THE USE OF CARBOXYLATES AS PRECURSORS IN THE POLYOL SYNTHESIS OF SILVER NANOPOWDERS

The aim of this work was to develop a simple method to prepare silver micro- and nanoparticles that can be used to fabricate electroconductive compositions, including pastes, inks, and adhesives. To achieve this goal, the reduction of silver alkyl carboxylates (SAC) with different lengths and structures of the methylene chain by ethylene and propylene glycol was studied. The possibility of preparing monodisperse silver nanoparticles without using polymers as dispersants and stabilisers was shown. The particles obtained were characterized by X-ray diffraction analysis and electron microscopy. It was found that complete reduction of the straight short-chain alkyl SAC occurred at lower temperature (100-130 °C) than long-chain ones (130-170 °C). The particles synthesised under these conditions were spherical, and their average size decreased from 70 to 16 nm with an increase in the length of methylene chain. In the case of branched SAC structure, the reduction with polyols started at lower temperatures and was accompanied by the formation of larger silver particles 150 to 450 nm in size. It was shown that the characteristics of particles obtained by the reduction of linear SAC were almost independent of the synthesis conditions, whereas in the case of branched analogues the temperature, synthesis time and polyol type affected the size of the particles formed. Based on the data obtained, a mechanism for the formation of silver nanoparticles was proposed. Silver particles synthesised according to the developed procedure can find application as metal fillers in 2D and 3D printing inks and pastes for the manufacture of functional components and devices, in conductive adhesive compounds, in polymer composites, in medicine and biology.