Study on Modification of Lignin as Dispersant of Aqueous Graphene Suspension and Corrosion Performance in Waterborne G/Epoxy Coating

Abstract

Though graphene (G) as an excellent protective material for metal, it can aggravate metal corrosion in other side. The modification of sodium lignin sulfonate was achieved by using itaconic acid and acrylamide，which was proved by UV-vis and Raman spectra. The modified sodium lignin sulfonate (LAI) with more carboxylic groups can be used as the dispersant for aqueous graphene suspension. The commercial graphene can be dispersed uniformly and stability in water via π-π interaction with LAI at high concentration (6 mg/mL)， and the LAI-G system can be used as an inhibitor in waterborne epoxy coatings too. Electrochemical impedance spectroscope (EIS) and Tafel polarization curves showed that the corrosion performance of waterborne epoxy system with well-dispersed G (0.5 wt %) was remarkably improved compared with pure epoxy coating.