Single-step exfoliation, acidification and covalent functionalization of α-zirconium phosphate for enhanced anticorrosion of waterborne epoxy coatings

Abstract

Abstract Epoxy resin is widely used in the field of anticorrosive coatings for its outstanding properties. However, environmentally friendly two-component waterborne epoxy coatings often have micropores in its films, making their barrier properties against corrosive media unsatisfactory. α-zirconium phosphate (α-ZrP), known as a kind of flexibly designable two-dimensional nanoparticle, has outstanding mechanical and barrier properties. However, the common problem of incorporating such inorganic fillers into epoxy resins is the poor interface compatibility. In this work, α-ZrP was firstly exfoliated by Tris-(hydroxymethyl)-aminomethane (Tris) aqueous solution, then acidified by diluted hydrochloric acid (HCl) and finally covalently functionalized by 3-aminopropyltriethoxy silane (KH-550). Subsequently, waterborne epoxy composite coatings (KWEPc) with K-ZrP as functional filler were prepared and applied on Q235 carbon steel substrates by blade-coating. With KH-550 modifying, K-ZrP showed an improved dispersion in waterborne epoxy coatings (WEPc). The structure and morphology of prepared K-ZrP was characterized and confirmed by FTIR spectra, XPS and EDS-mapping. The results showed that K-ZrP is evenly modified with amino siloxane. Electrochemical tests revealed that the corrosion rate of KWEPc was one order of magnitude lower than that of WEPc. KH-550 act as a “bridge” among inorganic filler, epoxy resin matrix and Q235 carbon steel substrates.