Block Copolymer Mediated Synthesis of Gold Quantum Dots and Novel Gold−Polypyrrole Nanocomposites

Abstract

Polystyrene-block-poly(2-vinylpyridine) with different block lengths, viz., 190−190 and 800−860 monomer units, have been employed in order to obtain monodisperse Au nanoparticles, dispersed in a polypyrrole (PPY) matrix. In consonance with optical absorption spectra, the formation of a nanodispersion of Au has been corroborated by Mie−Drude theory. The annealing process yields a single Au nanocluster (core) in each micelle, covered by a PPY shell, forming unique core−shell particles. By variation of the block length of the polymer, different sizes of Au nanoclusters, ranging from 7 to 13 nm, covered by a PPY shell within the spherical microdomains of the block copolymer, have been prepared. Different shapes of Au particles, viz., spherical, cubic, tetrahedral, and octahedral, have been observed, with a little nudge in the preparative strategies. Furthermore, we have also observed elegant dendritic nanostructures of Au−PPY in another different approach, by employing vapor phase polymerization of pyrrole onto solution-cast films of block copolymer ionomers. These novel Au−PPY nanocomposites could open up new avenues in the field of molecular electronics.