Macromolecular complexes of anionic-nonionic block copolymers and cationic antibiotic aminoglycosides have been formed by electrostatic condensation. Amphiphilicity of the complexes was introduced into the shells by incorporating a hydrophobic poly(propylene oxide) segment into the block copolymer. The resulting particles have an average hydrodynamic diameter of ~ 200 nm and contain up to 30-40 % of the drug payload. In vitro efficacies of such nanostructures in reduction of intracellular pathogens like Salmonella, Listeria, and Brucella were demonstrated. Current effort focuses on translation of this nano-drug delivery concept to in vivo model of intracellular infectious diseases. Atom transfer radical polymerization (ATRP) was utilized to prepare well-defined polymeric dispersion stabilizers that readily adsorb onto metal oxide surfaces. Two unimolecular bis(phosphonate) ATRP initiators were designed and prepared in good yield. These special initiators were successfully used to initiate polymerization of poly(N-isopropylacrylamide) (PNIPAM) in a controlled manner yielding PNIPAM with a bis(phosphonate) moiety at one terminus. The polymers readily adsorbed onto magnetite nanoparticle surfaces, thus creating thermosensitive magnetic nanostructures that form nanosized clusters upon heating above the lower critical solution temperature of PNIPAM. It is envisioned that modularity of this approach, relying on the applicability of ATRP to polymerize a vast array of monomers, could be used to prepare a library of polymeric shells for magnetic iron oxide nanoparticles. Medical intervention in drug delivery that includes detectability of drug carriers is greatly desirable. A real-time assessment of disease prognosis could be highly beneficial for developing personalized treatment strategies. As an example of this conceptual innovation, block ionomer functionalized magnetite complexes were synthesized and investigated as carriers for delivery of aminoglycosides into phagocytic cells for treatment of intracellular bacterial infections. The ionic block of copolymer contains multiple carboxylates for binding onto the iron oxide surface. The remaining unbound carboxylate anions were used to complex with cationic gentamicin in nanoshells of these complexes. The iron oxide particle core provides an imaging modality and serves as a pseudo-crosslinking site to enhance stabilities of the polyelectrolyte complexes, thus preventing them from disintegrating in the physiological environment. Currently, these hybrid complexes are being investigated in possible pharmaceutical formulations to eradicate intracellular pathogens in animal models. / Ph. D.

The structure property behavior of an ethylene-propylenediene ionic terpolymer containing varying amounts of ZnSt was investigated. Studies show that ZnSt acts as a reinforcing filler under ambient conditions. Stress-strain behavior, percent relaxation, hysteresis and permanent set were all found to increase with increasing ZnSt content. Increases in stress values upon annealing for all samples were attributed to increased ionic domain formation and growth. Aging was found to alter stress values at elongations beyond the elastic region. SAXS data indicates that structural rearrangement occurs with aging. DSC studies confirmed the effects of aging in that a difference occurred in thermal behavior between 1st and 2nd meltings. DSC also indicated the presence of an impurity, which is believed to be stearic acid. Water absorption studies conducted on the aged systems suggested that ZnSt either interacts with the Zn salt group tying up absorption sites or diffuses towards Zn salt groups as possible nucleation sites and forms a water barrier. Water negatively affects ZnSt's ability to act as a reinforcing filler. A rise in SOC values indicated non-Gaussian behavior for all samples. WAXS indicates that a portion of the ZnSt crystals hold their orientation upon stress release. The ZnSt loaded and unloaded systems had distinctly different morphologies. Both SEM and WAXS studies of the 303-50 sample indicated small ZnSt particles of less than 400°A in size. Comparison with modulus studies of other hard phase systems lent major support to the postulation of very small ZnSt crystals. / Master of Science

