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1
Elmaci, Aysegul. "Thermal Characterization Of Homopolymers, Copolymers And Metal Functional Copolymers Of Vinylpyridines." Master's thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/12609892/index.pdf.
Повний текст джерелаАнотація:
Although, the use of vinyl pyridine polymers, especially as matrices for
nanoparticle synthesis, is growing considerably, the knowledge of thermal
degradation behavior is still missing in the literature. In this study, thermal
degradation characteristics of the homopolymerspoly(4-vinylpyridine), P4VP, and poly(2-vinylpyridine), P2VP, the diblock copolymers
polystyrene-blockpoly( 2-vinylpyridine), (PS-b-P2VP) and polystyrene-block-poly(4-vinylpyridine), (PS-b-P4VP), and the metal functional vinyl polymers
cobalt-polystyrene-blockpoly( 2-vinylpyridine) and cobalt-polystyrene-block-poly(4-vinylpyridine) were investigated by direct pyrolysis mass spectrometry. The effects of the position of the nitrogen in the pyridine ring, composition and molecular weight of diblock copolymer and coordination of the metal to the pyridine ring of the copolymer on thermal behavior were also investigated. The results showed that unlike most of the vinyl polymers that decompose via depolymerization, P2VP degrades through opposing reaction pathways
depolymerization, proton transfer to N atom in the pyridine ring yielding unsaturated linkages on the polymer backbone that decompose slightly at higher temperatures and loss of pyridine units. On the other hand the thermally less stable P4VP decomposition follows v depolymerization in accordance to general expectations. Another finding was the independent decomposition of both components of the diblock polymers, (PS-b- P2VP) and (PS-b-P4VP). Thermal degradation occurs in two main steps, the thermally less stable P2VP or P4VP chains degrade in the first step and in the second step decomposition of PS takes place. It was also concluded that upon coordination of metal, thermal stability of both P2VP and P4VP increases significantly. For metal functional diblock copolymers thermal degradation of chains coordinated to Co metal through N in the pyridine ring occurred in three steps
cleavage of pyridine coordinated to Co, coupling and H-transfer reactions yielding unsaturated and/or crosslinked structure and decomposition of these thermally more stable unsaturated and/or crosslinked blocks. TEM imaging of the metal functional block copolymers along with the results of the pyrolysis mass spectrometry pointed out that PS-b-P2VP polymer is a better and more effective matrix for nanoparticle synthesis.
2
Borkar, Sachin. "Synthesis and characterization of functional diblock copolymers." [S.l. : s.n.], 2003. http://deposit.ddb.de/cgi-bin/dokserv?idn=971274886.
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3
Tam, Wing-yan. "Functional diblock copolymers for nanofabrications and photovoltaic applications." Click to view the E-thesis via HKUTO, 2010. http://sunzi.lib.hku.hk/hkuto/record/B43907301.
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4
Mantzana, Pavlina. "Novel surface coatings and microcapsules from functional copolymers." Thesis, University of Leeds, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.502771.
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5
Tam, Wing-yan, and 譚詠欣. "Functional diblock copolymers for nanofabrications and photovoltaic applications." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2010. http://hub.hku.hk/bib/B43907301.
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6
Böhm, Paul [Verfasser]. "Functional silicones and silicone-containing block copolymers / Paul Böhm." Mainz : Universitätsbibliothek Mainz, 2012. http://d-nb.info/1025407644/34.
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7
Schultz, Alison. "Functional Block Copolymers via Anionic Polymerization for Electroactive Membranes." Thesis, Virginia Tech, 2013. http://hdl.handle.net/10919/51115.
Повний текст джерелаАнотація:
Ion-containing block copolymers blend ionic liquid properties with well-defined polymer architectures. This provides conductive materials with robust mechanical stability, efficient processability, and tunable macromolecular design. Conventional free radical polymerization and anion exchange achieved copolymers containing n-butyl acrylate and phosphonium ionic liquids. These compositions incorporated vinylbenzyl triphenyl phosphonium and vinylbenzyl tricyclohexyl phosphonium cations bearing chloride (Cl), or bis(trifluoromethane sulfonyl)imide (Tf2N) counteranions. Differential scanning calorimetry and dynamic mechanical analysis provided corresponding thermomechanical properties. Factors including cyclic substituents, counteranion type, as well as ionic concentration significantly influenced phosphonium cation association.
1, 1\'-(1, 4-Butanediyl)bis(imidazole) neutralized NexarTM sulfonated pentablock copolymers and produced novel electrostatically crosslinked membranes. Variable temperature FTIR and 1H NMR spectroscopy confirmed neutralization. Atomic force microscopy and small angle X-ray scattering studied polymer morphology and revealed electrostatic crosslinking characteristics. Tensile analysis, dynamic mechanical analysis, thermogravimetric analysis, and vapor sorption thermogravimetric analysis investigated polymer properties. The neutralized polymer demonstrated enhanced thermal stability, decreased water adsorption, and well-defined microphase separation. These findings highlight NexarTM sulfonated pentablock copolymers as reactive platforms for novel, bis-imidazolium crosslinked materials.
4-Vinylbenzyl piperidine is a novel styrenic compound that observably autopolymerizes. In situ FTIR spectroscopy monitored styrene and 4-vinylbenzyl piperidine thermal polymerizations. A pseudo-first-order kinetic treatment of the thermal polymerization data provided observed rate constants for both monomers. An Arrhenius analysis derived thermal activation energy values. 4-Vinylbenzyl piperidine exhibited activation energy 80 KJ/mol less than styrene. The monomer differs from styrene in its piperidinyl structure. Consequently, in situ FTIR spectroscopy also monitored styrene thermal polymerization with variable N-benzyl piperidine concentrations. Under these circumstances, styrene revealed activation energy 60 KJ/mol less than its respective bulk value. The similarities in chemical structure between styrene and 4-vinylbenzyl piperidine suggested thermally initiated polymerization occurred by the Mayo mechanism. The unique substituent is proposed to offer additional cationic effects for enhancing polymerization rates.
Living anionic polymerization of 4-vinylbenzyl piperidine achieved novel piperidinyl-containing polymers. Homopolymer and copolymer architectures of this design offer structural integrity, and emphasize base stability. Sequential anionic polymerization afforded a 10K g/mol poly(tert-butyl styrene-co-4-vinylbenzyl piperidine) diblock and a 50K poly(tert-butyl styrene-co-isoprene-co-4-vinylbenzyl piperidine) triblock. Alkylation studies involving a phosphonium bromide salt demonstrated the future avenues for piperidinium based polymer designs. These investigations introduce piperidinyl macromolecules as paradigms for a new class of ammonium based ionic materials.Master of Science
8
Andrade, Genara Selene. "New comonomers and pet-based copolymers for functional high-barrier applications." Diss., Georgia Institute of Technology, 2003. http://hdl.handle.net/1853/29899.
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9
Noga, David Edward. "Synthesis of functional lactide copolymers for use in biomedical applications." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/29646.
Повний текст джерелаАнотація:
Thesis (Ph.D)--Chemistry and Biochemistry, Georgia Institute of Technology, 2009.Committee Chair: Collard, David M.; Committee Member: García, Andrés J.; Committee Member: Tolbert, Laren; Committee Member: Wang, Yadong; Committee Member: Weck, Marcus. Part of the SMARTech Electronic Thesis and Dissertation Collection.
10
Ibrahim, Saber. "Synthesis of Functional Block Copolymers for use in Nano-hybrids." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2011. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-67435.
Повний текст джерелаАнотація:
Polystyrene block polyethyleneimine (PS-b-PEI) copolymer prepared by combining PS and poly(2-methyl-2-oxazoline) (PMeOx) segments together through two strategies. Furthermore, PMeOx block was hydrolysis to produce PEI block which linked with PS block.
Macroinitiator route is one of these two ways to prepare PS-b-PEI copolymer. Polystyrene macroinitiator or poly(2-methyl-2-oxazoline) macroinitiator prepared through Nitroxide Mediate Radical Polymerization (NMRP) or Cationic Ring Opening Polymerization (CROP) respectively. Each macroinitiator has active initiated terminal group toward another block monomer. Second strategy based on coupling of PS segment with PMeOx block through “click” coupling chemistry. Polystyrene modified with terminal azide moiety are combined with PMeOx functionalized with alkyne group via 1,3 dipolar cycloaddition reaction “click reaction”.
PS-b-PMeOx was hydrolysis in alkaline medium to produce amphiphilic PS-b-PEI copolymer. A set of block copolymer with different block ratios was prepared and investigated to select suitable block copolymer for further applications. Stichiometric PS-b-PEI copolymer selected to stabilize gold nanoparticle (Au NPs) in polymer matrix. PEI segment work as reducing and stabilizing agent of gold precursor in aqueous solution. Various concentrations of gold precursor were loaded and its effect on UVVIS absorbance, particle size and particle distribution studied. In addition, reduction efficiency of PEI block was determined from XPS measurements. The thickness of Au NPs/PS-b-PEI thin film was determined with a novel model for composite system. On the other hand, Gallium nitride quantum dots (GaN QDs) stabilized in PS-b-PEI copolymer after annealing. Our amphiphilic block copolymer exhibit nice thermal stability under annealing conditions. GaN QDs prepared in narrow nano-size with fine particle distribution. Blue ray was observed as an indication to emission activity of GaN crystal. Over all, PS-b-PEI copolymer synthesized through macroinitiator and click coupling methods. It was successfully stabilized Au NPs and GaN QDs in polymer matrix with controlled particle size which can be post applied in tremendous industrial and researcher fields.
11
Gwyther, Jessica. "Nanostructured functional materials from self-assembled polyferrocenylsilane (PFS) block copolymers." Thesis, University of Bristol, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.541643.
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12
Tan, Wui Siew. "Strategies for incorporating functional block copolymers into polyelectrolyte multilayer coatings." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/69794.
Повний текст джерелаАнотація:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2011.Cataloged from PDF version of thesis.
Includes bibliographical references.
