The early stages of the sol-gel processing of TEOS

Gas-phase molecular structure and energetics of anionic silicates

“…The calculated 29 Si shift for the SN species is À73.1 ppm, which is in excellent agreement with the experimentally derived value in organic solution, À72.0 ppm (Unger et al, 1994). The 29 Si shifts for the dimer, linear trimer and cyclic trimer are similar to those calculated previously by Moravetski et al (1996) using coupled-perturbed Hartree-Fock and polarized basis sets, also with the GIAO method.…”

The role of H2O in the carbonation of forsterite in supercritical CO2

“…The −61.5 ppm peak is close to that of forsterite (−61.9 ppm) and is assigned to a silanol functional group (Si-OH), possibly at the forsterite surface (e.g., (MgO) 3 SiOH). The −78.8 ppm peak is tentatively assigned to a surface Q0 monosilicic acid species (Si(OH) 4 ) which was inferred by interpolating between experimentally determined values for Si(OH) 4 in aqueous solution (Cho et al, 2006;Unger et al, 1994) and the dimer, (HO) 3 Si-O-Si(OH) 3 (Cho et al, 2006). The peaks at −84.8 and the −91.8 ppm are assigned to Q1 and Q2 species (Kwak et al, 2010).…”

Properties of poly(2-hydroxyethyl acrylate)-silica nanocomposites obtained by the sol–gel process

“…The sol-gel reaction is a polymerization process in which a silica precursor hydrolyzes and condenses to form a network. The characteristics of the resulting network depend on some critical parameters of the reaction such as the relative rate of the hydrolysis and the condensation reactions [4,5], the molar ratio between water and alkoxide [6], the acidic or basic character of the environment [4], the nature [7] and quantity [8] of the solvent in which the sol-gel reaction takes place, and also on whether the hydrolysis takes place in a single or in multiple steps [9]. In this work the silica precursor used was tetraethoxysilane (also called tetraethyl orthosilicate, TEOS).…”