Miktoarm polymers, a relatively new and unique class of macromolecules, constitute a topical area of research due to their intriguing properties which can be tailored by varying their polymeric arms. Much emphasis has been placed in the recent past in developing synthetic methodologies to these star polymers, and examining their self-assembly behavior in solution. In this thesis, a simple and highly versatile synthetic methodology to ABC type miktoarm star polymers is developed using a combination of highly efficient Cu(I) catalyzed cycloaddition between an alkyne and azide, and ring opening polymerization. To carry out these reactions in sequence, a molecular building block with three orthogonal functionalities was first designed. The two alkynes on this trifunctional core were deprotected sequentially, and coupled with azide terminated poly(ethylene glycol) (PEG) and polystyrene (PS) respectively, using "click" chemistry. It was then followed by ring-opening polymerization of caprolactone at the third reactive centre of the building block. Using this methodology, a library of miktoarm polymers were prepared and characterized using a variety of techniques including 1H and 13C{1H} NMR and gel permeation chromatography. Aqueous self-assembly of these star polymers was examined using dynamic light scattering (DLS) and transmission electron microscopy (TEM). These miktoarm polymers form spherical micelles which were found to be stable over time, and an inverse relationship between the size of poly(ethylene glycol) and the hydrodynamic diameter of the micelles was observed. The sizes from DLS correlated well to those obtained from TEM which showed the presence of spherical micelles composed of a mixed PS and PCL core, with a PEG corona. The miktoarm polymer (PEG775-PS2700-PCL6900) showed a mixture of micelles and worm-like structures resembling a pearl necklace. The ability of miktoarm polymers to encapsulate small molecules was evaluated using disperse red 1, and / Les polymères de type « miktoarm », une relativement nouvelle et unique classe de macromolecules, constituent un domaine de recherche d'actualité étant donné leur propriétés intrigantes qui peuvent être adaptées en faisant varier leurs bras polymériques. L'emphase a récemment été mis sur le développement de méthodologies synthétiques pour la formation de ces polymères en forme d'étoile, et sur l'étude de leur comportement d'auto-assemblage en solution. Dans cette thèse, une méthodologie simple et hautement versatile pour la formation de polymères en forme d'étoile « miktoarm » de type ABC a été développée en faisant usage d'une combinaison de la très efficace réaction de cycloaddition entre un alcyne et un azide catalysée par le Cu(I), et de la polymérisation par ouverture de cycle. Pour effectuer ces réactions en séquence, un coeur comprenant trois fonctionalités orthogonales a été conçu. Les deux alcynes de ce cœur trifonctionnel ont été déprotégés en séquence, et couplés avec un azidure de poly(éthylène glycol) (PEG) et de polystyrène (PS), respectivement, en faisant usage de la chimie « click ». La réaction de polymérisation du caprolactone (CL) par ouverture de cycle a ensuite été effectuée au troisième centre réactif de ce coeur. En faisant usage de cette méthodologie, une librairie de polymères « miktoarm » a été préparée et caractérisée en utilisant une variété de techniques incluant la RMN de 1H et de 13C{1H} ainsi que la chromatographie sur gel perméable. L'auto-assemblage aqueux de ces polymères en forme d'étoile a été examiné en utilisant la diffusion dynamique de la lumière (« DLS ») et la microscopie électronique en transmission (« TEM »). Ces polymères « miktoarm » forment des micelles sphériques qui se sont avérées stables avec le temps, et une relation inverse entre la taille du poly(éthylène glycol) et le diamètre hydrodynamique des micelles a été obs

