Orientador: Maria Isabel Felisberti / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-22T10:53:23Z (GMT). No. of bitstreams: 1 Rufino_ThiagodoCarmo_M.pdf: 62178066 bytes, checksum: c86de8ad8c099d3ea0fb76540c55b0de (MD5) Previous issue date: 2013 / Resumo: Blendas de poli (L-Lactídeo) (PLLA) e poli(óxido de etileno) (PEO) têm sido amplamente estudadas devido às características destes polímeros tais como a biocompatibilidade e a biodegradabilidade e ao potencial de aplicação destas blendas nas áreas médica e farmacológica. Além disso, combinam um polímero hidrofóbico e quebradiço (PLLA) com um polímero hidrofílico/hidrossolúvel e flexível (PEO). A literatura apresenta estas blendas como sendo miscíveis na fase amorfa com base na depressão da temperatura de fusão dos componentes, porém não consideram possíveis efeitos morfológicos sobre a fusão e estes resultados são restritos a determinada faixa de massa molar. Neste contexto, este trabalho teve como objetivo avaliar se e como as propriedades térmicas e morfológicas de blendas PLLA/PEO são influenciadas pela composição e pela massa molar. Blendas com diferentes composições foram obtidas por criodessecação de soluções dos polímeros, com massas molares variando em ampla faixa, em benzeno. As blendas constituídas por PEO (Mw = 5,0 ¿¿ 163,0 kDa) e PLLA (Mw = 11,0 ¿¿ 199,0 kDa) mostraram-se imiscíveis na faixa de composição de 20 ¿¿ 80% de PEO. Blendas contendo 20% de PEO apresentaram comportamento de fusão e cristalização anômalo, atribuído a fatores de natureza cinética e morfológica. A cristalização fracionada do PEO nestas blendas sugere que o processo ocorreu sob confinamento. Para as demais composições a cristalização do PEO ocorreu sobre os esferulitos de PLLA, que atuou como um template para os cristalitos de PEO / Abstract: Blends of poly(l-lactic acid) (PLLA) and polyethylene oxide (PEO) have been studied by several authors, mainly due to the biocompatibility and biodegradability characteristics of these polymers, and to the potential application of their blends in medical and pharmacological areas. Besides, these blends combine a brittle and hydrophobic polymer (PLLA) with a exible and hydrophilic one (PEO). The current bibliography assumes the miscibility of these blends in the amorphous state based on the melting point depression. However, morphological e ects on the melting characteristics of the polymers are not considered and the results are restricted to a narrow molar mass range for both polymers. In this context, this work aims to evaluate if and how molar mass and compound ratio a ect the thermal properties and the morphology of these blends. The blends were prepared by freeze-drying of polymer solution in benzene. The results showed that the blends of PEO (Mw = 5 ¿¿ 163,0 kDa) and PLLA (Mw = 11,0 ¿¿ 199,0 kDa) are immiscible in the composition of 20 7! 80% of PEO. Blends containing 20% of PEO presented anomalous melting and fusion behavior as consequence of con ned fractioned crystallization, resulting in kinetic and morphological changes. The crystallization of PEO phase in blend during cooling from the melting state occured on the PLLA crystallites, which acted as template / Mestrado / Físico-Química / Mestre em Química

We present the phase behavior of soft sphere colloidal dispersions. The pH responsive and thermoresponsive microgels, poly(N-isopropylacrylamide-co-acrylic acid) (pNIPAm-co-AAc), were used as a new building block of colloidal crystals. The phase behavior of microgel dispersions was studied by different methods such as optical microscopy, particle trajectories, mean squared displacement (MSD) vs. lag time plots and radial distribution function. The results show that the phase of the sample relies on the particle concentration for dispersions of the same pH. As the pH approaches the pKa of microgels, the microgel dispersions show unusual crystalline phase at lower effective volume fraction than hard sphere melting transition. Also, at this pH regime, the microgel dispersions undergo slow and spatially heterogeneous crystal growth. The cooperative multi-body type attractive forces were proposed to explain the unusual stability at low effective volume fraction. Ion-dipole interactions were proposed to be the origin of the attractive forces. The melting point of bulk crystals at this pH regime is much higher than the volume phase transition temperature of the building block. These results are supportive of the attractive forces hypothesis.

