Flotação é uma operação unitária à base de química de superfície que envolve a captura de partículas hidrofóbicas por bolhas de ar na suspensão aquosa, na qual são transportadas para a superfície, com posterior remoção desta camada de espuma. Por outro lado, porque as partículas hidrofílicas não aderem a bolhas de ar, elas tendem a afundar e ir para o fluxo inferior do tanque de flotação. A separação de apatita-ganga através de flotação de espuma é o controle eficaz dos fenômenos de molhabilidade, que, por sua vez, determina a seletividade do processo. A regulação da interação de minerais (apatita e ganga) com moléculas de água (natureza hidrofílica) e também com as bolhas de ar (natureza hidrofóbica) é conseguida com a adição de reagentes químicos (coletores, modificadores e espumantes) na polpa de flotação. Adsorção de reagentes químicos na interface mineral/solução é o método mais eficaz para promover a hidrofobicidade das partículas de apatita (favorecendo sua flotação) e também reforçar a hidrofilicidade dos minerais de ganga, inibindo sua flotação. Este trabalho tem o objetivo de construir uma curva de calibração para o coletor Berol®867 através do método colorimétrico de Bradford, método na presença do corante Coomassie Brilliant Blue. Medidas simulando condições típicas de flotação foram também realizadas em laboratório. Medições em soluções de flotação foram realizadas pelo tensiômetro IP6000 que baseia-se no método da pressão máxima de bolha (MPMB) na qual é muito mais adequado para líquidos puros, mas não para soluções aquosas contendo surfactantes. Por conseguinte, os valores de L/G obtidos por MPMB são deterministicamente superiores aos gerados pelo Método com Wilhelmy (MPW), que é considerada como sendo adequada para soluções contendo tensioativos, mas não suficientemente robusta para aplicações industriais in-situ. / Froth flotation is a chemistry-based surface unit operation that involves the capture of hydrophobic particles by air bubbles in aqueous slurry, followed by levitation and collection in a froth layer. Conversely, because hydrophilic particles do not adhere to air bubbles, they are likely to sink and go to the underflow of the flotation cell. The selectivity of apatite-gangue separation via froth flotation is determined by the efficient control of the wetting phenomena. Adding chemical reagents to the flotation pulp, like collectors or frothers, it is possible to regulate the interfacial affinity of each mineral, apatite or gangue, turning them hydrophilic or hydrophobic. Adsorption of chemical reagents onto interfaces is the most effective approach to promote the hydrophobicity of the mineral, which is desired to float, and also the reinforcement of the wettability by water of the minerals which are desired to sink. This work had as objective to construct a calibration curve for the Berol®867 collector through the Bradford colorimetric method in the presence of Coomassie Brilliant Blue dye. Measurements simulating typical flotation conditions were also run at the laboratory. Measurements of flotation solution performed by tensiometer IP6000 are based on the Maximum Bubble Pressure Method (MBPM) which is very suitable for pure liquids, but not for aqueous solutions containing surfactants. Therefore, the values of ?LG yielded by MBPM are deterministically higher than those yielded by the Wilhelmy Plate Method (WPM), which is regarded as suitable for surfactant solutions but not sufficiently robust for in-situ industrial applications.

