Yuan, J.; Schacher, F.; Drechsler, M.; Hanisch, A.; Lu, Y.; Ballauff, M.; Müller, A.H.E.: Stimuli-Responsive Organosilica Hybrid Nanowires Decorated with Metal Nanoparticles. Chemistry of Materials 22 (2010), p. 2626-2634
10.1021/cm9038076
Abstract:
We report on the synthesis and characterization of water-soluble stimuli-responsive organosilica hybrid nanowires that can be used as carriers for metallic nanoparticles. The nanowires were prepared from core-shell-structured cylindrical polymer brushes that served as templates with uniform size and shape. The core of the nanowires consists of a silsesquioxane network synthesized through a precursor route. The shell consists of a dense layer of poly(N,N-dimethylaminoethyl methacrylate) (PDMAEMA). The hybrid nanowires exhibit pH-responsive behavior, because of the weak polyelectrolyte nature of the PDMAEMA shell. Simultaneously, the shell of PDMAEMA acts as a nanoreactor for the synthesis and immobilization of metal nanoparticles. It was further quaternized with methyl iodide, leading to a poly{[2-(methacryloyloxy)ethyl] trimethylammonium iodide} (PMETAI) cationic polyelectrolyte shell around the silsesquioxane core. The as-synthesized cationic organosilica hybrid nanowires are sensitive to salt concentration, in terms of their hydrodynamic radius. They can be functionalized with platinum nanoparticles as well, leading to stable composites of the nanowires and the platinum nanoparticles. The nanocomposites show high catalytic activity, as kinetically analyzed in the reduction of 4-nitrophenol by sodium borohydride.