| The emergence of the nanotechnology field has prompted intense research in the fabrication and development of submicron structured materials for separation, catalysis, and opti-electronic devices. The use of templates whose natural feature sizes range from several to a few hundred manometers in a self-assembly "bottom up" approach has proven to be advantageous in materials synthesis. Two systems utilizing such techniques are investigated in this thesis.; Porous metal oxides used as catalyst supports demand high surface areas to provide a large number of active sites and low mass transfer resistance to increase the overall reaction rate and minimize catalyst deactivation. The challenge in fabricating such an ideal catalyst support is obtaining an optimal pore structure which balances between small pores that provide high surface areas and large pores that increase mass transfer. In Chapter 2, I describe the synthesis of bimodally porous aluminosilica monoliths whose structure satisfies both requirements. The material consists of interconnected micron-scale macropores with manometer-scale mesoporous walls, using dual templating with oil emulsion droplets and block copoloymer micelles as templates, respectively. The catalytic activities of the meso/macroporous monoliths are investigated and compared with conventional zeolites and mesoporous materials, to study the effects of framework crystallinity, pore size, and pore structure on the overall conversion rate. The meso/marcroporous monoliths exhibit superior deactivation behavior and improvement in alkylation rate compared to conventional mono-pore catalysts.; Secondly, I describe a nanoparticle/block copolymer composite material in Chapter 3 and 4 and address some of the major challenges associated with the control of particle incorporation and location. Incorporation of nanoparticles in symmetric A-B diblock copolymer is done by functionalizing the particle surfaces with short A or B homopolymers; controlling particle location is done by varying the composition of homopolymers on the particle surface. Thus, particles coated with either A or B homopolymers are selectively incorporated into the respective blocks while particles coated with a mixture of homopolymers segregate to the interfaces between the blocks. Such success in controlling the location and structure of these sub-micron scale building blocks may offer new possibilities to engineer novel advanced materials. |