This thesis explores the creation of thin film responsive hydrogel coatings via Layer-by Layer assembly (LbL) of temperature (T) responsive block copolymer - polyelectrolyte multilayers (PEMs). First, the LbL conditions that allow for temperature driven, large, reversible swelling transitions of multilayer constructs are determined. Use of weak polyelectrolyte components and selection of an appropriate deposition pH were found to be the critical factors that allowed large scale reversible swelling. These factors were the missing pieces that explain the lack of temperature response reported in prior literature. A series of block copolymer (BCP) molecules were subsequently synthesized to expose the influence of BCP architecture on the temperature responses of these micelle-PEMs. Diblock architectures that lack connectivity in the Tresponsive poly(propylene oxide) block disintegrate quickly at low temperature. Triblock copolymers on the other hand allow access to a wide range of reversible swelling behavior. The dynamic interplay of various pH, salt concentration and T effects on the swelling and stability of these hydrogels are also further explored. In particular a critical ratio of charged block to Tresponsive block length is necessary for film stability at low temperature. As a whole these systems can be customized to either swell reversibly (by up to 6 times their dry thickness) or disintegrate under specific sets of pH, time, temperature, and salt conditions, making them useful for a wide range of smart applications. The application of these conformal temperature responsive coatings to T-gating of membranes; creation of nanotube structures; T-enabled loading and release of proteins; as well as their tunable disintegration, useful for triggered release, is discussed and demonstrated. On a separate note, the utility of inorganic nanoparticle LbL assembly in creating conformal thin UV anti-reflection coatings for PMMA Fresnel lenses is demonstrated. Key features of thin porous nanoparticle coating assembly via LbL is discussed, including how particle size and deposition pH can tune the coating porosity and refractive index. In addition, we develop several strategies for stabilization of these inherently weak systems largely composed of air. In particular, a novel means to generate stable inversely structured surface nanoporosity in thermoplastic materials is developed.
by Wui Siew Tan.
Ph.D.
13
Gapin, Adèle. "Elaboration of functional copolymers absorbing in the near infrared region." Thesis, Pau, 2020. http://www.theses.fr/2020PAUU3034.
Повний текст джерелаАнотація:
De nos jours, les matériaux organiques absorbant dans la région du proche infrarouge ont trouvé un terrain fertile dans une variété d'applications et ont contribué de manière significative à l'amélioration des dispositifs optoélectroniques, de la bioimagerie, de la biodétection et des thérapies biomédicales. Le développement de polymères à faible bande interdite retient particulièrement l'attention car leurs bandes interdites réduites conduisent à des propriétés optiques et électroniques intéressantes. La fonctionnalisation de ces polymères conjugués en bout de chaînes ouvre la voie au développement de matériaux hybrides susceptibles d'améliorer les performances des dispositifs optoélectroniques. En outre, les copolymères à blocs rigide-flexible intégrant des polymères à faible bande interdite sont désormais accessibles et pourraient fournir une plus large absorption de la lumière, une meilleure solubilité, ainsi que des propriétés d'auto-assemblage. Dans ce contexte, l'objectif de nos travaux a été de développer des matériaux innovants à base de polymères à faible bande interdite absorbant dans le domaine spectral 650-1000 nm afin d'obtenir des matériaux actifs dans la région proche infrarouge. Nous avons synthétisé un nouveau matériau hybride en greffant un polymère à faible bande interdite sur des nanosphères de ZnO via la technique de grafting onto. Nous avons conçu et préparé des copolymères à blocs rigide-flexible intégrant un bloc à faible bande interdite via deux méthodes de synthèse. Le premier copolymère est composé d'un bloc flexible aux propriétés filmogènes que nous prévoyons d'utiliser comme additif dans l'élaboration de photodétecteurs infrarouges organiques. Le second copolymère présente un bloc flexible biocompatible et hydrophile afin d'obtenir des nano-objets hydrosolubles aux propriétés photothermiquesNowadays, organic materials absorbing in the near infrared region have found fertile ground in a variety of applications and have significantly contributed in improving optoelectronic devices, bioimaging, biosensing, and biomedical therapies. The development of low band-gap polymers draw particular attention since their reduced bandgaps determine interesting optical and electronic properties. The end-functionalization of these conjugated polymers paves the way to the development of hybrid materials which could improve the performances of optoelectronic devices. Furthermore, rod-coil block copolymers incorporating low band-gap polymers are reachable and could provide broader light absorption, better solubility, as well as self-assembly properties. In this context, the objective of our work was to develop innovative materials based on low band-gap polymers absorbing in the spectral range 650-1000 nm in order to obtain active materials in the near infrared region. We synthesized a new hybrid material by grafting a low band-gap polymer onto ZnO nanospheres via the grafting onto technique. We designed and prepared rod-coil block copolymers involving a low band-gap block via two synthetic method. The first copolymer was based on the use of a coil block with filmogenic properties which we plan to employ as additive in the elaboration of organic infrared photodetectors. The second copolymer was based on the use of a hydrophilic biocompatible coil block in order to obtain water soluble nano-objects with photothermal properties
14
Justynska, Justyna. "Towards a library of functional block copolymers synthesis and colloidal properties /." Phd thesis, [S.l.] : [s.n.], 2005. http://deposit.ddb.de/cgi-bin/dokserv?idn=977274519.
Повний текст джерела
15
Kayandan, Sanem. "Synthesis and Characterization of Poly(lactide) Functional Oligomers and Block Copolymers." Thesis, Virginia Tech, 2013. http://hdl.handle.net/10919/49592.
Повний текст джерелаАнотація:
Amphiphilic block copolymers consisting of poly(ethylene oxide) and poly(lactide) have great potential for formulating drug delivery systems. Our approach was to synthesize poly(ethylene oxide-b-D,L-lactide), (PEO-b-PDLLA), block copolymers with controlled molecular weights and good functionality on the poly(ethylene oxide) end for the design of potential core-shell delivery vehicles for HIV drugs. PEO-b-PDLLA block copolymer was used as a polymeric nanocarrier to encapsulate the HIV protease inhibitor, Ritonavir, within magnetite nanoparticles. Well-defined multifunctional polymeric nanoparticles with controlled sizes and size distributions were fabricated by rapid nanoprecipitation using blends of the PEO-b-PDLLA block copolymer with poly(L-lactide), (PLLA) homopolymer. Heterobifunctional PEO oligomers were directly prepared by initiating ethylene oxide with functional alcohols bearing vinylsilane, vinylether and maleimide moieties to provide appropriate end groups for conjugating targeting ligands. The polyethers with narrow molecular weight distributions were utilized as macroinitiators for the synthesis of poly(lactide) block. Heterobifunctional diblock copolymers possessing carboxylic acids were prepared from ene-thiol addition reaction of mercaptoacetic acid across the vinyl group on the PEO end, while preserving the hydroxyl functionality on the other end. Additionally, PDLLAs bearing maleimide functionality with controlled molecular weights were synthesized using maleimide functional initiator. End group modification was performed via Michael addition using cysteamine hydrochloride to introduce an amino group over the vinyl bond. The resulting carboxylic acid functional PEO-b-PDLLA diblock copolymers, and amino functional PDLLAs are potential biocompatible polymers that can be utilized to encapsulate an array of bioactive molecules, targeting ligands. Master of Science
16
Addagulla, Swapna. "Functional silane based co-polymers for biofuntionalization studies, chemical sensing and separations /." View online ; access limited to URI, 2009. http://0-digitalcommons.uri.edu.helin.uri.edu/dissertations/AAI3401132.
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Varadharajan, Divya [Verfasser], and G. [Akademischer Betreuer] Delaittre. "From Block Copolymers to Functional Nanostructured Materials / Divya Varadharajan ; Betreuer: G. Delaittre." Karlsruhe : KIT-Bibliothek, 2018. http://d-nb.info/1199352349/34.
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18
Biswas, Sanchita. "Synthesis and applications of ring opening metathesis polymerization based functional block copolymers." Doctoral diss., University of Central Florida, 2010. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4655.
Повний текст джерелаАнотація:
Additionally, the organic soluble magnetic nanocomposites with high magnetizations were encapsulated in an amphiphilic copolymer and dispersed in water to assess their water stability by TEM. To gain a preliminary measure of biocopatibility of the micelle-encapsulated polymeric magnetic nanocomposites, cell-viability was determined. In Chapter 4, aggregation behaviors of two porphyrin-based dyes were investigated. A new amphiphilic homopolymer containing secondary amine moieties was synthesized and characterized. In low pH, the polymer became water soluble and initiated the stable J-aggregation of the porphyrin. Spectroscopic data supported the aggregation behavior. Two photon fluorescence microscopy (2PFM) has become a powerful technique in bioimaging for non-invasive imaging and potential diagnosis and treatment of a number of diseases via excitation in the near-infrared (NIR) region. The fluorescence emission upon two-photon absorption (2PA) is quadratically dependent with the intensity of excitation light (compared to the linear dependence in the case of one-photon absoprtion), offering several advantages for biological applications over the conventional one-photon absorption (1PA) due to the high 3D spatial resolution that is confined near the focal point along with less photodamage and interference from the biological tissues at longer wavelength (~700-900 nm). Hence, efficient 2PA absorbing fluorophores conjugated with specific targeting moieties provides an even better bioimaging probe to diagnose desired cellular processes or areas of interest The alpha subscript v beta subscript 3] integrin adhesive protein plays a significant role in regulating angiogenesis and is over-expressed in uncontrolled neovascularization during tumor growth, invasion, and metastasis.; Cyclic-RGD peptides are well-known antagonists of alpha subscript v beta subscript 3] integrin which suppress the angiogenesis process, thus preventing tumor growth. In Chapter 5 the synthesis, photophysical studies and bioimaging is reported for a versatile norbornene-based block copolymer multifunctional scaffold containing biocompatible (PEG), two-photon fluorescent (fluorenyl), and targeting (cyclic RGD peptide) moieties. This water-soluble polymeric multi scaffold probe with negligible cytotoxicity exhibited much stronger fluorescence and high localization in U87MG cells (that overexpress integrin) compared to control MCF7 cells. The norbornene-based polymers and copolymers have quite remarkable versatility for the creation of advanced functional magnetic, photonic, and biophotonic materials.; Ring opening metathesis polymerization (ROMP) is established as one of the efficient controlled living polymerization methods which have various applications in polymer science and technology fields. The research presented in this dissertation addresses several applications of multifunctional well-defined norbornene-based block copolymers synthesized by ROMP using ruthenium-based Grubbs catalysts. These novel block copolymers were applied to stabilize maghemite nanoparticles, creating the superparamagnetic polymeric nanocomposites. The J-aggregation properties of the porphyrin dyes were improved via self-assembly with a customized norbornene polymer. Novel multimodal copolymer probes were synthesized for two-photon fluorescence integrin-targeted bioimaging. In Chapter 1 a brief overview of ROMP along with ruthenium metal catalysts and selected applications of the polymers related to this research is presented. Superparamagnetic maghemite nanoparticles are important in biotechnology fields, such as enhanced magnetic resonance imaging (MRI), magnetically controlled drug delivery, and biomimetics. However, cluster formation and eventual loss of nano-dimensions is a major obstacle for these materials. Chapter 2 presents a solution to this problem through nanoparticles stabiulized in a polymer matrix. The synthesis and chracterization of novel diblock copolymers, consisting of epoxy pendant anchoring groups to chelate maghemite nanoparticles and steric stabilizing groups, as well as generation of nanocomposites and their characterization, including surface morphologies and magnetic properties, is discussed in Chapter 2. In Chapter 3, further improvement of the nanocomposites by ligand modification and the synthesis of pyrazole-templated diblock copolymers and their impact to stabilize the maghemite nanocomposite are presented.ID: 028916946; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Thesis (Ph.D.)--University of Central Florida, 2010.; Includes bibliographical references.
