Effective corrosion resistance and antifriction properties can prolong the durability of coatings. We demonstrate that hexagonal boron nitride (BN) nanosheets can be employed as the reinforcement in waterborne polyurethane (PU)-matrix composite coatings and lead to a significant improvement in their corrosion protection properties. The impedance modulus at 0.1 Hz dropped from 109 Ω cm2 to 108 Ω·cm2 for 2% BN/PU coatings after 114 h immersion in 3.5 wt% NaCl electrolyte, while it dropped from 108Ω·cm2 to 5×106 Ω·cm2 for neat PU coatings. The dynamic friction coefficient was decreased for 22.6% with the addition of 2 wt% BN in the PU composite coatings at 100 °C. The morphologies of the coating surfaces showed less abrasion than neat PU after the test. The major challenge of preparing BN/PU composite coatings was the dispersion of BN nanosheets in the waterborne polymer, which was solved by functionalization of BN nanosheets with hydroxyl groups.
Available online 30 April 2018