The research presented focused on the synthesis and the characterization of graft polymers, of interest either as model systems or for large-scale applications. The materials selected as substrates for grafting reactions were carbosilane dendrimers, linear and branched polystyrenes, and cross-linked polystyrene latex particles. The synthesis of dendrimer-arborescent polymer hybrids was thus achieved by derivatization of the carbosilane dendrimers with dichlorosilane moieties and coupling with 1,4-polybutadiene side chains with Mn ≈ 1000. A second derivatization and coupling reaction with Mn ≈ 1500, 5000, or 30000 side chains yielded hybrid polymers with narrow molecular weight distributions (Mw/Mn ≤ 1.16). In the second part of the thesis, a procedure for the large-scale (100-g) synthesis of arborescent styrene homopolymers and copolymers incorporating poly(2-vinylpyridine) segments is presented. End-capping of the polystyryllithium chains with 1,1-diphenylethylene in the presence of LiCl, followed by the addition of 3 – 6 equivalents of 2-vinylpyridine per side chain, eliminated side reactions and led to grafting yields of up to 95 %. A systematic investigation of the solution properties of polyelectrolytes obtained by protonation of the poly(2-vinylpyridine) arborescent copolymers with a strong acid (trifluoroacetic acid) is also presented. The relative importance of the electrostatic repulsion and the elastic deformation forces on molecular expansion was investigated by examining the solution properties of the copolymers as a function of structure, protonation level, and the presence of salts in polar solvents (methanol, DMF, H2O). The viscosity of the arborescent copolymer solutions was also found to be much lower than for linear P2VP samples under the same conditions. In the last part of the thesis, the synthesis of model filler particles was achieved by grafting polyisoprene chains onto cross-linked polystyrene latex particles derivatized with acetyl coupling sites. These substrates, which can be viewed as an extreme case of a dense (hard-sphere) arborescent polymer structure, were used to investigate the influence of filler-matrix polymer interactions on the rheological behavior of filled polyisoprene samples. The influence of the filler structure on the rheological behavior of the blends was examined by dynamic mechanical analysis in terms of frequency-dependent complex viscosity, storage modulus, and damping factor. All the blends exhibited enhanced complex viscosity, storage modulus, and decreased damping factor values relative to the matrix polymer.

The research presented focused on the synthesis and the characterization of graft polymers, of interest either as model systems or for large-scale applications. The materials selected as substrates for grafting reactions were carbosilane dendrimers, linear and branched polystyrenes, and cross-linked polystyrene latex particles. The synthesis of dendrimer-arborescent polymer hybrids was thus achieved by derivatization of the carbosilane dendrimers with dichlorosilane moieties and coupling with 1,4-polybutadiene side chains with Mn ≈ 1000. A second derivatization and coupling reaction with Mn ≈ 1500, 5000, or 30000 side chains yielded hybrid polymers with narrow molecular weight distributions (Mw/Mn ≤ 1.16). In the second part of the thesis, a procedure for the large-scale (100-g) synthesis of arborescent styrene homopolymers and copolymers incorporating poly(2-vinylpyridine) segments is presented. End-capping of the polystyryllithium chains with 1,1-diphenylethylene in the presence of LiCl, followed by the addition of 3 – 6 equivalents of 2-vinylpyridine per side chain, eliminated side reactions and led to grafting yields of up to 95 %. A systematic investigation of the solution properties of polyelectrolytes obtained by protonation of the poly(2-vinylpyridine) arborescent copolymers with a strong acid (trifluoroacetic acid) is also presented. The relative importance of the electrostatic repulsion and the elastic deformation forces on molecular expansion was investigated by examining the solution properties of the copolymers as a function of structure, protonation level, and the presence of salts in polar solvents (methanol, DMF, H2O). The viscosity of the arborescent copolymer solutions was also found to be much lower than for linear P2VP samples under the same conditions. In the last part of the thesis, the synthesis of model filler particles was achieved by grafting polyisoprene chains onto cross-linked polystyrene latex particles derivatized with acetyl coupling sites. These substrates, which can be viewed as an extreme case of a dense (hard-sphere) arborescent polymer structure, were used to investigate the influence of filler-matrix polymer interactions on the rheological behavior of filled polyisoprene samples. The influence of the filler structure on the rheological behavior of the blends was examined by dynamic mechanical analysis in terms of frequency-dependent complex viscosity, storage modulus, and damping factor. All the blends exhibited enhanced complex viscosity, storage modulus, and decreased damping factor values relative to the matrix polymer.

No description available.

A new method for enhancing rates of enzymatic hydrolysis for cellulosic fiber is presented. By adding a cationic polyelectrolyte to a cellulase/cellulose hydrolytic system, the polyelectrolyte binds to the cellulase and fiber forming flocs. The cellulase is bound by a patching mechanism. By using this technique, the rate of enzymatic hydrolysis can be enhanced. This thesis covered observations made about the cellulase/cationic polyelectrolyte/fiber interactions. A mechanism was proposed based on the experimental results.

