Effect of Conductivity of the Aqueous Solution on the Size of Printable Nanoparticle

Abstract

Direct writing technology using nano/microsize particles in aqueous solution is currently one of the leading candidates to bring a substantial advancement to the technical arena. However, little is known about an effect of conductivity of the solution including metal ions on nanoparticle size for the direct writing technology. It is believed that conductivity of solution can influence the size of particles in reducing environmental of aqueous solutions. In this study parameters which affect electric conductivity in solution were characterized by changing concentration of copper ion, concentration of surfactants, and anion of metal compounds. The mobility of ion in aqueous media with respect to copper ion concentration was the most pronounced factor to control the size of created copper nanometals in water. However, due to the high reactivity on large surface area, the nanocopper metal was oxidized in water. The electric conductivity varied in the range of 7 to 360 mS/cm when Cu(NO3)2⋅3H2O dissolved in water from 0.03–3.0 mol/dm3. In this condition, the size of nano particles can vary from 10 to 500 nm. Various concentrations of surfactants and two anion Cu compounds used to vary the conductivity of the solution to verify the effect of electric conductivity of solution on the particle size. Decreasing the conductivity had a corresponding effect on the particle size. The electric conductivity was decreased from 67 to 56 mS/cm by adding surfactant from 0.1 to 0.5 mol/dm3 consequently, the particle sizes were decreased from 89 to 21 nm. Copper nitrate and copper chloride were used to verify the anion effect on electrical conductivity and particle sizes. This effect was not dependent on the kind of ions chosen to change the conductivity. However, when Cu(NO3)2⋅3H2O was used, the size of the particles was 89 nm, while it was 91 nm when CuCl2⋅2H2O was used.