Interfacial instabilities and wetting phenomena of phase separated colloid-polymer mixtures are addressed in this study. Colloidal particles offer certain advantages over molecular systems, due to their larger lengthscales and slower timescales. Moreover, the phenomena can be directly visualised using laser scanning confocal microscopy, and a perfect match with soft-lithography fabrication techniques can be exploited. In particular, we study the viscous fingering instability in three dimensions, focusing on the role of wetting conditions and of thermal fluctuations. Combined with results obtained by lattice Boltzmann simulations, we reveal that the cross-over of the meniscus in the direction across the channel thickness is controlled by the capillary and Peclet numbers, and viscosity contrast of the system. The curvature of the meniscus has a pronounced effect on the onset of the Saffman-Taylor instability, in which the formation of the viscous fingers is suppressed up to a certain threshold. Furthermore, we investigate a related contact line instability, which leads to entrainment and subsequent droplet pinch-off. A theoretical prediction for the onset of the instability is developed, which shows a good agreement with the experimental observations and yields a method to directly measure the slip length of the interface. The large thermal fluctuations of our interface play an important role in pinch-off events, leading to periodic emission of droplets of similar sizes. Finally, we study wetting phenomena at geometrically sculpted walls. We focus on the shape, the thickness and the radius of curvature of the adsorbed liquid film, and find good agreement with theory. Changing the curvature of the wedge from a flat surface to a capil- lary slit furthermore smoothly connects wetting behaviour and capillary condensation, again in qualitative agreement with theory. Non-equilibrium effects may interfere with the data and are difficult to rule out. We end with recommendations for future work.

Alpha 2 agonists are frequently used in equine medicine. This study focused primarily on α2 agonist-induced changes in PCV and TSP. A secondary aim of this study was to investigate the effects of α2 agonist on selected serum biochemical parameters and splenic size in order to identify potential causes for the changes seen in PCV and TSP. Four healthy adult mares were treated in a blinded, randomized, cross-over design with a single dose of xylazine (0.5 mg/kg), romifidine (0.04 mg/kg) or detomidine (0.01 mg/kg) intravenously, or detomidine (0.02 mg/kg) intramuscularly. A 1-week washout period was allowed between treatments. Haematology, TSP, COP, plasma osmolality, glucose, BUN, serum lactate, electrolytes, venous blood pH, ultrasonographic splenic size and degree of clinical sedation were evaluated at different time points post-injection and compared to baseline values. All treatments induced similar clinical sedation in the mares. A significant change over time in PCV and TSP following each treatment was identified, with overall median (range) maximal reductions compared to baseline of 20.9% (12.9 - 27.3%) and 5.8% (3.0 - 10.3%), respectively. Additionally, changes over time were significant for RBC count, BUN, COP and Ca2+, which decreased; and glucose, plasma osmolality, Na+ and splenic size, which increased, when compared to baseline. There was no significant main effect of treatment on PCV, TSP or any other parameters measured except for glucose. This study concluded that changes in PCV, TSP and other biochemical parameters induced by α2 agonists should be taken into consideration when assessing critically ill horses that received these drugs. There was evidence of splenic RBC sequestration as well as fluid shifts; therefore, the results suggest a multifactorial cause for the changes in PCV and TSP. / Dissertation (MSc)--University of Pretoria, 2011. / Companion Animal Clinical Studies / unrestricted

