A eletrodeposição de ligas magnéticas de ferro, níquel e cobalto, além de permitir um maior controle sobre a composição e geometria dos filmes obtidas apresenta um fenômeno curioso: o filme apresenta uma maior quantidade do metal menos nobre do que a concentração do íon metálico no banho, o que contradiz o esperado termodinamicamente. A esse fenômeno deu-se o nome de codeposição anômala. A codeposição anômala já foi bastante estudada e muitos mecanismos foram propostos, mas não há um consenso na comunidade científica sobre eles. Os aditivos são usados nesses banhos para diversos fins, mas fora o seu efeito na composição dos filmes pouco é conhecido sobre seu papel no processo. Essa tese apresenta estudos realizados na tentativa de compreender o mecanismo da codeposição anômala da liga CoNi e a influência de glicina, o aditivo escolhido, no fenômeno. Várias técnicas de análise acopladas às técnicas eletroquímicas são empregadas, como a microbalança eletroquímica de cristal de quartzo, a espectroscopia no infravermelho por reflexão externa e medidas de stress no crescimento do filme. A presença do aditivo no banho da liga altera a composição da mesma, aumentando a quantidade do metal menos nobre, cobalto. A análise gravimétrica sugere que o aditivo mantém o pH superficial por meio do efeito tamponante ao mesmo tempo em que complexa com os íons metálicos, o que ocorre mesmo em meio ácido onde a concentração do agente complexante, glicinato, é baixa. A diferença entre suas constantes de complexação com os íons metálicos explica seu papel na composição do filme. A glicina torna o mecanismo de redução do níquel semelhante ao do cobalto além de indicar a ocorrência de fenômenos de oxidação na superfície do mesmo. A glicina pouco se adsorve sobre o eletrodo, mas há indícios através do stress de haver uma adsorção inicial sobre o Au. Há evidências da ocorrência de adsorção de hidrogênio na superfície do eletrodo, o que, acoplado com os altos valores de calor de adsorção, sugerem que o fenômeno da codeposição anômala pode estar atrelado à adsorção de H sobre os diferentes metais / Magnetic alloys, mainly the ones made of Fe, Ni or Co, have great technological importance, being used in many parts of our daily life, such as in magnetic recording devices. The electrodeposition of those alloys, which enables a greater control over the process, presents a curious phenomenon: the film has a greater amount of the less noble metal than the bath, something not expected thermodynamically. This phenomenon is called anomalous codeposition and it has been widely studied and although many mechanisms are available none is unanimous amongst the scientific community. Additives have been used to various extents in this baths but outside of controlling the composition of the film little is known. This thesis presents studies attempting to comprehend the anomalous codeposition mechanism of CoNi alloy and to understand the influence of glycine, the additive chosen, on the phenomenon. Many analytical techniques, coupled with electrochemical ones, have been used, such as quartz crystal electrochemical microbalance, external reflection FTIR spectroscopy and stress measurements during the film growth. The presence of glycine in the bath alters the film composition by increasing the quantity of the least noble metal, cobalt. The analysis through gravimetry suggests that glycine keeps the pH values at the surface by acting as a buffer and at the same time it forms complexes with the metallic ions. The different values of complexation constants with different metals explains its role in the film composition. Glycine changes the nickel reduction mechanism to one similar to that of cobalt. Besides that, its presence indicates that oxidation phenomena are happening at the surface of nickel films. The additive shows no signs of adsorption on the electrode, but stress measurements indicates that perhaps an initial adsorption on gold may happen. There are evidences that hydrogen adsorption may be happening in the electrodes surface which, coupled with the high values of heat of adsorption, suggests that the anomalous codeposition phenomenon may be linked to the effect of this species on different metals.

