Reduction–Coagulation Preparation of Hybrid Nanoparticles of Graphene and Halloysite Nanotubes for Use in Anticorrosive Waterborne Polymer Coatings

Graphene has been extensively concerned as an ideal modifier in the exploration on mordern polymer coatings with high performance. However, the poor dispersibility of graphene in water strongly limits the application in waterborne systems. Here, we demonstrate a simple but effective reduction–coagulation method for the preparation of hybrid nanoparticles of halloysite nanotubes (HNTs) and reduced graphene oxide (rGO). The work was started from the simple mixture of the aqueous dispersion of graphene oxide(GO) and HNTs. As the subtle introduction of the reducing agent, GO was reduced into rGO and co-coagulated with HNTs. Tailored by the residual hydrophilic groups inside the nanotube of HNTs, the phase separation was controlled in colloidal scale, and stable aqueous dispersion of HNTs–rGO hybrid nanoparticles was thereafter obtained conveniently. We directly blended the product into the polymer latex for the formation of coating films. The tests reveal that the composite coating system with the addition of 0.5 wt % of HNTs–rGO can provide excellent corrosion protection for more than 90 days in all the testing mediums except 10 wt % H2SO4, which is much superior to the blank polymer coating.