Ph.D.
Doctorate
Department of Chemistry
Sciences
19
Xiang, Yunjie. "Towards multifunctional supramolecular copolymers." Thesis, Strasbourg, 2014. http://www.theses.fr/2014STRAF015/document.
Повний текст джерелаАнотація:
Le but de cette thèse était de comprendre l'organisation supramoléculaire et le possible réarrangement dynamique de copolymères supramoléculaires multifonctionnels. Ainsi, nous avons synthétisé diverses molécules présentant un coeur urée ou pérylène fonctionalisé par différentes chaines latérales afin de combiner des propriétés de structuration, de fluorescence et de bioreconnaissance dans une même chaine de polymère supramoléculaire. En combinant différentes techniques de spectroscopie, de diffusion du rayonnement et de microscopie, nous avons montré que des molécules avec un même coeur mais des chaines latérales différentes conduisaient à des nanostructures différentes comme des rubans vrillés, des plaques 20 ou encore des fibres branchées. Enfin, plusieurs unités monomériques avec un même coeur mais des chaines latérales différentes ont été mélangées pour former des copolymères supramoléculaires multifonctionnels. La formation préférentielle d'une nanostructure unique dictée par un des monomères a été démontrée selon un mécanisme de tri dit social ( « social self-sorting » )The goal of this thesis was to understand the supramolecular organization and the possible dynamic rearrangement of multifunctional supramolecular copolymers. To this end, we havedeveloped a series of building blocks based on urea or perylene cores with various lateral side chains for combining structuring, fluorescence, and biorecognition properties in a singlesupramolecular polymer chain. Using a combination of spectroscopy, scattering, and microscopy techniques, we have shown that molecules with a same core but different lateral chains can lead to the formation of various nanostructures su ch as twisted ribbons, 20 plates, or branched fibers. Ultimately, by combining monomeric units with different functional side chains, multifunctional supramolecular copolymers have been obtained. Whereas radiation scattering and imaging techniques were used to demonstrate that one of the monomer can dictate the formation of a preferential nanostructure, optical spectroscopies revealed that the polymerization process of our systems indeed occurs via social self-sorting
20
Sheridan, Matthew Stanley. "Well defined graft copolymers and end functional materials: synthesis, characterization and adhesion studies." Diss., Virginia Tech, 1993. http://hdl.handle.net/10919/40414.
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21
Kynaston, Emily L. "Functional nanomaterials from the crystallisation driven self-assembly of π-conjugated block copolymers". Thesis, University of Bristol, 2015. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.686240.
Повний текст джерелаАнотація:
The work presented in this Thesis focuses on the solution-phase self-assembly behaviour of a series of di- and triblock copolymers with semicrystalline, π-conjugated segments, namely poly(3-alkylthiophene) (P3AT) and poly(3-alkylselenophene) (P3ASe) derivatives. Our group has shown that crystallisation-driven self-assembly (CDSA) of P3AT and P3ASe block copolymers (BCPs) in block-selective solvents allows access to colloidally-stable nanofibers with π-conjugated cores. In this thesis, we demonstrate that the contour length of P3ASe nanofibers can be controlled using a seeded-growth technique. Furthermore, we show that hierarchical nanostructures can be accessed from the coassembly of P3ATs and P3ASes using sequential CDSA. This "bottom-up" methodology could be employed as a facile route to nanomaterials with controlled dimensions, interesting optoelectronic properties and potential applications in polymer-based devices.
22
Huang, Jing. "Functional Polymers Containing Semi-Rigid Alternating Sequences." Diss., Virginia Tech, 2017. http://hdl.handle.net/10919/89884.
Повний текст джерелаАнотація:
Alternating copolymers represent a special class of copolymers in which the two comonomers copolymerize in a regular alternating sequence along the polymer chain. Of particular interest in our group are the stilbene-maleic anhydride/maleimide alternating copolymers. These copolymers possess sterically congested backbones and precisely placed functional groups arising from the strictly alternating copolymerization. The research in this dissertation is focused on the synthesis, characterization, and potential application of functionalized copolymers that contain semi-rigid alternating copolymer sequences.
The fluorescence properties of a series of non-conjugated, tert-butyl carboxylate functionalized alternating copolymers were investigated. Extraordinarily high fluorescent intensity with excellent linearity was observed for the di-tert-butyl group-containing stilbene and maleic anhydride alternating copolymer in THF. We attributed the origin of the strong fluorescence to the “through space” π – π interactions between the phenyl rings from the stilbene and C=O groups from the anhydride. The fluorescence was maintained when the copolymer was deprotected and hydrolyzed and the resulting carboxylic acid-functionalized copolymer was dissolved in water at neutral pH.
The tert-butyl carboxylate functionalized alternating copolymer sequences were incorporated into highly crosslinked polymer networks using suspension polymerization. After removing the tert-butyl groups by acidic hydrolysis, the surface area of the networks increased significantly. Using this facile two-step strategy, we were able to achieve nanoporous polymers with BET surface area up to 817 m2/g and carboxylic acid-functionalized surfaces. The BET surface area of deprotected polymers increased with increasing crosslinking density, and the stilbene-containing polymers showed systematically higher BET surface area than the styrene-containing polymers due to the stiffness of the alternating sequences. The resulting nanoporous polymers have potential to be employed as solid sorbents for CO2.
The same tert-butyl carboxylate functionalized alternating copolymer sequences were also incorporated into microgels via miniemulsion polymerization. The miniemulsion technique ensured the successful synthesis of microgels with ~100 nm diameter using solid stilbene and maleimide monomers. The resulting tert-butyl carboxylate-containing microgels were converted into carboxylic acid-containing aqueous microgels by acid hydrolysis. These aqueous microgels showed good and reversible lead and copper ion adsorption capacities.
Amine-functionalized nanoporous polymers were synthesized by the post-modification of highly-crosslinked divinylbenzene-maleic anhydride polymers. High amine-contents were achieved by covalently attaching multiamines to the acid-chloride functionalized polymer surface. The resulting polymers showed medium to high BET surface areas (up to 500 m2/g) and high CO2 capture capacities.PHD
23
Salunke, Namrata. "Self-Assembly of Functional Amphiphilic Triblock Copolymer Thin Films." University of Akron / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=akron1533137379044442.
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Turgut, Hatice [Verfasser], and C. [Akademischer Betreuer] Barner-Kowollik. "Functional Block Copolymers as Platforms for Patterned Immobilization / Hatice Turgut ; Betreuer: C. Barner-Kowollik." Karlsruhe : KIT-Bibliothek, 2016. http://d-nb.info/1122461593/34.
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Wiss, Kerstin T. [Verfasser]. "Synthetic routes toward functional block copolymers and bioconjugates via RAFT polymerization / Kerstin T. Wiss." Mainz : Universitätsbibliothek Mainz, 2012. http://d-nb.info/1029362890/34.
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Szkudlarek, Marian Verfasser], Martin [Akademischer Betreuer] [Möller, and Andrij [Akademischer Betreuer] Pich. "Functional copolymers of maleic anhydride : synthesis and application / Marian Szkudlarek ; Martin Möller, Andrij Pich." Aachen : Universitätsbibliothek der RWTH Aachen, 2019. http://d-nb.info/1211487644/34.
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Szkudlarek, Marian [Verfasser], Martin [Akademischer Betreuer] Möller, and Andrij [Akademischer Betreuer] Pich. "Functional copolymers of maleic anhydride : synthesis and application / Marian Szkudlarek ; Martin Möller, Andrij Pich." Aachen : Universitätsbibliothek der RWTH Aachen, 2019. http://d-nb.info/1211487644/34.
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Saito, Tomonori. "Synthesis and Characterization of Multiphase Block Copolymers: Influence of Functional Groups on Macromolecular Architecture." Diss., Virginia Tech, 2008. http://hdl.handle.net/10919/27440.
Повний текст джерелаАнотація:
Low molecular weight liquid polybutadienes (1000 â 2000 g/mol) consisting of 60 mol% 1,2-polybutadiene repeating units were synthesized via anionic telomerization and conventional anionic polymerization. Maintaining the initiation and reaction temperature less than 70 °C minimized chain transfer and enabled the telomerization to occur in a living fashion, which resulted in well-controlled molecular weights and narrow polydispersity indices. MALDI-TOF mass spectrometry confirmed that the liquid polybutadienes synthesized via anionic telomerization contained one benzyl end and one protonated end.
