Most in-hospital deaths secondary to infections in under-five deaths within sub-Saharan Africa (SSA) occur in the initial 24 hours of admission and shock has been identified as a major risk factor for the early deaths. However, controversies exist on the appropriate clinical diagnosis of shock, choice of ideal fluid for resuscitation (crystalloid or colloid), and safety of fluid resuscitation in severe malnutrition or severe malaria. This thesis investigates these aspects and also reviews the evidence base of current paediatric fluid resuscitation guidelines for children (aged >60 days and ≤12 years) with severe febrile illnesses. Capillary refill time >2 seconds, weak pulse volume, or bradycardia, in the presence of abnormal temperature and severe disease are predictive of impaired perfusion (defined by lactic acidosis) and death. Tachycardia and temperature gradient are neither associated with increased risk of death nor predictive of hypoperfusion. Existing international definitions of shock have low sensitivities (FEAST=44%, WHO=2%, and ACCM=59%) and high specificities (FEAST=82%, WHO=100%, and ACCM=66%) for diagnosis of impaired perfusion. Clinical criteria derived (called derived shock) had a sensitivity of 30% and specificity of 93%. Shock in children with severe febrile illnesses in Kilifi has a complex presentation but mainly presents with hyperdynamic circulation (high cardiac index) and vasodilatation. Cases with low cardiac index (myocardial dysfunction) are relatively rare but increase the risk of mortality when present. Synthetic colloids (gelofusine, hydroxyethyl starch 130/0.4 (HES), and dextran 70) are safe for use in fluid resuscitation in children with severe malaria. However, HES is the most promising compared to other synthetic colloids concerns still remain about its renal safety. However, further evaluation of synthetic colloids for treatment of shock is not warranted due to the findings of FEAST trial. A Pilot trial shows that bolus isotonic fluids are safe, have better efficacy, and produce faster resolution of shock compared to low-sodium solutions at volumes and rates recommended by WHO in children with severe malnutrition. Evidence available from all ten the trials in children with sepsis show that fluid resuscitation using crystalloids and colloids result in similar survival. However, fluid bolus resuscitation results in increased mortality compared to no bolus (control) in children in SSA. This finding excludes children with gastroenteritis, trauma, burns, and malnutrition. Colloids are better than crystalloids for severe dengue shock but both have similar efficacy in moderate dengue shock.

The behaviour of colloidal particles in two-dimensional (2D) systems is addressed in real space and time using magnetic fields, optical tweezers and optical video microscopy. First, the fluctuations of a grain boundary in a 2D colloidal crystal are analysed. A real space analogue of the capillary fluctuation method is derived and successfully employed to extract the key parameters that characterise the grain boundary. Good agreement is also found with a fluctuation-dissipation based method recently suggested in simulation. Following on from analysis of the interface fluctuations, the properties of the individual grain boundary particles are analysed to investigate the long standing hypothesis that suggests that grain boundary particle dynamics are similar to those in supercooled liquids. The grain boundary particle dynamics display cage breaking at long times, highly heterogeneous particle dynamics and the formation of cooperatively moving regions along the interface, all typical behaviour of a supercooled liquid. Next, the frustration induced by confining colloidal particles inside a pentagonal environment is investigated. The state of the system is adjusted via two separate control parameters: the inter-particle interaction potential and the number density. A gradual crystalline to confined liquid-like transition is observed as the repulsive inter-particle interaction potential is decreased. In contrast, re-entrant orientational ordering and dynamical effects result as the number density of the confined colloidal particles is increased. Finally, the dynamics of colloidal particles distributed amongst a random array of fixed obstacle particles is probed as a function of both the mobile particle and fixed obstacle particle number densities. Increasing the mobile and the obstacle particle number density drives the system towards a glass transition. The dynamics of the free particles are shown to behave in a similar way to the normal glass transition at low obstacle density and more analogous to a localisation glass transition at high obstacle density.

