Sh. Garofalini et G. Martin, MOLECULAR SIMULATIONS OF THE POLYMERIZATION OF SILICIC-ACID MOLECULESAND NETWORK FORMATION, Journal of physical chemistry, 98(4), 1994, pp. 1311-1316
Polymerization of 216 silicic acid molecules, H4SiO4, has been studied
using the molecular dynamics computer simulation technique. Multibody
potentials which reproduce bulk and surface structures of silica and
silicate glasses, as well as molecular configurations containing Si, O
, and H ions, were used in the simulations. Results of the simulations
are consistent with experimental data of sol-gel systems. Chains form
at the early stages of polymerization, followed by ring formation, co
nsistent with interpretations of NMR data and semiempirical molecular
orbital quantum calculations. The activation energy for formation of b
ranching Q(n) species is 12 kcal/mol, consistent with the experimental
data of 12 kcal/mol for gelation. The relative time evolution of the
various Q(n) species is consistent with experimental NMR data.