Encapsulating PDA-wrapped carbon fibers in waterborne epoxy zinc-rich coatings to enhance the utilization and bonding strength of Zn particles

Carbon fiber (CF) has been widely employed to enhance the mechanical properties of polymers owing to its superior chemical inertness , high tensile strength , and high conductivity. This study presents a surface chemistry-driven approach to enhance the corrosion resistance and mechanical performance of waterborne zinc-rich epoxy (ZRE) coatings by incorporating polydopamine (PDA)-coated carbon fibers (CF). The PDA layer, abundant in catechol and amine groups, facilitates dual interfacial bonding mechanisms—π-π stacking interactions and hydrogen bonding with the epoxy matrix . This synergistic interfacial engineering not only enhances the colloidal dispersion of CF but also results in an eightfold increase in adhesion strength and a 100 % improvement in tensile strength compared to the pristine ZRE coating. Additionally, the low-frequency impedance (|Z| at 0.01 Hz) is elevated by two orders of magnitude, and the cathodic protection duration provided by Zn is extended more than twofold relative to unmodified ZRE coating. These enhancements are attributed to two synergistic mechanisms: PDA-enhanced CF dispersion forming continuous conductive networks that facilitate electron transfer between zinc particles and the substrate, and amine-epoxy covalent bonding, constructing hierarchical barrier structures that hinder electrolyte penetration.