Ordered organic-inorganic mesostructures: Properties, structure and nanospace design

Interfacial interactions of ordered inorganic mesoporous materials and organic-inorganic mesostructures with silanes were studied. The main objective of this dissertation was to demonstrate applicability of organosilanes for design and characterization of ordered silica-based mesostructures and to investigate the modification of physical and chemical properties of mesostructured materials at the nanoscale level.; The complexity of interactions between alkylchlorosilanes and mesoporous silica was studied in details for the FSM-16 mesoporous material, a model silica with hexagonally ordered mesopores. This study allowed us to prepare highly hydrophobic mesoporous silicas, which were used as model adsorbents to improve the pore size analysis of hydrophobic materials.; It was shown that the reaction with alkylchlorosilanes provides a convenient tool to study mesoporous silicas with more complex pore networks than the two-dimensional hexagonal structure. The block-copolymer templated mesoporous-microporous materials such as SBA-15 and cage-like mesoporous structures such as FDU-1 were investigated by using reactions with silanes. A detailed study of the SBA-15 silica structure was accomplished through the selective pore blocking with organosilanes and nitrogen adsorption. The ability to control the thickness of the attached hydrophobic layer by varying the length of alkyl chain allowed us to estimate the size of pore openings.; The interfacial reactivity of ordered organic-silica mesostructures towards organosilanes was used to elaborate the template displacement synthesis (TDS), which allows one to prepare the mesoporous materials with tunable pores and desired surface functionality without necessity of calcination. During this process the relatively weak electrostatic interactions between negatively charged silica species and positively charged surfactant molecules are replaced by covalent bonds. The exploratory studies of 1-allyl-3-propylthiourea modified mesoporous silicas (MCM-41 and SBA-15) proved a great utility of such materials for adsorption of mercury ions from aqueous solutions.; The dissertation demonstrates that the organosilanes can be effectively used to design and tailor physical and chemical properties of ordered mesoporous silica-based materials at the nanoscale level. Innovative applications of the reaction of organosilanes with these materials, presented for the first time, allowed us to develop the template displacement synthesis and to perform the structural studies of the mesoporous cage-like structures and ordered microporous-mesoporous materials.