Model of synthesis of ZnS nanoparticles stabilized by cetyltrimethylammonium bromide

Abstract

A mathematical model of synthesis and stabilization of ZnS nanoparticles in aqueous solutions of cetyltrimethylammonium bromide (CTAB) is presented. ZnS nanoparticles precipitated by the reaction of sodium sulphide and zinc acetate are significantly influenced by CTAB both in a stage of nucleation and in a stage of growth and stabilization. The suggested model assumes a dominating influence of the nucleation stage on future properties of emerging ZnS nanoparticles. On the basis of a calculated nucleation rate depending on a degree of the ZnS supersaturation, the model adopts an approximate assumption that ZnS nuclei are formed all at one moment.Mathematical formulation of the nucleation model attempts to explain a recently observed relationship between ZnS nanoparticles radii and the CTAB concentration. The dependence of a surface tension of zinc acetate and CTAB aqueous solutions on the CTAB concentration was measured and further applied to obtain the relation between the CTAB monomer concentration and the CTAB total concentration. The nucleation model assumed a key role of CTAB monomers, which were considered as nucleation centres. The predicted radii