Tuesday, October 18, 2011: 10:00 AM
213 A (Minneapolis Convention Center)
Ordered nanoporous materials are of great scientific and technological importance. Understanding how such materials form and how to control and tailor the pore geometries will help facilitate advanced applications of these materials. Molecular modeling of syntheses of porous materials is challenging because large system sizes are needed to have representative sampling of the processes, and long time scales are required to observe the formation of ordered structures. To address this need, we have developed a relatively simple silicon-oxygen lattice model where each silicic acid molecule is represented as a tetrahedron on a body centered cubic lattice with one silicon atom at the center and hydroxyl groups at the corners [J. Chem. Phys., 134, 134703 (2011)]. The low-coordination lattice model captures the basic mechanism of silica polymerization and provides structural evolution information during the polymerization processes in dynamic Monte Carlo simulations. The simplicity of this lattice model makes it possible to study the polymerization process to higher degree of condensation and larger system sizes than has been possible with previous atomistic models. Using templating procedures at different length scales the model can be used to study the directed assembly of both ordered microporous crystalline materials and ordered mesoporous materials. Although this low-coordination lattice model may not represent real zeolite morphologies because of the lattice restrictions, it is capable of generating a variety of architectural motifs including layered materials, crystalline microporous materials and chalcogenide zeolite analogs. Combining silica polymerization with surfactant self-assembly using Larson’s lattice model of surfactants, we may also model the formation of ordered mesoporous materials with realistic atomic structure of the silica within these materials.