Effect of the grafting degree of (3glycidyloxypropyl)trimethoxysilane on the corrosion resistance of waterborne epoxy/Ti3C2 nanocomposite coatings

Modification of MXene is usually necessary for their application in corrosion resistant coatings. Nevertheless, the influence of the grafting degree of modifier is not concerned in the past. In this work, modified Ti3C2 nanosheets (G-Ti3C2) with different grafting degree of (3-glycidyloxypropyl)trimethoxysilane (GPS) were obtained by changing GPS dosage, and further incorporated into waterborne epoxy resin coatings (WEP). GPS modification led to deteriorated dispersion in water but improved dispersion stability of Ti3C2 nanosheets in waterborne epoxy resin at appropriate GPS-grafting degree presumably due to the interaction between the liquid epoxy resin droplet and G-Ti3C2 nanosheets. The GPS grafting degree was also critical to get the corrosion resistant nanocomposite coatings. The best corrosion resistance, i.e., with impedance modulus four orders of magnitude higher than that of pure WEP after 30 days' immersion in salt solution as well as the lightest corrosion in salt spray test, was achieved using the Ti3C2 nanosheets modified at the GPS-to-Ti3C2 mass ratio of 30:1. Better dispersion of G-Ti3C2 nanosheets and stronger interaction between epoxy resin matrix and G-Ti3C2 nanosheets should be responsible for the excellent corrosion resistance of the coatings at optimum GPS grafting degree.