A eletrodeposição de ligas magnéticas de ferro, níquel e cobalto, além de permitir um maior controle sobre a composição e geometria dos filmes obtidas apresenta um fenômeno curioso: o filme apresenta uma maior quantidade do metal menos nobre do que a concentração do íon metálico no banho, o que contradiz o esperado termodinamicamente. A esse fenômeno deu-se o nome de codeposição anômala. A codeposição anômala já foi bastante estudada e muitos mecanismos foram propostos, mas não há um consenso na comunidade científica sobre eles. Os aditivos são usados nesses banhos para diversos fins, mas fora o seu efeito na composição dos filmes pouco é conhecido sobre seu papel no processo. Essa tese apresenta estudos realizados na tentativa de compreender o mecanismo da codeposição anômala da liga CoNi e a influência de glicina, o aditivo escolhido, no fenômeno. Várias técnicas de análise acopladas às técnicas eletroquímicas são empregadas, como a microbalança eletroquímica de cristal de quartzo, a espectroscopia no infravermelho por reflexão externa e medidas de stress no crescimento do filme. A presença do aditivo no banho da liga altera a composição da mesma, aumentando a quantidade do metal menos nobre, cobalto. A análise gravimétrica sugere que o aditivo mantém o pH superficial por meio do efeito tamponante ao mesmo tempo em que complexa com os íons metálicos, o que ocorre mesmo em meio ácido onde a concentração do agente complexante, glicinato, é baixa. A diferença entre suas constantes de complexação com os íons metálicos explica seu papel na composição do filme. A glicina torna o mecanismo de redução do níquel semelhante ao do cobalto além de indicar a ocorrência de fenômenos de oxidação na superfície do mesmo. A glicina pouco se adsorve sobre o eletrodo, mas há indícios através do stress de haver uma adsorção inicial sobre o Au. Há evidências da ocorrência de adsorção de hidrogênio na superfície do eletrodo, o que, acoplado com os altos valores de calor de adsorção, sugerem que o fenômeno da codeposição anômala pode estar atrelado à adsorção de H sobre os diferentes metais / Magnetic alloys, mainly the ones made of Fe, Ni or Co, have great technological importance, being used in many parts of our daily life, such as in magnetic recording devices. The electrodeposition of those alloys, which enables a greater control over the process, presents a curious phenomenon: the film has a greater amount of the less noble metal than the bath, something not expected thermodynamically. This phenomenon is called anomalous codeposition and it has been widely studied and although many mechanisms are available none is unanimous amongst the scientific community. Additives have been used to various extents in this baths but outside of controlling the composition of the film little is known. This thesis presents studies attempting to comprehend the anomalous codeposition mechanism of CoNi alloy and to understand the influence of glycine, the additive chosen, on the phenomenon. Many analytical techniques, coupled with electrochemical ones, have been used, such as quartz crystal electrochemical microbalance, external reflection FTIR spectroscopy and stress measurements during the film growth. The presence of glycine in the bath alters the film composition by increasing the quantity of the least noble metal, cobalt. The analysis through gravimetry suggests that glycine keeps the pH values at the surface by acting as a buffer and at the same time it forms complexes with the metallic ions. The different values of complexation constants with different metals explains its role in the film composition. Glycine changes the nickel reduction mechanism to one similar to that of cobalt. Besides that, its presence indicates that oxidation phenomena are happening at the surface of nickel films. The additive shows no signs of adsorption on the electrode, but stress measurements indicates that perhaps an initial adsorption on gold may happen. There are evidences that hydrogen adsorption may be happening in the electrodes surface which, coupled with the high values of heat of adsorption, suggests that the anomalous codeposition phenomenon may be linked to the effect of this species on different metals.

Marek Spěšný - abstract This thesis has the nature of a survey report of a specific area. The task was to localize with the help of microgravimetry anomalous places in an area of a by-pass road construction, where subsurface inhomogeneities may possibly exist due to subsurface and surface historical mining of ceramic clay. The gravimetrical measurements were carried out with a relative gravimeter Scintrex model CG-5 AUTOGRAV. After the first stage of the gravimetrical measurements and following two weeks of recultivation works our assignment was to verify the success of the first measurements by the means of repeated microgravimetric control measurements. The results from both stages of measurement were processed into a 4D gravimetrical form. The results of the 4D gravimetry displayed that contrary to the expectations, the measured gravity of most of the area of interest decreased as much as by 30 ?Gal. We conclude that this is due to the drainage of injected material beyond the recultivated mining area, which washed and carried away a portion of the existing material. Our proposition was also supported by results of repeated leveling, which discovered subsidence of the road at times by up to 3 centimeters.

