Covalently immobilization of modified graphene oxide with waterborne hydroxyl acrylic resin for anticorrosive reinforcement of its coatings

Combining the advantages of solvent-based and water-based anticorrosive coatings, a waterborne composite dispersion of hydroxy acrylic resin (HAR) and modified graphene oxide (MGO) was prepared for application as an anticorrosive coating. MGO was obtained using 3-aminopropyltriethoxysilane as the coupling agent to introduce NH2 groups onto the graphene surface. HAR with COOH, OH and epoxy groups was prepared at a high solid content of up to 80% through solution copolymerization using methacrylic acid, hydroxyethyl methacrylate, methyl methacrylate, n-butyl acrylate and styrene as monomers, tert-butyl peroxybenzoate as the initiator, and propanediol butyl ether and dimethylbenzene as solvents. The covalent bonds between NH2 and epoxy groups would be formed after blending MGO dispersion and the neutralized HAR to improve its compatibility. The effect of dosage of MGO on the viscosity of water-dispersion of HAR (WHAR), and the hardness, adhesion, contact angle of film formed by WHAR, and the anticorrosive performance of the composite coatings were investigated in detail. Results showed that the more MGO added, the higher viscosity of WHAR-MGO. A small amount of MGO formed a barrier layer after being evenly distributed in the coatings, but excessive MGO agglomerated, thereby reducing the compatibility. Composite coatings with 0.25% MGO had the best corrosion performance in 3.0 wt% NaCl aqueous solution, and the |Z|0.01Hz was 10–20 times higher than other coatings with or without MGO, and the Icorr was 10 times lower than coating without MGO. This work provides a good way to balance the environmental issue of organic solvent emission and corrosive properties of water-borne polyacrylate coatings.