A direct one-step synthesis of a smart graphene/silica nanocomposite and its application for improving the acid resistance and corrosion resistance properties of waterborne epoxy coatings

Graphene has attracted tremendous attention as a potential building block of modern high performance coating systems. Herein, we demonstrate a green method for making reduced oxide graphene (rGO) using the natural product rutin as the reducing agent. The rGO, with residual rutin on the surface to provide surface affinity, is used in the one-step fabrication of a nanocomposite of rGO and silica nanoparticles (SN) with a corrosion inhibitor, benzotriazole (BTA), loaded in situ. The ternary nanocomposite, BTA@SN-rGO, can be easily dispersed in water. It not only has a high inhibitor loading capacity (85.1 mu g mg-1) but also can release the inhibitor in a controlled manner triggered by pH. Combining both the extraordinarily good barrier properties and smart nanocontainer features, BTA@SN-rGO was further incorporated into an epoxy latex to assemble an intelligent anticorrosion coating. The effective duration of the coating protection for steel was remarkably prolonged in different media, especially in acidic media. In addition to the barrier capability, smart self-healing of artificial damage to the modified coating films is also shown. Electrochemical impedance spectroscopy (EIS) was applied to monitor the failure process of different kinds of coatings. All the results confirm the synergy of the passive and active functions of the BTA@SN-rGO coating. A smart BTA@SN-rGO nanocomposite was obtained via a one-step synthetic method and can provide remarkable long-term corrosion protection on metal.