Nesta tese, dois projetos distintos que usaram a técnica do Espalhamento de Luz foram desenvolvidos. Estudou-se a influência de soluções concentradas de uréia sobre agregados supramoleculares de anfifilicos (ASA\'s), através de condutimetria, supressão de fluorescência e espalhamento de luz. A uréia causou aumento da concentração micelar crítica (CMC) em todos os sistemas micelares estudados. A uréia diminuiu a seletividade da ligação iônica entre cloreto e brometo em micelas de haleto de cetil-trimetil-amônio, estudada através de supressão de fluorescência. Este aditivo causou também aumento na segunda CMC de brometo de tetradeciltrimetil- amônio (TTAB) e diminuição do peso molecular das micelas em bastão formadas. Concluiu-se, desta primeira parte, que a uréia tende a interferir nas transições de fase apresentadas em sistemas micelares, provavelmente através da combinação dos mecanismos direto e indireto. A uréia apresenta potencial para uso como aditivo para modulação das propriedades estruturais de sistemas micelares. Na segunda parte da tese desenvolveu-se um sistema, baseado em espalhamento de luz, capaz de monitorar o peso molecular de polímeros durante a polimerização. O sistema foi eficiente no monitoramento da polimerização da N-vinil-pirrolidinona, mostrando que o peso molecular do polímero formado é constante durante a maior parte da reação. As teorias atuais de cinética de polimerização não foram capazes de explicar esse comportamento. / Light scattering techniques (static and dynamic) were used to detenninate the effect of urea on supramolecular aggregates and to monitor on-line molar mass ofpolymerization reactions. For the first set of investigation it was already established that urea increases the CMC and the dissociation degree (α) of ionic micelles (CTABr, TTABr, and SDS). From fluorescence suppression studies it was found that urea diminishes the ionic binding in zwitterionic and cationic micelles as well as in cationic vesicles. Bromide and chloride ionic selectivity in cationic micelles was found to nearly disappear in the presence of urea. Light scattering (static) detenninations showed that the weight averaged molecular weight (Mw) ofboth SDS and CTABr are invariant by the presence of the denaturant. A slight increase in the excluded volume tenn (A2) was detected for CTABr in the presence of 3M urea. In parallel both A2 and the radius of gyration (γ) of two polyelectrolytes (PAA and Hyaluronic acid) were not affected by the presence of urea. Sphere-to-rod concentration transitions (2nd CMC) of TIABr micelles increased in the presence of urea and the MW of rod particles were observed to decrease. For the insoluble mixture of CTABr/Polystyrenesulfonate solubilization was achieved in the presence of 3M urea. These set of results were explained as a result of the dual effect of urea, that is, the indirect effect by changing the properties of the solvent and the direct effect by solvating the hydrophilic domain of the aggregates and contributing with a stronger dipole moment. The second set of experiments was directed towards the real-time, on-line monitoring of Mw of polymerization reactions. This new approach could be succeeded by the coupling a light scattering detector, an UV photometer and a differential refractometer on line with a HPLC system. Mw growth formed in the polymerization of N-vynil-pirrolidone was accomplished with a small inherent error. Within the studied conditions Mw reached a plateau at early polymerization stages, after that only an increase in the number of polymer kinetic chains was observed. Current kinetic models were unable to predict the observed Mw growth pattern. This system is of great importance in basic and technological applications by virtue of its on-line capability.