Bentonite clay is intended to form one of the barriers in most repositories of spent nuclear fuel located in granite. One important function of the bentonite barrier is to retard transport of radionuclides in the event of waste canister failure. Bentonite has a high sorption capacity of cations and its main constituent is montmorillonite. In contact with groundwater of low ionic strength, montmorillonite colloids can be released from bentonite and thereby control transport of radionuclides sorbed onto the colloids. In colloid transport in bedrock fractures, size separation of clay colloids may occur due to physical and chemical interactions with the bedrock fracture surface. This may enhance or retard the overall transport of radionuclides, depending on the sorption capacities and stability of the differently sized clay colloids. The bentonite barrier will be exposed to γ-radiation from the spent nuclear fuel. Irradiation affects surface-related properties of bentonite. If an average sorption capacity value cannot be used for all colloid sizes or if sorption is affected by exposure to γ-irradiation, corrected sorption capacity values would give higher resolution in current reactive transport models. In order to study the size separation process, a protocol was developed and successfully applied to fractionate montmorillonite into different-sized colloid suspensions by means of sequential or direct centrifugation. The stability and sorption capacity were studied using these fractions. Both stability and sorption capacity were found to be similar for all colloid sizes. Bentonite exposed to γ-radiation sorbed less divalent cations with increasing radiation dose. The effect was not large enough to have any impact on diffusion. The presence of bentonite enhanced irradiation-induced corrosion of copper under anaerobic atmosphere. An average sorption capacity value for montmorillonite can be used for all colloid sizes in reactive transport models. The effect of γ-irradiation on sorption capacity is sufficiently large to require consideration in transport modelling. / Bentonite är planerad som en av barriärerna i de flesta slutförvar av använt kärnbränsle. Bentonite har en hög sorptionskapacitet för katjoner. Den huvudsakliga beståndsdelen av bentonit är montmorillonit. Montmorillonitkolloider kommer att frigöras från bentonitbufferten i kontakt med grundvatten av låg jonstyrka och på så vis styra transporten av sorberade radionuklider. Under den kolloidala transporten i bergsprickorna kan en separation med avseende på storlek uppstå genom interaktioner mellan kolloiderna och bergytan. Detta kan få till följd att den genomsnittliga transporten av radionuklider bromsas eller tilltar beroende på sorptionskapaciteten och stabiliteten av de olika kolloidstorlekarna. Bentonitbarriären kommer även att utsättas för γ-bestrålning från det använda kärnbränslet, vilket påverkar dess ytrelaterade egenskaper. Om inte ett medeltal för sorptionskapaciteten är giltigt för alla kolloidstorlekar eller om sorptionen påverkas av γ-bestrålning, behövs nya sorptionskapaciteter bestämmas och impliceras för noggrannare transportmodeller. En metod för att separera montmorillonitkolloider med avseende på storlek via direkt och stegvis centrifugering har utvecklats. Stabiliteten och sorptionskapaciteten för dessa fraktioner har studerats. Både stabilitet och sorptionskapacitet visade sig vara lika för alla kolloidstorlekar. Bestrålad bentonit sorberar mindre andel divalenta katjoner med ökad dos bestrålning. Effekten är dock inte stor nog för att slå igenom i diffusionsexperimenten. Förekomst av bentonit ökar även den strålningsinducerade korrosionen av koppar under anaeroba förhållanden. Ett medelvärde för sorptionskapaciteten kan användas för alla kolloidstorlekar i transportmodeller. Effekten av γ-bestrålning är dock stor nog för att implementeras i modellerna. / <p>QC 20150213</p>

