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Multi-step self-assembly route to three-dimensional block copolymer-semiconducting nanoparticle photonic arrays with structural hierarchyYusuf, Huda 24 November 2009 (has links)
A new multi-step self-assembly route to polymer-semiconducting nanoparticle photonic structures is described. The multi-step self-assembly strategy targets complex hierarchical structures in which organization of cadmium sulfide (CdS) nanoparticles on progressively longer length scales is introduced via a series of three self-assembly steps. each involving building blocks of increasing structural complexity. Each self assembly step can be described as follows: 1) SA1: self-assembly of PS-b-PAA to form block ionomer reverse micelles, followed by synthesis of a single CdS semiconducting nanoparticle in each core, forming the hybrid building blocks PS-CdS: 2) SA2: self-assembly of blends of PS-CdS and PS-b-PAA stabilizing chains in DMF/water mixtures by addition of water to form spherical nanoparticle assemblies, termed large compound micelles (LCMs); 3) SA3: self-assembly of LCMs into ordered close packed arrays by slow water evaporation. The kinetic freezing of building blocks at each stage offers the potential for unique control of nanoparticle self-assembly step since each step is "locked in", allowing structural features determined by the subsequent step to be independently tuned through a new set of experimental variables. Chapter 2 and 3 of this thesis investigate aspects of size and polydispersity control of spherical nanoparticle assemblies in the SA2 self-assembly step. Chapter 4 demonstrates that LCMs can be further assembled (SA3 step) to form three-dimensional hierarchical arrays.
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Random controlled free radical copolymerization of acrylic acidstyrene and tert-butyl acrylatestyrene mixtures using nitroxide mediatorsLessard, Benoît H., 1985- January 2008 (has links)
Controlled free radical polymerization facilitates the production of polymers with highly defined microstructures like traditional ionic polymerization; but in contrast allows for previously unattainable monomer combinations such as acrylic acid in its non-protected form. Incorporation of acrylic acid into styrene was done by random copolymerization of acrylic acid (directly and in its protected form as tert-butyl acrylate) with styrene. Styrene/tert-butyl acrylate (S/t-BuA) as well as styrene/acrylic acid (S/AA) mixtures were copolymerized to form tapered or gradient copolymers. Using an alkoxyamine unimolecular initiator, 2-[N- tert-butyl-2,2-(dimethylpropyl)aminooxy] propionic acid (BlocBuilder RTM), along with additional free nitroxide (SG1), the effect of acid protection on polymerization kinetics and copolymer composition was determined. Adding 4.5 mol% SG1/BlocBuilderRTM greatly improved the control of S/t-BuA copolymerization with low polydispersities (1.14-1.22) whereas the S/AA required higher levels of SG1 to produce polymers with low polydispersities that were comparatively still broader compared to the S/t-BuA system (polydispersities ∼ 1.3-1.4 at 9 mol% SG1/BlocBuilderRTM). S/AA copolymerization required higher SG1 concentrations to compensate for degradation of SG1 by attack from the acrylic acid monomer.
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Synthesis of Arborescent Amphiphilic CopolymersAlzahrany, Yahya 01 January 2013 (has links)
Living anionic polymerization techniques were applied to the synthesis of arborescent (dendritic)
well-defined graft polymers having core-shell morphologies, with a hydrophobic core and a
hydrophilic shell. Cycles of polystyrene substrate acetylation and anionic grafting yielded
successive generations of arborescent polystyrenes. The anionic polymerization of styrene with
sec-butyllithium provided polystyryllithium serving as side chains. These were coupled with a
linear acetylated polystyrene substrate to obtain a generation zero (G0) arborescent polymer. An
analogous G0 hydroxyl-functionalized polystyrene substrate with hydroxyl end groups was also
obtained by a variation of the same technique, using a bifunctional organolithium initiator
containing a hydroxyl functionality protected by a silyl ether group to generate the polystyrene
side chains. These were coupled with the linear acetylated polystyrene substrate and subjected to
a deprotection reaction to give the G0 polymer functionalized with hydroxyl groups at the chain
ends. A similar procedure was used to generate a hydroxyl-functionalized arborescent G1
polymer from the corresponding G0 acetylated polystyrene substrate. The growth of polyglycidol
chain segments was attempted from the hydroxyl-functionalized cores, to form a hydrophilic
shell around the hydrophobic cores, but led to extensive degradation. A click reaction was also
developed to synthesize the amphiphilic copolymers and was much more successful. In this case
alkyne-functionalized arborescent polystyrene substrates, obtained by a modification of the
hydroxyl-functionalized arborescent polystyrenes, were coupled with azide-functionalized
polyglycidol side chains.
