Metal Chelate Monomers Based on Nickel Maleate and Chelating N-Heterocycles as Precursors of Core-shell Nanomaterials with Advanced Tribological Properties

In this study, new metal chelate monomers based on nickel(II) maleate and chelating N-heterocycles (2,2 '-bipyridine and 1,10-phenanthroline) were synthesized and characterized. A detailed analysis of the main stages and features of the kinetics of thermal transformations of metal chelate monomers was carried out. Core-shell nanomaterials containing nanoparticles of nickel oxide and metallic nickel in a stabilizing nitrogen-containing polymer matrix were obtained by thermolysis of these monomers. The composition, properties and structure of the nanomaterials were studied using IR spectroscopy, thermal analysis, X-ray diffraction, atomic force microscopy, scanning electron microscopy, high-resolution transmission electron microscopy, and energy dispersive X-ray spectroscopy. The tribological characteristics of NiO nanoparticles as lubricant additives were studied using a pin-on-disc tribometer. The coefficient of friction (COF) is the lowest at the optimum concentration of nanoparticles and increasing the concentration above the optimum level leads to an increase in COF.