In this thesis detailed investigations of the phase behavior of poly(n-alkyl methacrylate-b-methyl methacrylate) diblock copolymers and its influence on the wettability of the polymer surfaces were carried out. For this investigation two polymethacrylic systems differing only in the alkyl rest of one block: poly(pentyl methacrylate-b-methyl methacrylate) and poly(propyl methacrylate-b-methyl methacrylate) have been chosen in order to prove how this substituent affects the phase behavior of whole system. The PnAlkMA-b-PMMA diblock copolymers in a wide range of molar masses, and with varied block length ratios were synthesized by living anionic polymerization. The syntheses were carried out in tetrahydrofuran (THF), at –78 °C, by using sec-buthyllithium as initiator, in the presence of lithium chloride (LiCl). Under these conditions highly syndiotactic products, rr ~ 0.82, with very narrow molar mass distribution, Mw/Mn ~ 1.1, were obtained. The phase behavior of PnAlkMA-b-PMMA diblock copolymers in bulk was investigated by means of DSC and SAXS measurements. The DSC analysis revealed that the PPMA-b-PMMA with weight fractions of PPMA, fPPMA, from 0.28 up to 0.86 showed two separate Tg’s, indicative of a phase separated system. However, by comparing the Tg’s of the diblock copolymers with the Tg’s of the corresponding homopolymers we found that in a few cases, mostly for samples with the high molar masses, they were slightly shifted. This finding pointed out the existence of two mixed phases, and hence partial miscibility between the both blocks was assumed. The SAXS patterns reflected for most diblock copolymers lamellae morphologies even in the case of very asymmetric composition, for instance with volume fraction of PPMA, 0.86 It was assumed that this behavior is caused by the chemical similarity of both blocks as well as by the differences in their molar volumes. The SAXS findings were further confirmed by the AFM measurements on the cutted “bulk” samples. From the solubility concept of Van Krevelen we obtained that the interaction parameter of PPMA-b-PMMA is rather low, 0.065, compared to the other well-known diblock copolymers. The calculated spinodals are characterized by a high asymmetry. The investigation of the phase behavior of PPMA-b-PMMA in thin films showed that the morphology as well as the topography of the thin films were strongly affected by the film thickness, when the films were prepared from a non-selective solvent (THF) onto silicon wafers. Well-recognizable nanostructures with long-range order were mainly found in thin films of diblock copolymers with high molar masses, above 100,000 g/mol, and with a high amount of PPMA. The lateral domain spacing obtained for these films from AFM corresponded well with that found in bulk. The study of the influence of the thermal as well as vapor annealing on the morphology and topography of the thin films provided additional information about the phase behavior of PPMA-b-PMMA diblock copolymers in thin films. Finally, the wettability of the investigated PPMA-b-PMMA surfaces was established by means of contact angle measurements. The measured contact angles were in most cases even on nicely nanostructured surfaces very similar to the contact angle of PPMA, indicating preferential segregation of PPMA to the film surface. Additional XPS measurements also showed an enrichment of the PPMA at the surface, independent of the morphology observed by AFM, and thereby confirmed the ADSA finding. In the next part of this work, investigations of the phase behavior of PPrMA-b-PMMA diblock copolymers were presented. In the contrary to the previous system the PPrMA-b-PMMA showed mostly a single Tg, which was further found to be depend on the weight fraction of PPrMA, fPPrMA. The SAXS data revealed that the PPrMA-b-PMMA diblock copolymers were phase separated in bulk, however the obtained scattering patterns exhibited mostly broad, not-well discernible higher-order peaks. Nevertheless, it was possible to identify the formed morphologies and depending on the volume fraction of PPrMA, hexagonally packed cylinders and