The area of periodic mesoporous materials prepared by cooperative assembly in the presence of amphiphile molecules underwent dramatic growth. Among the silica-based materials, many types may be regarded as ordered organic−inorganic nanocomposites. These were divided into five categories:  (i) noncalcined amphiphile/silica mesophases, (ii) mesoporous silicas with organically modified surfaces, (iii) expanded mesoporous silicas, (iv) mesoporous organosilicates, and (v) mesoporous silica with occluded organic materials such as polymers. The diversity of such nanocomposites created new potential opportunities in materials sciences, catalysis, separation, and environmental remediation. These applications involved the development of new chemistry not only within the confined pores and channels but also on functionalized surfaces as well as within the channels walls. The current review deals with recent progress in the synthesis, characterization, and applications of each of these types of periodic mesoporous silica-based hybrid materials.

Postsynthesis pore expansion of as-synthesized MCM-41 silica using N,N-dimethyldecylamine affords material A, with open pore structure and readily accessible amine groups. The selective removal of the occluded amine gives rise to B, a highly porous, hydrophobic material with large surface area and pore volume. Materials A and B were found to be fast, sensitive, high-capacity recyclable adsorbents for metallic cations and organic pollutants, respectively.

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Periodic mesoporous organosilicas with two-dimensional and three-dimensional hexagonal as well as cubic (Pm3n) symmetry were synthesized using bridged silsesquioxane species (RO)3Si−CH2−CH2−Si(RO)3 as precursors and cetyl- or octadecyltrimethylammonium chloride (C16TMACl or C18TMACl) as structure-directing species. These materials were characterized by N2 adsorption, SEM, TEM, and solid-state MAS NMR spectroscopy. 13C and 29Si NMR data showed unambiguously that all carbon atoms were covalently linked to Si. The cubic material obtained in the presence of C16TMACl and 1,2-bis(trimethoxysilyl)ethane (BTME) first formed into truncated rhombic dodecahedral particles that grew into spheres. The sample prepared in the presence of C18TMACl and BTME at 100 °C was entirely comprised of concentrically self-assembled 10-μm hexagonal rods. Using C16TMACl in the presence of 1,2-bis(triethoxysilyl)ethane (BTEE) at 95 °C afforded high-quality two-dimensional hexagonal organosilica comprised of unusually long (30−40 μm) faceted empty tubules.