Nanoparticulate Catalysts Based on Nanostructured Polymers

Lyudmila M. Bronstein, Valentina C. Matveeva, and Esther M. Sulman 

The catalytic nanoparticles possess unique catalytic properties due to their large surface area and considerable number of surface atoms leading to an increased amount of active sites [1-3]. The catalytic properties of nanoparticles depend on the nanoparticle size, nanoparticle size distribution, and nanoparticle environment [4]. Moreover, the surface of nanoparticles plays an important role in catalysis, being responsible for their selectivity and activity. As was demonstrated in the last decade, the formation of nanoparticles in a nanostructured polymeric environment allows enhanced control over nanoparticle characteristics, yet the stabilizing polymer (its functionality) is of great importance, determining the state of the nanoparticle surface [5-8]. 

Copyright 2008 WILEY-VCH Verlag GmbH Co. KGaA, Weinheim 

Unlike regular block copolymer micelles which are well permeable for reagents, triblock nanospheres with hydroxylated polyisoprene coronas, cross-linked poly(2-cinnamoyloxyethyl methacrylate) shells, and poly(acrylic acid) cores, filled with Pd nanoparticles, showed slower hydrogenation of alkenes than Pd blacks due to the need for the reactant(s) to diffuse into and the products to diffuse out of the encapsulating nanospheres [13]. On the other hand, microspheres formed by diblock poly(t-butyl acrylate)-hlocfe-poly(2-cinnamoyloxyethyl methacrylate) and filled with Pd nanoparticles demonstrated good permeability and higher catalytic activity in the hydrogenation of methyl methacrylate than the commercial Pd black catalyst [14]. 

Au nanoclusters formed in the PS-fe-P2VP micelles displayed catalytic activity in the electro-oxidation of CO [15,16]. The smallest particles studied (1.5 nm) were the most active for electro-oxidation of CO and had the largest fraction of oxygen associated with gold at the surface, as measured by Au /Au X-ray photoemission intensities. 

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