DEFECT-SPARSE 2D CARBON IN EPOXY POWDER COATINGS: PORE CONTROL AND EIS DURABILITY

Abstract

A thermoset powder-coating platform was formulated by integrating a defect-sparse two-dimensional carbon nanoadditive into an epoxy matrix to suppress microporosity, enhance network formation, and improve long-term barrier function against chloride brines. The nanoadditive was manufactured via benign liquid-phase shear exfoliation with polymeric stabilization, converted to a dry powder, dispersed at ultra-low loadings, electrostatically deposited onto steel, and oven cured to yield dense polymer films representative of industrial powder-coating practice.Polymer/coating diagnostics spanning SEM (microstructure), FTIR/Raman (chemical signatures), DSC (cure onset and heat transport), and adhesion by pull-off testing were coupled to electrochemical evaluations (EIS with equivalent-circuit modeling and Tafel analysis) to establish processing–structure–property relationships in the barrier film. Optimized low-loading formulations reduced cavity/micropore prevalence, preserved interfacial adhesion after aggressive salt exposure, and sustained high low frequency impedance over multi-week immersion, reflecting improved coating resistance and mitigated charge-transfer at the coating–metal interface. Cure-kinetic and thermal evidence indicate that the nanoadditive subtly advances epoxy ring-opening and promotes levelling-driven porosity reduction, complementing its physical tortuosity effect at sub-0.1 wt% concentrations. Together, these polymer-centric findings define a scalable, chromate-free route to epoxy powder barrier coatings in which 2D carbon modulates porosity, curing, and electrochemical response to deliver durable corrosion protection.