Understanding the effects of polar and non-polar surfactants on the oxidation performance of copper nanoparticles

Copper nanoparticles (Cu-NPs) have garnered attention due to their high electrical and thermal conductivity, high melting point, and relatively low cost compared to other metals (i.e., gold and silver). The widespread usage of Cu-NPs is hindered due to their susceptibility to oxidize and corrode, as well as the difficulty to achieve a synthetic route that is easily scalable with controlled morphology and does not encompass parasitic conditions (i.e., harsh reactants, high temperature). Many of the published routes involve harmful/toxic compounds and reducing agents, as well as very high temperatures/long reaction times, and despite the harsh synthetic conditions the nanoparticles are extremely susceptible to oxidation. Therefore, developing a cost effective and green synthesis that can produce Cu-NPs that are resilient/controllable to oxidation and corrosion environments is critical for Cu-NPs to be usable in industrial and commercial usage. In this work, a novel microwave-assisted synthetic route is demonstrated using an organometallic precursor (Copper (I)-Mesityl) and a variety of green solvents (glycols) and surfactants (hexadecylamine [HDA]). Numerous synthetic parameters (i.e., solvent/surfactant combinations) were systematically investigated to evaluate their effect on the particle size and morphology as well as how the solvent/surfactant prevent oxidation/corrosion in atmospheric corrosion environments. The various surfactant/solvent coated nanoparticles were subjected to a variety of environments such as 100% relative humidity (RH) and 10 ppm H 2 S/50% RH. The nanoparticles were characterized pre- and post-exposure to understand the role of the solvent and surfactant species effect on hindering oxidation. Particles were characterized via powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA), transmission electron microscopy (TEM), and Fourier transform-infrared (FT-IR) spectroscopy. The results show the combination of glycols/HDA yielded a synergistic effect that led to a reduction in the oxidation kinetics upon exposure to atmospheric corrosive environments, yielding oxidative resistant nanoparticle (> 14 days). Details on the synthesis route, characterization, and oxidation stability are presented.