Templated synthesis and adsorption investigations of mesoporous organosilicas and macroporous ceramics.

摘要

Inorganic and hybrid inorganic-organic materials with regular pore structures formed with organic templates are presented. Supramolecular assemblies of surfactants were used to synthesize mesoporous materials (“mesoporous” defined as having pore sizes in the range 2–50 nanometers) and polymer spheres were applied to template products with macropores (greater than 50 nanometers).; The creation of UOFMN (Unified Organically Functionalized Mesoporous Network) materials incorporated concepts employed in the synthesis of surfactant-templated mesoporous silicas that exhibit channels with uniform dimensions and high surface areas. UOFMNs templated with alkyl chain surfactants with ionic head groups were of hybrid organosilica composition in which each silicon atom was linked to one other silicon atom by an ethane or ethylene bridge. This was accomplished by using an organic bridged silsesquioxane [(R′ O)₃Si-R-Si(OR)₃) as the organosilica precursor. Surfactant was removed to yield highly porous materials having surface areas ca. 1200 square meters per gram. Hybrid products were more hydrothermally stable than mesoporous silica similarly synthesized. A material with ethylene groups in the pore walls could be modified further by bromination; the brominated product was itself reactive as a bromide source.; UOFMN materials containing varying amounts of diethylbenzene bridges in the pore walls were synthesized using a nonionic triblock copolymer. Such products demonstrated superior uptake of the organic contaminant p-chlorophenol in solid-liquid adsorption experiments compared to mesoporous silicas with ethane, ethylene, or no organic components in the frameworks.; Macroporous materials containing the bioceramic hydroxyapatite as well as other calcium phosphate and carbonate phases were templated with close-packed poly(methyl methacrylate) spheres of monodisperse size in the range 256–375 nanometers. The spaces between the close-packed polymer spheres were penetrated by a calcium phosphate precursor solution, after which the polymer was calcined (removed by burning) to yield materials with three-dimensionally ordered spherical pore structures. The concentration of a precursor solution and calcination temperature affected the crystallization of calcium phosphate phases and the periodicity of the macropore structure. An in vitro antibiotic drug release application was tested using a well-ordered macroporous hydroxyapaptite/tricalcium phosphate.