  Lattice Monte Carlo simulations are used to study the phase behavior of
self-assembling ordered mesoporous materials formed by an organic template with
amphiphilic properties and an inorganic precursor in a model solvent. Three
classes of inorganic precursors have been modeled: terminal (R-Si-(OEt)3) and
bridging ((EtO)3-Si-R-Si-(OEt)3)) organosilica precursors (OSPs), along with
pure silica precursors (Si-(OEt)4). Each class has been studied by analyzing
its solubility in the solvent and the solvophobicity of the inorganic group. At
high surfactant concentrations, periodic ordered structures, such as
hexagonally-ordered cylinders or lamellas, can be obtained depending on the
OSPs used. Ordered structures were obtained in a wider range of conditions when
bridging hydrophilic OSPs have been used, because a higher surfactant
concentration was reached in the phase where the material was formed. Terminal
and bridging OSPs produced ordered structures only when the organic group is
solvophilic. In this case, a partial solubility between the precursor and the
solvent or a lower temperature favored the formation of ordered phases. With
particular interest, we have analyzed the range of conditions leaving to the
formation of cylindrical structures, which have been evaluated according to the
pore size distribution, the pore wall thickness, the distribution and the
accessibility of the functional organic groups around the pores. The phase
behavior has been also evaluated by applying the quasi-chemical theory, which
cannot predict the formation of ordered structures, but confirmed the results
of simulations when no ordered structures were observed. The study of the phase
and aggregation behavior of two different surfactants, one modeled by a linear
chain of head segments and the other modeled by a branched-head, permitted us
to evaluate some structural differences of the materials obtained.