Non-covalent interactions including nucleobase hydrogen bonding and ionic aggregation were studied in block and end-functional polymers synthesized via living polymerization techniques such as nitroxide mediated polymerization and anionic polymerization. The influence of non-covalent association on the structure/property relationships of these materials were studied in terms of physical properties (tensile, DMA, rheology) as well as morphological studies (AFM, SAXS). Hydrogen bonding, a dynamic interaction with intermediate enthalpies (10-40 kJ/mol) was introduced through complementary heterocyclic DNA nucleobases such as adenine, thymine and uracil. Hydrogen bonding uracil end-functionalized polystyrenes and poly(alkyl acrylate)s were synthesized via nitroxide mediated polymerization from novel uracil-functionalized alkoxyamine unimolecular initiators. Terminal functionalization of poly(alkyl acrylate)s with hydrogen bonding groups increased the melt viscosity, and as expected, the viscosity approached that of nonfunctional analogs as temperature increased. A novel difunctional alkoxyamine, DEPN2, was synthesized and utilized as an efficient initiator in nitroxide-mediated controlled radical polymerization of triblock copolymers. Complementary hydrogen bonding triblock copolymers containing adenine (A) and thymine (T) nucleobase-functionalized outer blocks were synthesized. Hydrogen bonding interactions were observed for blends of the complementary nucleobase-functionalized block copolymers in terms of increased specific viscosity as well as higher scaling exponents for viscosity with solution concentration. Multiple hydrogen bonding interactions were utilized to attach nucleobase-functional quaternary phosphonium ionic guests to complementary adenine-functionalized triblock copolymers. Ionic interactions, which possess stronger interaction energies than hydrogen bonds (~150 kJ/mol) were studied in the context of sulfonated poly(styrene-b-ethylene-co-propylene-b-styrene) block copolymers. Strong ionic interactions resulted in the development of a microphase separated physical network and greater extents for the rubbery plateau in DMA analysis compared to sulfonic acid groups, which exhibit weak hydrogen bonnding interactions. In contrast to the physical networks consisting of sulfonated or hydrogen bonding block copolymers, covalent networks were synthesized using carbon-Michael addition chemistry of acetoacetate functionalized telechelic oligomers to diacrylate Michael acceptors. The thermomechanical properties of the networks based on poly(propylene glycol) oligomers were analyzed with respect to the molecular weight between crosslink points (Mc) and the critical molecular weight for entanglement (Me). / Ph. D.

Thesis (Ph. D. in Chemical Engineering)--Vanderbilt University, Dec. 2009. / Title from title screen. Includes bibliographical references.

Submitted by MONICA IRMA APARECIDA VALDECI DE SOUZA null (cristina_monicas@hotmail.com) on 2016-05-16T23:39:27Z No. of bitstreams: 1 tese correção biblio 5.pdf: 1814748 bytes, checksum: 1bfe9a56010305cbe2ef946d8d005ec9 (MD5) / Approved for entry into archive by Ana Paula Grisoto (grisotoana@reitoria.unesp.br) on 2016-05-17T20:04:08Z (GMT) No. of bitstreams: 1 souza_miav_me_arafo.pdf: 1814748 bytes, checksum: 1bfe9a56010305cbe2ef946d8d005ec9 (MD5) / Made available in DSpace on 2016-05-17T20:04:08Z (GMT). No. of bitstreams: 1 souza_miav_me_arafo.pdf: 1814748 bytes, checksum: 1bfe9a56010305cbe2ef946d8d005ec9 (MD5) Previous issue date: 2016-03-29 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O objetivo deste estudo foi avaliar a influência da incorporação de nanopartículas de óxido de zinco (NPZnO) nas concentrações de 3, 5 e 7%, sobre propriedades mecânicas e físicas do cimento de ionômero de vidro (CIV) Ketac Molar Easymix. A mistura das NPZnO ao CIV foi realizada pelo método manual e pela calcinação. As propriedades avaliadas foram: análise microestrutural, microdureza Vickers, resistência à compressão, à tração diametral e à flexão. A análise microesturural foi realizada por meio de MEV – FEG, a microdureza com auxilio de um microdurômetro digital (Micromet 2100) e os demais testes em máquina de ensaios mecânicos EMIC. Os dados foram avaliados pelo teste de ANOVA two-way e pelo post-hoc de Tukey, com nível de significância de 5%. Em relação à microestrutura, a calcinação proporcionou melhor distribuição e homogeneização das NPZnO entre as partículas de vidro do CIV. A microdureza, resistência à compressão, à tração diametral e à flexão, após utilização do método da calcinação, apresentaram os melhores resultados. Assim, este estudo indica o método de calcinação quando da mistura de NPZnO ao CIV, uma vez que o mesmo demonstrou ser promissor, diante de todos os testes analisados. / The aim of this study was to evaluate the incorporation of zinc oxide nanoparticles (NPZnO) in concentrations of 3, 5 and 7% on mechanical and physical properties of glass ionomer cement (GIC) Ketac Molar Easymix. The mixture of NPZnO the MIC was conducted by manual method and the calcination. The properties evaluated were: microstructural analysis, Vickers hardness, compressive strength, diametral tensile strength and flexural strength. The microesturural analysis was performed by SEM - FEG, the hardness with the aid of a digital microhardness (Micromet 2100) and other tests EMIC universal testing machine. Data were evaluated by two-way ANOVA test and the post-hoc Tukey, with 5% significance level. Regarding the microstructure, the calcination provided better distribution and mixing of NPZnO between the glass particles of the MIC. The hardness, compressive strength, diametral tensile strength and flexural strength after use of the calcination method, showed the best results. Thus, this study indicates the calcination method when mixing NPZnO the GIC once it has shown promise in front of all the analyzed tests.

