High-Temperature Synthesis of Cobalt Nanoparticles in Hyperbranched Polyester Polyol Medium

Abstract— The synthesis of CoNPs cobalt nanoparticles by the method of polyol- process was proposed, which consists in a high-temperature synthesis of polymer-stabilized metal nanoparticles in a matrix of a fourth-generation hyperbranched polyester polyol. Branched polyester polyol acts as both a reducing agent and a stabilizer at the same time. It has been found that the reduction of the precursor CoCl₂ with a hyperbranched polyester polyol occurs at 210°C. The introduction of NaOH into the reaction mixture makes it possible to lower the synthesis temperature by 50°C and leads to a change in the mechanism of in situ ripening CoNPs from the digestive mechanism to direct Ostwald ripening.