lamellae were detected. The PPrMA-b-PMMA is characterized by a significantly lower value of the interaction parameter, 0.022, than the PPMA-b-PMMA system. This difference clearly reflects the weakening of the interactions between the components with decrease of the length of the alkyl side chain. The thin films of PPrMA-b-PMMA diblock copolymers appeared mostly smooth and featureless, independent of the film thickness. From the contact angle and XPS measurements we obtained, that unlike the PPMA-b-PMMA, both components were always present on the top of the surface. / In der vorliegenden Arbeit wurden Untersuchungen zum Entmischungsverhalten von Poly(n-alkylmethacrylat-b-methylmethacrylat) Diblockcopolymeren und deren Einfluss auf die Benetzbarkeit der Polymeroberflächen dargestellt. Diese Untersuchungen wurden anhand der Poly(pentylmethacrylat-b-methylmethacrylat) und Poly(propylmethacrylat-b-methylmethacrylat) durchgeführt. Die Diblockcopolymere in einem weiten Molmassenbereich, mit enger Molmassenverteilung, abgestuften Zusammensetzung wurden erfolgreich mittels anionischer Polymerization synthetisiert. Die Synthese erfolgte in THF bei (-78 °C) in Gegenwart von Lithiumchlorid. Als Initiator wurde sec. Butyllithium genutzt. Das Phasenverhalten der Diblockcopolymere im Festkörper wurde mittels DSC und SAXS untersucht. Für die meiste PPMA-b-PMMA Diblockcopolymere wurden mittels DSC zwei getrennte Tg gefunden, die aber im Vergleich zu den Tg von den entsprechenden Homopolymeren leicht verschoben waren. Es wurde also eine partielle Mischbarkeit der Blöcke festgestellt. Mittels SAXS-Untersuchungen wurde für die Mehrzahl der Diblckcopolymere in einem weiten Zusammensetzungsbereich bis zum 0.86 Volumenanteil von PPMA, eine lamellare Anordnung beobachten. Diese Befunde wurden nachfolgend mit AFM–Untersuchungen an dünnen Polymerfolien bestätigt. Das mit der Mean-Filed-Methode berechnete Phasendiagramm zeigte eine Asymmetrie, die durch die Unterschiede in den molaren Volumina des Blöckes verursacht war. Es wurde aber eine gute Übereinstimmung mit der experimentell erhaltenen Daten gefunden. Der berechnete für das System Wechselwirkungsparameter beträgt 0,065. Die AFM-Untersuchungen zum Entmischungsverhalten in dünnen Filmen haben gezeigt, dass die Topographie als auch Morphologie des Films war von der Filmdicke beeinflusst. Die Polymerfilme wurden mittels dipcoating der Si-Wafer präpariert. Dazu wurden Polymerlösungen in THF verwendet. Reguläre Nanostrukturen, deren Abstände mit dem im Festkörper gefundenen sehr gut übereinstimmten, wurden bei den Proben mit höherem Anteil von PPMA erhalten. Es wurden auch der Einfluss der Temperatur und der Dampfbehandlung auf die Morphologie und Topographie des Films untersucht. Die Benetzbarkeit der untersuchte PPMA-b-PMMA Filme wurde mit der Kontaktwinkelmessungen (ADSA) bestimmt. Als Messflüssigkeit wurde Milipore Wasser genutzt. Für die Mehrzahl der Diblockcopolymere wurden Kontaktwinkel im Bereich um 95° ermitteln, unabhängig von der Zusammensetzung der Diblockcopolymere und der vorhandenen Nanostruktur. Dies entspricht dem Kontaktwinkel von PPMA Homopolymer. Die Benetzbarkeit der PPMA-b-PMMA Filme wurde also durch die Oberflächensegregation des Niedrigenergieblocks (PPMA) bestimmt. Dies wurde danach durch zusätzliche XPS Messungen bestätigt. Im Vergleich zu PPMA-b-PMMA, die nachfolgend untersuchte PPrMA-b-PMMA Diblockcopolymere wiesen eine höhere Tendenz zur Mischbarkeit auf. Anhand der DSC–Untersuchungen wurde hier vorübergehend eine Misch-Tg gefunden. Nur bei der Probe mit symmetrischer Zusammensetzung wurden zwei getrennte Tg beobachtet. Die Streukurven von diesem System waren sehr schwach ausgeprägt. Dadurch die Indizierung der vorhandenen Morphologien war nicht eindeutlich. Der berechnete Wechselwirkungsparameter beträgt 0,022. Bei den AFM-Untersuchungen zum Entmischungsverhalten in dünnen PPrMA-b-PMMA Filmen wurden entweder keine oder sehr schwach geordnete Nanostruktur gefunden. Im Gegensatz zu dem vorherigen System, die Benetzbarkeit der PPrMA-b-PMMA Filme war durch die Zusammensetzung der Diblockcopolymere bedingt.

