Abstract
We report here a novel and generic method for the synthesis of rod-shaped nanoparticles of AgBr, AgCl, and Fe2O3 using wormlike micelles (WLMs) in aqueous solution. It is observed that the presence of a wormlike micellar phase is critical to the formation of such anisotropic nanoparticles. Spherical nanoparticles are otherwise obtained when wormlike micelles are absent. Nanoparticle precursors first form spherical primary particles at short times, which then coagulate and consolidate on a surfactant backbone to form nanorods. Interestingly, when preformed spherical nanoparticles are added to a wormlike micellar system, nanorods similar to the in situ method are observed. This technique has been explored for the synthesis of anisotropic iron oxide particles as well. Further a mechanism for the formation of these nanorods is proposed and is simulated using a framework of slithering snake dynamics for WLM. In this study, the wormlike micelles are represented by flexible polymers of fixed contour length. A rule-based intermicellar particle exchange protocol is formulated and simulated on a periodic lattice. Simulations reveal that the particles start accumulating slowly on few of the micellar backbones; toward the end, the fraction of micelles carrying no particles increases drastically which is a typical behavior observed in coagulation processes. The particulate masses accumulated on the WLMs are then converted to their respective lengths and diameters.