Biomolecule detection assay applications range from diagnostics and pathogen detection, to the design of targeted medical care and drug development. A current limitation of this approach lies in the inherently small quantity of the analytes being detected. Therefore, a method to efficiently amplify either the analyte or the detection signal is necessary. We report a signal amplification approach that relies on self-assembled polymeric nanospheres, containing a large number of luminescent transition metal centers in their core and a biological recognition unit on their periphery. Initially, block copolymers containing a hydrophobic ruthenium bipyridine block, a hydrophilic PEG block, and a biotin biological recognition block were synthesized. Self-assembly of these copolymers in water, results in nanospheres that can be tethered to a target analyte using the biotin-streptavidin interaction. The ability to tether such a large number of metallic centers to each analyte provides a simple approach to signal amplification through luminescence. / Les analyses de détection biomoléculaire ont des applications qui s'étendent du diagnostic et de la détection de microbes pathogènes, à la conception de soins médicaux spécifiques et au développement de nouveaux médicaments. Une limitation actuelle de cette approche repose sur le fait que les analytes à détecter sont présentes qu'en faibles quantités. Par conséquent, une méthode efficace d'amplification de l'analyte ou du signal de détection est nécessaire. Nous présentons ici une approche d'amplification du signal qui se fonde sur les nanosphères polymères auto-assemblés, contenant dans leur noyau un grand nombre de centres luminescents basé sur des métaux de transition, et, sur leur périphérie, une unité biologique pour la reconnaissance. Tout d'abord, les copolymères à bloc contenant un bloc hydrophobe de bipyridine de ruthénium, un bloc hydrophile de PEG, et un bloc d'identification biologique de biotine, ont été synthétisés. L'auto-assemblage de ces copolymères dans l'eau donne lieu à la formation des nanosphères qui peuvent être attachés à un analyte cible en utilisant l'interaction entre la biotine et la streptavidin. La capacité d'attacher un si grand nombre de centres métalliques à chaque analyte fournit une méthode simple d'amplification du signal par la luminescence.

The aim of this study was to explore the effects of a range of variables on the properties of ionomers, and also to investigate the structure-morphology-property relationships in these materials in order to advance our understanding in the light of the EHM model. In the first part of the work, the influence of variables such as sample preparation conditions, molecular weight and degree of neutralization on the dynamic mechanical properties of ionomers were studied. / In the second part, the effects of surfactant addition and chemical structure of ionomers were investigated. Sodium sulfonated polystyrene ionomers were mixed with the surfactant sodium p-dodecylbenzene sulfonate. This surfactant molecule has a head group identical to the ionic group of the polymer chain. Therefore, the head group resides in the multiplets, and tail group in the restricted mobility region surrounding the multiples. This results in a dramatic decrease in the cluster $T sb{ rm g}$ as a function of the amount of added surfactant. In the next project, the contact surface area of the chain and its effect on multiplet size was studied. An inverse relationship between contact surface area and size of multiplet was found; if the size of multiplet is decreased, the cluster $T sb{ rm g}$ increases and the ionic plateau is also higher and longer. Furthermore, when the pendant group of the polymer is replaced by a bulkier group, the chain becomes stiffer. As a result, the two $T sb{ rm g}$s shift to higher temperatures. In still another part of the study, the dynamic mechanical properties of poly(styrene-co-sodium methacrylate) ionomers were re-investigated in detail. Discontinuities in the plots of various parameters obtained from the tan $ delta$ vs temperature and modulus vs temperature curves as a function of the ion contents were found. These discontinuities suggest that there are two morphological changes in the system as a function of the ion contents, one at ca. 4-6 and the other at ca. 12-14 mol % of ions. In addition, the data were interpreted using filler and percolation concepts. The Guth equation for modulus vs filler content is applicable up to 30 volume % of the clusters. The Halpin-Tsai equation for the regular system is also applicable at low ion contents. For the percolation approach, the percolation threshold was found at 5.4 mol % of ions. The critical exponent and critical volume fraction of clusters were found to be 1.31 and 0.64, respe

