Preparation Of Modified Polyaniline-Graphene Oxide Epoxy Coating And Its Anticorrosive Performance

Graphene-based anticorrosive pigments have excellent mechanical properties and aspect ratio,which can improve the mechanical properties and shielding of the coating.However,graphene or graphene oxide lacks electrochemical protection.In the event of water seepage or micro-damage of the coating,it is impossible to continue to provide effective protection.Polyaniline-graphene composites not only inherit the mechanical properties of graphene materials and the electrochemical protection function of Polyaniline,but also enhance their dispersion and reduce the agglomeration of graphene-based materials and Polyaniline in anticorrosive coatings.In this paper,Polyaniline-graphene oxide composites were prepared by in-situ polymerization,and the process parameters were optimized,so that Polyaniline could form a uniform and continuous network structure on the surface of graphene oxide,so as to obtain the most electrochemical active PGO material.On this basis,PGO-PPA and PGO-CSA materials doped with phenylphosphonate and camphor sulfonate were prepared by re-doping method,and added to the epoxy coating as pigments to improve the anti-corrosion performance of the coating.The electrochemical behavior of each pigment in the anticorrosive coating was studied,and the optimal addition amount of each pigment was obtained.The research contents and achievements of this paper are as follows:（1）Graphene oxide was prepared by improved Hummers method and Polyaniline was synthesized on graphene oxide sheet by in-situ polymerization.The parameters of the synthesis process are optimized,and the Polyaniline-graphene oxide material with the lowest resistivity can be prepared under these process parameters.At this time,Polyaniline is uniformly arranged on the surface of graphene oxide,and the material has the highest electrochemical activity and electrical conductivity.Polyaniline-graphene oxide material was redoped with phenylphosphonic acid and camphor sulfonic acid respectively to prepare PGO-PPA and PGO-CSA pigments.X-ray energy spectrum showed that phenylphosphonic acid and camphor sulfonic acid successfully replaced the chloride ion in Polyaniline.（2）The above pigments were used to modify epoxy coatings and waterborne epoxy coatings,and the anticorrosive properties and anticorrosive mechanism of PGO coatings doped with different acids were compared by means of electrochemical test,salt spray test,adhesion and so on.The experimental results show that PGO and PGO-CSA can form a black Fe₃O₄passivation film on the metal surface,while PGO-PPA can form a metal phosphating film to increase the coating-metal interface resistance.EIS electrochemical analysis and Tafel curve show that PGO-PPA has the best antiseptic effect,and the optimal addition of 1%PGO-PPA is0.25%.In addition,PGO,PGO-PPA and PGO-CSA have similar anticorrosive behavior in waterborne epoxy coatings,which can improve the charge transfer resistance and enhance the anti-corrosion performance of the coatings.