Lu, Y.; Ballauff, M.: Hybrids from Polymer Colloids and Metallic Nanoparticles: A Novel Type of "Green" Catalyst. In: Chauhan, Bhanu P. [Ed.] : Hybrid nanomaterials : synthesis, characterization, and applications. Hoboken, N.J.: Wiley, 2011. - ISBN 978-0-470-48760-0, p. 1-22
Metallic nanoparticles have interesting perspectives in the application of catalysis as they exhibit unusual chemical and physical properties differing from the bulk material. However, for all practical applications, metallic nanoparticles must be stabilized in solution in order to prevent from aggregation. Here we have reviewed our recent studies on metallic nanoparticles encapsulated in spherical polyelectrolyte brushes (SPBs) and thermosensitive core-shell microgels, respectively. SPB particles consist of a poly(styrene) (PS) core onto which long chains of polyelectrolyte brushes are densely grafted by a grafting-from technique. In the case of thermosensitive microgels, the core consists of PS whereas the network consists of poly(N-isopropylacrylamide) (PNIPA) cross-linked by N, N’- methylenebisacrylamide (BIS). Both polymeric particles present as excellent carrier systems for applications in catalysis. More importantly, the composite systems of metallic nanoparticles and polymeric carrier particles allow us to do “green chemistry”, that is, low temperature, easy removal of the catalyst, and low leaching of heavy metal into the product. The chemical reactions can be conducted in a very efficient way. In addition, in the case of using microgels as carrier system, the reactivity of composite particles can be adjusted by the volume transition within the thermosensitive networks. Hence, the present review gives clear indications on how carrier systems for metallic nanoparticles should be designed to adjust their catalytic activity.