Nano-epoxidized graphene oxide as a high-barrier film-forming component for purely Cardanol-based epoxy anticorrosion coatings

Herein the Nano-epoxidized graphene oxide (NE-GO) was demonstrated to be used as a film-forming component to enhance the barrier properties of purely bio-basedepoxy coatings, composed of a Cardol bifunctional epoxy resin and a Cardanol-basedamine curing agent. AFM has been used to characterize the local cross-linking densityof the coatings. It was found that discontinuous high-crosslinking regions were formedsurrounded by low-crosslinking regions, which decreased the barrier and mechanicalproperties of the coatings. Atomically-dense NE-GO was proposed to be used as thefilm-forming components to achieve a high crosslinking density of purely bio-basedcoatings. FT-IR, AFM, Raman, and XPS have demonstrated the successful preparationof NE-GO. Contact angle, SEM, and electrochemical impedance spectroscopy (EIS)tests demonstrated that the NE-GO worked as a film-forming component to enhancethe cross-linking density of the coating. Compared to the pristine purely bio-basedcoating, the barrier performance (|Z|0.01 Hz) of the epoxy coating with NE-GO as theepoxy film-forming components increased by four orders of magnitude after soaking inNaCl solution (3.5 wt%) for 140 days. The strategy of using 2D, flexible, highlyfunctional, and high-dense GO with a tailored size as the epoxy film-formingcomponents may also be useful for other bio-based epoxy coatings.