Solution-processable carboxylate-capped CuO nanoparticles obtained by a simple solventless method

Carboxylate-capped CuO nanoparticles were obtained via a simple solventless route, based on the thermal decomposition at 120 °C of solid precursors. The reaction mixture consisted of copper acetate monohydrate, acting as the CuO precursor, and different organic carboxylic acids (lauric, phenylvaleric or 3,6,9-trioxadecanoic acid) used as the capping agent. The proposed method, in good agreement with environmentally friendly practices, produced dry nanoparticles, thereby totally eliminating the need of washing, filtration, or other downstream steps. Transmission electron micrographs show crystalline roughly spherical CuO nanoparticles with average diameters between 3.1 and 5.5 nm depending on the capping ligand. The laurate-capped CuO nanoparticles showed a paramagnetic behaviour at room temperature, while a weak ferromagnetic component was detected at low temperature (<40 K). It was also proved that the chemical structure of the carboxylic acid tail enabled the straightforward dispersibility of nanoparticles in common solvents and assisted in the deposition of the material as thin films.