Photoreactive Surfactants: A Facile and Clean Route to Oxide and Metal Nanoparticles in Reverse Micelles

By de Oliveira, Rodrigo J.; Brown, Paul; Correia, Gemima B.; Rogers, Sarah E.; Heenan, Richard; Grillo, Isabelle; Galembeck, AndreÌ? & Eastoe, Julian
Published in Langmuir NULL 2011

Abstract

A new class of photoreactive surfactants (PRSs) is presented here, consisting of amphiphiles that can also act as reagents in photochemical reactions. An example PRS is cobalt 2-ethylhexanoate (Co(EH)2), which forms reverse micelles (RMs) in a hydrocarbon solvent, as well as mixed reversed micelles with the standard surfactant Aerosol-OT (AOT). Small-angle neutron scattering (SANS) data show that mixed AOT/PRS RMs have a spherical structure and size similar to that of pure AOT micelles. Excitation of the ligand-to-metal charge transfer (LMCT) band in the PRSs promotes electron transfer from PRS to associated metal counterions, leading to the generation of metal and metal -oxide nanoparticles inside the RMs. This work presents proof of concept for employing PRSs as precursors to obtain nearly monodisperse inorganic nanoparticles: here both Co3O4 and Bi nanoparticles have been synthesized at high metal concentration (10 -2 M) by simply irradiating the RMs. These results point toward a new approach of photoreactive self-assembly, which represents a clean and straightforward route to the generation of nanomaterials.

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