Micelle-Assisted One-Pot Synthesis of Water-Soluble Polyaniline−Gold Composite Particles

A micelle-based method to synthesize dispersed polyaniline (PANI)−Au composite particles by direct oxidation of aniline using AuCl4 - as the oxidant is presented. The obtained composite particles have a core−shell structure, where Au nanoparticles of 20 nm mean diameter are encapsulated by PANI of well-defined tetrahedron shape with 150 nm average edge length. The polaron band of the dispersed PANI−Au composite particles is centered at 745 nm and is rather narrow compared to the broad 835 nm absorption of PANI synthesized by the IUPAC procedure. The surface plasmon absorption of Au nanoparticles normally centered at around 520 nm is absent in the composite particles with oxidized PANI. Our results point to a strong electronic interaction between the encapsulated Au nanoparticles and the shell of oxidized PANI. Films and pellets produced from these composite particles show a twofold higher conductivity than IUPAC PANI.