Microfluidic synthesis of copper nanofluids

Copper nanofluids have been chemically synthesized by using home-made microfluidic reactors and by using a boiling flask-3-neck. The influence of flow rates of reactants, reactants concentrations, and surfactant concentrations on copper particle size and size distribution has been investigated. It has been found that neither of them has much influence on particle size and size distribution of copper nanoparticles synthesized in microfluidic reactors due to the fast and efficient mass diffusion in microscale dimension. The copper nanoparticles have an average size of about 3.4 nm with a relatively narrow size distribution of around 22% evaluated by the coefficient of variation. While the average size of copper nanoparticles synthesized by flask method changes from 2.7 to 4.9 nm with a coefficient of variation larger than 30%, depending on concentrations of [Cu(NH₃)₄]·(OH)₂ and surfactant sodium dodecylbenzenesulfonate. In addition, by using microfluidic reactors the synthesis time of copper nanofluids can be reduced as much as one order of magnitude, from ~10 min to ~28 s.