Enhanced corrosion resistance of self-healing waterborne polyurethane coating based on tannic acid modified cerium-montmorillonites composite fillers

Nanofiller composite coatings with synergistic properties for long-term corrosion protection of metals. In this work, a new composite waterborne polyurethane coating with both self-healing and active corrosion protection was developed for the corrosion protection of carbon steel. The composite coating demonstrated remarkable long-term corrosion resistance thanks to the labyrinth effect of MMT and the synergistic action of corrosion inhibitors Ce3+ and TA. The impedance modulus was still above 108 Ω·cm2 after 50 days of immersion, which was nearly three orders of magnitude higher than that of the pure PU coating. Moreover, the self-healing experiments confirmed that the physical damage was effectively repaired after heat treatment, which was attributed to the disulfide bond exchange reaction. Importantly, the healed coating also exhibited durable corrosion resistance. This kind of double functional anti-corrosive coating shows great potential in the field of long-term anti-corrosion.