xix, 190 p. : ill. A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number. / The electrical properties of conducting polymer-based devices are investigated in order to better understand charge transport through conducting polymers and charge transfer at conducting polymer interfaces with metals and inorganic semiconductors. Experiments on two specific systems are reported: (1) an anionically functionalized conducting polymer between metal electrodes and (2) nanostructured doped conducting polymer-semiconductor interfaces. Temperature dependent impedance measurements are reported on an anionically functionalized polyacetylene sandwiched between two gold electrodes (Au|P A |Au). These measurements provide key quantities regarding the ionic carriers in this system, such as the characteristic frequency for electrode polarization, ionic DC conductivity, activation energy, effective ion concentration, and hopping frequency. Impedance measurements are also reported on samples where excess electronic carriers had been introduced with a DC bias and at temperatures sufficiently low so as to freeze out the ionic carriers. In addition to providing information about the dielectric relaxation of electronic carriers such as the characteristic frequency for electrode polarization and activation energy, these low-temperature impedance measurements also support the ionic dielectric relaxation assignments. Temperature-dependent potential step experiments, in combination with the dielectric measurements probing ionic carriers, demonstrate the direct connection between the redistribution of ions and an enhancement in carrier injection in the Au|P A |Au system. Further potential step experiments followed by relaxation through either a short- or open-circuit configuration demonstrate that the electric field distribution is closely related to the amount of injected electronic carriers. The electric field distribution changes from being mostly determined by ionic carriers to being jointly determined by both ionic and injected electronic carriers when the density of injected electronic carriers is higher than that of the effective ionic carriers. To investigate charge depletion and transport at length scales less than the depletion width of a semiconductor interface, nanoscale metal-InP contacts with low barrier height were embedded within conducting polymer-InP contacts with high barrier height. Electrical measurements on these hybrid interfaces indicate that charge transport across the nanoscale metal contacts is affected by the neighboring high barrier region when the size of the metal contacts is less than the depletion width of the conducting polymer-InP background. / Adviser: Mark Lonergan

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

Orientador: Ângela Cristina Cilense Zuanon / Banca: João Neudenir Arioli filho / Banca: Maria Cristina Borsatto / Resumo: O objetivo deste estudo foi avaliar a influência da incorporação de nanopartículas de óxido de zinco (NPZnO) nas concentrações de 3, 5 e 7%, sobre propriedades mecânicas e físicas do cimento de ionômero de vidro (CIV) Ketac Molar Easymix. A mistura das NPZnO ao CIV foi realizada pelo método manual e pela calcinação. As propriedades avaliadas foram: análise microestrutural, microdureza Vickers, resistência à compressão, à tração diametral e à flexão. A análise microesturural foi realizada por meio de MEV - FEG, a microdureza com auxilio de um microdurômetro digital (Micromet 2100) e os demais testes em máquina de ensaios mecânicos EMIC. Os dados foram avaliados pelo teste de ANOVA two-way e pelo post-hoc de Tukey, com nível de significância de 5%. Em relação à microestrutura, a calcinação proporcionou melhor distribuição e homogeneização das NPZnO entre as partículas de vidro do CIV. A microdureza, resistência à compressão, à tração diametral e à flexão, após utilização do método da calcinação, apresentaram os melhores resultados. Assim, este estudo indica o método de calcinação quando da mistura de NPZnO ao CIV, uma vez que o mesmo demonstrou ser promissor, diante de todos os testes analisados. / Abstract: The aim of this study was to evaluate the incorporation of zinc oxide nanoparticles (NPZnO) in concentrations of 3, 5 and 7% on mechanical and physical properties of glass ionomer cement (GIC) Ketac Molar Easymix. The mixture of NPZnO the MIC was conducted by manual method and the calcination. The properties evaluated were: microstructural analysis, Vickers hardness, compressive strength, diametral tensile strength and flexural strength. The microesturural analysis was performed by SEM - FEG, the hardness with the aid of a digital microhardness (Micromet 2100) and other tests EMIC universal testing machine. Data were evaluated by two-way ANOVA test and the post-hoc Tukey, with 5% significance level. Regarding the microstructure, the calcination provided better distribution and mixing of NPZnO between the glass particles of the MIC. The hardness, compressive strength, diametral tensile strength and flexural strength after use of the calcination method, showed the best results. Thus, this study indicates the calcination method when mixing NPZnO the GIC once it has shown promise in front of all the analyzed tests. / Mestre

Résumé confidentiel / Résumé confidentiel

No description available.