Pickering Emulsions Stabilized\nby Nanoparticle Surfactants

Abstract

Amphiphilic gold nanoparticles are demonstrated to effectively\nstabilize emulsions of hexadecane in water. Nanoparticle surfactants\nare synthesized using a simple and scalable one-pot method that involves\nthe sequential functionalization of particle surfaces with thiol-terminated\npolyethylene glycol (PEG) chains and short alkane-thiol molecules.\nThe resulting nanoparticles are shown to be highly effective emulsifying\nagents due to their strong adsorption at oil–water and air–water\ninterfaces. The original nonfunctionalized gold nanoparticles are\nunable to effectively stabilize oil–water emulsions due to\ntheir small size and low adsorption energy. Small-angle X-ray scattering\nand electron microscopy are used to demonstrate the formation of nanoparticle-stabilized\ncolloidosomes that are stable against coalescence and show significant\nshifts in plasmon resonance enhancing the near-infrared optical absorption.