Nesta pesquisa teve-se como objetivo estudar as propriedades físicas de polpas de açaí disponíveis comercialmente, tais como: pH, condutividade, viscosidade, tensão superficial e atenuação acústica, em função da temperatura e de particulados presentes na suspensão de açaí. Foram selecionadas quatro marcas comerciais de polpa de açaí originárias da região norte do Brasil. As amostras foram estudadas na forma pura (sem diluição) e diluídas. As análises de tensão superficial foram conduzidas utilizando o tensiômetro da Sensadyne (modelo QC6000) na faixa de temperatura de 15ºC a 60ºC. Observou-se uma variação da tensão superficial entre as marcas estudadas e em todos os casos a polpa de açaí diluída apresentou tensão superficial superior à polpa pura. Para valores de temperatura maiores que 45ºC, a tensão superficial aumentou com a temperatura para duas marcas estudadas. A verificação da atenuação e do tamanho de partículas foi realizada utilizando a técnica de espectroscopia de atenuação acústica com o equipamento APS-100 (Matec Applied Science, Northborough, USA). A polpa diluída apresentou uma menor atenuação com relação à polpa pura. As polpas de açaí, pura e diluída, apresentaram partículas com tamanho inferior a 0,6 µm de diâmetro, sendo que a polpa pura apresentou partículas com diâmetros maiores. Na investigação reológica foram utilizados reômetros rotacionais (Modelo DVIII+) da marca Brookfield com geometrias de cone-placa e cilindros concêntricos na faixa de temperatura de 15ºC a 60ºC. Os reogramas obtidos foram ajustados aos modelos de Ostwald-de-Waale (Lei da Potência) e Herschel-Bulkley, sendo que o melhor ajuste foi obtido com o modelo de Lei da Potência. Todas as amostras estudadas apresentaram comportamento reológico não-Newtoniano, com características de fluidos tixotrópicos. Foi investigado também o comportamento reológico de polpas de açaí tratadas enzimaticamente para posterior processamento por microfiltração tangencial. As enzimas comerciais Pectinex Ultra SP-L, Biopectinase KK Plus e Ultrazym AFPL foram avaliadas separadamente e a respectiva eficiência foi analisada pela redução da viscosidade no reômetro rotacional com a geometria de cone-plana. A enzima comercial Ultrazym foi mais eficiente na redução da viscosidade aparente da polpa de açaí, sendo que as enzimas Pectinex e Biopectinase não apresentaram alteração significativa da viscosidade. A análise da viscosidade aparente dos produtos (permeado e retentado) da microfiltração utilizando membranas cerâmicas comerciais de 0,8 e 0,2 \'mü\'m foi feita utilizando o reômetro rotacional com a geometria de cone-placa, na temperatura de 25ºC. Para o processamento por microfiltração sem tratamento enzimático, o retentado apresentou valores de viscosidade aparente superior ao permeado e à polpa diluída, enquanto que a polpa diluída apresentou viscosidade aparente superior ao permeado. Na microfiltração com tratamento enzimático a polpa diluída apresentou viscosidade aparente inferior ao permeado, comportamento observado para as duas membranas estudadas (0,8 e 0,2 \'mü\'m). Com os resultados obtidos foi possível verificar a grande variação nas propriedades físicas de polpas comerciais de açaí e com isso, a importância de se realizar tais medidas para a otimização de processos como a microfiltração tangencial. / The main objective of this research was the study of physical properties of commercial types of açaí pulp; including pH, electric conductivity, viscosity, surface tension and acoustic attenuation as a function of temperature and particulates of açaí suspension. Four types of açaí pulp from north region of Brazil were selected. The samples were analyzed in pure (undiluted) and diluted form. Surface tension was measured with Sensadyne tensiometer (model QC6000) in the temperature range: 15º to 60º Celsius. In all types of pulp studied the surface tension of diluted sample was higher than pure sample. For temperatures above 45º Celsius surface tension increased for two types of açai pulp studied. Acoustic attenuation and particle size of samples were analyzed with the equipment APS-100 from Matec Applied Science, Northborough, USA. Acoustic attenuation of diluted samples is smaller for pure samples; the açaí pulp (pure and diluted) has particle sizes below 0,6 µm and the particle sizes of the pure samples were larger than the diluted samples. Brookfield/USA rotational rheometers (Model DVIII+) was employed for rheological analysis with two geometries: cone-plate and concentric cylinders in the temperature range: 15º to 60º Celsius. The rheological behavior was adjusted by Ostwald-de-Waale model (or Power-law model) and Herschel-Bulkley model; the Ostwald-de-Waale model showed a better fit. All brands of pulp studied presented non-Newtonian behavior with tixotropic characteristics. It also investigated the rheological behavior of açaí pulp treated enzymatically for later processing by tangential microfiltration. The commercial enzymes: Pectinex Ultra SP-L (Novozymes - Bagsvaerd, Dinamarca), Biopectinase KK Plus (Kerry Bio-Science) and Ultrazym AFPL (Novozymes - Bagsvaerd, Dinamarca), were utilized to reduce viscosity and the effect was evaluated with the cone-plate geometry of the Brookfield/USA rheometer (Model DVIII+). The data shows that the Ultrazym enzyme was the best option for viscosity reduction of açaí pulp, and the other presented no changes in the viscosity. The viscosity of the retentate and permeate from the microfiltration process (membranes with cut-off 0,8 and 0,2 µm) was determined with the cone-plate geometry of the Brookfield/USA rheometer (Model DVIII+) at 25º Celsius. In microfiltration process without enzymatic action, the apparent viscosity of retentate was always higher than the retentate from diluted pulp. With the results we observed the large variation in physical properties of commercial açaí pulp and thus, the importance of carrying out such measures for the optimization of processes such as tangential microfiltration.

