Application of Silica Aerogel Carrier via Supercritical Drying for Fragrance Controlled-release

Abstract

Silica aerogel with different hydrophilicities were prepared from tetramethoxysilane, Methymethoxysilane, tetramethoxysilane-propyltrimethoxysilane, or tetramethoxysilane-phenyltrimethoxysilane mixtures via supercritical drying process (labelled as TMOS-AG Me-TMOS-AG, Pr-TMOS-AG, or Ph-TMOS-AG, respectively). Three fragrances, including geraniol, ethyl vanillin, and menthol, were loaded to TMOS-AG. The thermal analysis confirmed all loading fragrances are stable until over 200 °C. And among all fragrances, geraniol presented the maximum loading contents (L _m). Concentration dependences indicated the geraniol was mono layer absorbed. Py-GC/MS of geraniol in TMOS-AG under both N₂ and mimic air atmosphere (90% N₂ and 10% O₂) confirmed that loaded geraniol could be thermally controlled-released beginning at 200 °C. As N₂ absorption confirmed, even absorption/desorption equilibrium constant (k) was determined mainly by hydrophilicity of silica aerogels, and the maximum loading contents (L _m) were influenced more by the pore size. Due to mono layered absorption, bigger pores usually give less specific areas and less absorbing sites for geraniol, and then present lower L _m.

Keywords

silica aerogel / fragrance / controlled-release