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IRTG / Soft Matter Science
Freiburger Materialforschungszentrum
Stefan-Meier-Str. 21
79104 Freiburg, Germany

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You are here: Home Events Dr. Yan Lu "Functional Hybrid Materials Based on Polymeric Colloidal Particles"

Dr. Yan Lu "Functional Hybrid Materials Based on Polymeric Colloidal Particles"

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Soft Matter and Functional Materials, Helmholtz-Zentrum Berlin für Materialien und Energie, Berlin, Germany

What
  • Seminar
When Mar 15, 2013
from 11:15 AM to 12:00 PM
Where Hörsaal Makromolekulare Chemie, Stefan-Meier-Str. 31, Freiburg
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We present the synthesis, characterization and possible applications of metallic nanoparticles immobilized in different colloidal carrier system, namely in i) spherical polyelectrolyte brushes (SPB) and ii) core-shell microgels. The polymeric carriers ensure the stability of metal nanoparticles against aggregation without impeding their catalytic activity which is measured in aqueous suspension [1]. We first present work done on facetted metal nanocrystals fabricated on cationic spherical polyelectrolyte brushes. The catalytic reduction of 4-nitrophenol (Nip) to 4-aminophenol using sodium borohydride as reducing agent is presented as model reaction for the catalytic studies of these systems in water [2]. All results demonstrate that the SPB are excellent passive carriers for metallic nanoparticles.

As the second system we present thermosensitive core-shell microgels consisting of a core of polystyrene whereas the shell is made up of crosslinked poly (N-isopropylacrylamide) (PNIPA). Different metal nanoparticles as well as bimetallic Au-Pt nanorods can be embedded into the microgel particles. The catalytic activity of metal nanoparticles immobilized in these thermosensitive microgels can be tuned by the volume transition within the microgel (see ref. [3]). Hence, the core-shell microgels act as active carriers for the nanoparticles. In addition to this, thermosensitive Au-PNIPA yolk-shell microgel systems in which a single Au-nanoparticles is immobilized in a hollow shell of PNIPA is presented [4]. The selectivity of this catalytic hybrid system can be tuned by temperature as is shown by the competitive reduction of the hydrophilic 4-nitrophenol and the hydrophobic nitrobenzene by borohydride. All data demonstrate that these polymeric carriers are ideally suited for anchoring metallic nanoparticles for their use as catalysts in aqueous suspension.

[1] Y. Lu, J. Yuan, F. Polzer, M. Drechsler, J. Preussner, ACS Nano 2010, 4, 7078.
[2] P. Hervés, M. Pérez-Lorenzo, L.M. Liz-Marzán, J. Dzubiella, Y. Lu, M. Ballauff, Chem. Soc. Rev. 2012, 41, 5577.
[3] Y. Lu, M. Ballauff, Prog. Polym. Sci. 2011, 36, 767.
[4] S. Wu, J. Dzubiella, J. Kaiser, M. Drechsler, X. Guo, M. Ballauff, Y. Lu, Angew. Chem. Int. Ed. 2012, 51, 2229.
 

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