Photoactive Gold Nanoparticle Soft-oxometalates (SOM) using a Keplerate for Synthesis of Polystyrene Latex Microspheres by Photo-polymerization

A green and facile synthetic protocol for the preparation of photoactive gold nanoparticle-soft oxometalates (AuNP-SOM) using a unique Keplarate type oxomolybdate cluster viz. {Mo$_{132}$}, is reported. The as synthesized AuNP-SOMs are fully characterized by Electronic absorption spectroscopy, Raman spectroscopy and High resolution transmission electron microscopy (HR-TEM). We further demonstrate that by merely tuning the ratio of the precursors in solution it is possible to control the morphology of AuNP-SOM nanostructures. Moreover, these photoactive AuNP-SOMs are employed as photocatalysts for the photopolymerization of styrene to generate colloidal monodisperse polystyrene microspheres in a controllable way in the absence of any external co-initiator or inert atmosphere. Effect of styrene concentration on the size of microspheres is studied using DLS and optical microscopy. Finally, the role of AuNP-SOMs as efficient photocatalyst is established through several control experiments and a reaction pathway is proposed.