Maze Effect or Antimaze Effect: The Double Effect of Modified 2D Fillers Ti₃C₂T_<i>x</i> on the Properties of Waterborne Polyurethane Coatings

With a high aspect ratio and a good ion barrier property, two-dimensional fillers can prevent the invasion of corrosive media by a "maze effect" when showing good interface compatibility with polymer. However, this blocking effect also affects the release of volatile substances during the coating curing process, leading to an ""antimaze effect" and an increase in internal coating defects. In this work, 2-D filler Ti₃C₂T_<i>x</i> was noncovalently modified with corrosion inhibitor 8-HQ and dopamine in one step to obtain a filler owing good interfacial compatibility with polyurethane. Its "antimaze effect" in waterborne polyurethane coating was studied. The results of electrochemical impedance spectroscopy and the water absorption test showed that the coating exhibited the best performance when the dosage of modified Ti₃C₂T_<i>x</i> was 0.25 wt %, by which the "maze effect" and "antimaze effect" reach balance. The low-frequency impedance modulus was 14 times higher than that of the control sample, and the saturated water absorption was reduced by 56.15%. The enhancement mechanism of the coating's anticorrosion property by modified Ti₃C₂T_<i>x</i> was analyzed. Results showed that the addition of modified fillers not only improves the "maze effect" but also reduces the internal defects of the coating. The corrosion inhibitor used for modification enhanced the adhesion. It also played a corrosion inhibition role in subsequent long-term service or when the coating was damaged. This study provides a new reference for the application of 2D fillers in organic coatings.