O presente trabalho tem como proposição investigar a hipótese de que a diminuição da tensão superficial do líquido favorece o comportamento reológico de suspensões concentradas, uma vez que as partículas estão mais próximas e a contribuição da força de capilaridade possivelmente aumenta. Como suspensões concentradas tendem ao comportamento viscoelástico, investigou-se métodos reológicos propícios para analisar possíveis consequências devido à alteração da tensão superficial da água. Foram utilizados dois carbonatos de cálcio equivalentes (P1 e P5) que se diferenciam pela distribuição granulométrica. Utilizou-se dois dispersantes de mercado e etilenoglicol como modificadores de tensão superficial. A análise de superfície pelo ensaio de potencial zeta, revelou carga superficial positiva. Embora os pós sejam equivalentes, a mobilidade eletroforética do P5 é menor. Verificou-se que o íon cálcio é determinante do potencial. Verificou-se contribuição eletrostática apenas dos dispersantes. O ensaio de gota pendente constatou diminuição da tensão superficial da água com os três aditivos. Ensaios de ascensão capilar pelo método de Washburn revelaram maiores ângulos de contato para ensaios com aditivos, sendo menor para P5. Avaliou-se geometrias e métodos reológicos a fim de selecionar bom conjunto para medidas de viscoelasticidade, sendo oscilatório de tensão e geometria vane escolhidos. O acréscimo dos dispersantes resultou em menores valores de G\' e tensões de escoamento, enquanto o etilenoglicol resultou em maiores. Não há relação clara entre valores calculados de ângulo de contato e mobilidade eletroforética. Os ensaio reológicos e de mobilidade relacionaram-se apenas para os dispersantes. A hipótese foi verificada pelos valores de tensão de escoamento e IPS. Para os dispersantes, foi possível observar comportamento próximo à hipótese, quanto menor foi a tensão superficial do líquido, menores valores de tensão para menores IPS. Explorou-se também a hipótese pelos ensaios de ângulo de contato, observou-se novamente curva próxima a hipótese. Embora necessidade de mais ensaios, o presente trabalho contribuiu para metodologia de exploração de características de superfície, dispersão e reológicas de suspensões concentradas. / The proposition of the present work is to investigate the hypothesis that the reduction of the surface tension of the liquid favors the rheological behavior of concentrated suspensions, since the particles are closer and the contribution of capillarity forces possibly increases. As concentrated suspensions tend to viscoelastic behavior, rheological methods were examined to analyze possible consequences due to changes of surface tension of the water. Two equivalent calcium carbonates (P1 and P5) were used and differ by particle-size distribution. Two market dispersants and ethylene glycol were used as surfactant. Surface analysis by the zeta potential test revealed positive surface charge and, although the powders are equivalent, the electrophoretic mobility of P5 is lower. The reults show that calcium is potential determining ion. Electrostatic contribution was found only for the dispersants. Pendant drop test showed a decrease in the surface tension of the water with the three additives. Washburn capillary rise technique estimated greater contact angles for tests with additives and lower ones for P5. Rheological geometries and methods were evaluated in order to select good set for viscoelasticity measurements, choosing oscillatory stress sweep and vane geometry. The addition of the dispersants resulted in lower values G \'and yield stress, while ethylene glycol resulted in higher values. There is no clear relation between contact angle and electrophoretic mobility. The rheological and eletrophoretic mobility showed relation only for dispersants. The hypothesis was verified by the values yield stress and IPS. For the dispersants, it was possible to observe behavior close to the hypothesis, the lower the surface tension of the liquid, the lower the yield stress for lower IPS. The hypothesis was also explored by the contact angle tests, a curve next to the hypothesis was observed again. Although the need for more tests, the present work contributed to the methodology of exploration of surface characteristics, dispersion and rheological characteristics of concentrated suspensions.