Subsequently, 2-ureido-4[1H]-pyrimidone (UPy) quadruple hydrogen-bonding was introduced to telechelic poly(ethylene-co-propylene), and mechanical characterization of the composites with UPy-functionalized carbon nanotubes was performed. The composites enhanced the mechanical properties and the UPy-UPy association between the matrix polymer and carbon nanotubes prevented the decrease of an elongation at break. The matrix polymer was also reinforced without sacrificing the processability. Additionally, UPy groups were introduced to styrene-butadiene rubbers (SBRs). Introducing UPy groups to SBRs drastically changed the physical properties of these materials. Specifically, the SCMHB networks served as mechanically effective crosslinks, which raised Tg and enhanced the mechanical performance of the SBRs.
Novel site-specific sulfonated graft copolymers, poly(methyl methacrylate)-g-(poly(sulfonic acid styrene)-b-poly(tert-butyl styrene)), poly(methyl methacrylate)-g-(poly(tert-butyl styrene)-b-poly(sulfonic acid styrene)), and the corresponding sodium sulfonate salts were successfully synthesized via living anionic polymerization, free radical graft copolymerization, and post-sulfonation strategies. The graft copolymers contained approximately 9 â 10 branches on average and 4 wt% of sulfonic acid or sodium sulfonate blocks adjacent to the backbone or at the branch terminus. The mobility of the sulfonated blocks located at the branch termini enabled the sulfonated blocks to more readily interact and form ionic aggregates. The glass transition temperatures (Tg) of the sulfonated graft copolymers with sulfonated blocks at the branch termini were higher than that of copolymers with sulfonated blocks adjacent to the backbone. More facile aggregation of sulfonated blocks at the branch termini resulted in the appearance of ionomer peaks in SAXS whereas ionomer peaks were not observed in sulfonated graft copolymers with sulfonated blocks adjacent to the backbone.
In addition, similar analogues, novel site-specific sulfonated graft copolymers, poly(methyl methacrylate)-g-(poly(sulfonic acid styrene)-b-poly(ethylene-co-propylene)) (PMMA-g-SPS-b-PEP), poly(methyl methacrylate)-g-(poly(ethylene-co-propylene)-b-poly(sulfonic acid styrene)) (PMMA-g-PEP-b-SPS), and the corresponding sodium sulfonate salts were successfully synthesized. Estimated ï £N values predicted the phase separation of each block and differential scanning calorimetry (DSC) and dynamic mechanical analysis confirmed the phase separation of each block component of the graft copolymers. The aggregation of sulfonic acid or sodium sulfonate groups at the branch termini restricted the glass transition of the PEP block. This lack of the glass transition of the PEP block resulted in higher storage modulus than a sulfonated graft copolymer with sulfonated blocks adjacent to the backbone. The location of sulfonated blocks in both sulfonic acid and sodium sulfonate graft copolymers significantly affected the thermal, mechanical and morphological properties.
Lastly, symmetric (16000 g/mol for each block) and asymmetric (14000 g/mol and 10000 g/mol for each block) poly(ethylene-co-propylene)-b-poly(dimehtylsiloxane) (PEP-b-PDMS) were synthesized using living anionic polymerization and subsequent hydrogenation. The onset of thermal degradation for the PEP-b-PDMS diblock copolymer was higher than 300 ºC and PEP-b-PDMS was more thermally stable than the precursor diblock copolymer, polyisoprene-b-PDMS. DSC analysis of PEP-b-PDMS provided Tg of PDMS -125 ºC, Tg of PEP -60 ºC, Tc of PDMS -90 ºC, and Tm of PDMS -46 and -38 ºC, respectively. Appearance of thermal transitions of each PEP and PDMS block revealed the formation of phase separation. Estimated Ï N also supported the phase separation.Ph. D.
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Schultz, Alison. "From Block Copolymers to Crosslinked Networks: Anionic Polymerization Affords Functional Macromolecules for Advanced Technologies." Diss., Virginia Tech, 2016. http://hdl.handle.net/10919/81835.
Повний текст джерелаАнотація:
Ion-containing macromolecules continue to stimulate new opportunities for emerging electro-active applications ranging from high performance energy devices to water purification membranes. Progress in polymer synthesis and engineering now permit well-defined, ion-containing macromolecules with tunable morphologies, mechanical performance, ion conductivity, and 3D structure in order to address these globally challenged technologies. Achieving tailored chemical compositions with high degrees of phase separation for optimizing conductivity and water adsorption remains a constant synthetic challenge and presents an exciting opportunity for engineering sophisticated macromolecular architectures. This dissertation will introduce unprecedented charged polymers using conventional free radical and anionic polymerization to incorporate ionic functionalities based on phosphonium cations. This new class of copolymers offers unique properties with ionic functionality for tailorable electro-active performance.Ph. D.
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Celebi, Oguzhan. "Synthesis and Characterization of Poly(2-Ethyl-2-Oxazoline) Functional Prepolymers and Block Copolymers." Diss., Virginia Tech, 2014. http://hdl.handle.net/10919/24908.
Повний текст джерелаАнотація:
This dissertation focuses on the synthesis and characterization of functional poly(2-ethyl-2-oxazoline) (PEtOx) containing homo- and block copolymers that are potential materials for membrane-based water purification and gas separation, drug delivery, magnetic resonance imaging and tissue engineering applications.
The polymerization of 2-ethyl-2-oxazoline (EtOx) was investigated with regard to the effects of initiator structures and reaction parameters such as polymerization time and temperature on molecular weight control and molecular weight distribution, endgroup functionality, living characteristics, and mechanism and kinetics. The structure of initiators was shown to significantly affect the molecular weight control and molecular weight distribution of PEtOx oligomers. Methyl triflate initiated polymerizations were found to result in oligomers with low polydispersity (PDI) values around 1.10-1.15 and symmetrical chromatograms were obtained via size exclusion chromatography (SEC) studies with the use of refractive index, light scattering and viscosity detectors. However, EtOx polymerizations initiated by halide containing initiators such as benzyl chloride, dibromo- and diiodo-p-xylene, and vinylsilylpropyl iodides yielded PEtOx oligomers with higher PDI values ~ 1.30-1.40. Higher molecular weight distributions can be attributed to the presence of covalent species during polymerization and slower initiation rate as evidenced by kinetic studies when compared to PEtOx prepared from methyl triflate initiators. In all cases, termination reactions with aliphatic cyclic amines were quantitative. Mono- and diamine functional PEtOx oligomers with controlled molecular weight and excellent end-group functionality may be used as prepolymers for incorporation into multiblock and graft copolymer and crosslinked structures for a variety of applications such as membranes and hydrogels for tissue engineering matrices.
Poly(2-ethyl-2-oxazoline) containing block copolymers were prepared using the macroinitiator method. First, amphiphilic triblock copolymers with hydrophobic poly(arylene ether sulfone) (PSF) central block and hydrophilic PEtOx side blocks were synthesized via polymerization of EtOx sequences from tosylate functional telechelic PSF macroinitiators. PSFs are well-known engineering thermoplastics with excellent resistance to hydrolysis and oxidation, as well as displaying good mechanical properties, thermal stability and toughness. Phenol functional PSFs were prepared via step-growth polymerization of dichlorodiphenylsulfone and bisphenol-A (slight excess) monomers. Phenolic chain ends were then converted to aliphatic hydroxyethyl endgroups by reaction with ethylene carbonate. Upon treatment with p-toluenesulfonyl chloride, tosylate functional PSF macroinitiators were prepared. PEtOx-b-PSF-b-PEtOx triblock copolymers (pendent acyl groups of PEtOx side blocks) were partially hydrolyzed in an acidic medium to introduce random charged poly(ethylene imine) units to prepare ionomer structures that may show good salt rejection, water flux and antibacterial properties for membrane-based water purification applications.
Phosphonic acid modified poly(ethylene oxide)-b-poly(2-ethyl-2-oxazoline) (PEO-b-PEtOx) diblock copolymers were prepared via cationic ring opening polymerization of EtOx monomers from tosylate functional PEO macroinitiators and subsequent functionalization reactions on the polyoxazoline block. Post-modification reactions included controlled partial pendent acyl group hydrolysis under an acidic medium to form the random block copolymers of PEtOx and poly(ethyleneimine) (PEI), Michael addition of diethylvinyl phosphonate groups to PEI units and hydrolysis of the ethyl groups on the phosphonates to yield pendent phosphonic acid groups on the polyoxazoline block. After each step of functionalization reactions, structures and compositions were confirmed utilizing 1H NMR and the degree of phosphorylation was found to be > 95%. Both PEO and PEtOx are biocompatible polymers and the anionic quality of the phosphonic acid has the potential to be pH controllable and provide an environment where cationic drugs and contrast agents can be attached. Thus, these polymers have potential as drug carriers and contrast enhancement agents for magnetic resonance imaging applications.Ph. D.
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Pettau, Robin [Verfasser], and Hans-Werner [Akademischer Betreuer] Schmidt. "Synthesis, Characterization, and Properties of Tailored Functional Block Copolymers / Robin Pettau. Betreuer: Hans-Werner Schmidt." Bayreuth : Universitätsbibliothek Bayreuth, 2011. http://d-nb.info/1018017720/34.
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Wolf, Florian Karsten [Verfasser]. "Poly(lactide): from hyperbranched copolyesters to new block copolymers with functional methacrylates / Florian Karsten Wolf." Mainz : Universitätsbibliothek Mainz, 2014. http://d-nb.info/1047523361/34.
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Gulfam, Muhammad. "Development of functional micelles from biodegradable amphiphilic block copolymers for drug delivery and tumour therapy." Thesis, University of Nottingham, 2017. http://eprints.nottingham.ac.uk/47106/.
