Pakstis, Lisa M.
Thesis (Ph.D.)--University of Delaware, 2006. / Principal faculty advisor: Darrin J. Pochan, Dept. of Materials Science & Engineering. Includes bibliographical references.
Kiley, Patrick Jerome
No description available.
Thesis (Ph.D.)--University of Nebraska-Lincoln, 2008. / Title from title screen (site viewed Feb. 17, 2009). PDF text: xii, 219 p. : ill. (some col.) ; 5 Mb. UMI publication number: AAT 3328256. Includes bibliographical references. Also available in microfilm and microfiche formats.
Thesis (Ph.D.)--University of Delaware, 2007. / Principal faculty advisor: Joel P. Schneider, Dept. of Chemistry & Biochemistry. Includes bibliographical references.
Thesis (Ph.D)--Chemistry and Biochemistry, Georgia Institute of Technology, 2009. / Committee Chair: Lyon, Louis; Committee Member: Breedveld, Victor; Committee Member: Bunz, Uwe; Committee Member: Collard, David; Committee Member: Srinivasarao, Mohan. Part of the SMARTech Electronic Thesis and Dissertation Collection.
28 August 2008
Not available / text
Rabideau, Brooks Douglas, 1979-
29 August 2008
As the feature size of new devices continues to decrease so too does the feasibility of top-down methods of patterning them. In many cases bottom-up methods are replacing the existing methods of assembly, as having building blocks self-organize into the desired structure appears, in many cases, to be a much more advantageous route. Self-assembled nanoparticulate films have a wide range of potential applications; high-density magnetic media, sensing arrays, meta-materials and as seeds for 3D photonic crystals to name a few. Thus, it is critical that we understand the fundamental dynamics of pattern formation on the nanoparticulate and colloidal scale so that we may have better control over the formation and final quality of these structures. We study computationally the self-organization of colloidal particles in 2D using both Monte Carlo and dynamic simulation We present 3 studies employing Monte Carlo simulation. In the first study, Monte Carlo simulations were used to understand the experimental observation of highlyordered 2D arrays of bidisperse, stabilized gold nanoparticles. It was shown that the LS lattice forms with the addition of interparticle forces and a simple compressive force, revealing that bidisperse lattice formation is, in fact, a dynamic process. It was evident that the LS lattice forms in large part because the particles within the lattice reside in their respective interparticle potential wells. In the second Monte Carlo study, this information was used to predict size-ratios and surface coverages for novel lattice structures. These predictions are intended to guide experimentalists in their search for these exciting new structures. In the third study it was shown that polydisperse amounts of amorphous-silicon nanoparticles could form 2D clusters exhibiting long-range orientational order even in the absence of translational order. Monte Carlo simulations were performed, which included lateral capillary forces and a simple stabilizing repulsion, resulting in structures that were strikingly similar to the experimentally observed In the fourth study we used dynamic simulation to study the hydrodynamicallyassisted self-organization of DNA-functionalized colloids in 2D. It was shown that hydrodynamic forces allow a more thorough sampling of phase space than through thermal or Brownian forces alone.
01 January 2006
No description available.
Self-assembly assisted polypolymerization (SAAP): a novel approach for the preparation of multiblock copolymers. / CUHK electronic theses & dissertations collectionJanuary 2007 (has links)
In Chapter 1-3, properties and applications of block copolymers, synthetic methods especially living anionic polymerization as well as the development of the SAAP concept with some of previous successful examples are reviewed. Experimental methods, including the design and establishment of a special high-vacuum system, size exclusion chromatography and laser light scattering, are explained. / In Chapter 4, living anionic polymerization of alpha,o-di bromobutyl end-capped PI-b-PS-b-PI triblock copolymers and the end-capping reaction with 1,4-dibromobutane at the end of polymerization are described, including a in-depth analysis of the reaction mechanism that involves the dimerization of two living oligomer chain during the reaction of living polymeric anions with haloalkanes, i.e., the Wurtz-type coupling reaction. The self assembly and coupling reaction of 1,4-dilithio-1,1,4,4-tetraphenylbutane (DD2-) in n-hexane to form long (PI- b-PS-b-PI)10 multiblock chains are discussed. The coupling efficiencies with and without the self assembly are compared to demonstrate the principle of SAAP. However, the coupling reaction with dianion linker is troublesome because a trace amount of impurities in the solvent can remove its activity. / In Chapter 5, a method of improving the coupling efficiency is described. In this method, PI-b-PS-b-PI triblock copolymers is end-capped with avo-dicarboxylic acid groups via a reaction between living