No laboratório de Análise, Processamento e Reologia de Materiais Poliméricos da Escola Politécnica da USP tem sido estudadas blendas de Poliamida-6 (PA-6) e filme de poli(vinil butiral) (PVB), como uma alternativa para reciclagem do filme de PVB oriundo do processo de separação dos componentes do vidro laminado pós-consumo. As propriedades mecânicas de uma blenda polimérica dependem da sua morfologia e, por sua vez, a morfologia depende das propriedades reológicas e da tensão interfacial entre os polímeros formadores da blenda, que para o caso de blendas envolvendo filme de PVB podem mudar em função da concentração de plastificante presente na composição do filme. Apesar da importância do seu conhecimento, a tensão interfacial entre PA-6 e filme de PVB não é conhecida. O presente trabalho teve como objetivo avaliar a tensão superficial do filme de PVB e da PA-6. O método utilizado foi o da gota pendente. Também estudou-se a influência da adição de plastificante na tensão superficial do filme de PVB. Os resultados mostraram que a tensão superficial dos polímeros estudados decresce com o aumento da temperatura (temperatura variando entre 240 e 260ºC). Em particular, para o filme de PVB a entropia de superfície ( (d/dT) ) apresentou um valor acima dos normalmente encontrados para polímeros fundidos. Este comportamento foi atribuído à estabilidade térmica do filme. O filme de PVB utilizado nos ensaios de tensão superficial foi caracterizado por Espectroscopia no Infravermelho (FTIR), Espectroscopia no Ultravioleta/Visível (UV-VIS), Espectroscopia Eletrônica para Análise Química (ESCA) e Análise Termogravimétrica (TG). Os resultados obtidos comprovaram que há mudanças na estrutura do PVB durante sua exposição a temperaturas elevadas, por longo período de tempo (condições do ensaio de tensão superficial). Foi observado, primeiramente, a evaporação do plastificante, seguida por perda de grupos polares (-OH, C=O e C-O-C) presentes na estrutura do PVB. A tensão superficial da Poliamida-6 foi determinada para temperaturas de 250 e 260ºC. Os resultados mostraram que a PA-6 manteve-se estável durante os ensaios. / In the Rheology and Polymer Processing Laboratory of Escola Politécnica of the University of São Paulo, Polyamide-6 / poly(vinyl butiral) film blends have been studied as an alternative for the recycling of post-consumption laminated glasses. The mechanical properties of these blends were studied and explained in light of their morphology. The morphology of polymer blends strongly depends on the rheological behavior of the blend and on the interfacial tension between the polymers forming the blend. In the case of Poliamide-6 (PA-6)/poly(vinyl butiral) (PVB) film blends, the interfacial tension depends on the plasticizer concentration present in PVB film. However, to our knowledge neither the PA-6/PVB film interfacial tension nor the surface tension of PVB film at temperatures above softening temperatures have been evaluated. In this work, the surface tension of poly(vinyl butyral) and polyamide was evaluated using the pendant drop method. Also it was tried to evaluate the surface tension of PVB film as a function of plasticizer content. The surface tension values obtained were in the same range as the ones obtained for other molten polymers: the surface tension decreases with increasing temperature (for temperatures ranging from 240 to 260°C). However, the value of PVB film surface entropy ((d/dT) where is the surface tension and T is the temperature) was much larger than values reported for other molten polymers. This result was attributed to thermal stability of PVB film during the surface tension measurement. The drops of PVB film after surface tension analysis were examined for any change in their functional groups using infrared spectroscopy (FITIR), ultraviolet-visible spectroscopy (UV/VIS), electron spectroscopy for chemical analysis (XPS/ESCA) and thermogravimetric analysis (TG). The results showed that changes in the chemical structure of PVB film occur during surface tension measurement. First, the plasticizer within the PVB film evaporates and, then, the PVB suffers reduction of polar units and creation of C=C bonds. The surface tension of PA-6 was evaluated for temperatures of 250 and 260°C. The PA-6 remained stable during tests.

No description available.

