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Synthesis and Characterization of Nanoporous Materials and Their Films with Controlled MicrostructureLee, In Ho 2010 August 1900 (has links)
Nanoporous materials have attracted tremendous interest, investment and effort
in research and development due to their potential applications in various areas such as
membranes, catalysis, sensors, delivery, and micro devices. Controlling a nanoporous
material’s microstructure is of great interest due to the strong influence on efficiency and
performance. For particles, microstructure refers to particle size, shape, surface
morphology, and composition. When discussing thin films, microstructure includes film
thickness, crystal orientation and grain boundaries. In this respect, we focus to develop
novel methods for the synthesis and characterization of nanoporous materials and their
films, which are capable of controlling the microstructure of material. This dissertation
is composed of two main sections and each explores the fabrication of a different
nanoporous material: 1) A simple fabrication method for producing oriented MFI zeolite
membranes with controlled thickness, orientation, and grain boundary; 2) A microfluidic
synthesis of ordered mesoporous silica particles with controllable size, shape, surface
morphology, and composition.
The first section of this dissertation demonstrates a simple and commercially
viable method termed the micro-tiles-and-mortar method to make continuous b-oriented
MFI membranes with controlled membrane microstructure. This simple method allows
for control of the thickness of the membrane by using plate-like seed crystals with
different thicknesses along the b-axis (0.5 μm to 2.0 μm), as well as to manipulate the
density and structure of grain boundaries. Microstructural effects of silicalite-1
membranes on the gas separation are investigated by measuring the permeation and
separation for xylene isomers.
In the second section of this dissertation, a new synthesis method for the ordered
mesoporous silica particles with controllable microstructure is demonstrated. This novel
method combines a microfluidic emulsification technique and nonaqueous inorganic
synthesis with a diffusion-induced self-assembly (DISA). The systematic control of the
particle microstructure such as size, shape, and surface morphology is shown by
adjusting microfluidic conditions.
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