A di-2-piridil cetona benzoilhidrazona (DPKBH) é um reagente solúvel em uma série de solventes orgânicos mas pouco solúvel em água. Vem sendo utilizado para a determinação de metais, (principalmente do grupo de transição) como Fe(II), Fe(III), Ni(II), Cu(II), entre outros e como ligante de referência para estudar o comportamento dos íons Fe(II) e Fe(III) em presença de espécies orgânicos encontrados em águas naturais. Com o objetivo de entender melhor as propriedades do DPKBH em meio de etanol, foi necessário determinar as constantes de dissociaçãolionização em diferentes porcentagens desse solvente orgânico (10, 19, 29 e 48 %). Nestas porcentagens de etanol, através de medidas absolutas de pH determinaram-se os pKs do DPKBH utilizando-se a técnica potenciométrica e em 10 e 48 % de etanol através de medidas absolutas de pH associadas às absorbâncias das espécies presentes nos equilíbrios, utilizando-se a técnica espectrofotométrica. Nas devidas porcentagens de etanol, o comportamento do eletrodo foi previamente determinado. Os valores de pK1 3,210; 3,342; 3,398 e 3,360 e de pK2 10,834; 11,013; 11,793 e 11,382 foram obtidos respectivamente para 10, 19, 29 e 48 % de etanol, utilizando-se a técnica potenciométrica. Através da técnica espectrofotométrica os valores de pK1 foram 3,257 e 3,322 e pK2 10,880 e 11,820, em 10 e 48 % de etanol, respectivamente. / The di-2-pyridyl ketone benzoylhydrazone (DPKBH) is a soluble reagent in different organic solvents but slightly soluble in water. It has been used for metal determinations, (mainly transition metals) such as for Fe (II), Fe(III), Ni(II), Cu(II) and also like a reference ligand to study the behavior of Fe(II) and Fe(III) ions in the presence of organic species found in natural waters. So as to better understand the DPKBH properties In ethanol, it was necessary to determine the dissociation/ionization constant in different percentages of ethanol (l0, 19, 29 and 48%). In these ethanol percentages, through absolute pH measurements, pKs of DPKBH could be the found by using the potentiometric technique, and in 10 and 48% of ethanol the pKs of DPKBH were determined with pH measurements associated to absorbance of the species present in the equilibria by using the spectrophotometric technique. In appropiate percentage of ethanol the behavior of the glass electrode was previously determined. The pK1 values 3.210; 3.342; 3.398 and 3.362, and pK2 10.834; 11.013; 11.793 and 11.382 were found for 10,19,29,48 % of ethanol, by using the potentiometric technique. The spectrophotometric technique led to pK1 values 3.257 and 3.322, and the pK2 ones 10.880 and 11. 820 in 10 and 48 % of ethanol respectively.

This thesis is mainly concerned with some important properties of complex fluids, and how these properties are influenced by structures in the nano/mesoscopic scale. Short-range assembly of the constituent molecules results in an amazing variety of phase behavior in these systems. Liquid-liquid phase transitions, or transitions from a homogeneous(mixed) phase to an immiscible phase (two-phase coexistence), are the outcome of a competition between entropy and short-ranged attractive forces, and form an important part of this thesis. A rich phase behavior is uncovered by a detailed study of liquid-liquid phase transitions in a mixture of ethanol(E) and water(W), induced by the addition of ammonium sulfate(AS) ions (E and W are otherwise completely soluble in each other). This is the main motivation for choosing this system. Furthermore, experimental evidence of the presence of supramolecular association in alcohol-water mixtures [J.-H. Guo et al., Phys. Rev Lett, 91, 15401(2003)] enhances our interest to study the phase behavior in more detail. The presence of a critical point, at which there is a second order phase transition, is quite common in complex fluids. An issue which has been the subject of extensive scientific research in recent years is the influence of nano/mesoscopic structure on the critical behavior of these fluids corresponds to the Ising universality class. However, the approach to the asymptotic regime is governed by a competition between the correlation length of critical concentration fluctuations and the additional length scale arising due to structuring., which results in a crossover from the universal Ising behavior to the mean-field behavior, sometimes within the critical domain. This phenomenon of crossover criticality is presently explored in the E + W + AS system. A significant portion of the thesis presents explorations on the critical behavior in the vicinity of special critical points (SCP), which are formed by the coalescence of two or more critical points. Recentrant liquid-liquid phase transitions observed in the E + W + AS system, furnishes an unique opportunity for the realization of three SCPs – the double critical point(DCP) and the critical double point(CDP) formed by the merger of two critical points , and a critical inflection point(CIP), formed by the merger of three critical points. A CIP had not been experimentally realized prior to the studies presented in this thesis. Apart from the above studies investigations are also carried out on the conformational changes of a technologically important conducting polymer, polyethylene dioxythiophene doped with polystyrene suflonate (PEDOT-PSS), in various solvents. The electrical and optical properties of the polymer films get enhanced when solution processed with specific solvents. The experiments presented in this thesis are directed at unraveling the role of conformational modifications in the electrical and optical properties of these systems. The experimental techniques that were employed in the present studies are: Laser light scattering, small-angle X-ray scattering(SAXS) measurements and visual observations. The eoexistence surface of the system E + W + AS was determined by visual observations. Laser light scattering measurements were conducted to study the critical behavior of osmotic susceptibility (xr) of E + W + As, whereas SAXS studies were conducted to ascertain the existence, and quantify the spatial extent of the additional length scale in the two systems investigated. The main objectives of this research were: (i) to study the phase behavior of the ternary mixture E + W + AS at atmospheric pressure; (ii) to check the existence of crossover from 3-D Ising to mean-field critical behavior while moving away from Tc in this system; (iii) to determine the nature (monotonic or nonmonotonic) of crossover; (iv) to provide some insight into the origin of this crossover behavior in terms of an additional length scale characteristic of the system; (v) to understand the evolution of the critical behavior in the proximity of CDP, and DCP; (vi) to experimentally realize the CIP; and (vii) to investigate the presence of solvent-induced conformational changes in conducting polymer.

