Polyhedral oligomeric silsesquioxane grafted covalent organic frameworks for simultaneously improved tribological and corrosion resistance of epoxy coatings

In this work, polyhedral oligomeric silsesquioxane (POSS) was covalently grafted on 2D covalent organic framework of TpPa-1 through Schiff base reaction (POSS-TpPa-1) to synergistically improve the corrosion and tribological resistance of epoxy coating. The results show that compared with the hydrophilic TpPa-1, POSS-TpPa-1 exhibits excellent hydrophobicity, and the water contact angle can reach 134°. Furthermore, POSS-TpPa-1 with different weight ratios was added into epoxy coating, and the anti-corrosion and wear resistance of the composite coatings were studied through electrochemical impedance spectroscopy (EIS) and friction and wear tests, respectively. The EIS results show that when the additive amount of POSS-TpPa-1 is 2 wt%, the impedance modulus in the low frequency region can maintain 1.04 × 109 Ω·cm2 even after being immersed in 3.5 wt% NaCl solution for 60 days, indicating its good anti-corrosion performance. The friction and wear experiments show that the epoxy composite coating with 2 wt% POSS-TpPa-1 exhibits the lowest friction coefficient of 0.23, suggesting that POSS-TpPa-1 can effectively improve the friction resistance of the coating under the premise of good dispersion. This work develops a new composite filler to simultaneously improve the anticorrosion and wear resistance of epoxy coating, which might be able to trigger further studies to develop more advanced composite coating by incorporating 2D-COF.