Les polyélectrolytes sont une classe importante de polymères qui ont été étudiés durant plus de 3 décennies. Le domaine des polyélectrolytes subit actuellement une étonnante explosion d'activité dans plusieurs champs scientifique: chimie, biologie, médecine, physique, nanomatériaux, nanotechnologies L'intérêt particulier montré aux polyélectrolytes est dû non seulement au besoin d'une meilleure compréhension de leur comportement, mais aussi à leurs applications commerciales potentielles.<br />La solubilité dans l'eau est la propriété la plus importante des polyélectrolytes, ce qui nous permet d'obtenir des dérivés multifonctionnels avec une toxicité réduite, respectueux de l'environnement et à bas prix. Une des applications nouvelles et prometteuses des polyélectrolytes est l'auto-assemblage électrostatique pour la formation de films minces multicouches avec une vaste gamme de propriétés électriques, magnétiques et optiques. En réponse à la demande en croissance de dispositifs électroniques respectueux de l'environnement, nous avons conçu, synthétisé et caractérisé de nouveaux copolymères hydrosolubles à chromophore pendant a base d'anhydride maléique. Ces dérivées solubles dans l'eau peuvent s'auto-organiser à partir d'une solution en films multicouches. L'utilisation des copolymères d'anhydride maléique est attirante par la variabilité de leurs propriétés réalisées par l'introduction de comonomères différents.<br />D'autre part, ces copolymères contiennent l'unité réactive anhydride, qui offre des possibilités pour la modification chimique ultérieure du polymère, dans des conditions douces (températures basses, sans catalyseur). Les réactifs nucléophilies utilisés pour la fonctionnalisation étaient: Disperse Red 1, 3-amino-ethyl-carbazole, 9-ethanol-9 carbazole, 1-aminopyrene, 2-(4-aminophenyl)-5-(4-biphenylyl)-1,3,4-oxadiazole, 1-aminohexane, 4-aminoazobenzene, 4-nitroaniline and [6,6]-C61-bismethanoic acid ethyl ester 6-hydroxyhexyl ester.<br />Ces réactions ont un grand intérêt parce que l'ouverture de l'anneau d'anhydride fait apparaître un groupe carboxylique permettant l'hydrosolubilité ou l'hydrophilicité des produits finaux. Ainsi, les copolymères d'acide maléique peuvent être utilisé comme partenaires anioniques dans l'interaction électrostatique, connu comme technique de Couche-Par-Couche (LbL).

This thesis research focuses on fundamental understanding regarding the morphological transitions of weak polyelectrolyte multilayers (PEMs) formed by the layer-by-layer (LbL) electrostatic assembly of oppositely charged polymers. he first part of this thesis focuses on patterning polyelectrolyte multilayers that are able to undergo transitions from continuous films to porous materials by using hydrogel stamps. The stamping process is able to locally etch and pattern the porous transition in the LbL films by using reactive wet stamping (r-WETS). It was found that r-WETS of PEMs can also enable the modification of chemical functionality. The second part is an investigation about morphological changes of weak polyelectrolyte multilayers assembled with PAH and PAA using r-WETS in which hydrogel stamp material was soaked into various salt solutions and then applied to the LbL films. Also, in this study we presented a novel strategy to create a continuous gradient structure in thickness or porosity along the lateral direction of the thin films using concentration gradient salt stamping. The third part is an investigation regarding the mechanism of the transition from a continuous morphology to a porous morphology within weak polyelectrolyte multilayers. These morphological changes were able to be created by both acidic and basic post-assembly treatments, showing various morphological transitions from the introduction of porosity to the collapse of these porous structures and the eventual dissolution of the films. A similar observation of morphological transitions in weak polyelectrolyte multilayers was obtained by applying an electric field to the films in the fourth part of this thesis. Exposure to an electric field resulted in the creation of a porous structure, which can be ascribed to local changes in pH and subsequent structural rearrangements of the weak polyelectrolyte constituents. The final part of this thesis is to make PEMs into nanostructured matrices for inorganic synthesis. Multilayers possessing ion-exchangeable carboxylic acid groups were used for binding metal catalysts such as platinum (Pt) nanoparticles (NPs) within the film. Therefore, polyelectrolyte multilayers were able to stabilize catalytic Pt NPs in order to increase the useful time of catalyst materials suitable for use in proton exchange membrane fuel cells.