<p>Denna avhandling presenterar experimentella studier av polyelektrolytadsorption på motsatt laddade ytor, där substrat av både kiseloxid och blekt barrsulfatmassa har använts. Ett huvudsakligt syfte med denna forskning var att karaktärisera konformationen hos adsorberade skikt av katjonisk polyakrylamid (CPAM) i jämförelse med katjonisk dextran (Cdextran) och relatera denna information till inbindningskapaciteten av kolloidal kiselsyra. Ett andra syfte i denna avhandling var att studera kinetiken för sekventiell adsorption av polyamidamin epiklorhydrin (PAE) och karboxymetyl cellulosa (CMC) på massafibrer och att bestämma adsorptionsisotermer för deponering av polyelektrolyter skikt för skikt på massafibrer.</p><p>Adsorptionen av CPAM på kiseloxidytor studeras med stagnationspunkts-reflektometri och kvartskristalls-mikrogravimetri för att bestämma adsorptionskinetiken och mättnadsadsorptionens beroende av polyelektrolytens laddningstäthet, pH och NaCl koncentration. Konformationen hos adsorberade skikt av CPAM och Cdextran bestämdes både före och efter sekundär tillsats av kolloidal kiselsyra (CS) och adsorptionen av CS kvantifierades också som funktion av yttäckningen av polyelektrolyt.</p><p>Resultaten indikerar att laddningstätheten hos CPAM kontrollerar den adsorberade mängden på kiseloxidytor vid låga NaCl koncentrationer. Både adsorptionen av CPAM och Cdextran på kiseloxid visades vara effektiv i NaCl koncentrationer upp till 1 M, vilket indikerar ett signifikant bidrag av icke-jonisk interaktion mellan polyelektrolyterna och kiseloxid. Adsorptionen av CS var högre på föradsorberad CPAM än Cdextran. Konformationen hos de adsorberade skikten efter tillsats av CS sågs expandera signifikant för skikt baserade på CPAM medan skikt av Cdextran vid låga salthalter verkade återta sin konformation efter en temporär expansion.</p><p>I den andra delen av avhandlingen studerades sekventiell adsorption av PAE och CMC på massafibrer. Adsorptionsisotermer skikt för skikt på avkryllad massa visade att PAE adsorberade i större mängd än CMC, både i hänseende av massa och laddning. Adsorptionen av PAE var signifikant långsammare än CMC och adsorptionstiden till 90% av mättnadsadsorptionen bestämdes till 3 respektive 1 minut. Zetapotentialen för kryll bestämdes för adsorption av de två första polyelektrolytskikten och resultaten tydde på att kryllmaterialet omladdade inom en minut efter tillsatserna av polyelektrolyt. Reflektometriförsök inom sekventiell adsorption av PAE och CMC på kiseloxid antydde att den låga molekylviktsfraktionen av PAE störde uppbyggnaden av polyelektrolyt-multiskikten.</p> / <p>This thesis presents experimental studies of polyelectrolyte adsorption on oppositely charged surfaces, where substrates of both silica and bleached softwood kraft pulp were used. A major aim of this research was to characterise the conformation of adsorbed layers of cationic polyacrylamide (CPAM), in comparison to cationic dextran (Cdextran), and relate this information to the binding capacity of colloidal silica. A second aim in this thesis was to study the kinetics of the sequential adsorption of polyamide epichlorohydrine (PAE) and carboxymethyl cellulose (CMC) on pulp fibres, and to determine the adsorption isotherms for the layer-by-layer deposition of polyelectrolytes on pulp fibres.</p><p>The adsorption of CPAM on silica surfaces was studied using stagnation point adsorption reflectometry and quartz crystal microgravimetry to determine its adsorption kinetics as well as the dependencies of polyelectrolyte charge densities, pH, and NaCl concentration on saturation adsorption. The conformation of adsorbed layers of CPAM and Cdextran, analysed in terms of amount of water and layer thickness, was determined both before and after the secondary adsorption of colloidal silica (CS), and the adsorption of CS was also quantified as a function of the surface coverage of the polyelectrolyte.</p><p>Results indicate that the charge density of CPAM controlled the amount of the polyelectrolyte adsorbed on silica surfaces at low NaCl concentrations. The adsorption of both CPAM and Cdextran on silica was shown to be effective at up to 1 M NaCl concentrations, which indicates that non-ionic interactions between the polyelectrolytes and silica contribute significantly. CS adsorption was higher on pre-adsorbed CPAM than on Cdextran. The conformation of the adsorbed layer after CS addition was seen to expand significantly in CPAM-based layers, while the Cdextran layer appeared to restore its conformation after a temporary expansion at low salt concentrations.</p><p>In the second part of the thesis, the sequential adsorption of PAE and CMC on pulp fibres was determined using the polyelectrolyte titration technique. Layer-by-layer adsorption isotherms derived on fractionated pulp showed that PAE adsorbed in higher amounts than CMC did, both in terms of adsorbed mass and adsorbed charge. The adsorption of PAE was significantly slower compared to CMC, and the adsorption times required to reach 90% of the saturation adsorption were 3 and 1 min, respectively. The zeta potential of pulp fines was determined for the adsorption of the two first polyelectrolyte layers, and data indicated that the fines recharge within one minute after the polyelectrolyte additions. Reflectometry experiments regarding the sequential adsorption of PAE and CMC on silica indicated that the low-molecular-weight fraction of PAE disturbed the formation of polyelectrolyte multilayers.</p>