Повний текст джерелаАнотація:
Drug delivery systems in the size range of ~ 10-250 nm are enabling tools for site-specific targeting and controlled release applications. To take advantage of these capabilities, various nanocarriers e.g., micelles, dendrimers, liposomes, nanoparticles, nanocapsules, nanotubes, and nanogels, have been designed for drug delivery. Specifically, micelle-based drug carrier systems have emerged as promising tools for site-specific delivery and controlled release applications. Despite several advantages over conventional drugs, some limitations of micelle-based drug delivery have also been reported. These drawbacks include low stability in vivo, poor penetration, modest accumulation in tumour tissues, and inadequate control over drug release. To overcome these limitations, stimuli-responsive or smart polymeric nanocarriers have been developed for drug delivery and tumour therapy, previously. The most well-known internal stimuli in cancerous regions include higher acidity associated with dysregulated metabolism in tumour tissues, elevated levels of glutathione in the cytosol and nucleus of cancer cells, and altered degradative enzymes in the lysosomes, and reactive oxygen species in the mitochondria. These intrinsic microenvironments can be exploited as internal stimuli to attain active drug release in the tumour tissues or cancer cells. In particular, the reducing potential inside the cancer cells is considerably higher than found in the extracellular environment and bloodstream. Such varying redox potential can be exploited for tumour-specific drug delivery and controlled release applications. Various types of redox-responsive micelles have been developed, previously. Generally, redox-responsive micelles have disulfide linkages that undergo rapid cleavage in the presence of reducing agents in the intracellular components, however, are stable at oxidising extracellular environment. The redox-responsive disulfide bridges can be incorporated into nanocarriers by placing multiple disulfide bonds in the hydrophobic backbone or by conjugating therapeutic agents to the side chain of the polymer via a disulfide linker. Another strategy to construct redox-responsive linkages is to crosslink the polymeric nanocarriers with a disulfide crosslinker. Studies have shown that polymeric micelles can dissociate, especially upon administration when they are diluted below their critical micelle concentration. The stability of polymeric micelles can be enhanced by chemical crosslinking. Various types of crosslinked micelles can be prepared subjected to the localisation of the crosslinking, e.g. shell crosslinked micelles, and core crosslinked micelles. Introducing redox-responsive bridges through disulfide crosslinkers may not only provide stability to nano-carriers against dilutions during circulation, but also render them responsive to reducing conditions. Specifically, redox-responsive core-crosslinked micelles have demonstrated good stability and better ‘stealth’ properties, nevertheless, the hydrophobic core of most of the existing core-crosslinked micelles have been based on non-degradable polymers such as polyacrylamide or polyacrylate. The non-degradable constituent of the block copolymer may cause complications in clinical applications. Therefore, reduction-responsive core-crosslinked micelles comprising entirely of biologically inert or biocompatible and biodegradable polymers would be better candidates for drug delivery and controlled release application. To overcome these limitations, micelles based on polyesters (a class of aliphatic biodegradable polymers) can used for drug delivery application. In the last few decades, various FDA approved aliphatic polyesters e.g. poly(lactic-co-glycolic acid) (PLGA), poly(ε-caprolactone), and poly(lactic acid), have been intensively studied to exploit their potential in drug, gene and protein delivery and controlled release applications. Nevertheless, most of these polyesters lack functional groups, making it difficult to incorporate redox-responsive linkages to core-crosslink their micelles. To address these issues, we have synthesised functional biodegradable and biocompatible block copolymers based on methoxypoly(ethyleneglycol)-b-poly(-caprolactone-co--azido--caprolactone) (mPEG-b-poly(CL-co-N3CL)). The pendent chloro groups of the block copolymer were converted into azides using nucleophilic substitution reaction to obtain mPEG-b-poly(CL-co-N3CL) block copolymer as a precursor of reactive polymeric micelles. The synthesised polymers were characterised by NMR, FT-IR and size exclusion chromatography (SEC). Micelles were prepared using the dialysis method and methotrexate (an anticancer drug) was loaded into the hydrophobic core of the reactive micelles. Micelles were subsequently crosslinked by a redox-responsive bis-alkyne ethyl disulfide crosslinker. The size distributions and morphology of core-crosslinked micelles were assessed using dynamic light scattering (DLS) and transmission electron microscopy. The drug release studies were performed under simulated non-reducing and reducing conditions. Cellular uptake studies in human breast cancer cells (MCF7 cells) were performed using Oregon-green loaded core-crosslinked micelles. The MTX-loaded core-crosslinked micelles were assessed for their cytotoxicity in human breast cancer cells by MTT assays. The apoptosis inducing potential of MTX-loaded core-crosslinked micelles was analysed using Hoechst/PI assays and was further probed by annexin-V/PI assays. The data from these studies indicate that drug release from these crosslinked micelles can be controlled and that redox-responsive micelles are more effective carriers for MTX than non-cross-linked analogues in the cell lines tested. In another strategy, a multifunctional amphiphilic block copolymer based on -amine-PEG-b-poly(CL-co-N3CL) was synthesised and subsequently was used to conjugate methotrexate on the hydrophilic block for receptor mediated targeting of breast cancer cells. Cellular uptake studies revealed 2.3-fold higher uptake of MTX-conjugated micelles as compared with un-conjugated micelles. The blank micelles showed low cytotoxicities in breast cancer cells, however, MTX-conjugated micelles exhibited greater antitumor activity in contrast to the free-MTX. We hypothesise that these functional micelles could be potentially powerful nanocarriers for stimuli-responsive controlled release, active tumour targeting, and cancer therapy.
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Roerdink, Monique. "Macromolecule - substrate interactions in directed self-assembly from tailored block copolymers with polyferrocenylsilanes towards functional nanoplatforms /." Enschede : University of Twente [Host], 2007. http://doc.utwente.nl/57869.
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Bowens, Andrea Demetrius. "Synthesis and Characterization of Poly(siloxane imide) Block Copolymers and End-Functional Polyimides for Interphase Applications." Diss., Virginia Tech, 1999. http://hdl.handle.net/10919/29985.
Повний текст джерелаАнотація:
End-functional poly(ether amic acid)s and poly(siloxane imide) multiblock copolymers, comprised of 2,2'-Bis[4-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride (BPADA) / meta-phenylene diamine (MPDA) and hexafluoroisopropylidene-2-bis(phthalic acid anhydride) (6FDA) / meta-phenylene diamine (MPDA) polyimide segments, have been prepared and characterized to explore possibilities for controlling interface properties. Incorporation of polydimethylsiloxane (PDMS) components into polyimide backbone structures can yield advantageous properties such as low energy surfaces and low stress interfaces.
End-functional BPDA/MPDA poly(amic acid) salts and poly(siloxane amic acid) salts were prepared in methanolic or aqueous tripropylamine solutions. The polymeric salts formed stable water solutions (or dispersions) and imidized in less than 10 minutes at 260°C. The water solubility and rapid imidization times are ideal for on-line processing. Thus, these materials can be used as sizing and interface toughening agents for fiber reinforced composite manufacturing. Epoxy-polyimide networks prepared from the amine functionalized polyimide with DER 331 epoxy resin and diamino diphenylsulfone showed microphase separation (100-300 nm inclusions) by transmission electron microscopy. Slight toughening of the cured epoxy with 9 weight % imide was observed with the imide as the included phase. Epoxy bilayer films of polyimide (amine end-functional and commercial Ultem⠢) and poly(siloxane imide) multiblock copolymers were prepared to evaluate the polymer-matrix interphase region. Atomic force microscopy (AFM) analysis of the bilayer films showed diffusion at the interphase for the bilayers prepared with the polyimides and the BPADA/MPDA block copolymers containing polyimide continuous phases.
Poly(siloxane imide) multiblock copolymers comprised of 6FDA/MPDA polyimide structures are ideal candidates for controlling interfacial properties between silicon substrates layered with thin films for microelectronic applications. These high Tg materials offer an approach for obtaining reduced moisture absorption and low stress interfaces. Evaluation of the refractive indices of the block copolymer films showed a decrease with increasing siloxane content thus suggesting the possibility of lower dielectric constants. The polymer-metal interfacial properties were investigated for films cast on titanium and tantalum substrates. The results suggested a correlation between the surface hydroxyl concentration of the metal oxide layer with the interfacial properties of the cast poly(siloxane imide) block copolymer films. The surface hydroxyls were thought to hydrogen bond with the PDMS component of the block copolymer. Since the titanium substrate has a higher surface hydroxyl concentration than the tantalum, higher silicon concentrations were observed.
The melt imidized end-functional polyimides and poly(siloxane imide) block copolymers produced thermally stable materials with 5% weight loss temperatures well above 400°C. However, the block copolymers showed slightly lower 5% weight loss temperatures as a function of siloxane content with a significant increase in char formation. Correlation of the upper glass transition temperatures with the imide segment length was consistent with findings noted for other phase separated randomly segmented block copolymers.
Incorporating PDMS into the polyimide backbone structure has an effect on the bulk and surface properties. The bulk properties of the poly(siloxane imide) block copolymers were characterized using TEM. The morphologies were consistent with classical block copolymers. Surface properties of the block copolymer films as a function of PDMS content were investigated using angular dependent X-ray photoelectron spectroscopy at take-off angles of 15, 30, and 45°. Surface enrichment of PDMS content over that of the bulk was observed at all three sampling depths. Further evidence of this siloxane enrichment in the surface was demonstrated with water contact angle analyses. With as little as 5 weight % PDMS (Ph. D.
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Elsbernd, Cheryl L. Senger. "Synthesis, kinetics and supercritical fluid fractionation studies of functional organosiloxanes and their incorporation into segmented copolymers." Diss., Virginia Polytechnic Institute and State University, 1988. http://hdl.handle.net/10919/74779.
Повний текст джерелаАнотація:
The synthesis of organosiloxanes via equilibration processes is fairly well known, but relatively little is known about the detailed kinetics and mechanisms involved, particularly in the presence of functional endblockers. A major focus of the present study was to investigate aspects of the kinetics of siloxane equilibration polymerizations in the presence of 1,3-bis(3-aminopropyl) tetramethyldisiloxane. Catalysts studied included the commonly used potassium siloxanolate catalyst, as well as the analogous tetramethylammonium and tetrabutylphosphonium siloxanolate catalysts. The reactions of the quaternary ammonium and phosphonium systems were limited to about 80°C due to the known transient nature of those species at elevated temperatures. The rates of disappearance of the cyclic tetramer D₄ and aminopropyl disiloxane were monitored through the use of HPLC and GC techniques. The results indicated that the ammonium and phosphonium catalysts were much more efficient at early incorporation of the aminopropyl disiloxane into the oligomer. By contrast, studies using the potassium siloxanolate catalyst were less effective, even at much higher temperatures such as 160°C. The explanations for this behavior may be related to the higher degree of dissociation and possibly enhanced solubility of the ammonium and phosphonium systems relative to the more studied potassium system. The significance of these results with respect to functional siloxane systems has not been previously appreciated.
