Synthesis and characteristic of silica aerogels

Influence of Chemical Conditions on the Nanoporous Structure of Silicate Aerogels

“…The lowest density (0.08 g cm -3 ) and the most transparent (90%) aerogels can be obtained with molar ratios between 6 and 10 [90]. In another study, the highest surface area (~1,000 m 2 g -1 ) could be achieved at stoichiometric amount of water (molar ratios ~4) [79]. Both deficiency (−20%) and excess (+20%) of water result in a reduction of surface area by 200–300 m 2 g -1 .…”

Aerogels: Tailor-made Carriers for Immediate and Prolonged Drug Release

“…To convert a gel into an aerogel, the solvent is removed by extraction with supercritical CO 2 or by the direct conversion of the solvent in supercritical state in order to prevent the structure collapse caused by capillary forces [Fricke 1986]. The chemistry of aerogel materials is relatively f lexible: their pore size and surface area can be tailored during the synthesis by changing the solvent and catalysts [Rao et al 1993, Pajonk 1998, Stolarski et al 1999]. Furthermore, different functional groups can be implemented in the structure of silica aerogels by surface modification or by reaction during sol-gel processes Schubert 1997, Husing et al 1998].…”

29Si CPMAS NMR and near-IR study of sol–gel microporous silica with tunable surface area

“…For some applications the sol-gel route has proved to be effective to produce good quality silica fibers, coatings and bulk supports for catalytic materials [10,12]. In particular, the possibility of varying the surface area and/or the porosity has been widely explored by acting on the several parameters of the sol gel process, like pH, solvent, drying and thermal treatment [13][14][15][16].…”