The advent of microfluidic technology presents many difficulties but also many opportunities for separation science. Leveraging the potential of micro- and nanofluidic geometries is not only a matter of shrinking systems. Miniaturization can shift the relative importance of physical phenomena leading to separation. Theoretical and computational studies into the consequences of miniaturization are vital. Mesoscopic, multi-particle collision dynamics simulations are performed on polyelectrolytes and hard, colloidal solutes. Multiple variations of this simulation algorithm are implemented to achieve versatility for simulating non-equilibrium flows and dispersed solutes. The algorithm is extended to simulate the effects of finite Debye layers on the electro-hydrodynamics of electrophoresing macromolecules and used to study the electrophoresis of charged oligomers, polyelectrolytes and polyampholytes in both free-solution and confined geometries. Multi-particle collision dynamics simulations of hydrodynamic chromatography and field-flow fractionation are also performed to test the predictions of the derived unified, ideal retention theory. This unified, ideal retention predicts the transitions between multiple operational modes, including Faxén-mode FFF. Simulations and the theory show that increases in drag due to hydrodynamic interactions with microfluidic channel walls perturb the retention curves from the ideal predictions at large particle sizes. Further complications to field-flow fractionation including undesirable forces perpendicular to the flow direction, slip at channel walls and rectangular channel geometries are investigated. These theoretical studies lead to the proposal of several novel fractionation techniques, namely adverse-mode FFF, slip-mode FFF and polymer/depletant HC.

Thesis ( Ph.D) -- McMaster University, 2001. / Includes bibliographical references. Also available via World Wide Web.

xvii, 159 p. : ill. A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number. / Experimental studies on mix-conducting hetero-ionic junctions of anionically (PA A ) and cationically (PA C ) functionalized polyacetylene ionomers, as well as each individual ionomer, in thin-film sandwich configurations are reported for the purpose of better understanding the interaction between ionic and electronic charge transports in mixed ionic-electronic conductor (MIEC) systems. The transport of ions in both individual ionomers as well as their hetero-ionic junction was investigated via small-amplitude AC impedance spectroscopy in the absence of significant interference from the electronic charge transport. Modeling of the impedance results reveal important information about the materials such as: ion conductivity, activation energy of ion conduction, ion hopping frequency, dielectric constant, interfacial capacitance, and estimates of effective ion density. Electrochemical injection of electronic charge carriers into PA A and PA C from gold electrodes was monitored to determine the applied potentials needed to drive hole and electron injection into each ionomer. It is found that for both ionomers, the onset voltages for unipolar and bipolar charge injection are similar, and holes can be injected at close to zero bias. The responses of the complete Au|PA A |PA C |Au hetero-ionic junction, as well as each constituent ionomer layer in Au|Ionomer|Au configuration, to various stepping biases were investigated through current-voltage and impedance measurements to study the origin of the asymmetric current-voltage response observed in the hetero-ionic junction. Analysis of the results reveal a working mechanism of a mix-conducting junction that is fundamentally different from that of a purely electronic pn junction. When illuminated with light, the Au|PA A |PA C |Au junction exhibits unidirectional photovoltage and photocurrent with the PA A side at higher potential, while the Au|PA A |Au and Au|PA C |Au samples exhibit symmetric photoresponses. The efficiency of photocurrent generation in the Au|PA A |PA C |Au junction was found to be strongly dependent on the direction of illumination and on the sample thickness. These observations can be explained by the difference in the mobility of holes and electrons and the existence of a built-in ionic space charge region at the PA A |PA C interface. A mechanism of photoresponse unique to MIEC junctions was proposed, and the magnitude of built-in potential was estimated. / Committee in charge: J David Cohen, Chairperson, Physics; Mark Lonergan, Advisor, Chemistry; Roger Haydock, Member, Physics; David Strom, Member, Physics; David Tyler, Outside Member, Chemistry

