UV aerosol synthesis: a one-step route to silica, organic-silica and surfactant/silica nanostructured materials

Abstract

Aerosol flame technology has been used for decades to fabricate on an industrial scale a range of inorganic (nano)particles, including carbon blacks, titania, and fumed silica. Nevertheless, the high local temperatures inherent to this technique prevent direct organic functionalization or loading by organic derivatives, which is essential in many applications to achieve specific properties and optimal dispersion within an organic matrix. We describe herein a novel eco-friendly UV process allowing single-step manufacture of high-value silica and organosilica particles at ambient temperature. Atomized alkoxysilane precursor droplets are produced within an annular photoreactor including 6 fluorescent UV lamps (maximum emission: 312 nm), and photocondensed continuously after a 1 min single pass. Droplet condensation is controlled by the release of a photoacid catalyst localized in the droplets, affording spherical polydisperse powder particles with a mean diameter ranging around 400–700 nm. In the presence of an amphiphilic block copolymer template, a silica/surfactant mesostructured film was deposited using this UV aerosol technology, resulting in a wormlike mesoporous structure after calcination.