Cette thèse porte sur l’étude de trois phénomènes interfaciaux reliés à l’eau : (i) la diffusion de protons dans un environnement complexe, (ii) la formation de gouttes et (iii) le déplacement d’huile sous l’effet du déplacement d’une phase aqueuse dans un circuit microfluidique poreux. Dans un premier temps, nous étudions une « quasi-interface », constituée de deux solutions complexes aqueuses de différents pH, telles qu’on les trouve dans les milieux cellulaires. La diffusion des protons ainsi que les dynamiques de réorientation des molécules d’eau sont examinés et nos résultats suggèrent que le transport des protons serait médié par des molécules tampons. La deuxième partie de cette thèse porte sur la rupture de gouttes à l’interface liquide/air. La rupture de gouttes de fluides non-visqueux est un phénomène extrêmement riche et sa description théorique constitue un des cas les plus simples des singularités à temps fini. Dans le chapitre 4 on met en évidence par l’imagerie ultrarapide que l’eau possède une tension de surface dynamique à l’échelle de la milliseconde. Dans le chapitre 5, on s’intéresse à la dynamique de rupture de métaux en évaluant si des mesures électriques permettent de se rapprocher temporellement (et spatialement) au plus près de la rupture (ns). Dans la dernière partie (chapitre 6), on revisite le problème classique du déplacement d’huile avec de l’eau, rencontré dans les techniques de récupération assistée du pétrole (RAP). On s’intéresse au rôle de la topologie de surface de la roche poreuse sur le piégeage de gouttes d’huile et dégage une loi d’échelle générale liant les effets de la rugosité au déplacement du fluide au sein du canal. / Water is the most abundant molecule on earth, indispensable for a plethora of chemical reactions and vital to the functioning of most living organisms. Interfacial water is particularly interesting to study as its physicochemical properties deviate significantly from the bulk whilst being of crucial importance to both fundamental research and industrial process design. In this thesis we study the interfacial water dynamics of three highly relevant phenomena by primarily recurring on microfluidics and ultrarapid imaging approaches. The first part focusses on proton diffusion in complex aqueous environments such as the the cytoplasm which remains a central issue in the biowater controversy. We evaluate and discuss the relevance of different proton diffusion mechanisms in cellular mimic solutions. The second part of this thesis is centred around droplet formation dynamics which are not only omnipresent in nature and technology, but also constitute a very rich phenomenon involving finite time singularities. We evaluate the outstanding pinch-off behaviour of water and aqueous solutions at the water/air interface that significantly deviates from other comparable non-viscous liquids on the millisecond time scale. In the last part we study a three phase system consisting of water and oil embedded in different ‘rough’ microstructures. Surface topology is identified as important determinant for the relative wettability behaviour of oil and water which constitutes a key finding for the development of efficient and environmentally compatible enhanced oil recovery strategies.

Les phénomènes de mouillage et la rhéologie des fluides à seuil sont deux domaines de la physique des matériaux mous dans lesquels de grandes avancées ont été faites lors des derniers siècles. De plus ces questions sont d'une grande importance au niveau des applications industrielles, ce qui contribue à leur dynamisme. En revanche, le mouillage des fluides à seuil a été peu étudié, alors que c'est une situation fréquente. En effet, presque tous les fluides rencontrés dans l'industrie et la vie quotidienne sont des fluides à seuil. D'autre part, la connaissance des propriétés de mouillage est cruciale lors de leur manipulation car la plupart des processus font intervenir des interfaces.Dans ma thèse, je m'intéresse aux questions suivantes : comment la tension de surface apparente est-elle affectée par le seuil ? Comment le seuil influence-t-il la dynamique du mouillage, habituellement décrite par la loi de Tanner ? Pourquoi l'angle de contact d'une goutte de fluide à seuil n'est-il pas prédit par la loi d'Young-Dupré ?J'ai réalisé des expériences sur un fluide à seuil modèle appelé carbopol. La première expérience a consisté à mesurer la force d'adhésion d'un pont capillaire, qui a été comparée au cas des fluides simples. Les résultats ont montré l'importance de l'histoire de la déformation et de l'élasticité du fluide. La seconde expérience a porté sur l'étalement de gouttes sur une surface hydrophile. J'ai étudié la dynamique d'étalement, ainsi que l'angle de contact final. Alors que la dynamique est contrôlée par la viscoélasticité, l'état final est déterminé par le seuil / Wetting phenomena and yield-stress fluids rheology are subfields of soft matter physics where big understanding steps have been made during the last centuries. In addition, these two fields have very important potential implications for industry, which contributes to their dynamism. But their combination, the wetting of yield-stress fluids, has received little interest until the very last years, although it is a situation that happens all the time. Indeed, yield-stress fluids gather nearly all the fluids encountered in food industry, cosmetics, building industry, oil and gas industry… and wetting properties are crucial when processing or using the fluids, as many processes involve interfaces with air or a solid surface.In this thesis, I consider the following questions: how is the apparent surface tension affected by yield stress? How does the yield stress influence the wetting dynamics, classically described by Tanner’s law? Why can the final contact angle of a sessile drop of yield-stress fluid not be predicted by Young-Dupré’s theory?I performed experiments with a model yield-stress fluid called carbopol. The first experiment consisted in measuring the adhesion force of a capillary bridge and comparing it to the case of simple fluids. The main results show the importance of the deformation history and of the fluid elasticity. The second main experiment concerned spreading of drops on a hydrophilic surface. I studied the short-time dynamics and the long-time dynamics, as well as the final contact angle. The first regime is controlled by viscoelasticity, whereas the final state is determined by the yield stress

