aspects

Abstract

In this study, ZIF-8 metal–organic framework decorated on surface of graphene oxide nanosheets and functionalized with silane moieties (F-GO@MOF) is employed to enhance the anti-corrosion, anti-bacterial, and anti-fouling properties of epoxy coatings modified with polydimethylsiloxane (epoxy-PDMS). The epoxy-PDMS/F-GO@MOF sample has revealed super-hydrophobic behavior with least water contact angle changes (Δθ ≈ 5° while Δθ ≈ 17° is recorded for epoxy-PDMS sample) during 20 days of immersion, twice pull-off adhesion strength (6.8 MPa compared to 3.7 MPa for epoxy-PDMS coating), and significantly higher impedance modulus (8.82 × 108 Ω·cm2 which is 3 times more than the epoxy-PDMS sample) during 60 days of immersion in NaCl electrolyte. The anti-bacterial test against Pseudomonas sp. and anti-fouling monitoring in Qingdao port have shown that fewer bacteria and marine organisms are attached on the epoxy-PDMS/F-GO@MOF coating, respectively, indicating advanced fouling and bacterial resistance of the nanocomposite sample. Based on the theoretical studies by density functional theory (DFT) method, the binding of the components in the GO@MOF complex is notably large which could inhibit the penetration of corrosive agents toward the steel substrate. In addition, the stabilization of the GO@MOF nanohybrid is mainly controlled through van der Waals (vdW) forces.