Active/passive protection and anti-UV waterborne epoxy coatings based on low defect functionalized PDA-GO-CeO2 material for excellent corrosion control

Abstract

In the marine environment, besides external damage and internal defects, ultraviolet (UV) radiation is also a pivotal factor affecting the stable properties of coatings. Improving the anti-UV aging and active protection properties is beneficial to prolong the service life of coatings. Herein, the PDA-GO-CeO2 composite material is obtained through a facile stepwise growth of polydopamine (PDA) and CeO2 on GO nanosheets and further preparing a multifunctional anti-corrosion PDA-GO-CeO2-EP coating. As expected, composite coating displays strong adhesion force (6.9 MPa) and tensile strength (21.1 MPa), profiting from the enhanced crosslinking density and interface structure caused by PDA-GO-CeO2 and resin matrix interaction. Since low defect functionalized PDA-GO-CeO2 constructs the reinforced physical barrier, the anti-corrosion ability of PDA-GO-CeO2-EP coating (109.7 Ω·cm2) is more dependable than those of EP (106.7 Ω·cm2), GO-EP coating (108.8 Ω·cm2) and PDA-GO-EP (109.1 Ω·cm2) coatings after immersing in 3.5 wt.% NaCl solution for 100 d. Thanks to the synergistic effect of PDA/CeO2, the active protection performance of PDA-GO-CeO2-EP coating is endowed, which is further proved through the in situ scanning vibrating electrode technique (SVET). Following the UV aging treatment, PDA-GO-CeO2-EP coating shows minor gloss loss (20.4 %) and better adhesion force (4.3 MPa). Furthermore, the resistance value of PDA-GO-CeO2-EP coating is 7.03 × 106 Ω cm2 after 30 d immersion in saline solution, which is 242 times greater than that of EP coating (2.90 × 104 Ω cm2). This dependable performance of PDA-GO-CeO2-EP coating comes from the reflection, refraction, and absorption of UV rays by nanoscale CeO2 particles. Consequently, this work offers a simple and promising strategy for fabricating multifunctional long-term protection coatings, thus hopefully extending the service life of marine engineering equipment.