Even in times of renewable energy revolution fossil fuels will play a major role in energy supply, transportation, and chemical industry. Therefore, increasing demand for crude oil will still have to be met in the next decades by developing new oil re-serves. To cope with this challenge, companies and researchers are constantly seeking for new methods to increase the recovery factor of oil fields. For that reason, many enhanced oil recovery (EOR) methods have been developed and applied in the field. EOR methods alter the physico-chemical conditions inside the reservoir. One possibility to achieve this is to inject an aqueous solution containing special chemicals into the oil-bearing zone. Polymers, for example, increase the viscosity of the injected water and hence improve the displacement of the oil to the production well. The injection of surfactant solutions results in reduced capillary forces, which retain the oil in the pores of the reservoir. Some surfactants form viscoelastic solutions under certain conditions. The possibil-ity to apply those solutions for enhanced oil recovery has been investigated by some authors in the last years in low salinity brines. Reservoir brines, however, often contain high salt concentrations, which have detrimental effects on the properties of many chemical solutions applied for EOR operations. The Triphenoxymethane derivatives, which were the subject of study in this thesis, form viscoelastic solutions even in highly saline brines. The aim of this thesis was to investigate the efficiency and the mode-of-action of this new class of chemical EOR molecules with respect to oil mobilization in porous media.

Mixed association of calix[4]resorcinarene with ethyl sulfonate groups on the lower rim and dimethylaminomethyl groups on the upper rim (CR) and cationic surfactant 4-aza-1-hexadecyl-azoniabicyclo[2.2.2]octane bromide (DABCO-16) is studied by methods of tensiometry, conductometry, potentiometry and NMR spectroscopy at fixed CR concentration and varied surfactant concentration. Beyond ca. 0.4 mM of DABCO-16, mixed aggregates enriched by CR are proved to be formed due to electrostatic forces, while beyond ca. 5 mM, aggregates enriched by surfactant occur due to the hydrophobic effect. Spectrophotometry monitoring of the solubilization of a hydrophobic dye, Orange OT, demonstrated that only the second type of mixed aggregate enriched by DABCO-16 is capable of binding the organic probe, while the mixed system where the surfactant is a minor component shows no binding capacity towards Orange OT. This finding can be used for the design of nanocontainers with controllable binding/release properties. / Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.

Even in times of renewable energy revolution fossil fuels will play a major role in energy supply, transportation, and chemical industry. Therefore, increasing demand for crude oil will still have to be met in the next decades by developing new oil re-serves. To cope with this challenge, companies and researchers are constantly seeking for new methods to increase the recovery factor of oil fields. For that reason, many enhanced oil recovery (EOR) methods have been developed and applied in the field. EOR methods alter the physico-chemical conditions inside the reservoir. One possibility to achieve this is to inject an aqueous solution containing special chemicals into the oil-bearing zone. Polymers, for example, increase the viscosity of the injected water and hence improve the displacement of the oil to the production well. The injection of surfactant solutions results in reduced capillary forces, which retain the oil in the pores of the reservoir. Some surfactants form viscoelastic solutions under certain conditions. The possibil-ity to apply those solutions for enhanced oil recovery has been investigated by some authors in the last years in low salinity brines. Reservoir brines, however, often contain high salt concentrations, which have detrimental effects on the properties of many chemical solutions applied for EOR operations. The Triphenoxymethane derivatives, which were the subject of study in this thesis, form viscoelastic solutions even in highly saline brines. The aim of this thesis was to investigate the efficiency and the mode-of-action of this new class of chemical EOR molecules with respect to oil mobilization in porous media.

No description available.

Specific interactions of ligands with receptors is one of the approaches for active targeting of anticancer drugs to cancer cells. Over expression of integrin receptors is a physiological manifestation in several cancers and is associated with cancer progression and metastasis, which makes it an attractive target for cancer chemotherapy. The peptide sequence for this integrin recognition is the Arg-Gly-Asp (RGD). Self-assembly offers a unique way of presenting ligands to target receptors for recognition and binding. This study focuses on development of integrin specific peptide amphiphile self-assemblies as carriers for targeted delivery of paclitaxel to α v β 3 integrin overexpressing cancers. Amphiphiles composed of conjugates of different analogs of RGD (linear, cyclic or glycosylated) and aliphatic fatty acid with or without 8-amino-3,6-dioxaoctanoic acid (ADA) as linker were synthesized and characterized. The amphiphiles exhibited Critical Micellar Concentration in the range of 7-30 μM. Transmission electron microscopy images revealed the formation of spherical micelles in the size range of 10-40 nm. Forster Resonance Energy Transfer studies revealed entrapment of hydrophobic dyes within a tight micellar core and provided information regarding the cargo exchange within micelles. The RGD micelles exhibited competitive binding with 55% displacement of a bound fluorescent probe by the cyclic RGD micelles. The internalization of fluorescein isothiocynate (FITC) loaded RGD micelles was significantly higher in A2058 melanoma cells compared to free FITC within 20 minutes of incubation at 37°C. The same micelles showed significantly lower internalization at 4°C and on pretreatment with 0.45M sucrose confirming endocytotic uptake of the RGD micellar carriers. The IC50 of paclitaxel in A2058 melanoma cells was lower when treated within RGD micelles as compared to treatment of free drug. On the other hand, IC50 values increased by 2 to 9 fold for micellar treatment in comparison to free drug in Detroit 551 cells. In A2058 melanoma xenograft mice model, the Paclitaxel-RGD micelles exhibited a significant inhibition of tumor growth in comparison to control treatment for both alternate day and twice weekly treatments. The studies showed the feasibility of using the non covalent peptide based self-assemblies as vehicles for targeted delivery in cancer.

