Novel nitrogen doped carbon dots enhancing the anticorrosive performance of waterborne epoxy coatings

There are lots of research studies reporting the excellent performances of waterborne epoxy resin coatings to reduce environmental VOC levels. However, it has also been manifested that waterborne epoxy resin coatings do not have high corrosion resistance because of being hydrophilic. Herein, we utilized a kind of N doped carbon dot (N-CD) which has high ethanol solubility and low cytotoxicity to enhance the corrosion resistance of waterborne epoxy resin coatings as a nanofiller. The N-CDs were obtained through a solvothermal method by using 4-aminosalicylic acid (ASA) as a precursor. The diameter and height of N-CDs confirmed by scanning probe microscopy and transmission electron microscopy are 3-5 nm. Corrosion resistance performance of the coatings without and with N-CDs is investigated by electrochemical impedance spectroscopy by immersing them in 3.5 wt% NaCl (aq) for 70 days. The results indicate that the composite coatings with 0.5 wt% N-CDs show superior anticorrosive performance due to bond interactions between N-CDs and polymer chains, the defect repairing effect of N-CDs and the formation of compact Fe₂O₃ and Fe₃O₄ passivation layers.