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] .Recently, catalytic nanoparticles formed in various types of nanostructured polymers have been extensively studied in major catalytic reactions [5 -7] . Although traditional polymer -based catalysts may be faulted by such shortcomings as uncontrolled swelling or poor accessibility of nanoparticles in the polymer bulk, the nanostructured polymers are mainly free from these limitations due to the small size of the nanoparticle -containing zones. Moreover, some swelling can even be advantageous, providing better access to the nanoparticle surface. The majority of nanostructured polymers for catalytic applications are amphiphilic block copolymers and dendrimers while some other polymers have also been explored. The ability of amphiphilic block copolymers to form micelles in dilute solutions in selective solvents [9, 10] has been used to stabilize catalytic nanoparticles in the functionalized micelle cores [11,12] . Pd nanoparticles formed in PS -b -P4VP micelles were used as a catalyst for the cross -coupling reaction between aryl halides and alkenes (Heck reaction) [12] . These hybrid systems exhibited nearly the same effi ciency as low -molecular -mass palladium complexes (conventional catalysts of the Heck reaction), being at the same time much more stable. The PS -b -P4VP micelles containing Pd and Pd/Au nanoparticles were studied in the hydrogenation of cyclohexene, 1,3 -cyclooctadiene, and 1,3 -cyclohexadiene [11] . A strong infl uence of the synthetic pathway to form nanoparticles and the type of 93 Nanoparticles and Catalysis. Edited by Didier Astruc