No description available.

<p></p><p>This doctoral dissertation takes the reader through a journey where applied shear rheology and flow-velocimetry are used to understand the mesoscopic factors that control the flow behavior of three microstructured fluids. Three individual protocols that measure relative physical and mechanical properties of the flow are developed. Each protocol aims to advance the particular transformation of novel soft materials into a commercial product converging in the demonstration of the real the chemical, physical and thermodynamical factors that could potentially drive their successful transformation. </p> <p> </p> <p>First, this dissertation introduces the use of rotational and oscillatory shear rheometry to quantify the solvent evaporation effect on the flow behavior of polymer solutions used to fabricate isoporous asymmetric membranes. Three different A-B-C triblock copolymer were evaluated: polyisoprene-<i>b</i>-polystyrene-<i>b</i>-poly(4-vinylpyridine) (ISV); polyisoprene-<i>b</i>-polystyrene-<i>b</i>-poly(<i>N</i>,<i>N</i>-dimethylacrylamide) (ISD); and polyisoprene-<i>b</i>-polystyrene-<i>b</i>-poly(<i>tert</i>-butyl methacrylate) (ISB). The resulting evaporation-induced microstructure showed a solution viscosity and film viscoelasticity strongly dependent on the chemical structure of the triblock copolymer molecules. </p> <p> </p> <p>Furthermore, basic shear rheometry, flow birefringence, and advanced flow-velocimetry are used to deconvolute the flow-microstructure relationships of concentrated surfactant solutions. Sodium laureth sulfate in water (SLE₁S) was used to replicate spherical, worm-like, and hexagonally packed micelles and lamellar structures. Interesting findings demonstrated that regular features of flow curves, such as power-law shear thinning behavior, resulted from a wide variety of experimental artifacts that appeared when measuring microstructured fluids with shear rheometry.</p> <p> </p> <p>Finally, the successful integration of shear rheometry to calculate essential parameters to be used in a cost-effective visualization technique (still in development) used to calculate the dissolution time of polymers is addressed. The use of oscillatory rheometry successfully quantify the viscoelastic response of polyvinyl alcohol (PVA) solutions and identify formulations changes such as additive addition. The flow behavior of PVA solutions was correlated to dissolution behavior proving that the developed protocol has a high potential as a first screening tool.</p><br><p></p>

The thesis outlines possible medical applications of soft matter assemblies as nanotechnology based systems as well as their potential in the emerging field of nanomedicine. Nanomedicine can be defined as the investigation area encompassing the design of diagnostics and therapeutics at the nanoscale, including nanobots, nanobiosensors, nanoparticles and other nanodevices, for the remediation, prevention and diagnosis of a variety of illnesses. The ultimate goal of nanomedicine is to improve patient quality-of-life. Because nanomedicine includes the rational design of an enormous number of nanotechnology-based products focused on miscellaneous diseases, a variety of nanomaterials can be employed. Therefore, the thesis is driven by a focus on recent advances in the manufacture of soft matter-based nanomedicines specifically designed to improve cancer diagnostics and chemotherapy efficacy. It will in particular highlight liposomes, polymer-drug conjugates, drug- loaded block copolymer micelles and biodegradable polymeric nanoparticles, emphasizing the current investigations and potential novel approaches towards overcoming the remaining challenges in the field as well as a brief overview of formulations that are in clinical trials and marketed products. Based on vehicle-related and...