Cette thèse porte sur le mouvement de particules colloïdales induit par l’effet thermoélectrique (ou effet Seebeck). Dans un électrolyte soumis à un gradient de température, les ions ont tendance à migrer à des vitesse qui différent d'une espèce à l'autre. On observe alors une accumulation de charge aux bords de l’échantillon. Ce déséquilibre induit un champ électrique qui agit sur les colloïdes chargés présents dans la solution. Cette contribution électrophorétique dans le champ de Seebeck s'additionne à la contribution directe de thermodiffusion. Comme résultat principal,nous obtenons la vitesse phorétique en fonction de la fraction volumique des particules et, dans le cas de polyélectrolytes, du poids moléculaire. Dans la seconde partie, nous étudions l’effet thermoélectrique pour une particule chauffée par absorption d’un faisceau laser. Le gradient de température est alors radial et l’effet Seebeck induit une charge nette dans le voisinage de la particule. Enfin, nous discutons les applications possibles de ce phénomène de thermocharge / In this work we study the motion induced in a colloidal dispersion by thethermoelectric or Seebeck effect. As its basic principle, the ions of the electrolytesolution start moving in a temperature gradient. In general, the velocity of one iondiffers from another. As a result, one observes a charge separation and a macroscopicelectric field. This thermoelectric field, in turn, acts upon the charged colloidalparticle present in the solution. Thus thermophoresis of the particle comprises of anelectrophoretic motion in the thermoelectric or Seebeck field. As an important result,we derive how the corresponding velocity of a colloidal particle depends upon thecolloidal volume fraction or on molecular weight for polymers. In a second part, westudy the thermoelectric effect due to a hot colloidal particle where a radialtemperature gradient is produced by the particle itself. In this temperature gradientthe same Seebeck effect takes place in the electrolyte solution. We find that the hotparticle carries a significant amount of charge around it. Whereas the amount ofsurface charges present at the boundaries of the sample container in the onedimensionalcase is rather insignificant. Possible applications of this thermochargingphenomenon are also discussed.

Colloid thrusters are under consideration for NASA missions such as the Laser Interferometer Space Antenna (LISA), which requires the continuous cancellation of external disturbances (approximately 25 microNewtons over a 3-10 year mission). Emissive probes are one diagnostic for the measurement of plasma potential, which can provide valuable information on the level of space-charge neutralization in a thruster plume. Understanding how to achieve effective space-charge neutralization of the positive-droplet thruster plume is important for efficient operation and to minimize the risk of contamination. In this Thesis we describe a laboratory electrospray (colloid) source and accompanying power processing electronics developed for testing of diagnostics in colloid thruster plumes. We present results of an initial series of emissive probe measurements using floating probe and swept bias probe techniques. These measurements were carried out using a single needle emitter operating on a mixture of EMI-IM (an ionic liquid) and tributyl phosphate. For a spray operating at a discharge voltage and current of 2.0kV and 200nA respectively, a potential of 5.0V was measured using the floating probe technique with the probe located at a distance of 2.7cm from the electrospray source. The interpretation of this floating potential as the plasma potential is discussed. In a separate set of tests, we used the swept bias emissive probe technique at the same distance and measured a plasma potential of 2.0V at a discharge voltage of 2.0kV. The discharge current in this latter test was somewhat unstable and varied from approximately 250 nA to over 1000nA. Numerical integration of the Poisson equation was performed to better understand space charge limitations of a probe emitting into a low density plasma. These results are presented and some implications for the measurements discussed. While the electrospray droplet number density was not measured, calculations to estimate this number density are also presented. Based on these estimates and our numerical calculations, the“knee" in the current voltage characteristic measured using the swept probe technique is estimated to be within 1.3 V of the actual plasma potential.

