The formation of thick, robust, mesoporous titania films is of particular interest and the focus of this thesis has been the study and comparison of the surfactant templated formation of such materials by three methods. film structure has been studied using TEM and small angle X-ray and neutron scattering while formation was studied using Brewster angle microscopy and X-ray and neutron reflectometry. Repetitive dip-coating was used to produce films for development into dye sensitized solar cells allowing development of cells of reasonable efficiency when four depositions were used. This research showed that repetitive deposition does not necessarily lead to a linear increase in film thickness, as subsequent depositions may be thinner making the future application of this method for solar cells problematic. In contrast to dip-coating, a fluorinated surfactant was used in a largely alcohol solvent to produce mesostructured films at the air-solution interface. Film formation occurred by a surface driven mechanism via addition of individual precursors and micelles producing a lamellar structure in-situ. After removal from the interface a cubic phase developed after drying of the film. Although films are not stable to calcination the calcined material remains porous. The surfactant templated formation of ZnO films at the air-solution interface was also studied. The di-block copolymer PEPEG2250 was also used to template titania films at the air-solution interface from alcoholic solvent. Film formation occurred via a bulk driven mechanism. Although these films were found to be disordered at the interface and not stable to calcinations they were unusually robust and self supporting after removal from the interface. Studies of subphase development allowed the first time-resolved observation of surfactant templated titania particle formation.

Surfactant templating provides for the synthesis of ordered mesoporous silica and the opportunity to tailor the pore size, pore structure, particle morphology and surface functionality of the silica through the selection of synthesis conditions and surfactant template. This work extends the synthesis of nanostructured silica using fluorinated surfactant templates to the synthesis of organic/inorganic composites. The effect of fluorinated surfactant templates (C6F13C2H4NC5H5Cl, C8F17C2H4NC5H5Cl and C10F21C2H4NC5H5Cl), which have highly hydrophobic fluorocarbon tails, on functional group incorporation, accessibility, and silica textural properties is examined and compared to properties of hydrocarbon surfactant (C16H33N(CH3)3Br, CTAB) templated silica. Hydrocarbon (vinyl, n-decyl and 3-aminopropyl) and fluorocarbon (perfluoro-octyl, perfluorodecyl) functional group incorporation by direct synthesis is demonstrated, and its effects on silica properties are interpreted based on the aggregation behavior with the surfactant templates. Silica materials synthesized with CTAB possess greater pore order than materials synthesized with the fluorocarbon surfactants. The incorporation of the short vinyl chain substantially reduces silica pore size and pore order. However, pore order increases with functionalization for materials synthesized with the fluorinated surfactant having the longest hydrophobic chain. The incorporation of longer chain functional groups (n-decyl, perfluorodecyl, perfluoro-octyl) by direct synthesis results in hexagonal pore structured silica for combinations of hydrocarbon/fluorocarbon surfactant and functional groups. The long chain of these silica precursors, which can be incorporated in the surfactant micelle core, affect the pore size less than vinyl incorporation. Synthesis using the longer chain fluoro-surfactant (C8F17C2H4NC5H5Cl) template in ethanol/water solution results in highest incorporation of both n-decyl and the fluorocarbon functional groups, with a corresponding loss of material order in the fluorinated material. Matching the fluorocarbon surfactant (C6F13C2H4NC5H5Cl) to the perfluoro-octyl precursor did not show improved functional group incorporation. Higher incorporation of the perfluoro-octyl functional group was observed for all surfactant templates, but the perfluoro-decyl silica is a better adsorbent for the separation of hydrocarbon and fluorocarbon tagged anthraquinones. Incorporating a reactive hydrophilic functional group (3-aminopropyl) suggests further applications of the resulting nanoporous silica. Greater amine incorporation is achieved in the CTAB templated silica, which has hexagonal pore structure; the order and surface area decreases for the fluorinated surfactant templated material.

Self-assembled nonionic alkyl glycoside surfactants are of interest for creating functional adsorption and catalytic sites at the surface of mesoporous metal oxides, but they typically impart poor long-range order when used as pore templates. Improved order and control over the functional site density may be achieved by mixing them with a cationic surfactant. To confirm this hypothesis, we investigate the lyotropic liquid crystalline (LLC) phase behavior of aqueous solutions of the functional nonionic surfactant n-dodecyl β-D-maltoside (C12G2) and cationic cetyltrimethylammonium bromide (C16TAB). A ternary phase diagram of the C16TAB-C12G2-water system is developed at 50 °C. By replacing the volume of water in the phase diagram with an equivalent volume of silica, ordered mesoporous materials are prepared by nanocasting with variable C12G2/C16TAB ratios. Metal oxide mesophases can almost always be predicted from the ternary phase diagram, except that silica prepared with high C12G2/C16TAB ratios are very weakly ordered, perhaps due to differences in hydrogen bonding or rate of assembly. Based on the ternary phase diagram of the system, a systematic approach is taken to the incorporation of titania sites via complexation to the maltoside headgroup of C12G2. Complexation to a saccharide is expected not only to guide titanium to the pore surface, but also to prevent uncontrolled hydrolysis and condensation of the (usually quite reactive) titanium precursor. Tetrahedrally coordinated titanium atoms incorporated into a silica network are believed to be the active oxidation sites required for heterogeneous silica-supported titania oxidation catalysts. To promote well-ordered materials and to allow control over titania site density, the mixed C12G2 / C16TAB system is used for pore templating. Series of Si-Ti mixed oxide thin films and bulk materials are synthesized with different amounts of titanium loading by utilizing pre-complexation between C12G2 and titanium isopropoxide. The degrees of homogeneity (indicated by tetracoordinated Ti) in these films are superior to those of films synthesized with the same loading of titanium but without C12G2 or without pre-complexation. Transition metal-carbohydrate complexation provides highly dispersed, tetrahedrally coordinated titanium atoms rather than the octahedral sites found without saccharide complexation.

The synthesis of mesoporous silica thin films using surfactant templating typically leads to an inaccessible pore orientation, making these films not suitable for membrane applications. Recent advances in thin film synthesis provide for the alignment of hexagonal pores in a direction orthogonal to the surface when templated on chemically neutral surfaces. In this work, orthogonal thin film silica membranes are synthesized on alumina supports using block copolymer poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) (P123) as the template. The orthogonal pore structure is achieved by sandwiching membranes between two chemically neutral surfaces, resulting in 90 nm thick films. Solvent flux of ethanol through the membrane demonstrates pore accessibility and suggests a silica pore size of approximately 10 nm. The permeability of ions and fluorescently tagged solutes (ranging from 4,000 to 70,000 Da) is used to demonstrate the membrane’s size selectivity characteristics. A size cut off occurs at 69,000 Da for the model protein BSA. By functionalizing the silica surface with a long chained alkyl group using n-decyltriethoxysilane (D-TEOS), the transport properties of the membranes can be altered. Contact angle measurements and FTIR results show the surface to be very hydrophobic after functionalization. Solvent flux of ethanol through the silica thin film membrane is similar before and after functionalization, but water flux decreases. Thin film silica membranes show much promise for applications in catalysis, bio-sensing, and affinity separations.