New classes of monomers containing heterocyclic groups have been prepared in good yield from readily available compounds. The heterocyclic groups were phthalazinone, quirnazolinone, benzopyrenequinone and acridone. / Bisphthalazinones, such as oxy-7-bis(1,2-dihydro-4-phenylphthalazinone) were reacted with a series of activated aryl halides to give high molecular weight novel poly(phthalazinone)s in a one-step reaction involving the formation of a N-C bond. / A series of novel quinazolinone containing monomers synthesized for nucleophilic aromatic displacement polymerization reactions, bisphenols and activated difluorides, were unstable under the polymerization conditions. Only low molecular weight oligomers were formed. / Two new quinazolinone diamines, oxy-bis(1,4-phenylene)-bis[3-(4-aminophenyl)-1-oxo-quinazolin-2-yl] and 2-(4-aminophenyl)-3-amino-4-quinazolinone were synthesized. They did not form high molecular weight polyimides because of low reactivity or instability of the monomers. A series of high molecular weight polyimides were synthesized from 2-(4-aminophenyl)-16-amino-4-quinazolinone either by one-step solution polymerization or two-step low temperature solution polymerization followed by thermal cyclodehydration. / The new monomer, 1,5-bis(4-fluorobenzoyl)naphthalene, was polymerized with a series of bisphenols to form high molecular weight poly(arylene ether)s containing the 1,5-dibenzoyl unit. / 1,5-bis(4-fluorobenzoyl)naphthalene was converted to 2,3;7,8-bis(4-fluorobenzoyl)pyrene-1,6-quinone by a Scholl reaction using antimony pentafluoride. It was reacted with bisphenols, however because of side reactions only crosslinked insoluble material formed. / A series of novel acridone containing monomers, such as N-benzyl-3-chloro-6-fluoroacridone were synthesized for nucleophilic aromatic displacement polymerization reactions. High molecular weight poly(arylene ether)s containing the acridone, moiety could not be obtained because of instability or low reactivity of the monomers. Model reactions on acridone derivatives were carried out. The fluorine at the 3-position on acridone can be displaced by phenolate anion quantitatively. New acridone monomers which can be synthesized using this reaction were proposed. / All the high molecular weight novel polymers synthesized have very high glass transition temperatures and excellent thermal stabilities. Films made from the polymers had high moduli and maintained the high moduli to high temperatures.

A series of novel biphenols and activated aromatic difluorides of general structure 1 and 2, respectively, were prepared employing readily available starting materials and reagents. These monomers were subsequently polymerized by nucleophilic aromatic substitution using anhydrous potassium carbonate as base in a dipolar aprotic solvent (equation 1)* to afford a series of high molecular weight (inherent viscosity = 0.5-1.24 dl/g) poly(aryl ether)s of the type 3 which exhibit high glass transition temperatures (160-314$ sp circ$C) and exceptional thermo-oxidative stability ($-$10% weight loss in the range 500-560$ sp circ$C). Most of these materials are readily soluble in common organic solvents such as methylene chloride and chloroform, allowing for facile solution processing to afford tough and flexible films. We also synthesized polymers from aromatic difluorides 2 which contain a moiety Y which can be cross-linked thermally. The resulting poly(aryl ether)s can be rendered solvent-resistant by heating. (Abstract shortened by UMI.) ftn*Please refer to dissertation for diagram.

Cascade poly(aryl ether) containing aryl sulfide or aryl sulfone groups, and aryl fluoride terminal functionality, were synthesized. Four generations of the dendrimers were prepared. The divergent initiator core method was employed, using 4,4$ sp prime$-difluorodiphenyl sulfone, as the core precursor, and a relatively high molecular weight phenol as the monomer. The strategy is based on an activation/condensation sequence that involves oxidation of the aryl sulfide group and the displacement of the activated aryl halide moiety by a phenolate ion. The aryl halide was activated by a sulfone group formed by oxidation of a sulfide group. / Optimum conditions for the condensation reaction utilized a very active metal carbonate, such as cesium carbonate, in conjunction with magnesium hydroxide or calcium carbonate which removes some of the fluoride ions formed. The phenolate was generated in situ from an organic carbonate, thus eliminating the usual dehydration step. NMR characterization indicated that the reactions were most quantitative and MALDI-TOF-MS confirmed those results up to the third generation. No reaction intermediates were detected. Imperfections in some molecules of the dendrimers, formed by reaction of the core precursors with an impurity present in the phenol, were also identified. / Simultaneously, aryl halide-terminated and phenol-terminated hyperbranched poly(ether sulfone)s were prepared by the polycondensation of A$ sb2$B monomers via a one-pot approach. Syntheses were developed for all the new monomers required. The main advantage of this method is its simplicity, which allows rapid access to large amounts of hyperbranched polymers. Molecular weights and viscosities were controlled by the concentration of the monomer and temperature of the reaction. The best conditions were obtained when the condensation agent was a mixture of $ rm Cs sb2CO sb3$ and Mg(OH)$ sb2$ and the displaced halide was a fluoride.