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / Neste trabalho, estudamos as propriedades do transporte de partÃculas em sistemas mesoscÃpicos. Na primeira parte, usamos o modelo proposto anteriormente por Zapperi et al. (Phys. Rev. Lett. 86, 3622 (2001)) para descrever o transporte de partÃculas superamortecidas e interagentes no estado estacionÃrio, na presenÃa de um obstÃculo para o fluxo, e confinadas em um canal com largura da ordem do comprimento caracterÃstico do sistema. Com este modelo, obtivemos uma equaÃÃo diferencial de primeira ordem nÃo-linear, cuja soluÃÃo em 1D à capaz de descrever a densidade ao longo de um canal 2D para diferentes sistemas de partÃculas (e.g., vÃrtices em supercondutores, colÃides e pedestres, todos simulados por dinÃmica molecular) e diferentes tipos de obstÃculos (e.g., uma barreira de energia, um canal com uma constriÃÃo e uma rede de pinos no centro do canal). Observamos que este modelo pode ser usado para descrever o escoamento de qualquer sistema de partÃculas superamortecido, desde que as interaÃÃes entre elas possam alcanÃar distÃncias maiores que os primeiros vizinhos. Na segunda parte deste trabalho, estudamos o escoamento de partÃculas interagentes (nÃo necessariamente superamortecidas) confinadas por paredes assimÃtricas. Aqui o objetivo à descrever a dinÃmica de pedestres e a dinÃmica de vÃrtices em supercondutores. Em ambos os sistemas, as paredes assimÃtricas sÃo responsÃveis pela introduÃÃo de um sentido preferencial para o fluxo. No caso da dinÃmica de pedestres, estudamos as propriedades do sistema quando os pedestres andam em sentidos opostos. Verificamos que este confinamento induz uma ordem responsÃvel pela maximizaÃÃo do escoamento. Esta ordem pode ser destruÃda quando variamos a densidade, a velocidade, a razÃo entre a largura do canal e a sua rugosidade, o ruÃdo externo e a assimetria do canal. Verificamos tambÃm que as transiÃÃes de ordem-desordem neste sistema sÃo acompanhadas de metaestabilidades e ciclos de histerese. No caso de vÃrtices em supercondutores, verificamos que, para pequenos campos de comensurabilidade entre o nÃmero de "catracas" e o nÃmero de vÃrtices, o sistema apresenta mÃltiplas transiÃÃes de depinamento. / In this work we investigate the transport properties of particles in mesoscopic systems. In the first part, we use the model originally proposed by Zapperi et al. (Phys. Rev. Lett. 86, 3622 (2001)) to describe the steady-state transport of overdamped particles in the presence of an obstacle and confined to a channel with width of the order of the characteristic size of the system. With this model, we obtain a non-linear first-order differential equation, whose solution in 1D is capable to describe the behavior of the particle density along a 2D channel for different particle systems (e.g., superconducting vortices, colloids and pedestrians, all simulated with molecular dynamics) and obstacle types (e.g, one energy barrier, a channel constriction and a network of pinning centers). We observe that such a model can be used to represent the flow of any system of overdamped particles, as long as the interactions between them can reach a distance greater than only the first neighbors. In the second part of this work, we investigate the flow of interacting particles (not necessarily overdamped) confined to a channel of asymmetrical walls. Here the main objective is to describe through molecular dynamics techniques both the flow of pedestrians as well as the transport of superconducting vortices through irregular channels. In both cases, we observe that the asymmetry of the confining walls can induce a preferential direction to the flow. In the case of pedestrians, our results indicate that, when two groups of people move in opposite directions in a ratcheted type of corridor, this induced order is also responsible for flow maximization. This order can be destroyed, however, when we change the total number of particles in the system, their target speed, the amplitude of the external added noise or the degree of the asymmetry of the channel. We also observe that the order-disorder transitions in this system are usually followed by metastability and hysteresis cycles. In the case of superconducting vortices, multiple depinning transitions are observed when there is a small comensurability field between the number of ratchets in the channel and the number of particles (vortices) in the system.

