Comparative study of the properties of silver hydrosols prepared by “citrate” and “citrate-sulfate” procedures

Abstract

Comparative study of the properties of silver hydrosols prepared with the use of two classical procedures (“citrate” and “citrate-sulfate”) is performed. The possibility of using these procedures for the synthesis of stable monodisperse silver hydrosols with particle diameters of 20 nm and more is studied. The effect of the main parameters of synthesis (the ratio of initial components, the rate of their mixing, etc) on the hydrosol characteristics is investigated. It is revealed that, in the case of “citrate” synthesis, it is quite impossible to realize conditions ensuring the reproducible preparation of colloidal solutions with particles having sufficiently uniform size and shape. The procedure for the one-stage preparation of “citrate-sulfate” hydrosol (without multiple precipitation-redispersion of nanoparticles) is elaborated and it is shown that the thus prepared hydrosol is greatly superior in both the optical characteristics and the morphological uniformity of particles to the citrate sol. An increase in synthesis temperature to 100°C leads to a substantial enhancement of the stability of colloidal solution. The possibility of using “citrate-sulfate” hydrosol for the design of two-dimensional ensembles of silver nanoparticles on the quartz and silicon surfaces modified with poly(2-vinylpyridine) is demonstrated. It is shown that such ensembles possess optical properties that allow to use them in designing “two-dimensional” polymer-metal nanocomposites potentially suitable for using as active media in devices working on the principle of surface plasmon resonance.