In-situ formation of silver nanoparticles using nonionic surfactant reverse micelles as nanoreactors

In this paper, we report the one-step synthesis of metallic silver nanoparticles (Ag NP) using nonionic surfactant reverse micelle as nanoreactors. Diglycerol monolaurate (C12G2) spontaneously self-assemble into spheroid reverse micelles having size 10-12 nm in cyclohexane under ambient conditions of temperature and pressure. The spheroid C12G2 reverse micelles swell with water. Swollen reverse micelles having size - 20 nm are formed upon incorporation of 1% water. We used C12G2 reverse micelles as nanoreactors for making ordered nanostructure of Ag-NP by replacing water with aqueous silver nitrate solution. The diglycerol moiety of the surfactant reduces silver ions into metallic silver and thereby stabilizes the generated Ag NP. We found that shape and size of the Ag NP is closely related to the structure of nanoreactor. Similar results have been observed in linear chain alkane n-octane. We found bigger Ag NP from the C12G2/octane reverse micelle system as the size of the micelle in this system is bigger than that of the C12G2/cyclohexane system. This simple approach based on in-situ reduction of metal ions (without the need of reducing agent) opens a new possibility for the development of controlled synthesis of nanostructured noble metallic nanoparticles.