anions and carbon dioxide. Such prepared HOOC-ISI-COOH chains can be coupled with 1,6-hexamethylenediamine (HDA) in the presence of 1,3-dicyclohexylcarbodiimide (DCC) after the self assembly. The size exclusion chromatography (SEC) analysis shows that the SAAP method mainly leads to the formation of triblock copolymer chain dimers and the coupling efficiency is close to 50%. There is no coupling in THF without the self assembly. Further, a much better method of using alpha,o-diacyl chloride end-capped PI-b-PS-b-PI triblock copolymer chains in SAAP to prepare long multiblock copolymer chains is described. Using this recently developed method, we are able to prepared long ∼90-block copolymer chains (PI-b-PS-b-PI)30 which clearly shows the advantage of using SAAP to prepare long multiblock copolymers with a controllable sequence and different block lengths. / In this thesis, we have proposed and developed a novel method: The Self-Assembly Assisted Polypolymerization (SAAP). Namely, using the self-assembly of A-B-A triblock copolymers with two active end groups in a selective solvent for the A-block to concentrate and expose the active end groups on the periphery of the resultant core-shell polymeric micelles, we can effectively couple each two active ends on different chains together to form a long multiblock copolymer chain with its sequence and block length well controlled by the initial triblock copolymer. To accomplish this project, we first built a high-vacuum system for living anionic polymerization and then synthesized and characterized narrowly distributed polyisoprene-b-polystyrene- b-polyisoprene (PI-b-PS-b-PI) triblock copolymer chains with their both ends capped respectively with bromobutyl and carboxylic acid active groups. The self assembly of such prepared triblock copolymers in n-hexane, a selective solvent for PI, was studied by a combination of static and dynamic laser light scattering (LLS). Finally, the self-assembled end-functionalized PI-b-PS-b-PI chains were coupled together by difunctional small molecules (linkers) to form long multiblock copolymers with a controlled structure. / Hong, Liangzhi. / "Aug 2007." / Adviser: Chi Wu. / Source: Dissertation Abstracts International, Volume: 69-02, Section: B, page: 1036. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong,  System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract in English and Chinese. / School code: 1307.
A Study of Fragmentation and Spontaneous Covalent Self-Assembly of the <i>Azaorcus</i> Ribozyme from Multiple Small Inactive RNA FragmentsJayathilaka, Tharuka Sewwandi 06 June 2018 (has links)
The question about the origins of life often appears as a difficult question to answer. A more reliable candidate molecule for the chemical origins of life would be a molecule that is capable of making copies of itself from simple precursors. With the finding of the catalytic activities of RNA molecules by Thomas Cech and Sid Altman in late 1980s, the term ribozyme was introduced to define an RNA molecule with catalytic activity. The RNA World is a conceptual period in the early stages in the development of life because RNA simultaneously possesses evolvability and catalytic function. An RNA molecule that could evolve in such a fashion is likely to have been one of the Earth's first life forms. The most important problem facing the RNA World is the difficulty of prebiotic synthesis of RNA. Different prebiotic environments could provide the right reaction conditions for synthesis of catalytically active RNA molecules. Most importantly, these environments can support new ways to assemble monomers into polymers. In order to understand and demonstrate how small inactive RNA oligomers can self-assemble into an autocatalytic ribozyme molecule, here I have used the Azoarcus Group I intron. First, the fragmentation and the self-assembly reactions were done using the natural IGS-tag combination of the Azoarcus group I intron, which is GUG/CAU. The main purpose was to experimentally demonstrate that the ribozyme can be broken down into five or more shorter RNA fragments and these fragments can self-assemble into a catalytically active covalent full-length molecule. Then, with the successful demonstration that five inactive RNA fragments can self-assemble, the next step to test the other possible breaking locations with mutated IGS/tag combinations. A new IGS/tag pair GCG-CGU also successfully demonstrated the five-piece self-assembly reaction. Finally, we tested these reactions in different Mg2+ concentrations to optimize the self-assembly reactions. By focusing not only one single reaction but on a collection of different sequence requirement combinations and with the development of evaporation and subsequent rehydration by spinning down methods this study successfully illustrates that covalent self-assembly from inactive RNA oligomers is possible. Therefore, this thesis work focuses on a more broader aspect of intermolecular interactions in the study of the RNA World, as illustrated in following chapters.
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