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Mechanism of the Formation of Amorphous Gold Nanoparticles within Spherical Polyelectrolyte Brushes
Author(s) -
Schrinner Marc,
Polzer Frank,
Mei Yu,
Lu Yan,
Haupt Björn,
Ballauff Matthias,
Göldel Astrid,
Drechsler Markus,
Preussner Johannes,
Glatzel Uwe
Publication year - 2007
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/macp.200700161
Subject(s) - polyelectrolyte , nanoparticle , colloidal gold , dynamic light scattering , materials science , chemical engineering , polystyrene , cationic polymerization , colloid , polymer chemistry , amorphous solid , transmission electron microscopy , nanotechnology , chemistry , polymer , crystallography , composite material , engineering
We present a comprehensive investigation on the formation of gold nanoparticles in spherical polyelectrolyte brushes. These colloidal carrier particles consist of a solid polystyrene core onto which long cationic polyelectrolyte chains are grafted. Immersed in water these polyelectrolyte chains can be used to enrich AuCl 4 −ions. The metal ions thus confined in the polyelectrolyte layer can be reduced to gold nanoparticles of approximately 1 nm diameter. Cryogenic transmission electron microscopy shows that the Au particles are located near the surface and exhibit a narrow size distribution. Measurements by dynamic light scattering demonstrate that the polyelectrolyte chains are located near the surface of the core particles. This is explained by a crosslinking of the cationic polyelectrolyte chains by the nanoparticles that carry a negative charge. If the Au nanoparticles are removed, the spherical polyelectrolyte brushes re‐expand. High‐resolution electron microscopy together with wide‐angle X‐ray scattering measurements demonstrates that the Au nanoparticles are amorphous. We demonstrate that these Au nanoparticles exhibit catalytic activity for hydrogenation reactions that is slightly below the one of Pt and Pd nanoparticles.