Growth of ordered silver nanoparticles in silica film mesostructured with a triblock copolymer PEO-PPO-PEO

Elaboration of mesostructured silica films with a triblock copolymer polyethylene oxide-polypropylene oxide-polyethylene oxide, (PEO-PPO-PEO) and controlled growth of silver nanoparticles in the mesostructure are described. The films are characterized using UV-visible optical absorption spectroscopy, TEM, AFM, SEM, X-ray diffraction (XRD) and Rutherford backscattering spectrometry (RBS). Organized arrays of spherical silver nanoparticles with diameter between 5 and 8 nm have been obtained by NaBH4 reduction. The size and the repartition of silver nanoparticles are controlled by the film mesostructure. The localization of silver nanoparticles exclusively in the Upper-side part of the silica-block copolymer film is evidenced by RBS experiment. Oil the other hand, by using a thermal method, 40 nm long silver sticks call be obtained, by diffusion and coalescence of spherical particles ill the silica-block copolymer layer. In this case, migration of silver Particles toward the glass substrate-film interface is shown by the RBS experiment. (C) 2009 Elsevier Inc. All rights reserved.