Advanced anticorrosive coatings prepared from electroactive polyimide/graphene nanocomposites with synergistic effects of redox catalytic capability and gas barrier properties

In this study, electroactive polyimide (EPI)/graphene nanocomposite (EPGN) coatings were prepared by thermal imidization and then characterized by Fourier transformation infrared (FTIR) and transmission electron microscope (TEM). The redox behavior of the as-prepared EPGN materials was identified by in situ monitoring for cyclic voltammetry (CV) studies. Demonstrating that EPGN coatings provided advanced corrosion protection of cold-rolled steel (CRS) electrodes as compared to that of neat EPI coating. The superior corrosion protection of EPGN coatings over EPI coatings on CRS electrodes could be explained by the following two reasons. First, the redox catalytic capabilities of amino-capped aniline trimer (ACAT) units existing in the EPGN may induce the formation of passive metal oxide layers on the CRS electrode, as indicated by scanning electron microscope (SEM) and electron spectroscopy for chemical analysis (ESCA) studies. Moreover, the well-dispersed carboxyl-graphene nanosheets embedded in the EPGN matrix hinder gas migration exponentially. This would explain enhanced oxygen barrier properties of EPGN, as indicated by gas permeability analysis (GPA) studies.