Exfoliation and functionalization of a zirconium phosphate in one pot for waterborne epoxy coatings with enhanced anticorrosion performance
Abstract Having high aspect ratio and excellent gas barrier property, two dimensional a zirconium phosphate nanosheets (a ZrP) are one of the promising anticorrosive nanofillers. In this work, under mild conditions, layered a ZrP were effectively exfoliated by Tris buffer solution and functionalized by situ polymerization of polydopamine (PDA) in one pot. And then the functionalized a ZrP (f ZrP) were introduced into waterborne epoxy (WEP) coatings that were applied on the mild steel for electrochemical corrosion tests. Results of TEM, XRD and AFM reveal that a ZrP are successfully exfoliated with an interlayer space of 1.72 nm and a thickness of 0.78 nm. Characterizations of FTIR spectra, TEM image and EDS mapping confirm that a ZrP are decorated by PDA. With PDA decoration, f ZrP gain a better compatibility with WEP than pristine a ZrP do, leading to a homogeneous distribution in the polymer matrix. And the exfoliation by Tris buffer provides f ZrP with high aspect ratio, which is beneficial for f ZrP/WEP to fight against the permeation of corrosive mediums. Therefore, after 15 day immersion in 3.5 wt% NaCl solution, the f ZrP/WEP composite coatings show high value of |Z0.01Hz| (1.90 x 107 O*cm2) which is about one order of magnitude over that of blank WEP coatings (2.33 x 106 O*cm2)