Well-defined functional block copolymers containing either a fluorinated or a hydrophilic segment can be synthesized via a controlled free-radical technique, known as atom transfer radical polymerization (ATRP). Their self assembly characteristics in the solid state and in solution were examined in this work with the aim of developing ultralow dielectric constant materials and templates for conductive polymer synthesis, respectively. We demonstrated the controlled synthesis via ATRP of block copolymers containing poly(pentafluorostyrene) (PPFS) and a degradable polymer, such as poly(methyl methacrylate) (PMMA), poly([epsilon]-caprolactone) (PCL), or poly(D,L-lactide) (PLA). These block copolymers microphase separate in the solid state to form periodic nanostructures, such as alternating lamellae, a bicontinuous gyroid on a cubic lattice, cylinders on a hexagonal lattice, or spheres on a body-centered-cubic lattice, depending on the volume fraction of each block and the interblock segregation strength. Additionally, we quantified the interblock segregation strength of PPFS/PMMA, demonstrating that this block copolymer is only approximately twice as segregated as its nonfluorinated counterpart poly(styrene-[beta]-methyl methacrylate) due to the symmetric placement of the polar C-F bonds on the benzene ring in PPFS. We also showed that the self-assembly characteristics of PPFS-containing block copolymers can be used to create nanoporous fluorinated films with ultra-low dielectric constants in the range of 1.7 - 1.9. The dielectric constants are tunable through manipulation of the volume fraction of the degradable block in the parent block copolymers. We also demonstrated the controlled synthesis via ATRP of block copolymers containing poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (PAAMPSA) with either poly(oligo(ethylene glycol) methyl ether methacrylate) (PEGMA) or poly(methyl acrylate) (PMA). We showed that PEGMA/PAAMPSA formed well-ordered nanostructures in the solid state when cast from strong hydrogen bond accepting solvents, such as DMSO and DMF. PEGMA/PAAMPSA can also be used as the acid dopant in the synthesis of conductive polyaniline (PANI). Additionally, we studied the micelle formation of PMA/PAAMPSA and subsequently used these micelles as templates to create spherical conductive PANI nanoparticles. The size and size distribution of these PANI nanoparticles were dictated by the corresponding characteristics of the micellar template. / text

Texte remanié de: Diss.--Fachbereich Kulturgeschichte und Kulturkunde--Hamburg--Universität, 1996. / Bibliogr. p. 243-245. Index.

A coarse-grain parallel multi-block algorithm was designed for CHEQNS - a multi-block solver for solving chemically reacting flows in local chemical equilibrium and has been implemented using the Message Passing Interface (MPI). The parallel implementation confirms to the Single Program Multiple Data (SPMD) model. The parallel implementation uses synchronous update of fluxes across the block-block boundaries. The solution algorithm consists of block-decoupled Gauss-Seidel iterations. The coupling between the sub-domains on different processors occurs at the Newton iteration level. The parallel implementation is general and can accept an arbitrary arrangement of blocks in multi-block configuration with multiple blocks per processor. The parallel implementation has been verified against the results from the sequential multi-block solver for different types of flows. The parallel performance has been studied in terms of speed-up and efficiency. The influence of parallelization on the convergence was also studied.

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This thesis addresses three issues. These are the self-assembly of block copolymer in selective solvents, hierarchical assembly of micelles or crosslinked micelles of block copolymers, and the application of block copolymers as solid state compatibilizers in polymer-based photovoltaic cells. Poly(acrylic acid)-block-(2-cinnamoyloxylethyl methacrylate)-block-poly(perfluorooctylethyl methacrylate) or PAA-b-PCEMA-b-PFOEMA self-assembles in solvent mixtures of α,α,α-trifluorotoluene (TFT) and methanol, which are selective towards PAA. At TFT volume fraction (fTFT) of 40 %, the copolymer forms vesicles at 70 oC and cylinders at 21 oC. These two structures inter-convert via meta-stable intermediates including jellyfish-like, tethered vesicular, and bilayer sheet-like structures. These structures occur in kinetic experiments involving quick temperature swing from 21 to 70 oC or vice versa and also in experiments involving annealing samples long at temperatures between 21 to 70 oC. Thus, they are meta-stable and point to complex pathways for the morphological transition. At fTFT = 10 %, the polymer forms vesicles with bumpy surface at 70 oC and toroids with sharp angles at 21 oC. Closely examined is how the liquid crystalline nature of the PFOEMA block affects the formation of these unique morphologies and their morphological transitions. Two types of hierarchical assembly of cylindrical micelles (cylinders) or crosslinked cylindrical micelles (fibers) of block copolymers are examined. First, carboxyl-bearing nanofibers of PAA-b-PCEMA and amino-bearing nanocylinders from poly(tert-butyl acrylate)-block-poly(2-cinnamoyloxyethyl methacrylate)-block-poly(2-dimethylamino-ethylmethacrylate), PtBA-b-PCEMA-b-PDMAEMA, are mixed in solvent. The two species firstly aggregate via electrostatic interaction. Upon heating and aging, the cylinders dissociate on the fibers and eventually evolve into composite multilayered cylindrical structures. Second, layer-by-layer (LBL) deposition of carboxyl- and amine-bearing nanofibers yielded multilayer films. These films detached from a substrate separate nanospheres based on their size and surface charge differences. Diblock copolymers poly(3-hexylthiophene)-block-poly(2-cinnamoyloxyethyl methacrylate-random-2-[6,6]-phenyl-C61-butyroyoxyethyl methacrylate) (T-C60C) and poly(3-hexylthiophene)-block-poly(2-acetoxyethyl methacrylate-random-2-[6,6]-phenyl-C61-butyroyoxyethyl methacrylate) (T-C60A) are synthesized and used as compatibilizers for polymer-based photovoltaic cells containing poly(3-hexylthiophene) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM). Both copolymers can stabilize the morphology of the active layer and thus the device performance. T-C60A in the active layer yields longer life-times and better initial performance of the devices, due to the matching of surface tensions between C60A and PCBM. / Thesis (Ph.D, Chemistry) -- Queen's University, 2013-02-05 13:45:04.189

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Chen, Qianjin. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

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