Formation of Metal Nanoparticles in Multilayered Poly(octadecylsiloxane) As Revealed by Anomalous Small-Angle X-ray Scattering

• Published in: Chemistry of materials 2000-12, Vol.12 (12), p.3552-3560
• Main Authors: Svergun, Dmitri I, Kozin, Mikhail B, Konarev, Peter V, Shtykova, Eleonora V, Volkov, Vladimir V, Chernyshov, Dmitri M, Valetsky, Peter M, Bronstein, Lyudmila M
• Format: Article
• Language: English
• ISSN: 0897-4756; 1520-5002
• DOI: 10.1021/cm001103j

Novel hybrid polymeric systems with noble metal nanoparticles located inside specific areas of the material were developed. A self-assembled multilayered polymer, poly(octadecylsiloxane) (PODS), provided a nanostructured matrix for incorporation of gold and platinum compounds and for metal nanoparticle formation. The internal structure of PODS and the nanoparticle size distributions were examined using anomalous small-angle X-ray scattering. The ordering in PODS was largely preserved after interaction with metal compounds and reducing agents. The degree of incorporation of the compounds into PODS depended on the reaction conditions and on the compound type. For the metal-containing PODS isolated from the reaction medium before reduction, the major fraction of the nanoparticles had radii around 2 nm, and the size distributions depended neither on the compound loading nor on the reducing agent. This points to a “cage”-controlled particle growth restricted by the cavity size in the siloxy bilayer. This hypothesis is corroborated by the computed density profiles across the PODS lamella. Incorporation of cetylpyridinium chloride in the hydrophobic layers of PODS promotes formation of nanoparticles also between the hydrophobic tails. This location does not restrict the particle growth so that the nanoparticle sizes strongly depend on the reduction conditions.