Os polissabões são polímeros constituídos de unidades monoméricas anfifílicas. Em meio aquoso, os polissabões formam microdomínios intra- ou inter-poliméricos capazes de mimetizar muitas das propriedades de micelas, como solubilizar moléculas orgânicas, trocar contraíons e catalisar reações químicas. Os polissabões utilizados em nossos estudos foram os [n,m]-Ionenos, cuja estrutura química consiste de grupos dimetilamônio interligados por segmentos de cadeia alifática. [-(CH2)n-+N(CH3)2-(CH2)m-+N(CH3)2-]x Br- Br-[n,m]-Ioneno. Em solução aquosa, os [n,m]-Ionenos com segmentos metilênicos curtos, como por exemplo o [3,10]-Ioneno, adotam uma conformação extendida tipo \"bastão\". Por outro lado, ionenos com segmentos mais compridos, como o [3,22]-Ioneno, preferem conformações globulares, formando microdomínios através de um processo de agregação intra-polimérica dos segmentos compridos. Pelo fato de ionenos serem polímeros, podem ser imobilizados em suportes sólidos, tanto covalentemente como por adsorção eletrostática. O objetivo desse trabalho foi desenvolver novas estratégias para a eficiente imobilização covalente de ionenos sobre suportes sólidos. Os ionenos podem ser seletiva e quantitativamente desquaternizados (desmetilados), formando a poli(amina terciária) correspondente: [-(CH2)n-+N(CH3)2-(CH2)m-+N(CH3)2-]x &#8594; [-(CH2)n-N(CH3)-(CH2)m-N(CH3)-]x. Ao contrário do ioneno, a poli(amina terciária) é solúvel em meio orgânico, não apresenta forte tendência de adsorver em superfícies e possui numerosos grupos reativos (as aminas terciárias) distribuídos ao longo de toda cadeia polimérica, adequados para a imobilização da poli(amina terciária) em sílica funcionalizada com grupos cloropropil. A requaternização foi feita com vários reagentes, incluindo haletos de alquila com comprimentos de cadeia distintos (e.g., brometo de etila ou brometo de dodecila) e com 1,3-propanosultona (que fornece ionenos zwitteriônicos com grupos amôniopropano-sulfonato). A fluorescência (comprimento de onda máximo e emissão) do ácido 4-amino-1-naftaleno sulfônico (AMS) mostrou-se útil para a detecção da presença de microdomínios formados pelos ionenos imobilizados na sílica. A relação de intensidades das bandas vibracionais I/III do espectro de fluorescência do pireno dissolvido nos microdomínios permitiu inferir o grau residual de contato entre pireno e a água na superfície dos microdomínios. As propriedades \"catalíticas\" dos ionenos imobilizados foram averiguadas por meio de medidas da velocidade da hidrólise alcalina do octanoato de p-nitrofenila (NPO) e do brometo de N-dodecil-4-cianopiridíneo (DCP). A espessura da camada formada pelos ionenos imobilizados na presença de água foi medida experimentalmente ex-situ e in-situ por elipsometria. Finalmente, alguns ensaios de HPLC utilizando a sílica funcionalizada com ionenos como fase estacionária foram feitos de modo a avaliar sua aplicabilidade real. / Polysoaps are polymers consisting of amphiphilic monomeric units. In aqueous medium, the polysoaps form intra- or inter-polymeric microdomains capable to mimicking many of the properties of micelles, such as solubilization of organic molecules, exchanging counter-ions and catalyzing chemical reactions. The polysoaps used in our studies were [n, m]-ionenes, whose chemical structure consists of dimethylammoniun groups interconnected by aliphatic chain segments. [-(CH2)n-+N(CH3)2-(CH2)m-+N(CH3)2-]x Br- Br-[n,m]-Ioneno. In aqueous solution, [n, m]-ionenes with short methylenic segments, for example [3,10]-ionene, adopt an extended or rodlike conformations. In contrast, ionenes with longer segments, as the [3,22]-ionene, prefer globular conformations, forming microdomains through a process of intra-polymeric aggregation of the long segments. Because the ionenes are polymers, they can be immobilized on solid supports by covalent or electrostatic adsorption. The objective of this work was to develop new strategies for the efficient covalent immobilization of ionenes on solid supports. Ionenes can be selectively and quantitatively dequaternized (demethylated), forming the corresponding poly(tertiary amine): [-(CH2)n-+N(CH3)2-(CH2)m-+N(CH3)2-]x &#8594; [-(CH2)n-N(CH3)-(CH2)m-N(CH3)-]x. Unlike the ionene, the poly(tertiary amine) is soluble in organic medium, does not adsorb onto surfaces and possesses numerous reactive groups (the tertiary amines) distributed throughout the polymer chain. Suitable for immobilization of poly(tertiary amine) on silica funcionalizada with chloropropyl groups. The requaternization was performed with alkyl halides with distinct chain lengths (e.g., ethyl bromide or dodecyl bromide) and with 1,3-propanosultone (yielding zwitterionic ionenes with amoniopropane-sulfonate groups). The fluorescence (maximum wavelength and emission) of 4-amino-1-naphthalene sulfonic acid (AMS) was useful for the detection of the presence of microdomains formed by the immobilized ionenes on silica. The intensity ratio of the I/III vibrational bands of the fluorescence of pyrene dissolved in the microdomains was used to infer the residual degree of contact between pyrene and water at surface of the microdomains. \"The catalytic\" properties of the immobilized ionenes was invetigated by measuring the rate of alkaline hydrolysis of p-nitrophenyl octanoate (NPO) and of the N-dodecyl-4-cyanopyridinium ion (DCP). The thickness of the layer formed by the immobilized ionenes in the presence of water was measured experimentally ex-situ and in-situ by ellipsometry. Finally, some HPLC tests using silica functionalized with ionenes as the stationary phase were made in order to evaluate thesis applicability.