Kinetic results indicated that the apparent rates are proportional to the square root of the catalyst concentration, in agreement with earlier studies on the potassium catalyst in nonfunctional siloxane systems. The reaction order with the bulky tetrabutylphosphonium catalyst was slightly higher, again indicating a more dissociated active siloxanolate species. Despite the rate differences, the same equilibrium number average molecular weight was obtained, regardless of catalyst concentration. The effect of catalyst is manifested mainly in the rate at which equilibrium is reached.
Supercritical fluid fractionation studies of the functional siloxanes were demonstrated to be quite feasible. Relatively narrow molecular weight distribution fractions were obtained when compared with polysiloxane standards synthesized via the organolithium initiated polymerization of the cyclic trimer. Excellent agreement was realized between the molecular weight values determined by titration of the amine endgroups and those calculated by GPC.
Additional aspects of this study included the preparation of alkyl-substituted polyarylesters and polyformals, and modification of these materials with polydimethylsiloxanes. Tough transparent films were readily solution cast from these materials, which may have potential use as permselective gas separation membranes. Due to the intentionally short segment lengths, evidence of significant amounts of phase mixing was observed by DSC and TEM.Ph. D.
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Wu, Tianyu. "Synthesis and Characterization of Zwitterion-Containing Acrylic (Block) Copolymers for Emerging Electroactive and Biomedical Applications." Diss., Virginia Tech, 2012. http://hdl.handle.net/10919/39332.
Повний текст джерелаАнотація:
Conventional free radical polymerization of n-butyl acrylate with 3-[[2-(methacryloyloxy)ethyl](dimethyl)-ammonio]-1-propanesulfonate (SBMA) and 2-[butyl(dimethyl)amino]ethyl methacrylate methanesulfonate (BDMAEMA MS), respectively, yielded zwitterionomers and cationomers of comparable chemical structures. Differential scanning calorimetry (DSC), small-angle X-ray scattering (SAXS), and atomic force microscopy (AFM) revealed that zwitterionomers promoted more well-defined microphase-separation than cationic analogs. Dynamic mechanical analyses (DMA) of the copolymers showed a rubbery plateau region due to physical crosslinks between charges for zwitterionomers only. We attributed improved microphase-separation and superior elastomeric performance of the zwitterionomers to stronger association between covalently tethered charged pairs.
Zwitterionomer / ionic liquid binary compositions of poly(nBA-co-SBMA) and 1-ethyl-3-methylimidazolium ethylsulfate (EMIm ES) were prepared using both the 'swelling– and the –cast with– methods. Dynamic mechanical analysis revealed that the 'swollen– membranes maintained their thermomechanical performance with up to 18 wt% EMIm ES incorporation, while that of the –cast with– membranes decreased gradually as the ionic liquid concentration in the composite membranes increased. Small-angle X-ray scattering results indicated that the 'swollen– and the –cast with– membranes have different morphologies, with the ionic liquid distributed more evenly inside the –cast with– membranes. Impedance spectroscopy results showed that the –cast with– membranes had better ionic conductivity than the 'swollen– membrane at high ionic liquid concentration, in agreement with our proposed model. The results indicated that the different processing methods had a significant impact on thermomechanical properties, ionic conductivities, as well as morphologies of the zwitterionomer / ionic liquid binary compositions.
Reversible addition-fragmentation chain transfer polymerization (RAFT) strategy afforded the synthesis of well-defined poly(sty-b-nBA-b-sty). 2-(Dimethylamino)ethyl acrylate (DMAEA), a tertiary amine-containing acrylic monomer, exhibited radical chain transfer tendency toward itself, which is undesirable in controlled radical polymerization processes. We employed a higher [RAFT] : [Initiator] ratio of 20 : 1 to minimize the impact of the chain transfer reactions and yielded high molecular weight poly[sty-b-(nBA-co-DMAEA)-b-sty] with relatively narrow PDIs. The presence of the tertiary amine functionality, as well as their quaternized derivatives, in the central blocks of the triblock copolymers afforded them tunable polarity toward polar guest molecules, such as ionic liquids. Gravimetric measurements determined the swelling capacity of the triblock copolymers for EMIm TfO, an ionic liquid. DSC and DMA results revealed the impact of the ionic liquid on the thermal and thermomechanical properties of the triblock copolymers, respectively. Composite membranes of DMAEA-derived triblock copolymers and EMIm TfO exhibited desirable plateau moduli of ~ 100 MPa, and were hence fabricated into electromechanical transducers.
RAFT synthesized poly(sty-b-nBA-b-sty) triblock copolymer phase separates into long-range ordered morphologies in the solid state due to the incompatibility between the poly(nBA) phases and the poly(sty) phases. The incorporation of DMAEA into the central acrylic blocks enabled subsequent quaternization of the tertiary amines into sulfobetaine functionalities. Both DSC and DMA results suggested that the electrostatic interactions in the low Tg central blocks of poly(sty-b-nBA-b-sty) enhanced block copolymer phase separation. SAXS results indicated that the presence of the sulfobetaine functionalities in acrylate phases increased electron density differences between the phases, and led to better defined scattering profiles. TEM results confirmed that the block copolymers of designed molecular weights exhibited lamellar morphologies, and the lamellar spacing increased with the amount of electrostatic interactions for the zwitterionic triblock copolymers.
Acrylic radicals are more susceptible to radical chain transfer than their styrenic and methacrylic counterparts. Controlled radical polymerization processes (e.g. RAFT, ATRP and NMP) mediate the reactivity of the acrylic radical and enable the synthesis of well-defined linear poly(alkyl acrylate)s. However, functional groups such as tertiary amine and imidazole on acrylic monomers interfere with the controlled radical polymerization of functional acrylates. Model CFR and RAFT polymerization of nBA in the presence of triethylamine and N-methyl imidazole revealed the interference of the functional group on the polymerization of acrylate. Various RAFT agents, RAFT agent to initiator ratios, degree of polymerization and monomer feed concentrations were screened with an imidazole-containing acrylate for optimized RAFT polymerization conditions. The results suggest that the controlled radical polymerization of functional acrylates, such as 2-(dimethylamino)ethyl acrylate and 4-((3-(1H-imidazole-1-yl)propanoyl)oxy)-butyl acrylate (ImPBA), remained challenging.Ph. D.
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Topuz, Fuat [Verfasser], Martin [Akademischer Betreuer] Möller, and Jürgen [Akademischer Betreuer] Groll. "Functional star-type polyethylene glycol copolymers for hydrogels and biohybrid gels / Fuat Topuz ; Martin Möller, Jürgen Groll." Aachen : Universitätsbibliothek der RWTH Aachen, 2015. http://d-nb.info/1127232029/34.
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Mao, Min. "Synthesis and Characterization of Highly Functional Substituted Stilbene Copolymers and Semi-crystalline Poly(aryl ether sulfone)s." Diss., Virginia Tech, 2007. http://hdl.handle.net/10919/29028.
Повний текст джерелаАнотація:
Novel, highly functional rod-like copolymers have been synthesized by alternating copolymerization of N, N, Nâ , Nâ -tetraalkyl-4, 4â -diaminostilbenes (TDAS) with maleic anhydride. Dynamic light scattering, 2H solid state NMR and persistence length measurement reveal high chain rigidity of the polymer backbone. Double quantum heteronuclear local field solid state NMR spectroscopy (2Q-HLF Solid State NMR) has been employed to investigate the chain structure of 13C labelled copolymer. The torsional angle of the H-13C-13C-H part of the anhydride ring was zero degrees, indicating an all cis configuration of the H-13C-13C-H moiety of the anhydride ring.
Rod-coil block copolymers containing rigid polyampholyte blocks were designed and synthesized by addition-fragmentation chain transfer (RAFT) copolymerization. The rigid polyampholytes blocks were formed by hydrolysis of alternating copolymers and the flexible coil block consists of poly(oligo(ethylene glycol) methacrylate). The rod-coil block copolymers form polyion complex (PIC) aggregates even when the polyampholyte blocks are charge imbalanced. The aggregates did not dissociate upon the addition of high concentrations of NaCl unlike the dissociation of flexible polyampholytes in NaCl solution. These unique solution properties are induced by â like-charge attractions' of the rigid polyampholytic alternating copolymer chains.
An example, of what is birefringent to be a novel class of material, has been prepared which enables the control of the birefringence of a polymer film by controlling the rotation of aromatic groups pendant to the polymer backbone.
A linear rigid bisphenol monomer, 4,4â -dihydroxyterphenyl (DHTP), has been incorporated into poly(aryl ether sulfone)s (PAES) in a study to impart crystallization to these amorphous polymers. Three bisphenols, 4, 4â -isopropylidenediphenol, 4, 4â -(hexafluoroisopropylidene)diphenol and 4,4â -dihydroxybiphenyl have been copolymerized with DHTP and dichlorodiphenylsulfone. Only the segmented polysulfone containing 50% BP and 50% DHTP was semi-crystalline. This PAES had a melting temperature (Tm) 320oC in the first heating cycle of a DSC measurement and the presence of crystallites was confirmed by wide angle X-ray diffraction (WAXS).Ph. D.
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El, jundi Ayman. "DEGRADABLE DOUBLE HYDROPHILIC BLOCK COPOLYMERS FOR HEALTH APPLICATIONS." Thesis, Montpellier, 2019. http://www.theses.fr/2019MONTS141.