A limited number of laboratory studies and pilot programs have been reported in chemical Enhanced Oil Recovery (EOR) flooding of carbonate reservoirs (Adams & Schievelbein, 1987). Fewer still have involved surfactants in limestone reservoirs. No surfactant/polymer flood on a field wide basis of a carbonate reservoir has ever been documented in the literature (Manrique, Muci, & Gurfinkel, 2010). This void represents a colossal opportunity given that nearly a third of the 32 billion barrels of oil consumed in the world each year come from carbonate reservoirs (Sheng, 2011, pp. 1, 254). This thesis is based on experiments with a high hardness (~5,000 ppm divalent ions) carbonate field. Phase behavior, aqueous stability, and core flood experiments were performed using polymer and various surfactants and co-solvents. Both commercially available and laboratory synthesized surfactants were tested. The objective was to optimize the chemical injection design in order to lower interfacial tension between water and oil in the reservoir. Research was also done with alkali intended for use with hard brines. The main challenges when working with hard brine were poor solubilization and low aqueous stability limits. However, highly propoxylated and ethoxylated surfactants mixed with internal olefin sulfonates, hydrophilic sulfates, and sec-butanol were observed to have very high solubilization ratios, fast phase behavior equilibration times, negligible viscous macroemulsion effects, and excellent aqueous stability. Spinning drop interfacial tensiometer tests confirmed low IFT values were obtained for a range of acceptable salinities with hard brine. Three core floods were performed using one of the surfactant formulations developed. One flood was done with field core, brine, and crude oil and failed to meet expectations because of high levels of heterogeneity (vugs) within the core that lead to an elongated oil bank and low and slow oil recovery. The other floods were done with Estillades Limestone. The first Estillades flood used hard synthetic field brine and had better mobility but poor oil recovery. The last core flood had good mobility and recovered 90% of the residual oil to water flooding, but only after a total of 1.1 pore volumes of 1.0 wt% surfactant solution were injected. The results provided in this thesis constitute proof of concept that S/P flooding can be done in high salinity and hardness reservoirs. / text

There is a vast deposit of viscous and heavy oil, especially in Canada and Venezuela. Typically thermal methods are used to recover heavy oil. However, thermal methods are inefficient when the depth of the reservoir is high and pay thickness is low. Non-thermal methods need to be developed for viscous and heavy oils. Alkaline-surfactant-polymer (ASP) floods can be used for improving the displacement efficiency, but its effect on sweep efficiency in viscous oil recovery has not been studied. The objective of this research was to investigate 2D ASP floods in a quarter five-spot pattern. Through careful phase behavior screening, the surfactant formulation was developed that produced ultra-low interfacial tension with reservoir viscous oil (100 cp). After verifying that the design of surfactant formulation was robust and can recover more than 90% of oil in a 1D ASP sandpack flood, it was tested in a 2D geometry. Both stable and unstable tertiary ASP floods were performed in a 2D quarter five-spot sandpack using the surfactant formulation developed in 1D ASP sandpack flood. In a stable ASP quarter five-spot sandpack flood, the oil recovery was excellent (~97% of ROIP). Oil recovery in the stable 2D ASP flood behaved similar to oil recovery in the 1D stable ASP flood. However, pressure drop obtained was high which would be unsustainable in field applications. Interestingly, unstable 2D flood performed well even with an adverse mobility ratio between oil/water bank and ASP slug with a recovery of 80% ROIP. Decreasing the viscosity of ASP slug 6 times decreased the maximum pressure drop 5 times; thus, the maximum pressure drop was almost proportional to the ASP slug viscosity in a 2D pattern. This research showed that unstable ASP flood in a 2D geometry can recover significant amount of oil with a practical pressure gradient. / text

Numerical simulation has been used, as common practice, to estimate the CO2 storage capacity of depleted reservoirs. However, this method is time consuming, expensive and requires detailed input data. This investigation proposes an analytical method to estimate the ultimate CO2 storage in depleted oil and gas reservoirs by implementing a volume constrained thermodynamic equation of state (EOS) using the reservoir?s average pressure and fluid composition. This method was implemented in an algorithm which allows fast and accurate estimations of final storage, which can be used to select target storage reservoirs, and design the injection scheme and surface facilities. Impurities such as nitrogen and carbon monoxide, usually contained in power plant flue gases, are considered in the injection stream and can be handled correctly in the proposed algorithm by using their thermodynamic properties into the EOS. Results from analytical method presented excellent agreement with those from reservoir simulation. Ultimate CO2 storage capacity was predicted with an average difference of 1.3%, molar basis, between analytical and numerical methods; average oil, gas, and water saturations were also matched. Additionally, the analytical algorithm performed several orders of magnitude faster than numerical simulation, with an average of 5 seconds per run.

