Graphene-Oxide-Reinforced Perfluorocyclobutyl Polymer Coatings for Tunable Tortuosity-Driven Corrosion Protection

Polymeric coatings are widely used to mitigate corrosion by limiting the transport of water, oxygen, and aggressive ions, yet their long-term performance is often constrained by permeability, electrostatic heterogeneity, and mechanically induced defects. Perfluorocyclobutyl (PFCB) polymers offer intrinsically low permeability and high chemical stability, but opportunities remain to further engineer ion-transport pathways without sacrificing adhesion or durability. The role of two-dimensional nanofillers in fluoropolymer matrices and the limits at which they enhance rather than degrade corrosion resistance also remain poorly understood. Here, we examine how the dispersion state of graphene oxide (GO) in an elastomer-modified PFCB (EPFCB) network couples ion-transport resistance with the electrical response of the coating and buried interface. At 0.10 wt % GO, the coating sustains low-frequency electrochemical impedance values on the order of 109-1010 Ω·cm2 for over 30 days in 3.5 wt % NaCl solution, representing three orders of magnitude improvement over the neat EPFCB coating. This performance is supported by Raman-verified defect-rich GO, homogeneous platelet dispersion observed by electron microscopy, suppression of surface potential fluctuations by Kelvin probe force microscopy, and a controlled increase in glassy modulus from ∼218 MPa to ∼1.6-1.9 GPa without excessive brittleness. In contrast, higher GO loadings (>0.25 wt %) promote aggregation, greater morphological and electrostatic heterogeneity, earlier electrolyte breakthrough, and accelerated scribe creep during cyclic corrosion testing. These findings demonstrate that GO influences EPFCB performance through the combined effects of platelet-induced transport obstruction and dispersion-dependent electrostatic behavior, rather than through tortuosity alone.