Core-shell effects of functionalized oxide nanoparticles inside long-range meso-ordered spray-dried silica spheres

Abstract

Core-shell and homogeneous distributions of functionalized cerium oxide nanoparticles within spraydried mesostructured silica spheres are achieved by modification of synthesis parameters such as the templating agent and nanoparticle capping functions.Keywords Mesoporous silica Á Embedded nanoparticles Á Functionalized nanoparticles Á Evaporation induced self assembly Á Spray-dryingIn the past 15 years a large number of studies has been focused on long-range ordered mesoporous materials obtained in solution through the self-assembly of a variety of amphiphilic templating agents with a growing inorganic phase [1]. Recently, several works showed that their well known structural characteristics (high surface area, tunable geometry of the porous network, narrow pore size distribution) [2] are preserved and enhanced by mean of a spray drying process, which revealed to be interesting for its ease and possibility to obtain spherical particles. In Refs. [2c, 3], experimental conditions as well as different structuring agents were succesfully tested while in Ref.[4] SAXS, TEM and mainly solid state NMR were used to better understand the process of particle and mesophase formation with time. As far as the last point is concerned, Boissière et al.[5] used time-resolved in-situ SAXS to determine the required conditions for the mesophase to form. Regarding applications, spherical shaping and possibility to embed maghemite nanoparticles within a mesoporous silica matrix readily showed an interest in combined applications like drug delivery and magnetic resonance imaging [6] while catalysis was rather explored in presence of Pd nanoparticles [7] and nanowires [8]. In these cases, the way in which nanoparticles are distributed inside the silica particles is of primary importance according to the final application. For instance, in catalytic application, one could hope to enhance interactions between external fluids and embedded nanoparticles by placing them in the silica surface rather than in its bulk. In this way, diffusion paths are limited to the external crust. On the contrary, if the application involves magnetic or optical properties, an homogenous distribution within the silica bulk is required in order to avoid destructive interactions (magnetic coupling, optical quenching…) origined from clustering of nanoparticles.For these reasons, we want to show the possibility of tuning the spatial distribution of plain and functionalized cerium oxide nanoparticles inside spherical mesostructured silica particles produced by the spray-driyng technique. The goal is double: firstly we would like to show some tricky interactions effects between functionalized Electronic supplementary material The online version of this article

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