The synthesis of copper nanoparticles (Cu NPs) stable to chemical oxidation has attracted much attention due to their novel application possibilities. The physicochemical properties of Cu NPs define their utilization in diverse fields, including biological applications, solar cells, high conductivity inks for printed electronics, and other specific applications. In this study we present the synthesis of oxide-free Cu NPs by wet chemistry routes and their chemical oxidation during the storage exposed to ambient conditions. The Cu NPs synthesized in PAAm and AAm/glycerol presence exhibit no oxidation during synthesis and atmospheric conditions storage for 60 and 37 months, respectively. The obtained results compared with those coming from oxidation of partially passivated commercial Cu NPs at 99.8% purity, are presented. The role of the Cu NPs coating is critical to avoid oxidation, and it can be an important feature to achieve good dispersion in different polymers. The Cu NPs oxidation was studied by XRD, TGA, TEM, FTIR, and HR-TEM.

Copper nanoparticles (CuNPs) functionalized with polyethyleneimine (PEI) and 4-aminobutyric acid (GABA) were used to obtain composites with isotactic polypropylene (iPP). The iPP/CuNPs composites were prepared at copper concentrations of 0.25–5.0 wt % by melt mixing, no evidence of oxidation of the CuNP was observed. Furthermore, the release of copper ions from iPP/CuNPs composites in an aqueous medium was studied. The release of cupric ions was higher in the composites with 2.5 and 5.0 wt %. These composites showed excellent antibacterial activity (AA) toward Pseudomona aeruginosa (P. aeruginosa) and Staphylococcus aureus (S. aureus). The incorporation of CuNP into the iPP polymeric matrix slightly decreased the thermal stability of the composite material but improved the crystallinity and the storage modulus. This evidence suggests that CuNPs could work as nucleating agents in the iPP crystallization process. The iPP/CuNPs composites presented better AA properties compared to similar composites reported previously. This behavior indicates that the new materials have great potential to be used in various applications that can be explored in the future.