Web Release Date: July 15,
Star-Block Copolymers as Templates for the Preparation of Stable Gold Nanoparticles
and
Unité de Chimie des Matériaux Inorganiques et Organiques (CMAT) and Research Center in Micro- and Nano-Materials and Electronic Devices (CERMIN), Université catholique de Louvain, Place Pasteur 1, 1348 Louvain-la-Neuve, Belgium, and Laboratory of Macromolecular Chemistry and Nanoscience, Eindhoven University of Technology and Dutch Polymer Institute (DPI), Post Office Box 513, 5600 MB Eindhoven, The Netherlands
Received February 10, 2005
In Final Form: June 16, 2005
Abstract:
Gold nanoparticles of improved stability against aggregation were prepared using poly(ethylene oxide)-block-poly(
-caprolactone) (PEO-b-PCL) star-block copolymers. A five-arm star-shaped macroinitiator (PEO)
was utilized for the automated parallel controlled ring-opening polymerization of -caprolactone to prepare
a series of PEO-b-PCL star-block copolymers with a constant PEO core linked to PCL blocks of variable
length. The PEO core was swelled with KAuCl4 in N,N-dimethylformamide (DMF), and gold nanoparticles
were subsequently obtained by reduction with NaBH4. Since the process was always templated by the
same PEO core for all investigated polymers, the average dimension of the formed gold nanoparticles was
in the same range for all star-block copolymers. In sharp contrast, the size distribution and long-term
stability against aggregation of the gold nanoparticles dispersed in DMF were strongly dependent on the
PCL block length, confirming the role of PCL blocks as stabilizing blocks for these nanoparticles.
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