Electrophoretic mobility of silver nanoparticles stabilized with nonionic surfactant Ecosurf SA4: Origin of charged particles, concentration by electrophoresis and production of conductive coatings

Abstract

Linear electrophoresis in silver organosols was investigated in this work. Silver nanoparticles were obtained in reverse micelles of the nonionic ethoxylated surfactant Ecosurf SA4. Electrokinetic phenomena in media with low dielectric permittivity are described for the first time for this class of surfactants. The study of the composition of this surfactant showed weakly bound chlorine. This allowed us to propose a mechanism for the stabilization of charged particles similar to the action of solvating nonpolar solvents like chloroform. This mechanism differs from that previously described for the case of both ionic and nonionic surfactants. The dependence of the electrokinetic ζ-potential of nanoparticles on the concentration of surfactant is investigated. Electrophoretic concentration with close to quantitative degree of extraction was carried out for the systems with a maximum ζ-potential value. Silver content in the concentrate is up to 1.9 mol L−1. Thermal treatment allows getting films with a silver content of up to 97% and a conductivity of up to 20 µOhm/□.