Anticorrosion performance of hydrophobic acid-modified-MOFs/epoxy coatings

Abstract

Two nano metal-organic frameworks (NMOFs), [Cu(2,6-dmy-3,5-pyda)4]n (namely Cu-MOFs) and {[Zn(2,6-dmy-3,5-pyda)2(4,4′-bipy) (H2O)]•H2O}n (namely Zn-MOFs) with the unsaturated metal sites were hydrophobically modified by octadecylphosphonic acid (OPA) to prepare MOFs/OPA hydrophobic composites, which were added as hydrophobic additives to the epoxy (EP) coating to prepare Cu-MOFs/OPA/EP and Zn-MOFs/OPA/EP anticorrosion coating. The corrosion protection behavior of these coatings was examined in 3.5 wt% NaCl solution by using EIS, the capacitive arc of the coating modified with Cu-MOFs/OPA and Zn-MOFs/OPA was larger than EP, and Rp increases from 1.283 × 107 to 6.111 × 108 and 7.415 × 108, respectively. The two anticorrosion coatings showed higher impedance modulus values in low frequency region. All the study results proved that both Cu-MOFs/OPA and Zn-MOFs/OPA composite materials with the EP coating provided a very strong barrier and shielding effect, and have the ability to enhance the anticorrosive performance of the epoxy coating