Les solutions colloïdales constituées de nanoparticules en solution sont une famille d'objets aux propriétés optiques uniques. Leur utilisation comme élement de base à la fabrication de composants optiques sublongueur d'onde pourrait permettre la naissance de nouvelles applications en particulier dans le domaine de l'optique intégrée et de la détection biologique. La manipulation de ces particules reste toutefois un défi en raison de leur taille et de leur dispersion aléatoire dans un milieu liquide. Dans ce contexte, nous avons réalisé des nouveaux composants optiques grâce au développement de techniques de fabrication basées sur la méthode d'assemblage capillaire assisté par convection. Deux types de structures ont été réalisés puis évalués en terme de comportement optique : les dimères métalliques d'Au et les microsphères diélectriques de polystyrène assemblées en chaînes ou en réseaux. Pour les dimères, une étude fondamentale a été effectuée sur les phénomènes plasmoniques régissant les propriétés optiques de ces objets. Leur potentiel en tant que détecteur ultrasensible SERS et nanoantenne à boîtes quantiques a ensuite été approfondi. Pour les microsphères, une étude sur la propagation et la diffusion des modes de galerie présents dans ces objets a tout d'abord été réalisée dans le but d'en faire des candidats pour la détection ultrasensible. Les propriétés de guidage de la lumière dans des assemblages en chaîne ont ensuite été traitées. Afin de compléter ce travail un dernier composant optique a été développé en complément des guides et capteurs colloïdaux déjà réalisés. Il s'agit d'une nouvelle génération d'émetteurs localisés conçus pour un usage large et versatile et qu'il est possible de définir comme microsource de lumière blanche. / Colloids -- e.g. nanoparticles in solution -- are objects that exhibit original optical properties. Their use as building block for fabrication of subwavelength optical components may allow novel applications in the field of integrated optics and biological detection. Anyway colloidal particles handling remains a challenge because of their small size and their random dispersion into a liquid medium. In this context, we created new colloidal optical components thanks to nanofabrication techniques based on the convective assisted capillary force assembly method. Two different kinds of structure were made and their optical behavior was studied: gold colloidal dimers and polystyrene dielectric microspheres assembled as chains or arrays. For the dimers, a fundamental study was performed on plasmonic phenomena that rule the optical properties of these objects. Next, their potential was evaluated in terms of ultrasensitive SERS sensor and also as optical nanoantenna of quantum dot emitters. For the microspheres, the propagation and scattering behaviors of whispering gallery modes that travel into the microspheres were first investigated. Their potential use as ultrasensitive sensors was also discussed. In addition, a second study was made on the guiding properties of linear microspheres chains. In order to complete this work, one last optical component was developped in addition to the fabricated colloidal waveguides and colloidal sensors. This component is a white light microsource that was designed for applications as a versatile localized emitter for integrated optics.

Die ellipsometrische Lichtstreuung wird als eine neue, leistungsfähige Methode zur Charakterisierung von Schichten um kolloidale Partikel vorgestellt. Theoretische Grundlage der Methode ist die Mie-Theorie der Lichtstreuung. Experimentell wurde die Polarisationsoptik eines Null-Ellipsometers in den Strahlengang eines Lichtstreuaufbaus eingebaut. Wie in der Reflexionsellipsometrie um den Brewsterwinkel herum erhält man in der ellipsometrischen Streuung einen Winkelbereich, in dem die Methode empfindlich auf Schichten an der Oberfläche der Partikel ist. An verschiedenen Systemen wurde die Tauglichkeit der ellipsometrischen Streuung zur Charakterisierung von Schichten auf Partikeln demonstriert. So wurden Dicke und Brechungsindex einer thermosensitiven Schicht von Poly(N-isopropylacrylamid) auf einem Poly(methylmethacrylat)-Kern bestimmt. Damit ist es möglich, experimentell den Schichtbrechungsindex und damit den Quellungsgrad zu bestimmen. Des Weiteren wurde der Einfluss der NaCl-Konzentration auf die Polyelektrolythülle von