Повний текст джерелаАнотація:
Les copolymères amphiphiles dégradables à base de poly (éthylène glycol) PEG et de polyesters aliphatiques (poly(ε-caprolactone) (PCL), poly(lactide) (PLA), poly(glycolide) (PGA)) sont largement utilisés dans les applications médicales en raison de leur innocuité et leur acceptation par les autorités de santé. Cependant leur capacité à répondre aux enjeux auxquels sont confrontés les nanomédicaments (ciblage, réponse programmée etc…) est limitée du fait de l’absence de groupes fonctionnels. Pour pallier cette limitation, ce travail de thèse s’intéresse aux voies de modification post-polymérisation de copolymères amphiphiles PEG-b-PCL donnant un accès simple à des familles de copolymères à blocs double hydrophiles (DHBC) dégradables. Nous nous intéressons en particulier à la synthèse de DHBC en trois étapes incluant une étape de photoaddition thiol-yne qui permet à partir d’un même précurseur macromoléculaire la synthèse de familles de DHBC à bloc PEG et blocs PCL fonctionnalisés en chaîne latérale à caractère neutre, cationique ou anionique. Le potentiel de ces DHBC pour la formulation d’actifs au sein de nanosystèmes de libérations pH-répondants est tout d’abord évalué à l’aide d’un anti-cancéreux à large spectre d’activité antitumorale. Dans un second temps, la formulation de micelles de complexes polyioniques tripartites de siRNA pour application en thérapie génique à partir de DHBC anioniques est étudiée. Enfin, la préparation de nanocomplexes DHBC/gadolinium pour imagerie médicale par résonance magnétique nucléaire (IRM) est abordéeBiodegradable amphiphilic copolymers based on poly(ethylene glycol) PEG and aliphatic polyesters (poly(ε-caprolactone) (PCL), poly(lactide) (PLA), poly(glycolide) (PGA)) are widely used in medical applications due to their safety and their acceptance by health authorities. However, their ability to address the challenges faced by the nanomedicines (targeting, programmed response etc…) is limited due to the absence of functional groups. To overcome this limitation, this work focuses on the post-polymerization modification strategies of amphiphilic PEG-b-PCL giving easy access to families of degradable double hydrophilic block copolymers (DHBC). We are particularly interested in the three-step synthesis of DHBC including a thiol-yne photoaddition step which allows, starting from the same macromolecular precursor, the synthesis of DHBC families composed of PEG blocks and side chain functionalized PCL blocks with a neutral, cationic or anionic character. The potential of these DHBC for the formulation of active pharmaceutical ingredients within pH-responsive drug delivery nanosystems is first evaluated using an anti-cancer agent with a broad spectrum of antitumor activity. In another part, we study the formulation of tripartite polyionic complex micelles with an anionic DHBC and siRNA for applications in gene therapy. Finally, the preparation of DHBC/gadolinium nanocomplexes for medical imaging by nuclear magnetic resonance (MRI) is discussed
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McGrath, Nina. "Solvent-free liquid viruses and functional nanostructures from the solution-state self-assembly of polyferrocenylsilane containing block copolymers." Thesis, University of Bristol, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.573151.
Повний текст джерелаАнотація:
Chapter 2 reports the synthesis of liquid viruses by nanoscale engineering of the capsids of cowpea mosaic virus (CPMV) and tobacco mosaic virus (TMV). This was achieved by cationization of the capsid surfaces by EDC-mediated coupling of ethylenediamine to the capsid surfaces followed by electrostatic attachment of an anionic polyethylene glycol-based surfactant. Characterization by transmission electron microscopy (TEM), dynamic light scattering (DLS) and analytical ultracentrifugation (AUC) confirmed the existence of discrete CPMV/polymer surfactant nanoconjugates. Retention of the protein secondary structure was confirmed by Fourier-Transform infrared spectroscopy (FT-IR) and circular dichroism spectroscopy (CD). Rheological investigations were performed on the liquid virus material. A series of infection studies revealed that the modified polymer-surfactant/virus nanoconstruct remained infective to the plant, V. unguiculata. Furthermore, the surfactant-bound conjugates showed solubility in a range of organic solvents as well as increased thermal stability (cf wild-type CPMV). Chapter 3 discusses the preparation of monodisperse conducting polyaniline (PAni) nanofibres using polyferrocenylsilane-b-poly(2-vinyl pyridine) (PFS-b-P2VP) block copolymer micelles as templates. PFS-b-P2VP cylindrical micelles with narrow length distributions (Lw/Ln < 1.04) were prepared using a one-dimensional (1-0) self-seeding procedure. These micelles were subsequently used in the template-directed synthesis of monodisperse leucoemeraldine (LEB) PAni nanofibres with lengths of up to 1200 nm. The LEB-PAni nanofibres were then oxidized and doped to the conductive emeraldine salt (ES) oxidation state. The oxidation states of the PAni nanofibres were determined using ultraviolet-visible (UV - Vis) spectroscopy. Retention of the same lengths and narrow length distributions of the micellar templates throughout the templating and doping processes was confirmed by statistical analysis of the PAni nanofibres lengths from TEM micrographs. Preliminary experiments into the characterization of the conductive properties of the PFS-b-P2VP micellar templates, LEB-PAni nanofibres and ES-PAni nanofibres were carried out by scanning conductance microscopy (SCM).
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Seger, Mark J. "OPTIMIZATION OF THE OPTICAL AND ELECTROCHEMICAL PROPERTIES OF DONOR-ACCEPTOR COPOLYMERS THROUGH FUNCTIONAL GROUP AND SIDE CHAIN MODIFICATION." UKnowledge, 2013. http://uknowledge.uky.edu/chemistry_etds/25.
Повний текст джерелаАнотація:
Donor-acceptor copolymers have received a great deal of attention for application as organic semiconductors, in particular as the active layers in low-cost consumer electronics. The functional groups grafted to the polymer backbones generally dictate the molecular orbital energies of the final materials as well as aid in self-assembly. Additionally, the side chains attached to these functional groups not only dictate the solubility of the final materials, but also their morphological characteristics. The bulk of the research presented in this dissertation focuses on the synthesis and structure-property relationships of polymers containing novel acceptor motifs. Chapter 2 focuses on the synthesis of 1,2-disubstituted cyanoarene monomers as the acceptor motif for copolymerization with known donors. It was found that cyanation of both benzene and thiophene aromatic cores resulted in a decrease of the molecular orbital energy levels. Additionally, the small size of this functional group allowed favorable self-assembly and close π-stacking to occur relative to related acceptor cores carrying alkyl side chains as evidenced by UV-Vis and WAXD data. Chapter 3 describes the systematic variation of side chain branching length and position within a series of phthalimide-based polymers. Branching of the side chains on bithiophene donor units resulted in the expected increase in solubility for these materials. Furthermore, a correlation was found between the branching position, size, and the HOMO energy levels for the polymers. Additionally, it was demonstrated that branching the alkyl side chains in close proximity to polymer backbones does not disrupt conjugation in these systems. A novel acceptor motif based on the 1,3-indanedione unit is presented in Chapter 4. Despite the stronger electron withdrawing capability of this functional group relativeto phthalimide, it was found that polymers based on this unit have the same HOMO molecular orbital energy levels as those presented in Chapter 3. It was found, however, the presence of orthogonal side chains greatly enhanced the solubility of the final polymers. Additionally, UV-Vis and WAXD measurements revealed that thermal annealing had a profound effect on the ordering of these polymers. Despite the presence of orthogonal side chains, long range order and close π-stacking distances were still achieved with these materials. Finally, alkynyl “spacers” were used in Chapter 5 to separate the solubilizing alkyl side chains from the polymer backbones on bithiophene donor monomers. The alkynyl groups allowed for conjugated polymer backbones to be achieved as well as low HOMO energy levels. A correlation between the side chain size, π-stacking distances and HOMO-LUMO energy levels was measured in this polymer series.
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Viswanathan, Kalpana. "Synthesis and Characterization of Novel Polymers for Functional and Stimuli Responsive Silicon Surfaces." Diss., Virginia Tech, 2006. http://hdl.handle.net/10919/27052.
Повний текст джерелаАнотація:
The synthesis of a variety of novel functionalized polymers using living polymerization techniques to achieve functional and stimuli responsive coatings on silica surfaces are described. Since microscopic features on a surface influence the overall wetting properties of the surface, a systematic investigation of the influence of polymer architecture on the microscopic characteristics of the modified surfaces was studied using silane-functionalized linear and novel star-branched polystyrene (PS). Star-branched modifiers provide functional and relatively well-defined model systems for probing surface properties compared to ill-defined highly branched systems and synthetically challenging dendrimers. Using these simple star-shaped macromolecules it was shown that the topographies of the polymer-modified surfaces were indeed influenced by the polymer architecture. A model explaining the observed surface features was proposed.
A living polymerization strategy was also used to synthesize centrally functionalized amphiphilic triblock copolymers. The amphiphilic copolymers exhibited stimuli responsive changes in surface hydrophobicity. In spite of multiple solvent exposures, the copolymer films remained stable on the surface indicating that the observed changes in surface properties were due to selective solvent induced reversible rearrangement of the copolymer blocks. The chemical composition of the copolymers was tailored in order to tune the response time of the surface anchored polymer chains. Thus, the polymer coatings were used to reversibly change the surface polarities in an on-demand fashion and could find possible applications as smart adhesives, sensors and reusable membrane devices.
In contrast to the afore-mentioned covalent modification approach, which often leads to permanent modification of surfaces, renewable surfaces exhibiting â universalâ adhesion properties were also obtained through non-covalent modification. By employing hydrogen bonding interactions between DNA bases, surfaces functionalized with adenine groups were found to reversibly associate with thymine-functionalized polymers. This study describing the solvato-reversible polymer coating was the first demonstration on silica surfaces. A systematic investigation of the influence of surface concentration of the multiple hydrogen bonding groups and their structure on the extent of polymer recognition by the modified surfaces is also discussed.Ph. D.
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Ding, Yi Ph D. Massachusetts Institute of Technology Department of Materials Science and Engineering. "Directed self-assembly of block copolymers with functional materials : a study of nanocomposite thin film fabrication on graphoepitaxial templates." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/113926.
Повний текст джерелаАнотація:
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Materials Science and Engineering, 2017.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 159-169).
Block copolymers (BCPs) are a class of soft materials consisting of two (or more) different chains joint together by covalent bond. This special chemical structure leads to microphase separation and consequently a variety of highly controllable self-assembly patterns. Directed self-assembly (DSA) of BCPs has therefore emerged as one of the most promising technologies to fabricate functional nanostructures and is able to produce patterns with ultra-small resolution (sub-10 nm) while maintaining high throughput and order. However, existing DSA methods depend mostly on carbon or silicon-based BCPs, thus lack functionality for sophisticated applications. This work aims at expanding the capability of DSA techniques by exploring new ways of incorporating functional materials into the BCP matrix and by imposing non-native symmetries on the BCP patterns. First, we focused on constructing nanocomposite thin films composed of BCPs and various types of functional materials (i.e., inorganic ions, inorganic-organic complex, organic compounds and nanoparticles). Based upon this methodology, we developed novel ways of fabricating mesoporous thin film structures with rectangular, triangular and quasicrystalline symmetries by means of graphoepitaxial post array templates. On the other hand, we also examined the limits of DSA by introducing artificial noise to mimic fabrication errors and studied the corresponding responses from BCP. This study demonstrates the potential of DSA of BCP in building thin film nanostructure of unconventional symmetries with functional components.
by Yi Ding.
