“Kill two birds with one stone” strategy to attain intelligent early warning anti-corrosion coating with a dual response mechanism

Abstract

Corrosion of metal materials has become a major challenge for marine facilities. Traditional anti-corrosion coatings cannot detect local corrosion in time, leading to significant maintenance costs. Therefore, providing an intelligent response performance to traditional anticorrosive coatings is essential. This study proposes an intelligent epoxy anticorrosion system based on the dual-mode response mechanism of visual color development and fluorescence quenching. The molecular structure was designed with the combination of 1,10-phenanthroline-5-amine (APhen) and E44 epoxy resin through a simple ring-opening reaction to obtain modified epoxy resin (EAPhen). The intelligent responsiveness of the epoxy resin was achieved through a simple and efficient complexation reaction. Subsequently, under the curing crosslinking of polyether amine D400, an epoxy resin anticorrosive coating (EAD-x) with excellent mechanical properties and visual response to corrosion products (Fe²⁺) was prepared. Furthermore, the high crosslinking density and dense three-dimensional network structure provided EAD-4 coating with good physical barrier properties. Additionally, APhen and local corrosion product Fe²⁺ were able to form a passivation layer protective film after a complexing reaction. The synergistic effect of these mechanisms gave the epoxy resin excellent corrosion resistance. After 7 days of immersion in 3.5 wt% NaCl solution, the |Z|_{0.01 Hz} value of the EAD-4 coating remained as high as 2.56 × 10¹¹ Ω•cm². Moreover, due to the “pinning” effect of E44, the adhesion level of EAD-4 coating to the substrate reached 5 B. In conclusion, this study provides a concept for realizing the visual self-warning function of local corrosion which is expected to offer a more reliable and efficient anti-corrosion protection scheme for marine engineering facilities while promoting sustainable development in this field.