Poly(methylmethacrylat)-Poly(styrolsulfonat)-Blockcopolymer-Partikeln untersucht. Die Polyelektrolytketten liegen im hier untersuchten Beispiel nicht gestreckt vor. Als drittes wurde die Verteilung von niedermolekularen Ionen um elektrostatisch stabilisierte Poly(styrol)-Latexpartikel in Wasser untersucht. Hier wurde gezeigt, dass die beobachteten Schichtdicken und Schichtbrechungsindizes viel größer sind, als nach der klassischen Poisson-Boltzmann-Theorie zu erwarten ist. Des Weiteren wurde die Doppelbrechung von unilamellaren Lipidvesikeln bestimmt. Außerdem wurden Messungen der dynamische Lichtstreuung im Intensitätsminimum der Ellipsometrie durchgeführt. Dabei wird ein Prozess mit einer Korrelationszeit, die unabhängig vom Streuvektor, aber abhängig von der verwendeten Wellenlänge ist, sichtbar. Die Natur dieses Prozesses konnte hier nicht vollständig geklärt werden. / Ellipsometric light scattering is introduced as a new and powerful technique to characterize layers on colloidal particles. For the experiments, the polarization optics used reflection ellipsometry was installed in the beam of a light scattering setup. Using the priciples of null ellipsometry, a small range of scattering angles is obtained, were the method is sensitive to layers on the surface of colloidal particles. This is an analogy to the layer sensitivity of reflection ellipsometry at planer interfaces close to the Brewster angle. The theoretical basis for ellipsometric scattering is the Mie theory with its modern supplements. The feasibility of characterizing layers on colloidal particles was demonstrated with several systems. First, layer thickness and layer refractive index of poly(N-isopropylacrylamide) layers on a poly(methylmethacrylate) core were determined. This was the first time that the refractive index and with that the degree of swelling of a layer was directly determined in an scattering experiment. Second, polyelectrolyte layers on Poly(methylmethacrylate)-Poly(styrenesulfonate)-blockcopolymer particles were characterized. The influence of the salt concentration on the parameters of the layer was determined. The results show that the polyelectrolyte chains in the system investigated are not streched. Third, layers of ions around electrostatically-stabilized poly(styrene) particles were characterized. The layer thickness and layer refractive index in these examples are shown to be much larger than predicted by the classical Poisson-Boltzmann-theory. In addition, the birefringence of lipid vesicles was determined. Another interesting application of the ellipsometric scattering is the dynamic light scattering with ellipsometric optics. Its results show a characteristic process with a correlation time independent of the scattering vector, but wavelength dependent. The origin of this mode is not yet completely clarified.

Understanding the principles of self-organisation exhibited by block copolymers requires the combination of synthetic and physicochemical knowledge. The ability to synthesise block copolymers with desired architecture facilitates the ability to manipulate their aggregation behaviour, thus providing the key to nanotechnology. Apart from relative block volumes, the size and morphology of the produced nanostructures is controlled by the effective incompatibility between the different blocks. Since polymerisation techniques allowing for the synthesis of well-defined block copolymers are restricted to a limited number of monomers, the ability to tune the incompatibility is very limited. <br><br> Nevertheless, Polymer Analogue Reactions can offer another possibility for the production of functional block copolymers by chemical modifications of well-defined polymer precursors. Therefore, by applying appropriate modification methods both volume fractions and incompatibility, can be adjusted. Moreover, copolymers with introduced functional units allow utilization of the concept of molecular recognition in the world of synthetic polymers.