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Synthesis Of Thiophene Capped Polytetrahydrofuran Conducting CopolymersUnur, Ece 01 January 2003 (has links) (PDF)
Living polytetrahydrofuran (PTHF) was terminated with sodium thiophenemethonate to yield a polymer with thiophene groups at one (PTHF1) and both ends (PTHF2). Copolymerizations of PTHF1 and PTHF2 insulating polymers with pyrrole and thiophene were achieved in water-p-toluene sulfonic acid (PTSA) and acetonitrile (AN)-tetrabutylammonium tetrafluoroborate (TBAFB) solvent-electrolyte couples via constant potential electrolysis. Characterization of the samples were performed by Nuclear Magnetic Resonance Spectroscopy (NMR), cyclic voltammetry (CV), Fourier Transform Infrared Spectroscopy (FT-IR), Thermal Analyses (TGA), (DSC) and Scanning Electron Microscopy (SEM). Electrical conductivities were measured by four-probe technique. PTHF1/PTh and PTHF2/PTh films which were deposited on ITO-glass in dichloromethane-TBAFB solvent-electrolyte couple found out to be anodically coloring copolymers that electrochemically switch between an oxidized blue and reduced red state exhibiting electrochromic behavior. Spectroelectrochemical Analysis (SEC) was run in UV-VIS region to reach a better understanding of the band structures of PTHF1/PTh and PTHF2/PTh electrochromic copolymers. Optoelectrochemical analyses were introduced as a new method for the characterization of copolymers.
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Poly(N-isopropylacrylamide) at the air/water interface /Zhang, Ju. January 1998 (has links)
Thesis (Ph.D.) -- McMaster University, 1999. / Includes bibliographical references. Also available via World Wide Web.
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Nanoscale investigation of polarization interaction and polarization switching in ferroelectric P(VDF-TrFE) copolymer samplesKim, Jihee. January 1900 (has links)
Thesis (Ph.D.)--University of Nebraska-Lincoln, 2008. / Title from title screen (site viewed July 22, 2008). PDF text: ix, 169 p. : ill. (some col.) ; 8 Mb. UMI publication number: AAT 3299685. Includes bibliographical references. Also available in microfilm and microfiche formats.
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Supramolecular block and random copolymers in multifunctional assembliesBurd, Caroline Glenn January 2008 (has links)
Thesis (Ph.D.)--Chemistry and Biochemistry, Georgia Institute of Technology, 2009. / Committee Chair: Marcus Weck; Committee Member: Bunz, Uwe; Committee Member: Collard, David; Committee Member: Jones, Christopher; Committee Member: Payne, Christine
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Molecular dynamics simulations of polymer nanocomposites containing polyhedral oligomeric silsesquioxanesPatel, Reena R. January 2004 (has links)
Thesis (M.S.)--Mississippi State University. Department of Computational Engineering. / Title from title screen. Includes bibliographical references.
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Orthogonal functionalization strategies in polymeric materialsYang, Si Kyung. January 2009 (has links)
Thesis (Ph.D)--Chemistry and Biochemistry, Georgia Institute of Technology, 2010. / Committee Chair: Weck, Marcus; Committee Member: Breedveld, Victor; Committee Member: Fahrni, Christoph; Committee Member: Kelly, Wendy; Committee Member: Lyon, L. Andrew. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Thermodynamic and kinetic control of charged, amphiphilic triblock copolymer assembly via interaction with organic counterions in solvent mixturesCui, Honggang. January 2007 (has links)
Thesis (Ph. D.)--University of Delaware, 2007. / Principal faculty advisor: Darrin J. Pochan, Dept. of Materials Science & Engineering. Includes bibliographical references.
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