<p>"Smart" polymers that sense stimuli in aqueous environments and that respond with a pronounced change in their solvation are of great utility in biotechnology and medicine. Currently, however, only few peptide polymers are known to display this behavior. Here, we uncover the syntax -- defined as the arrangement of amino acids (letters) into repeat units (words) that have a functional behavior of interest -- of a novel and extensive family of genetically encoded "smart" peptide polymers, termed syntactomers, that dictates their ability to undergo a soluble to insoluble phase transition at temperatures above a lower critical solution temperature (LCST) or below an upper critical solution temperature (UCST). We show that this syntax ranges from phase transition polymers composed of simple repeats of a few amino acids to polymers whose syntax resembles the complex sequence of peptide drugs and protein domains that exhibit dual levels of function, as seen by their stimulus responsiveness and biological activity. This seamless fusion of materials and protein design embodied by syntactomers promises, we hope, a new generation of designer polymers with multiple levels of embedded functionality that should lead to new functional materials of broad interest</p> / Dissertation

Microgels are a class of colloids that are mechanically soft, and while in many cases can behave similarly to their hard-sphere counterparts, their interaction potentials are quite different. The softness of the interaction between microgels makes them capable of deformation and compression into more concentrated assemblies. This concentrated regime is interesting because little, if any, experimental work has been done to see how the bulk properties of soft-sphere assemblies deviate from those of hard-spheres at the point where their interaction potentials begin to diverge. In this thesis the effects on assembly phase behavior and dynamics of both particle compression and softness of the interaction potential are addressed. Poly(N-isopropylacrylamide) (pNIPAm) microgels are an excellent model system in which to study these effects. The thermoresponsivity of the polymer provides the experimentalist with a dial to tune the volume fraction of an assembly, while maintaining a constant particle number density in the system. Optical microscopy, particle tracking analysis and rheology have been used to investigate the effects of packing and particle structure on equilibrium phase behavior and localized perturbations to the phase of the assembly of this soft-sphere system. It has been elucidated from these experiments and others involving deswelling of large microgel particles in the presence of high concentrations of smaller microgels, that the soft, repulsive interaction between microgels is caused by a longer-range repulsion than was previously believed. The particles are acting on each other from a distance through the osmotic pressure of the assembly, which causes each particle to deswell without coming into direct contact with a neighboring particle.

