Preparation Of Graphene Oxide-based Epoxy Modified Polyurethane Composite Coating And Its Anticorrosive Performance

With the development of new materials and technologies,anti-corrosion technology gradually tends to develop in the direction of functional composite,in which micro-nano materials play a very important role.Owing to the impermeability to gas and H₂O molecules,large specific surface area,and thin-layer sheet structure,Graphene oxide（GO）becomes an effective nano-filler that can slow down the diffusion of corrosive media in the coating.However,GO nanosheets are easily agglomerated due to their inherent Van der Waals forces and have poor compatibility with organic coatings,which limits their application in the field of anti-corrosion.Therefore,GO nanosheets were modified to improve the dispersion of GO nanosheets in the resin matrix,which provide self-healing functions and long-term anticorrosion performance.This paper is committed to building a set of green,highly-efficiency,and functionalized in one corrosion inhibition and protection coating system.The polypyrrole-benzotriazole-graphene oxide nanomaterial（GBP）with sandwich structure was prepared by in-situ polymerization using pyrrole as the monomer,and GBP/epoxy modified polyurethane resin（EP-PU）composite coating was prepared.The polarization curve test shows that the corrosion current density(I_corr)of carbon steel in 3.5 wt%Na Cl solution added with GBP is 233.92μA cm^-2,the corrosion rate is 70.42%lower than that in blank solution,indicating that GBP has excellent corrosion inhibition performance on the matrix.The results of electrochemical impedance test（EIS）showed that the low-frequency impedance modulus(|Z|_{10 m Hz})of 0.15%GBP/EP-PU composite coating remained10¹⁰Ωcm² after immersion for 50 days,which showed long-term corrosion resistance.For the 0.15%GBP/EP-PU coating with scratches,the|Z|_{10 m Hz} increased during the 4-48 h immersion process,which showed self-healing performance.The polyaspartic acid crosslinked chitosan（CS）modified graphene oxide composites（GCP）were prepared,and GCP/EP-PU composite coatings were prepared.The polarization curve test shows that the I_corr of carbon steel in 3.5 wt%Na Cl solution added with GCP is149.69μA cm^-2,the corrosion rate is 72.59%lower than that in blank solution.EIS results showed that the|Z|_{10 m Hz} of the GCP/EP-PU coating remained 10¹⁰Ωcm² after immersion for35 days,which was 2 orders of magnitude higher than that of blank EP-PU coating,showing excellent corrosion resistance.The GCP/EP-PU composite coating with scratch increased|Z|_{10m Hz} after immersion for 4 hours of immersion,indicating the release of polyaspartic acid corrosion inhibitor and the formation of passive film.CeO₂ was loaded in a cyclodextrin（CD）modified GO nanocontainer（GCC）by hydrothermal method,and GCC was added to EP-PU resin to form composite coating.The polarization curve test showed that the corrosion rate of the EP-PU composite coating with GCC added after being immersed for 38 d was 1.8150 mm a^-1,which was significantly lower than that of the pure EP-PU coating(9.4691 mm a^-1),showing excellent corrosion resistance performance.The EIS test results showed that the|Z|_{10 m Hz} of the EP-PU coating with GCC added remains 10¹⁰Ωcm² after being immersed for 38 d,which was 2 orders of magnitude higher than that of the blank EP-PU coating,showing good corrosion resistance.In the GCC/EP-PU composite coating with scratch,the|Z|_{10 m Hz} increased during the 4-48 h immersion process,showing active protection performance.