Foi estudado o comportamento eletroquímico de interfases Cu/H2SO4 0,5 mol L-1 na ausência e presença de compostos triazólicos - benzotriazol (BTAH) e tolitriazol (TTAH) e de surfactantes: dodecilsulfato de sódio (SDS aniônico) e cloreto de dodecilamônio (DAC catiônico) a 25ºC, empregando eletrodo parado e de disco rotativo (EDR). Foram empregadas como técnicas medidas de potencial de circuito aberto, polarização potenciostática e potenciodinâmica, cronoamperometria, espectroscopia de impedância eletroquímica e microscopia óptica. As características inibidoras do filme formado dependem da natureza dos aditivos e das condições hidrodinâmicas. As interfases contendo BTAH, TTAH, BTAH + TTAH, BTAH + SDS e TTAH + SDS apresentaram uma faixa ampla de potencial em que o cobre se mostrou passivado, chegando a 200 mV para a mistura BTAH + SDS empregando EDR. Densidades de corrente de passivação tão baixas quanto 2µA cm-2 foram observadas com EDR na presença de BTAH + TTAH. As misturas composto triazólico - surfactante mostraram filmes menos resistentes. Os surfactantes isolados não produzem faixa passiva e antecipam o potencial de oxidação do cobre com eletrodo parado. As misturas triazol - DAC só produzem faixa passiva com EDR. Todos os aditivos se mostraram inibidores para a reação H+/H2, destacando-se, com eletrodo parado, BTAH, TTAH e BTAH + TTAH. / The electrochemical behavior of 0.5 mol.L-1 Cu/H2SO4 interphases has been studied in the presence and in the absence of triazolic compounds-benzotriazole (BTAH) and tolitriazole (TTAH) and of surfactants - sodium dodecylsulphate (anionic, SDS) and dodecylammonium chloride (cationic, DAC) at 25ºC, using non-stirred electrode and rotating disc electrode (RDE). Open circuit potential, potentiostatic and potenctiodinamic polarization, chronoamperometry, electrochemical impedance spectroscopy, and optical microscopy were used as techniques. The inhibitive features of the formed film depend on both the nature of the additives and on the hydrodynamic conditions. The interphases containing BTAH, TTAH, BTAH + TTAH, BTAH + SDS e TTAH + SDS presented a wide potential range where the copper is passivated, reaching to 200 mV for BTAH + SDS mixture using RDE. Low passivating current densities (2µA cm-2) were observed with RDE in the presence of BTAH + TTAH. Triazolic compound?surfactant mixtures have originated less resistant films. Isolated surfactants do not originate passive ranges and anticipate the oxidation potential of copper under non stationary conditions. The mixtures triazole-DAC only produce passive range at stationary conditions. All the additives have shown to be inhibitors for the H+/H2 reaction, specially BTAH, TTAH e BTAH + TTAH using non stirred conditions.

Foi estudado o comportamento eletroquímico de interfases Cu/H2SO4 0,5 mol L-1 na ausência e presença de compostos triazólicos - benzotriazol (BTAH) e tolitriazol (TTAH) e de surfactantes: dodecilsulfato de sódio (SDS aniônico) e cloreto de dodecilamônio (DAC catiônico) a 25ºC, empregando eletrodo parado e de disco rotativo (EDR). Foram empregadas como técnicas medidas de potencial de circuito aberto, polarização potenciostática e potenciodinâmica, cronoamperometria, espectroscopia de impedância eletroquímica e microscopia óptica. As características inibidoras do filme formado dependem da natureza dos aditivos e das condições hidrodinâmicas. As interfases contendo BTAH, TTAH, BTAH + TTAH, BTAH + SDS e TTAH + SDS apresentaram uma faixa ampla de potencial em que o cobre se mostrou passivado, chegando a 200 mV para a mistura BTAH + SDS empregando EDR. Densidades de corrente de passivação tão baixas quanto 2µA cm-2 foram observadas com EDR na presença de BTAH + TTAH. As misturas composto triazólico - surfactante mostraram filmes menos resistentes. Os surfactantes isolados não produzem faixa passiva e antecipam o potencial de oxidação do cobre com eletrodo parado. As misturas triazol - DAC só produzem faixa passiva com EDR. Todos os aditivos se mostraram inibidores para a reação H+/H2, destacando-se, com eletrodo parado, BTAH, TTAH e BTAH + TTAH. / The electrochemical behavior of 0.5 mol.L-1 Cu/H2SO4 interphases has been studied in the presence and in the absence of triazolic compounds-benzotriazole (BTAH) and tolitriazole (TTAH) and of surfactants - sodium dodecylsulphate (anionic, SDS) and dodecylammonium chloride (cationic, DAC) at 25ºC, using non-stirred electrode and rotating disc electrode (RDE). Open circuit potential, potentiostatic and potenctiodinamic polarization, chronoamperometry, electrochemical impedance spectroscopy, and optical microscopy were used as techniques. The inhibitive features of the formed film depend on both the nature of the additives and on the hydrodynamic conditions. The interphases containing BTAH, TTAH, BTAH + TTAH, BTAH + SDS e TTAH + SDS presented a wide potential range where the copper is passivated, reaching to 200 mV for BTAH + SDS mixture using RDE. Low passivating current densities (2µA cm-2) were observed with RDE in the presence of BTAH + TTAH. Triazolic compound?surfactant mixtures have originated less resistant films. Isolated surfactants do not originate passive ranges and anticipate the oxidation potential of copper under non stationary conditions. The mixtures triazole-DAC only produce passive range at stationary conditions. All the additives have shown to be inhibitors for the H+/H2 reaction, specially BTAH, TTAH e BTAH + TTAH using non stirred conditions.

The thesis deals with the study of hydrophobic domains in phase separated hydrogels. Two types of polyelectrolytes (hyaluronan, dextran) and oppositely charged surfactants (carbethopendecinium bromide, sodium dodecylsulphate ) are used. Phase separated hydrogels are formed by electrostatic interactions. The target of the thesis is to study the polarity of environment in phase separated hydrogeles by fluorescence spectroscopy. Fluorescence measurements is performed by using pyrene, Nile red and laurdane as fluorescence probes. All probes are sensitive to the polarity of the environment. The results showed that probes can be expected in the polar environment of hydrogels.

This diploma thesis deals with the study of physical hydrogels based on positively-charged polyelectrolyte. The study is to investigate the interaction of selected positively-charged polyelectrolytes with oppositely charged surfactants in water and in physiologicla saline solution (0.15 M NaCl). The influence of the process for preparing hydrogels. Hydrogels were prepared by dry or wet. Were tested solubilization abilities hydrogels prepared using the hydrophobic dye oil red O were also measured rheological properties of the hydrogels prepared using frequency oscillatory tests and flow tests, depending on the concentration of the polymer or surfactant. For the rheological experiments suggest that chitosan is capable of forming rigid hydrogels with better mechanical properties than the dextran in the presence of both surfactants. Selected samples were also carried out experiments using fluorescent sold prodan, nile red and -naphthol as fluorescent probes. And in selected experiments was determined by solids content in percentage depending on the concentration used polyelectrolytes or surfactants.