Poly(N-isopropylacrylamide-co-acrylic acid) (pNIPAm-AAc) copolymeric multi-responsive microgels demonstrate responsivity to temperature, pH, and ionic strength. A temperature-programmed polymerization protocol is proposed for the synthesis of large pNIPAm-AAc microgel particles with a hydrodynamic diameter of 2~5 μm. Immediately after preparation of concentrated pNIPAm-AAc dispersions in closed system, the average hydrodynamic diameter is smaller than the unperturbed diameter probably due to osmotic de-swelling effect. During the aging process, pNIPAm-AAc microgel particles start to swell while their dynamics slow down. The snapshots of phase behavior of pNIPAm-AAc microgel dispersions at different pH values are illustrated. The formation of crystalline phase should follow a nonergodic path in which microgel particles swell to the extent that they build up weak attractive interaction to allow them to associate while maintaining the opportunity of rearrangement to minimize local Gibbs free energy. The age-dependent thermostability of pNIPAm-AAc microgel dispersions suggests strong attractive interactions evolve between particles during aging-convoluted crystallization. Finally, to introduce multiple biological "handle"s on the microgel particles for biomedical applications, the Cu(I)-catalyzed azide-terminal alkyne 1,3-dipolar cycloaddition, also called Sharpless-Meldal "click" reaction, is used to functionalize pNIPAm-AAc microgel particles.

Orientador: Watson Loh / Texto em português e inglês / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-21T09:28:37Z (GMT). No. of bitstreams: 1 Silva_AnaMariaPercebomSetteda_D.pdf: 24339728 bytes, checksum: 5607616747acea067ac22294eb185712 (MD5) Previous issue date: 2012 / Resumo: Este trabalho se insere em uma linha de pesquisa de nosso grupo sobre a autoassociação de surfatantes iônicos que são neutralizados por contraíons poliméricos, formando os chamados sais complexos. A proposta do presente projeto trata da verificação do efeito de diferentes arquiteturas ou composições químicas de poliânions sobre as propriedades de autoassociação do surfatante catiônico hexadeciltrimetilamônio, utilizando copolímeros aleatórios. A mistura estequiométrica de poli-íons e surfatantes opostamente carregados geralmente leva à separação de uma fase concentrada em sal complexo. Esta fase pode apresentar diferentes estruturas (cristais líquidos ou sistemas micelares) e é interessante para aplicações como moldes para matérias mesoporosos e alguns cosméticos, mas inviabiliza o seu uso em soluções aquosas, como por exemplo, para carreadores de fármacos. Para evitar a separação de fases de sais complexos em água, a estratégia utilizada neste trabalho foi usar copolímeros que possuem comonômeros aniônicos e cadeias laterais hidrofílicas. Dentro do contexto de se estudar complexos de copoli-íons, este projeto também envolve o estudo de sais complexos formados por um copolímero que possui comonômeros hidrofóbicos e hidrofílicos, para verificar seu efeito sobre o comportamento de fases. Para identificar e caracterizar as fases formadas, a principal técnica usada foi a de espalhamento de raios-X a baixos ângulos, que permitiu determinar os diagramas de fases. Também permitiu, em conjunto com o resultado de outras técnicas (espalhamento de luz dinâmico, difusão por ressonância magnética nuclear, tensiometria e fluorescência), mostrar que alterações na estrutura dos polímeros diversifica as estruturas formadas pela autoassociação do surfatante e, consequentemente, suas propriedades / Abstract: This project is part of a research in our group involving the selfassembly of ionic surfactants neutralized by polymeric counterions, forming the so-called complex salts. The main goal of this study is to verify the effect of different architectures or different chemical compositions of polyanions on the self-assembly of the cationic surfactant hexadecyltrimethylammonium, by using different random copolymers. The stoichiometric mixture of poly-ions and oppositely charged surfactants generally leads to the separation of a phase concentrated in complex salt. This phase can display different structures (liquid crystal or micellar systems) and is interesting for applications such as templates for mesoporous materials or cosmetics, but forbids the use in aqueous solutions, such as for drug carriers. To avoid phase separation of complex salts in water, the strategy was to use copolymers with anionic comonomers and hydrophilic neutral side-chains. In the context of studying complex salts of copolyions, this project also involves the study of complex salts formed by a copolymer with both hydrophilic and hydrophobic comonomers, to verify the effect on the phase behavior. In order to identify and characterize the obtained phases, the main technique used was small angle X-ray scattering, which provided information to determine the phase diagrams. These data along with the results from other techniques (dynamic light scattering, nuclear magnetic resonance, surface tension measurements and fluorescence) show that changes on the polymer structure provide a diversification of the surfactant assembles and, as a consequence, of the resulting properties / Doutorado / Físico-Química / Doutora em Ciências