The miscibility of poly(vinyl pyrrolidone) PVP with copolymers of vinyl butyral and vinyl alcohol, containing 11% and 19% by weight of vinyl alcohol, has been investigated. To examine how the state of miscibility of these blends varies with the vinyl alcohol content of the copolymers, differential scanning calorimetry(DSC) and solid-state NMR methods were employed. PVP was found to form miscible blends with poly(vinyl butyral) PVB, containing 11wt% of vinyl alcohol, up to a weight ratio of 40/60(PVP/PVB11). At higher PVP loading, phase separated blends were obtained. In contrast, poly(vinyl butyral) containing 19wt% vinyl alcohol units was found to be miscible with PVP, over the entire composition range, with an estimated domain size of 2.5nm. Taken together, the results indicate the importance of the number of hydroxyl groups in achieving miscibility.

The synthesis, characterization and an evaluation of the physical properties including infrared, UV-Vis absorption and fluorescence spectra, quantum yields and thermal stability of a variety of 2,5- and 2,6-diethynylypyridine based organic and Pt(II)-$ sigma$-acetylide monomers, oligomers and polymers, are reported. Quaternization of the pyridine-nitrogen in these compounds via solution nucleophilic substitution reactions with methyl iodide and methyl triflate yield stable pyridinium analogs. The introduction of positive charge into the backbone by this simple solution chemistry has a significant effect on the $ pi$-electron delocalization. For example, quaternization of the pyridine-nitrogen is accompanied by strong red-shifts in the UV-Vis absorption spectra. The latter is indicative of enhanced $ pi$-electron delocalization along the backbone upon quaternization. These compounds exhibit strong fluorescence, with quantum yields of 0.015 to 0.058 for the monomers, and 0.060 to 0.223 for the polymers. Quaternization is also observed to enhance fluorescence intensities and quantum efficiencies. These polymers are insulators in the ground state, however, upon doping with iodine exhibit semiconducting behavior. The $ pi$-electron delocalization is maintained through Pt(II) centers in the organometallic polymers, and similar effects of quaternization are observed in these highly soluble polymers.

This dissertation describes the characterization of polystyrene- b-poly(acrylic acid) (PS-b-PAA) copolymer micelles by nuclear magnetic resonance spectroscopy (NMR). The segmental chain dynamics of the polystyrene-b-poly(acrylic acid) copolymer during the micellization process was investigated by solution-state proton NMR measurements. The spin-lattice and spin-spin relaxation parameters revealed the increased motional restriction of the PS blocks of the PS-b-PAA copolymer as aggregation was induced. The mobility of the PAA segments also decreased during the micellization process. However, the PAA blocks experienced greater motional freedom than the PS component forming the aggregate core. / 129Xenon NMR spectroscopy was used to determine the glass transition temperature of the PS core of the polystyrene-b-poly(acrylic acid) copolymer aggregates in dioxane/water mixtures. The temperature dependence of the NMR line shapes and resonance shifts of xenon in the PS and solvent phases of the PS-b-PAA copolymer micelles was analyzed. Discontinuities in the slope of the chemical shift-temperature curves for xenon sorbed in the PS component revealed phase transitions in the copolymer micelles. The PS core of the phase separated PS100-b-PAA 25 copolymer aggregates underwent the glass transition in the temperature region of 40°C to 45°C. The glass transition temperature of the PS core of PS218-b-PAA20 copolymer aggregates suspended in solution was in the 33°C to 35°C temperature region.

The colloidal properties of AS diblock copolymers, and the dynamic mechanical properties of ABA triblock copolymers of polystyrene (B) and poly(methacrylic add) or poly(sodium, methacrylate) (A) were investigated. In solvents which are selectively good for the B block, the diblock copolymers form very stable micellelike aggregates which were characterized by size-exclusion chromatography, dynamic light scattering, and viscometry. This micellar system showed no apparent dissociation-associafion equilibrium within the time scale of a few days. The hydrodynamic radii of the micelles increased with the length of both the A and B blocks. The aggregation numbers were determined primarily by the length of the A block and increased with it. For the triblock copolymers, the dynamic mechanical analyses showed the presence of two glass transition temperatures (Tg) associated with microdomains of A and of B. For the neutralised materials, the Tg of the A microdomains increased with the length of the A block. The height of the rubbery plateau located between the T g's increased with the length of the A block.