Monte Carlo Simulations of Silica Polymerization and Network Formation

Abstract

U nderstanding the polymerization of silicic acid in aqueous solution has been an active area of research for some time. 1,2 This reaction system lies at the heart of solÀgel processing as well as the synthesis of porous materials such as zeolites 3 and ordered mesoporous materials. 4,5 Improved understanding of the fundamental mechanisms involved can be expected to have a significant impact in the control of material structure and proper-

Advances in theory and their application within the field of zeolite chemistry

“…[57][58][59][60] Fig. It is computationally not feasible to study a realistic reaction mixture with QM methods, but kinetic models have been developed that use output of QM calculations to determine the reaction profiles of the relevant reactions and then describe the reacting mixture with thousands of monomers using Monte Carlo methods.…”

Impact of Organic Templates on the Selective Formation of Zeolite Oligomers

“…Precursors have been mainly followed by NMR, [3, 4] mass spectroscopy and in situ X‐ray scattering techniques [5, 6] . By contrast, many simulation studies have explored the reaction pathways in solution, [7–13] shedding light on the nature and structure of initial silicate oligomers, ranging from small oligomers to larger cyclic species [10, 11, 14] . These computational studies exploring the oligomerisation process of silicates have included the impact of small cationic templates (Li + , NH 4 + ) [15] .…”

Reactive modeling of the initial stages of alkoxysilane polycondensation: effects of precursor molecule structure and solution composition

“…The general characteristics of Figure 4 (i.e. the progressive evolution of higher-bridged silicon atoms with increasingly longer timescales of condensation to form these species) are observed in simulation 14,24,32,50,51 and NMR 10,16 studies. The siloxane cluster size distribution is illustrated in Figure 5.…”

“…The fluctuations in the percentages of condensed non-ring silicon correspond to the ring closure and cleavage reactions. Siloxane rings formed from condensation of hydroxysilanes have been predicted by Monte Carlo 50,51 and molecular dynamics 14,24,32 simulations to have four to five silicon atoms. In this work, after 5 ns, the average number of silicon atoms in each siloxane ring is predicted to be about 4.2.…”