Ph. D.
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Ibrahim, Saber [Verfasser], Brigitte [Akademischer Betreuer] Voit, and Steffen [Akademischer Betreuer] Kaskel. "Synthesis of Functional Block Copolymers for use in Nano-hybrids / Saber Ibrahim. Gutachter: Brigitte Voit ; Steffen Kaskel. Betreuer: Brigitte Voit." Dresden : Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2011. http://d-nb.info/1067188371/34.
Повний текст джерела
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Mertoglu, Murat. "The synthesis of well-defined functional homo- and block copolymers in aqueous media via Reversible Addition-Fragmentation Chain Transfer (RAFT) Polymerization." Phd thesis, Universität Potsdam, 2004. http://opus.kobv.de/ubp/volltexte/2005/233/.
Повний текст джерелаАнотація:
New chain transfer agents based on dithiobenzoate and trithiocarbonate for free radical polymerization via Reversible Addition-Fragmentation chain Transfer (RAFT) were synthesized. The new compounds bear permanently hydrophilic sulfonate moieties which provide solubility in water independent of the pH. One of them bears a fluorophore, enabling unsymmetrical double end group labelling as well as the preparation of fluorescent labeled polymers. Their stability against hydrolysis in water was studied, and compared with the most frequently employed water-soluble RAFT agent 4-cyano-4-thiobenzoylsulfanylpentanoic acid dithiobenzoate, using UV-Vis and 1H-NMR spectroscopy. An improved resistance to hydrolysis was found for the new RAFT agents, providing good stabilities in the pH range between 1 and 8, and up to temperatures of 70°C. Subsequently, a series of non-ionic, anionic and cationic water-soluble monomers were polymerized via RAFT in water. In these experiments, polymerizations were conducted either at 48°C or 55°C, that are lower than the conventionally employed temperatures (>60°C) for RAFT in organic solvents, in order to minimize hydrolysis of the active chain ends (e.g. dithioester and trithiocarbonate), and thus to obtain good control over the polymerization. Under these conditions, controlled polymerization in aqueous solution was possible with styrenic, acrylic and methacrylic monomers: molar masses increase with conversion, polydispersities are low, and the degree of end group functionalization is high. But polymerizations of methacrylamides were slow at temperatures below 60°C, and showed only moderate control. The RAFT process in water was also proved to be a powerful method to synthesize di- and triblock copolymers including the preparation of functional polymers with complex structure, such as amphiphilic and stimuli-sensitive block copolymers. These include polymers containing one or even two stimuli-sensitive hydrophilic blocks. The hydrophilic character of a single or of several blocks was switched by changing the pH, the temperature or the salt content, to demonstrate the variability of the molecular designs suited for stimuli-sensitive polymeric amphiphiles, and to exemplify the concept of multiple-sensitive systems. Furthermore, stable colloidal block ionomer complexes were prepared by mixing anionic surfactants in aqueous media with a double hydrophilic block copolymer synthesized via RAFT in water. The block copolymer is composed of a noncharged hydrophilic block based on polyethyleneglycol and a cationic block. The complexes prepared with perfluoro decanoate were found so stable that they even withstand dialysis; notably they do not denaturate proteins. So, they are potentially useful for biomedical applications in vivo.Ziel der vorliegenden Arbeit war es, neue Kettenübertragungs Agenzien, basierend auf Dithiobenzoat- und Trithiocarbonatderivaten zu synthetisieren, welche in der "Reversiblen Additions-Fragmentierungs Kettenübertragungs-Polymerisation" (RAFT) eingesetzt werden können. Die neu synthetisierten Verbindungen zeichnen sich durch permanent hydrophile Sulfonatgruppen aus, welche eine pH-unabhängige Löslichkeit in Wasser ermöglichen. Eine dieser Verbindungen trägt ein Fluorophore, wodurch eine asymmetrische doppelte Endgruppenmarkierung sowie die Herstellung von Fluoreszenzmarkierten Polymeren möglich ist. Die Hydrolysestabilität dieser Verbindungen in wässriger Lösung im Vergleich mit dem z. Zeit bekanntesten wasserlöslichen RAFT Agenz (4-Cyano-4-thiobenzoylsulfanylpentansäuredithiobenzoate) wurde unter Anwendung spektroskopischer Methoden (UV-Vis, 1H-NMR) untersucht. Dabei wurde festgestellt, dass diese neue Verbindungen deutlich bessere Hydrolysestabiltäten im pH-Bereich von 1-8 und bis zu einer Temperatur von 70°C besitzen. Die neuen RAFT-Verbindungen wurden ebenfalls bezgl. Ihrer Eignung in der Polymerisation von wasserlöslichen nichtionischen, anionischen und kationischen Monomeren in wässrigem Medium bei 48°C und 55°C getestet. Unter diesen Bedingungen konnten Vinylverbindungen wie z. B. Styrenderivate. Acrylate und Methacrylate kontrolliert polymerisiert werden: Die Molmasse stieg mit dem Umsatz, die Polydispersitäten waren niedrig und die isolierten Polymere zeigten Grad an Endgruppenfunktionalität. Bei der Polymerisation von Methacrylamiden wurde bei Polymerisationstemperaturen unter 60°C nur eine mäßige Kontrolle gefunden.
Es konnte weiterhin die RAFT Polymerisation in Wasser als leistungsstarke Methode zur Herstellung definierter Di- und Triblockcopolymere, einschließlich der Synthese von funktionalen Polymeren mit komplexer Struktur – beispielsweise amphiphiler- und schaltbare (stimuli responsive) Blockcopolymere entwickelt werden. Dies beinhaltet auch Polymere, die einen oder zwei schaltbare hydrophile Polymerblöcke enthalten. Der hydrophile Eigenschaft eines oder mehrer Blöcke kann durch äußere Reize wie pH-Änderung, Temperatur oder Salzgehalt geändert werden. Diese Beispiele demonstrierten die Variabilität des für schaltbare Polyamphiphile notwendigen Designs und zeigten exemplarisch das Konzept für multi-sensitive Systeme.
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Christmann, Sarah [Verfasser]. "Synthesis of functional amphiphilic block copolymers as stabilizer for various nanocarriers and further surface functionalization to change protein interactions / Sarah Christmann." Mainz : Universitätsbibliothek Mainz, 2017. http://d-nb.info/1131115260/34.
Повний текст джерела
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Mertoğlu, Murat. "The synthesis of well defined functional homo- and block copolymers in aqueous media via Reversible Addition Fragmentation Chain Transfer (RAFT) Polymerization." [S.l. : s.n.], 2005. http://deposit.ddb.de/cgi-bin/dokserv?idn=974309133.
Повний текст джерела
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Hörenz, Christoph [Verfasser], Felix [Gutachter] Schacher, and Andrea [Gutachter] Balducci. "Amphiphilic (Block) Copolymers with Crosslinkable Moieties : from Functional Building Blocks to Nanostructured Materials / Christoph Hörenz ; Gutachter: Felix H. Schacher, Andrea Balducci." Jena : Friedrich-Schiller-Universität Jena, 2017. http://d-nb.info/1177833700/34.
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Erothu, Harikrishna. "Synthesis and photovoltaic applications of novel copolymers based on poly(3-hexylthiophene)." Thesis, Bordeaux 1, 2011. http://www.theses.fr/2011BOR14227/document.
Повний текст джерелаАнотація:
Dans cette étude, des copolymères à blocs rigide-flexible comprenant des segments donneur [poly(3-hexylthiophène) régiorégulier, (rr-P3HT)] et accepteurs d’électrons (C60) ont été synthétisés. L’auto-assemblage en masse de ces copolymères à blocs avait pour objectif d’atteindre des morphologies dont la taille des domaines coïncide avec la distance idéale de transport de l’exciton (~10 nm) en vue d’utiliser ces systèmes comme matériaux de couche active dans les cellules photovoltaïques organiques de type P3HT-PCBM.La maîtrise et l'optimisation des conditions de synthèse de rr-P3HT de fonctionnalité terminale bien définie nous ont permis d'accéder à différentes architectures de copolymères linéaires di- et triblocs, constitués de P3HT comme bloc rigide et de polystyrène ou poly(4-vinylpyridine) comme bloc ‘flexible’. La fonctionnalisation du bloc flexible avec des dérivés du fullerène (C60 ou PCBM) a ensuite été réalisée et ces copolymères utilisés comme additifs pour stabiliser la morphologie de la couche active des cellules solaires organiques de type P3HT/PCBM. Les caractéristiques photovoltaïques des matériaux ainsi préparés ont été déterminées et corrélées aux analyses morphologiques de la couche activeThe performance of organic photovoltaic cells mainly depends on the active layer nano-morphology. Rod-coil block copolymers (BCPs) are well known in their ability to self-assemble into well-ordered nanoscopic morphologies. BCPs containing electron-donor and acceptor segments are of particular interest for use in photovoltaic cells because electronic light-excited states exist over distances similar to the typical size of block copolymer domains (~10 nm). Therefore, we designed novel donor-acceptor BCPs to exploit this coincidence in dimensions. This thesis is focused on BCPs based on regioregular poly(3-hexylthiophene) (rr-P3HT) due to its high hole mobility and good processibility from various solvents. Simplified and versatile syntheses of donor-acceptor rod-coil di- and tri- BCPs consisting of the donor block P3HT (rod) and polystyrene or poly(4-vinylpyridine) (coil) blocks to carry the acceptor C60 in different ways were developed. These materials were used as surfactants to stabilize the nano-morphology of reference P3HT: [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) based devices. Photovoltaic characterizations were then tied to copolymer structural data with the help of AFM and a range of complementary characterization techniques