<br><br> The present work describes a modular synthetic approach towards functional block copolymers. Radical addition of functional mercaptanes was employed for the introduction of diverse functional groups to polybutadiene-containing block copolymers. Various modifications of 1,2-polybutadiene-poly(ethylene oxide) block copolymer precursors are described in detail. Furthermore, extension of the concept to 1,2-polybutadiene-polystyrene block copolymers is demonstrated. Further investigations involved the self-organisation of the modified block copolymers. Formed aggregates in aqueous solutions of block copolymers with introduced carboxylic acid, amine and hydroxyl groups as well as fluorinated chains were characterised. Study of the aggregation behaviour allowed general conclusions to be drawn regarding the influence of the introduced groups on the self-organisation of the modified copolymers. Finally, possibilities for the formation of complexes, based on electrostatic or hydrogen-bonding interactions in mixtures of block copolymers bearing mutually interacting functional groups, were investigated. / Um die Prinzipien der Selbstorganisation von Blockcopolymeren zu verstehen, ist es notwendig das Wissen auf den Gebieten der Synthese und der Physikochemie zu kombinieren. Die Fähigkeit, Blockcopolymere mit gewünschter Architektur zu synthetisieren, gibt einem auch die Möglichkeit das Aggregationsverhalten zu steuern, was wiederum der Schlüssel zur Nanotechnologie ist. Abgesehen von den relativen Blockvolumina, wird die Größe und Morphologie der gebildeten Nanostrukturen durch die effektive Inkompartibilität zwischen den unterschiedlichen Blöcken bestimmt. Da die Polymerisationstechniken, mit denen man gut definierte Blockcopolymere synthetisieren kann, auf bestimmte Monomere beschränkt sind, läßt sich diese Inkompatibilität nur eingeschränkt abstimmen. Polymeranaloge Reaktionen können dagegen eine Möglichkeit bieten, funktionale Blockcopolymere durch die chemische Modifizierung von gut definierten Copolymeren zu erhalten. Somit können, bei Verwendung von geeigneten Modifikationsmethoden, die Volumenanteile sowie die Inkompatibilität der Blöcke angepasst werden. Außerdem können Copolymere, die funktionelle Gruppe enthalten, es ermöglichen das Prinzip der molekularen Erkennung (Schloss-Schlüssel) auf dem Gebiet der synthetischen Polymere anzuwenden.<br><br> Die vorleigende Arbeit beschreibt einen Ansatz zur modularen Synthese von funktionalen Blockcopolymeren. Durch radikalische Addition von funktionellen Mercaptanen wurden in Copolymere mit einem Polybutadien-Block verschiedenen funktionelle Gruppen eingebracht. Von 1,2-Polybutadien-Polyethylenoxid Blockcopolymeren werden dabei mehrere Modifikationen im Detail beschrieben. Zudem wird die Erweiterung des Konzepts auf 1,2-Polybutadien-Polystyrol Blockcopolymere gezeigt. Die weiteren Untersuchungen betrafen die Selbstorganisation der modifizierten Blockcopolymere in Lösung. Hierbei wurden die Aggregate, die in wässriger Lösung von Blockcopolymeren mit Carbonsäure-, Amin- und Hydroxylgruppen sowie fluorierte Ketten gebildet werden, charakterisiert. Die Untersuchung des Aggregationsverhaltens erlaubt es, generelle Aussagen über den Einfluss der eingebrachten Gruppen auf die Selbstorganisation der modifizierten Copolymere zu treffen. Abschließend wurde die Bildung von Komplexen auf der Basis von elektrostatischer Wechselwirkung oder Wasserstoffbrückenbindung in Mischungen aus Copolymeren, die untereinander Wechselwirkende funktionale Gruppe besitzen, untersucht.

Fibrin is the body's natural provisional matrix activated in response to vascular injury in which noncovalent knob:hole interactions between fibrin monomers lead to the assembly of fibrin for clot formation. In this study we aimed to exploit fibrin knob:hole affinity interactions with swelling, space filling microgels for the development of a potential bio-synthetic hybrid polymer system with hemostatic properties. Previous work has explored the inherent binding interactions of various fibrin knobs and their complementary polymerization holes, which have led to the development of fibrin knob peptide mimic (GPRPFPAC) with enhanced binding affinity for fibrin(ogen) holes. By coupling this enhanced fibrinogen binding peptide with a pNIPAm microgel system capable of being dynamically tuned and self-assembled, we hypothesized the specific and rapidly triggered formation of a bulk hydrogel in a wound environment (i.e. in the presence of fibrinogen). We found that at the peptide ligand density and concentrations of microgels used, that a rapid formation of a gel did not occur in the presence of fibrinogen alone. However with fibrinogen and thrombin, we found that fibrin network polymerization, structure, and viscoelastic properties were greatly altered in the presence of knob peptide-conjugated microgels.