Synthesis and characterization of templated mesoporous materials using molecular simulation

Lattice Monte Carlo simulations are used to calculate equilibrium propertie s of surfactant-solvent-silica liquid-crystal systems under no-polymerizati on conditions. The formation of a high-surfactant high-silica concentration phase in equilibrium with a dilute phase is observed when the surfactant-s ilica interactions are stronger than the surfactant-solvent interactions. D ifferent silica structures that are similar to the M41 family are observed, depending on the overall concentration of the system. The formation of a h exagonal phase is favored at a surfactant/silica ratio of 0.2, whereas a la mellar phase is observed a surfactant/silica ratio of 1. Argon adsorption properties on a model porous structure of the MCM-41 type prepared using this mimetic simulation protocol are calculated using grand canonical Monte Carlo simulation. Heats of adsorption are calculated from f luctuations in the energy and number of molecules [1] following the work of Nicholson and Parsonage [Computer Simulation and the Statistical Mechanics of Adsorption (Academic Press, London), 1982, p 97 8 pp]. A decrease in th e heats of adsorption for coverage less than one statistical monolayer is e vidence of surface heterogeneity. The results are in qualitative agreement with experimental measurements for argon on MCM-41.