La complexité anatomique de l'endodonte implique un protocole d'irrigation efficace. L'hypochlorite de sodium doit donc pouvoir pénétrer dans l'ensemble du réseau endodontique afin d'exercer son activité antiseptique et protéolytique. Dans cet objectif, l'utilisation d'un tensioactif mélangé à l'hypochlorite de sodium constitue une approche potentiellement intéressante pour optimiser la pénétration et l'étalement de l'hypochlorite de sodium au sein du système canalaire. Cette thèse sur publications a donc pour objectif d'étudier l'influence de la modification de l'hypochlorite de sodium par adjonction de tensioactifs sur l'énergie interfaciale et la viscosité dynamique de la solution d'irrigation. Le premier chapitre décrit les enjeux, les différentes problématiques liées à l'irrigation ainsi qu'une revue de littérature critique des différentes techniques d'irrigation disponibles. Le second chapitre se focalise sur les propriétés physico-chimiques des solutions d'irrigation et sur des aspects plus spécifiquement liés à l'hydrodynamique et au mouillage des liquides et en particulier les notions d'énergie interfaciale, de concentration micellaire critique, de viscosité dynamique et de régime d'écoulement. Après une synthèse des aspects théoriques et des implications potentielles en endodontie, l'ensemble des matériels et méthodes expérimentales est détaillé dans le troisième chapitre. Le quatrième chapitre décrit l'influence de l'adjonction d'un tensioactif sur le mouillage de la solution d'irrigation sur la base d'une étude préliminaire et d'études complémentaires ayant abouti à une première publication internationale. Le cinquième chapitre décrit l'influence de l'adjonction d'un tensioactif sur l'écoulement de la solution d'irrigation, cette étude ayant débouché sur une seconde publication internationale. Enfin, le sixième chapitre constitue la conclusion de ce travail et les perspectives de recherche sur la thématique. / The complexity of the root canal anatomy requires an efficient irrigation protocol. Sodium hypochlorite must penetrate in the whole of the endodontic system in order to be strongly active in terms of antiseptic and solvant properties. Therefore, the use of surfactants mixed to sodium hypochlorite is a promising approach to enhance the penetration depth and the spreading of endodontic irrigant within the root canal. The purpose of this thesis based on two international publications is to study the influence of surfactant addition to sodium hypochlorite on its surface tension and dynamic viscosity. The first chapter describes the different stakes, issues and irrigation techniques thanks to a critical review of the literature. The second chapter focuses on hydrodynamics and wetting properties especially surface energy, critical micellar concentration, dynamic viscosity and flow regimen. After a description of the theoretical aspects and the potential applications in root canal therapy, all the materials and methods used in this thesis are detailed in the third chapter. The fourth chapter describes the influence of surfactant addition on the wettability of endodontic irrigant on the basis of a preliminary study and several additional studies that led to a first international publication. The fifth chapter describes the influence of surfactant addition on the dynamic viscosity of endodontic irrigant and its flow regimen on the basis of a study which led to a second international publication.The final chapter of this thesis constitues the conclusion of this work and the associated prospects regarding this topic.

Vliv hyaluronanu na micelizaci tenzidů byl studován různými fyzikálně-chemickými metodami. Byly zvoleny dva kationaktivní tenzidy, a to tetradecyltrimethylammonium bromid (TTAB) a cetyltrimethylammonium bromid (CTAB). Metoda izotermické titrační kalorimetrie byla využita pro stanovení entalpie micelizace, tenziometrie popisuje povrchové vlastnosti daných vzorků. Byl sledován také vliv různé molekulové hmotnosti použitého hyaluronanu a délka alkylového řetězce tenzidu na agregační chování daného systému. Výsledkem jsou hodnoty kritické micelární nebo agregační koncentrace tenzidu. V neposlední řadě se diskutuje využití agregátů hyaluronan-tenzid jako možné nosiče pro cílenou distribuci léčiv.

This work deals with preparation of microbubble suspension from a mixture of phospholipids, palmitic acid and polyethylene glycol. Properties of prepared systems were studied using bubble tensiometry and dynamic light scattering method and were compared with commercial contrast agent SonoVue®. Suspensions were prepared in various conditions including different atmosphere and increased temperature in some steps of preparation and different solution. Effect of polyethylene glycol addition on surface activity of the system was studied. Surface activity of phospholipids was insignificant. Surface tension decreased with increasing concentration and molecular weight of polyethylene glycol in the system. Effect of different atmosphere and increased temperature showed no substantial trend. It emerged that dynamic light scattering is not suitable for this type of samples because of high polydispersity and phase separation of the system.