Covalently silane-bridged e-graphene oxide nanosheets toward year-long dispersion-stable epoxy nanocomposites with superior corrosion protection

Abstract

Epoxy resins are extensively used in protective coating applications owing to their excellent adhesion, mechanical strength, and chemical resistance; however, maintaining these properties under prolonged service environments remains challenging. Although nanoscale fillers have been widely explored to enhance the durability of epoxy coatings, the long-term dispersion stability of nanofillers in epoxy matrices remains severely limited by interfacial incompatibility and aggregation. In this work, electrochemically synthesized graphene oxide (e-GO) nanosheets are successfully prepared in an aqueous environment, with intrinsically abundant oxygen-containing functional groups. By carefully selecting silane molecules with high chemical compatibility toward epoxy, a covalent silane-bridging (CSB) strategy is established to chemically integrate e-GO nanosheets into the epoxy matrix, enabling strong interfacial compatibility and long-term dispersion stability. As a result, the epoxy/CSB-eGO nanocomposites exhibit exceptional dispersion stability exceeding one year without observable aggregation, together with simultaneous enhancements in mechanical performance and corrosion resistance. At an optimized CSB-eGO loading of 0.5 wt%, the tensile and flexural strengths are enhanced by 26% and 43%, respectively, while the impact strength increases by 36% at a low loading of 0.1 wt%. Electrochemical impedance spectroscopy further demonstrates outstanding corrosion resistance at an optimized CSB-eGO loading of 1.0 wt%, with the pore resistance (R_pore) increasing from 8488 Ω for pristine epoxy to 2.46 × 10⁵ Ω, corresponding to an approximately 30-fold enhancement. This work provides a scalable strategy for developing durable epoxy nanocomposite coatings with long-term mechanical reliability and corrosion protection.