Regensburg 2010 – scientific programme
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 41: Nanoparticles and Composite Materials II
CPP 41.9: Talk
Thursday, March 25, 2010, 16:15–16:30, H48
Electron beam-induced nanoparticle formation in Au and Pt salt-loaded polystyrene-block-poly(4-vinylpyridine) micelles — •Volkmar Zielasek1, Christian Kübel2, Willian G. Menezes1, Karsten Thiel3, and Marcus Bäumer1 — 1Universität Bremen, Institut für Angewandte und Physikalische Chemie — 2Forschungszentrum Karlsruhe/KIT — 3Fraunhofer IFAM, Bremen
Using diblock copolymer micelles as nanoreactors for the generation of metal colloids has proven to be a universal route to regular arrays of uniformly sized nanoparticles (NPs) for a variety of metals [1]. When PS-b-P4VP micelles in toluene are loaded with metal salts, the formation of a single NP in each P4VP core can be achieved in a subsequent reduction step induced either chemically, by plasma or by UV or electron irradiation. We will present a detailed TEM study of metal colloid formation during this reduction step in Au and Pt salt-loaded PS-b-P4VP micelles at variable temperature in the range 95 - 300 K. Electron irradiation-induced coagulation of metal and initial formation of particulates with subnanometer diameters within the P4VP cores is observed in the entire temperature range for Au as well as for Pt. Particle coarsening and ripening, however, strongly depend on the metal, the electron dose and, in particular, on temperature. Counter-intuitively, the dynamics of metal aggregation into a single NP within each micelle core is faster at low temperature whereas at 300 K even high densities of subnanometer particulates remain stable. Stability of the P4VP is probably essential for metal mobility within the core.
[1] S. Förster, M. Antonietti, Adv. Mater. 10 (1998) 195.