The Study of the Stability of Colloid Dispersions of Copper Nanoparticles Based on Sodium Dodecyl Sulfate

Abstract

Methods for the synthesis of copper nanoparticles in a micellar solution of an anionic surfactant, sodium dodecyl sulfate, are improved by optimizing the molar ratios of the precursor and the reductant, Cu(II): N₂H₄ of 1 : 4, 1 : 8, 1 : 20, 1 : 40, 1 : 100, and 1 : 150 at a pH of 11.1 and pH values of the reaction medium of 10.9, 11.0, 11.2, and 11.9 at the optimum Cu(II): N₂H₄ molar ratio of 1 : 150. The effect of increasing the Cu(II) : N₂H₄ molar ratio on the growth in the absorbance of suspensions of copper nanoparticles is established. The stability of solutions over time is studied using the spectrophotometric analysis of colloidal dispersions of copper nanoparticles obtained at a Cu(II) : N₂H₄ molar ratio of 1 : 150 and values of pH of 10.9, 11.0, 11.2, and 11.9. The process of the aggregation of copper particles accompanied by a hypsochromic shift of the absorption band of surface plasmon resonance towards larger wavelengths is studied by dynamic light scattering. Scanning electron microscopy has shown that copper particles obtained at a Cu(II) : N₂H₄ molar ratio of 1 : 150 and pH values of 10.9, 11.0, and 11.2 have a spherical shape with dimensions in the range from 12 to 176 nm.