Role of ionic surfactants on the nucleation and growth of silver nanoparticles

Abstract

Sodium dodecyl sulfate (SDS) and cetyltrimethylammonium bromide (CTAB) were used as stabilizers for the preparation of silver nanoparticles (AgNPs) by the reduction of silver nitrate with proanthocyanidines (Pas). UV–visible spectra shows that the surface Plasmon resonance (SPR) intensity of AgNPs increases and decreases with increasing SDS and became constant at higher concentration. CTAB has no effect on the nucleation of AgNPs due to the insolubility of Pas. The position of SPR band (λmax = from 438 to 476 nm) depends on the concentration of Pas and a red shift of 38 nm was observed in absence of externally added SDS. The micellar pseudo phase proposed by Menger and Portnoy, modified by Bunton was used to determine the rate constants in micellar media. The Ag+ ions were formed complex with negative head group (OSO3−) of SDS electrostatically. Raman scattering spectroscopy, transmission electron microscopy, and scanning electron microscopy were used to discuss the capping action of SDS. Zeta potential of SDS-capped AgNPs was negative and resulting sols were stable for many months.