Preparation of alkali-resistant aluminum pigment encapsulated with fluoropolymer by in situ polymerization

Abstract

Flaky aluminum pigments with excellent corrosion resistance have found applications in diverse fields. In this study, a fluoropolymer has been incorporated in the aluminum pigment to effectively enhance its corrosion resistance, along with the improvement in the chemical resistance and thermal stability. Specifically, a uniform dense layer of poly(trifluoroethyl methacrylate) (PTFEMA) has been directly coated on the surface of the flaky aluminum pigment by in situ polymerization. The encapsulated aluminum pigment exhibited high stability upon dipping in the alkaline solution (pH = 13) due to protection imparted by the fluoropolymer layer. The morphology of the fluoropolymer layer on the surface of the aluminum pigment was characterized by scanning electron microscopy (SEM). Moreover, the thermal stability of the encapsulated aluminum pigment was analyzed by thermogravimetric analysis (TG). The structure and composition of the fluoropolymer layer were further characterized by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The stability of the aluminum pigment in alkaline aqueous media was investigated via hydrogen evolution experiments. Overall, the corrosion resistance of the aluminum pigment encapsulated with fluoropolymer was observed to be markedly improved owing to the presence of the PTFEMA layer.