Design of large pore ordered mesoporous silicas, related silica/polymer composites and carbon replicas
Item
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Title
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Design of large pore ordered mesoporous silicas, related silica/polymer composites and carbon replicas
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Identifier
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d_2009_2013:cacb5852d74f:10557
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identifier
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10782
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Creator
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Cao, Liang,
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Contributor
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Michal Kruk
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Date
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2010
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Language
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English
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Publisher
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City University of New York.
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Subject
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Polymer chemistry | Inorganic chemistry | Physical chemistry | mesoporous carbon | mesoporous silica | nanocomposite | nanopores | nano structure | polymer
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Abstract
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This dissertation includes four chapters, namely, the introduction to development and current research interests in mesoporous materials, the "soft-templating" synthesis of large pore 2-D hexagonal ordered mesoporous silicas, the synthesis of mesoporous polymer/silica composites via surface-initiated controlled polymerization, and the "hard-templating" method to fabricate ordered mesoporous carbons.;In Chapter 2, the synthesis of SBA-15 silica with 2-D hexagonal structure of large and ultra-large cylindrical mesopores is outlined. Our work on hexane and 1,3,5-triisopropylbenzene, as suitable micelle expanders, allowed us to tailor SBA-15 pore diameter up to ~15 nm and ~30 nm, respectively. Silica precursors tetraethylorthosilicate (TEOS) and tetramethylorthosilicate were both found suitable, but TEOS was preferred. We also developed a facile and rapid method to synthesize SBA-15 and other mesoporous silicas (FDU-12) in a few hours instead of at least 2 days as originally reported. We also found that the use of static conditions can induce formation of large-pore SBA-15 with platelet morphology.;In Chapter 3, the synthesis of well-defined mesoporous polymer/silica composites via surface-initiated atom transfer radical polymerization (ATRP) was described. 2-(4-chlorosulfonylphenyl)ethyltrichlorosilane was successfully proven as a cost-effective and powerful initiator to initiate polymerizations of various monomers from SBA-15 silicas. We further demonstrated the ATRP with activators regenerated by electron transfer (ARGET) as a more convenient and more environmentally friendly pathway to synthesize polymer/silica composites under mild conditions with hundred ppm levels of copper catalyst and tolerance of limited initial amount of air. In both methods, tunable surface properties, such as adjustable polymer loadings and polymer film thicknesses, can be achieved.;In Chapter 4, high quality ordered mesoporous carbons were synthesized using mesophase pitch or grafted polyacrylonitrile (PAN) as carbon precursors. The infiltration of mesophase pitch into the silica host was effective for synthesis of semi-graphitic carbons with different framework geometries, such as 2-D hexagonal array of nano-rods or cubic carbon structures, even at low carbonization temperature (850 °C). After stabilization and carbonization of silica/PAN composites, and removal of silica templates, mesoporous carbon materials had ordered structures with hollow nanoscale features, nanopipes or nanospheres from replication of SBA-15 or FDU-12 silicas, respectively.
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Type
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dissertation
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Source
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2009_2013.csv
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degree
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Ph.D.
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Program
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Chemistry