Denna avhandling presenterar experimentella studier av polyelektrolytadsorption på motsatt laddade ytor, där substrat av både kiseloxid och blekt barrsulfatmassa har använts. Ett huvudsakligt syfte med denna forskning var att karaktärisera konformationen hos adsorberade skikt av katjonisk polyakrylamid (CPAM) i jämförelse med katjonisk dextran (Cdextran) och relatera denna information till inbindningskapaciteten av kolloidal kiselsyra. Ett andra syfte i denna avhandling var att studera kinetiken för sekventiell adsorption av polyamidamin epiklorhydrin (PAE) och karboxymetyl cellulosa (CMC) på massafibrer och att bestämma adsorptionsisotermer för deponering av polyelektrolyter skikt för skikt på massafibrer. Adsorptionen av CPAM på kiseloxidytor studeras med stagnationspunkts-reflektometri och kvartskristalls-mikrogravimetri för att bestämma adsorptionskinetiken och mättnadsadsorptionens beroende av polyelektrolytens laddningstäthet, pH och NaCl koncentration. Konformationen hos adsorberade skikt av CPAM och Cdextran bestämdes både före och efter sekundär tillsats av kolloidal kiselsyra (CS) och adsorptionen av CS kvantifierades också som funktion av yttäckningen av polyelektrolyt. Resultaten indikerar att laddningstätheten hos CPAM kontrollerar den adsorberade mängden på kiseloxidytor vid låga NaCl koncentrationer. Både adsorptionen av CPAM och Cdextran på kiseloxid visades vara effektiv i NaCl koncentrationer upp till 1 M, vilket indikerar ett signifikant bidrag av icke-jonisk interaktion mellan polyelektrolyterna och kiseloxid. Adsorptionen av CS var högre på föradsorberad CPAM än Cdextran. Konformationen hos de adsorberade skikten efter tillsats av CS sågs expandera signifikant för skikt baserade på CPAM medan skikt av Cdextran vid låga salthalter verkade återta sin konformation efter en temporär expansion. I den andra delen av avhandlingen studerades sekventiell adsorption av PAE och CMC på massafibrer. Adsorptionsisotermer skikt för skikt på avkryllad massa visade att PAE adsorberade i större mängd än CMC, både i hänseende av massa och laddning. Adsorptionen av PAE var signifikant långsammare än CMC och adsorptionstiden till 90% av mättnadsadsorptionen bestämdes till 3 respektive 1 minut. Zetapotentialen för kryll bestämdes för adsorption av de två första polyelektrolytskikten och resultaten tydde på att kryllmaterialet omladdade inom en minut efter tillsatserna av polyelektrolyt. Reflektometriförsök inom sekventiell adsorption av PAE och CMC på kiseloxid antydde att den låga molekylviktsfraktionen av PAE störde uppbyggnaden av polyelektrolyt-multiskikten. / This thesis presents experimental studies of polyelectrolyte adsorption on oppositely charged surfaces, where substrates of both silica and bleached softwood kraft pulp were used. A major aim of this research was to characterise the conformation of adsorbed layers of cationic polyacrylamide (CPAM), in comparison to cationic dextran (Cdextran), and relate this information to the binding capacity of colloidal silica. A second aim in this thesis was to study the kinetics of the sequential adsorption of polyamide epichlorohydrine (PAE) and carboxymethyl cellulose (CMC) on pulp fibres, and to determine the adsorption isotherms for the layer-by-layer deposition of polyelectrolytes on pulp fibres. The adsorption of CPAM on silica surfaces was studied using stagnation point adsorption reflectometry and quartz crystal microgravimetry to determine its adsorption kinetics as well as the dependencies of polyelectrolyte charge densities, pH, and NaCl concentration on saturation adsorption. The conformation of adsorbed layers of CPAM and Cdextran, analysed in terms of amount of water and layer thickness, was determined both before and after the secondary adsorption of colloidal silica (CS), and the adsorption of CS was also quantified as a function of the surface coverage of the polyelectrolyte. Results indicate that the charge density of CPAM controlled the amount of the polyelectrolyte adsorbed on silica surfaces at low NaCl concentrations. The adsorption of both CPAM and Cdextran on silica was shown to be effective at up to 1 M NaCl concentrations, which indicates that non-ionic interactions between the polyelectrolytes and silica contribute significantly. CS adsorption was higher on pre-adsorbed CPAM than on Cdextran. The conformation of the adsorbed layer after CS addition was seen to expand significantly in CPAM-based layers, while the Cdextran layer appeared to restore its conformation after a temporary expansion at low salt concentrations. In the second part of the thesis, the sequential adsorption of PAE and CMC on pulp fibres was determined using the polyelectrolyte titration technique. Layer-by-layer adsorption isotherms derived on fractionated pulp showed that PAE adsorbed in higher amounts than CMC did, both in terms of adsorbed mass and adsorbed charge. The adsorption of PAE was significantly slower compared to CMC, and the adsorption times required to reach 90% of the saturation adsorption were 3 and 1 min, respectively. The zeta potential of pulp fines was determined for the adsorption of the two first polyelectrolyte layers, and data indicated that the fines recharge within one minute after the polyelectrolyte additions. Reflectometry experiments regarding the sequential adsorption of PAE and CMC on silica indicated that the low-molecular-weight fraction of PAE disturbed the formation of polyelectrolyte multilayers. / QC 20101112