Functionalization and morphology control of graphene oxide for intelligent barrier coatings against corrosion

Abstract

Designing intelligent fillers for high-performance corrosion protection coatings, especially for the strong corrosion harsh environment of desulfurized flue gas, remains a huge challenge. In this paper, a novel graphene-based intelligent nanofiller with tunable morphology was successfully synthesized via a self-assembly strategy. Using polydopamine (PDA) as gatekeeper, the mesoporous silica nanocontainer (MSNs) was loaded with the corrosion inhibitor benzotriazole (BTA), preparing the pH response MSNs-BTA/PDA (PBM) nanocontainers. Graphene oxide (GO) was modified by PBM through non-covalent interactions including hydrogen bond and π-π stacking. A self-unfolding GO/PBM (GO@PBM-5) was obtained through adjusting the ratio of GO to PBM. The active/passive corrosion protection properties of the novolac epoxy coating (EPN) are endowed by the GO@PBM-5 intelligent nanofiller with a self-unfolding structure, which can be ascribed to the corrosion inhibition and labyrinth effect. As a result, the value of |Z|_0.01Hz of coating reinforced with GO@PBM-5(GO@PBM-5/EPN) remained above 10¹⁰ Ω cm² after immersion in 10 wt% H₂SO₄ solution at 55 °C for 60 days. The thermal conductivity of GO@PBM-5/EPN is 0.312 W m⁻¹ K⁻¹. In addition, no cracking occurred after 400 cycles of −60–140 °C cold-thermal shock. Moreover, the GO@PBM-5/EPN is intact and no rust spots, bubbles, or peeling occur after the salt spray test for 14 days. Showing extremely strong barrier performance as well as thermal conductivity, cold-thermal shock resistance and high self-healing properties. This study opens a new avenue for improving the service life of organic coating in the strong corrosion environment of desulfurized flue gas.