Made available in DSpace on 2014-12-17T15:42:26Z (GMT). No. of bitstreams: 1 ZilvamMS_TESE_reduzido.pdf: 9108618 bytes, checksum: 613dad3fd1a359dce84e2af73b067934 (MD5) Previous issue date: 2013-02-22 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Surfactant-polymer interactions are widely used when required rheological properties for specific applications, such as the production of fluids for oil exploration. Studies of the interactions of chitosan with cationic surfactants has attracted attention by being able to cause changes in rheological parameters of the systems making room for new applications. The commercial chitosan represents an interesting alternative to these systems, since it is obtained from partial deacetylation of chitin: the residues sites acetylated can then be used for the polymer-surfactant interactions. Alkyl ethoxylated surfactants can be used in this system, since these non-ionic surfactants can interact with hydrophobic sites of chitosan, modifying the rheology of solutions or emulsions resultants, which depends on the relaxation phenomenon occurring in these systems. In this work, first, inverse emulsions were prepared from chitosan solution as the dispersed phase and cyclohexane as the continuous phase were, using CTAB as a surfactant. The rheological analysis of these emulsions showed pronounced pseudoplastic behavior. This behavior was attributed to interaction of "loops" of chitosan chains. Creep tests were also performed and gave further support to these discussions. Subsequently, in order to obtain more information about the interaction of chitosan with non-ionic surfactants, solutions of chitosan were mixed with C12E8 and and carried out rheological analysis and dynamic light scattering. The systems showed marked pseudoplastic behavior, which became less evident when the concentration of surfactant was increased. Arrhenius and KWW equations were used to obtain parameters of the apparent activation energy and relaxation rate distribution, respectively, to which were connected to the content of surfactant and temperature used in this work / As intera??es tensoativo-pol?mero s?o amplamente usadas quando s?o necess?rias propriedades reol?gicas para aplica??es espec?ficas, como a produ??o de fluidos para explora??o do petr?leo. Estudos das intera??es de quitosana com tensoativos cati?nicos tem chamado aten??o por serem capazes de causar mudan?as nos par?metros reol?gicos dos sistemas abrindo espa?o para novas aplica??es. A quitosana comercial representa uma alternativa interessante para estes sistemas, uma vez que ela ? obtida a partir da desacetila??o parcial da quitina: os s?tos acetilados residuais podem, ent?o, ser usados para as intera??es pol?mero-tensoativo. Tensoativos alquil etoxilados podem ser utilizados neste sistema, pois estes tensoativos n?o i?nicos podem interagir com s?tios hidrof?bicos da quitosana, modificando a reologia de solu??es ou emuls?es resultantes, os quais dependem do fen?meno de relaxa??o ocorrendo nestes sistemas. Neste trabalho, primeiramente, foram preparadas emuls?es inversas de solu??o de quitosana como fase dispersa e cicloexano como fase cont?nua usando CTAB como tensoativo. A an?lise reol?gica destas emuls?es mostrou pronunciado comportamento pseudopl?stico. Esta pseudoplasticidade foi atribu?da ? intera??o por la?os loops de cadeias de quitosana. Ensaios de flu?ncia tamb?m foram executados e deram maior suporte a estas discuss?es. Em seguida, a fim de se obter maiores informa??es sobre as intera??es da quitosana com tensoativos n?o i?nicos, solu??es de quitosana foram misturadas com C12E8 e levadas ?s an?lises reol?gica e de espalhamento din?mico de luz. Os sistemas tiveram elevado comportamento pseudopl?stico, o qual se tornava menos evidente, quando o teor de tensoativo foi aumentado. Equa??es de Arrhenius e de KWW foram usadas para obter par?metros de energia de ativa??o aparente e de distribui??o da taxa de relaxa??o, respectivamente, aos quais foram relacionados em fun??o do teor de tensoativo e da temperatura, usados neste trabalho

Le caractère cohérent du processus de doublage de fréquence, processus de<br />conversion de deux photons à la fréquence fondamentale en un photon à la fréquence<br />harmonique, permet de sonder la matière à des échelles sub-longueur d'onde. Pour mettre en<br />évidence cette propriété, la technique de diffusion hyper Rayleigh a été employée pour sonder<br />l'organisation dans des assemblages moléculaires dispersés en solution liquide. Après une<br />étude initiale de quelques solvants usuels purs, l'influence de l'environnement sur la réponse<br />du cristal violet, une sonde moléculaire octupolaire de référence, a été étudiée. Ces études ont<br />été poursuivies pour des sondes moléculaires amphiphiles afin d'étudier des solutions mixtes<br />comprenant à la fois des sondes libres et des sondes engagées dans des assemblages<br />moléculaires appelés micelles. En raison de la centrosymétrie de ces assemblages, la<br />composante dipolaire de la réponse harmonique diffusée s'affaiblit, laissant la réponse<br />harmonique totale dominée par une forte contribution quadripolaire clairement mise en<br />évidence par ces mesures de diffusion hyper Rayleigh résolue en polarisation. Un modèle<br />complet décrivant les différentes composantes de la réponse harmonique totale est introduit<br />pour interpréter globalement les observations sur ces solutions mixtes. Enfin, les études<br />préliminaires d'un système biomimétique reconstitué à l'interface air-eau par doublage de<br />fréquence sont présentées.