A di-2-piridil cetona benzoilhidrazona (DPKBH) é um reagente solúvel em uma série de solventes orgânicos mas pouco solúvel em água. Vem sendo utilizado para a determinação de metais, (principalmente do grupo de transição) como Fe(II), Fe(III), Ni(II), Cu(II), entre outros e como ligante de referência para estudar o comportamento dos íons Fe(II) e Fe(III) em presença de espécies orgânicos encontrados em águas naturais. Com o objetivo de entender melhor as propriedades do DPKBH em meio de etanol, foi necessário determinar as constantes de dissociaçãolionização em diferentes porcentagens desse solvente orgânico (10, 19, 29 e 48 %). Nestas porcentagens de etanol, através de medidas absolutas de pH determinaram-se os pKs do DPKBH utilizando-se a técnica potenciométrica e em 10 e 48 % de etanol através de medidas absolutas de pH associadas às absorbâncias das espécies presentes nos equilíbrios, utilizando-se a técnica espectrofotométrica. Nas devidas porcentagens de etanol, o comportamento do eletrodo foi previamente determinado. Os valores de pK1 3,210; 3,342; 3,398 e 3,360 e de pK2 10,834; 11,013; 11,793 e 11,382 foram obtidos respectivamente para 10, 19, 29 e 48 % de etanol, utilizando-se a técnica potenciométrica. Através da técnica espectrofotométrica os valores de pK1 foram 3,257 e 3,322 e pK2 10,880 e 11,820, em 10 e 48 % de etanol, respectivamente. / The di-2-pyridyl ketone benzoylhydrazone (DPKBH) is a soluble reagent in different organic solvents but slightly soluble in water. It has been used for metal determinations, (mainly transition metals) such as for Fe (II), Fe(III), Ni(II), Cu(II) and also like a reference ligand to study the behavior of Fe(II) and Fe(III) ions in the presence of organic species found in natural waters. So as to better understand the DPKBH properties In ethanol, it was necessary to determine the dissociation/ionization constant in different percentages of ethanol (l0, 19, 29 and 48%). In these ethanol percentages, through absolute pH measurements, pKs of DPKBH could be the found by using the potentiometric technique, and in 10 and 48% of ethanol the pKs of DPKBH were determined with pH measurements associated to absorbance of the species present in the equilibria by using the spectrophotometric technique. In appropiate percentage of ethanol the behavior of the glass electrode was previously determined. The pK1 values 3.210; 3.342; 3.398 and 3.362, and pK2 10.834; 11.013; 11.793 and 11.382 were found for 10,19,29,48 % of ethanol, by using the potentiometric technique. The spectrophotometric technique led to pK1 values 3.257 and 3.322, and the pK2 ones 10.880 and 11. 820 in 10 and 48 % of ethanol respectively.

Drug administration through the pulmonary route is an ancient technique that evolved from inhaling the smoke of certain leaves as a medicine. The optimum droplet diameter for the pulmonary system deposition has been identified to be in the range from 2 to 3.5 μm, with potential deposition rates of up to 80% of this size range. Currently, the most used aerosol generator methods are the pressurized metered dose inhalers. However, they generally exhibit low deposition efficiency with less than 20 % of the spray reaching the target area of the lungs as most of the drug deposited in the upper airways. This is for the most part due to the droplet size polydispersity that is inherent in these systems. The droplets of the biggest diameter will deposit in the upper airways, and then the deposited medicine will be swallowed and absorbed in the gastrointestinal tract. This can produce adverse medical side effects. Electrospray (ES) or electrohydrodynamic atomization (EHDA) is a promising atomization process due to its ability to produce a spray with monodisperse droplet size. The current study will investigate the feasibility of using electrospray in a pulmonary drug delivery system. Assessments, selection and characterization of suitable biocompatible solvents that can be used as a lung obstruction relief drug were carried out. Tests to identify the electrospray setup necessary to produce droplet sizes in the appropriate range for deposition in the lungs were carried out. The study found that both stable and pulsating cone jet modes can produce the required droplet size and the pulsating mode can produce at least four times higher flow than stable cone jet mode. A low-cost image analysis technique developed for this work gave satisfactory results that could be compared to droplet size scaling laws from the literature. However, it proved to be relatively time consuming and further automation of this technique would make it more suitable for large-scale studies. The image analysis results show a correlation between the cone length, cone angle and the applied voltage. The droplet scaling laws discrepancies such as the solution flow rate exponent and the constant that is used by some scaling laws may be attributed to the droplet evaporation time which is quite short for the water/ ethanol solutions. The emitter diameter and the conductivity effect on the I(Q) power law and the sensitivity of the onset voltage (Vonset) to the liquid flow rate (Q), were demonstrated for solutions of triethylene-glycol (TEG), and for an ethanol-water mixture solution.