POSS-tetraaniline modified graphene for active corrosion protection of epoxy-based organic coating

Abstract

In this study, the tetraaniline (TA) grafted polyhedral oligomeric silsesquioxane (POSS) giant molecule was synthesized and used as graphene (G) dispersant to prepare a functionalization molecule (POSS-TA-G). Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and ultraviolet visible spectroscopy (UV–Vis) were selected to evaluate the existence form and distribution state of pristine and modified graphene. After that, the epoxy coating with proper POSS-TA-G were coated on the surface of Q235 steel to form a function epoxy composite coating. Electrochemical impedance spectroscopy (EIS) and local electrochemical impedance techniques (LEIS) were chosen to estimate the effect of POSS-TA-G on barrier and self-healing performance of as-prepared coating. Results revealed that the POSS-TA intercalated graphene presented a good dispersibility based on the π-π interaction between POSS-TA and graphene. Compared with pristine graphene, the POSS-TA-G displayed a good electroactivity and relatively lower conductivity, which could promote the formation of passivation film and reduce the risk of galvanic corrosion during long-term anti-corrosion process. The addition of 0.5 wt% POSS-TA-G could endow coating with superior anti-corrosion performance, including effective shielding properties caused by well-dispersion graphene and self-healing ability derived from POSS-TA.