Co-modification of epoxy based polyhedral oligomeric silsesquioxanes and polyaniline on graphene for enhancing corrosion resistance of waterborne epoxy coating

Firstly, polyaniline (PANI) was used to improve dispersibility of graphene (Gr) in water through pi-pi interactions. Then, the obtained Gr/PANI products was further decorated with the epoxy based polyhedral oligomeric silsesquioxane (EPOSS) to enhance the hydrophobic properties of hybrid materials and compatibility with epoxy resins, thus leading to the increase of corrosion protection properties. From the wettability test results, the contact angle of the cross section of the composite coating reached up to 112.7 degrees after grafting EPOSS, indicating that the hydrophobicity of the coating was improved significantly. Besides, the tensile strength of Gr/PANI@EPOSS/epoxy (0.7%) increased to 25.6 MPa, which proves the increase of interface force due to the introduction of epoxy group. The results of electrochemistry test illustrated that the impedance of Gr/PANI@EPOSS/epoxy (0.7%) is still as high as 2.79 x 10(7) Omega cm(2) after 60 days of immersion, which is much higher than that of other samples.