<p>Controlling the surface chemistry of 2D materials is critical for the development of next generation applications including nanoelectronics and organic photovoltaics (OPVs). Further, next generation nanoelectronics devices require very specific 2D patterns of conductors and insulators with prescribed connectivity and repeating patterns less than 10 nm. However, both top-down and bottom-up approaches currently used lack the ability to pattern materials with sub 10-nm precision over large scales. Nevertheless, a class of monolayer chemistry offers a way to solve this problem through controlled long-range ordering with superior sub-10 nm patterning resolution. Graphene is most often functionalized noncovalently, which preserves most of its intrinsic properties (<i>i.e.,</i> electronic conductivity) and allows spatial modulation of the surface. Phospholipids such as 1,2-bis(10,12-tricsadiynoyl)-<i>sn­</i>-glycero-3-phosphoethanolamine (diyne PE) form lying down lamellar phases on graphene where both the hydrophilic head and hydrophobic tail are exposed to the interface and resemble a repeating cross section of the cell membrane. Phospholipid is made up of a complex headgroup structure and strong headgroup dipole which allows for a diverse range of chemistry and docking of objects to occur at the nonpolar membrane, these principals are equally as important at the nonpolar interface of 2D materials. A key component in the development of nanoelectronics is the integration of inorganic nanocrystals such as nanowires into materials at the wafer scale. Nanocrystals can be integrated into materials through templated growth on to surface of interest as well as through assembly processes (i.e. interfacial adsorption). </p> <p>In this work, I have demonstrated that gold nanowires (AuNWs) can be templated on striped phospholipid monolayers, which have an orientable headgroup dipoles that can order and straighten flexible 2-nm diameter AuNWs with wire lengths of ~1 µm. While AuNWs in solution experience bundling effects due to depletion attraction interactions, wires adsorb to the surface in a well separated fashion with wire-wire distances (e.g. 14 or 21 nm) matching multiples of the PE template pitch. This suggests repulsive interactions between wires upon interaction with dipole arrays on the surface. Although the reaction and templating of AuNWs is completed in a nonpolar environment (cyclohexane), the ordering of wires varies based on the hydration of the PE template in the presence of excess oleylamine, which forms hemicylindrical micelles around the hydrated headgroups protecting the polar environment. Results suggest that PE template experience membrane-mimetic dipole orientation behaviors, which in turn influences the orientation and ordering of objects in a nonpolar environment.</p> <p>Another promising material for bottom-up device applications is MoS₂substrates due to their useful electronic properties. However, being able to control the surface chemistry of different materials, like MoS₂, is relatively understudied, resulting in very limited examples of MoS₂substrates used in bottom-up approaches for nanoelectronics devices. Diyne PE templates adsorb on to MoS₂­in an edge-on conformation in which the alkyl tails stack on top of each other increasing the overall stability of the monolayer. A decrease in lateral spacing results in high local concentrations of orientable headgroups dipoles along with stacked tails which could affect the interactions and adsorption of inorganic materials (i.e. AuNW) at the interface. </p> <p>Here, I show that both diyne PE/HOPG and diyne PE/MoS₂ substrates can template AuNW of various lengths with long range ordering over areas up to 100 µm². Wires on both substrates experience repulsive interactions upon contact with the headgroup dipole arrays resulting in wire-wire distances greater than the template pitch (7 nm). As the wire length is shortened the measured distance between wires become smaller eventually resulting in tight packed ribbon phases. Wires within these ribbon phases have wire-wire distances equal to the template. Ribbon phases occur on diyne PE/HOPG substrates when the wire length is ~50 nm, whereas wire below ~600 nm produce ribbon phases on diyne PE/MoS_2­substrates. </p> <p>Another important aspect to future scientific development is the catalysis of organic reactions, specifically oxygenation of organic sulfides. Sulfide oxygenation is important for applications such as medicinal chemistry, petroleum desulfurization, and nerve agent detoxification. Both reaction rates and the use of inexpensive oxidants and catalysts are important for practical applications. Hydrogen peroxide and <i>tert</i>-butyl hydroperoxide are ideal oxidants due to being cost efficient and environmentally friendly. Hydrogen peroxide can be activated through transition metal base homogeneous catalysts. Some of the most common catalysts are homo- and hetero-polyoxometalates (POMs) due their chemical robustness. Heptamolybdate [Mo₇O₂₄]^6-is a member of the isopolymolybdate family and its ammonium salt is commercially available and low in cost.²² Heteropolyoxometalates have been widely studied as a catalyst for oxygenation reactions whereas heptamolybdate has been rarely studied in oxygenation reactions. </p> <p> Here I report sulfide oxygenation activity of both heptamolybdate and its peroxo derivate [Mo₇O₂₂(O₂)₂]^6-. Sulfide oxygenation of methyl phenyl sulfide (MPS) by H₂O₂to sulfoxide and sulfone occurs rapidly with 100 % utility of H₂O₂ in the presence of [Mo₇O₂₂(O₂)₂]^6-, suggesting the peroxo adduct is an efficient catalyst. However, heptamolybdate is a faster catalyst compared to [Mo₇O₂₂(O₂)₂]^6- for MPS oxygenation and all other sulfides tested under identical conditions. Pseudo-first order <i>k</i>_cat constants from initial rate kinetics show that [Mo₇O₂₄]^6-catalyzes sulfide oxygenation faster. The significant difference in the <i>k</i>_cat suggests differences in the active catalytic species, which was characterized by both UV-Vis and electrospray ionization mass spectrometry. ESI-MS suggest that the active intermediate of [Mo₇O₂₄]^6-under catalytic reaction conditions for sulfide oxygenation by H₂O₂ is [Mo₂O₁₁]^2-. These results show that heptamolybdate is a highly efficient catalyst for H₂O₂oxygenation of organic sulfides.</p>

M. Tech. (Biotechnology, Department of Biosciences, Faculty of Applied and Computer Sciences), Vaal University of Technology. / Reverse osmosis (RO) membranes are widely used in water purification. The presence of biofilms in water and industrial water purification systems is prevalent. As a result, biofouling which is a biofilm problem causes adverse effects on reverse osmosis process, which include flux decline, shorter membrane lifetime and an increase in energy consumption The effect of biofouling on RO membranes was investigated at a water treatment facility at Sasol, Sasolburg by investigating the quality of water purified by the RO system and the extent of fouling that is attributed to biofouling. Chemical and microbiological data was averaged based on the results obtained from water analysis and samples from a fouled membrane. Bacteriological plate counts ranged between log 1.5 to 4 cfu/ml in water samples and log 3.9 to 4.5 cfu/cm2 on biofilm from the membrane surface. Water analysis indicated a high conductivity of 121 µS/cm in the feed and 81 ppm of the TDS, whereas in the permeate conductivity was found to be around 6 µS/cm and 3.8 ppm of the TDS. This indicated that components present in the feed were retained by the membrane. This was supported by membrane autopsy which showed that the bacteria and elements found in the feedwater were also present on the membrane surface, hence contributing to fouling. An average of 33% of cellular ATP was measured on the biofilm from membrane sample, showing that the fouling bacteria are metabolically active in situ. The results clearly indicated that an important biological activity occurred at the membrane surface.

<p>The strong metal support interaction (SMSI) is among the best-known classes of metal-oxide interfacial interactions in heterogeneous catalysis, which is defined by the coverage of surface oxide on metal nanoparticles, forming a metal-oxide interface. However, there is limited insight in the atomic scale understanding of the structure of the SMSI oxide. In this work, surface science techniques including scanning tunneling microscopy (STM), X-ray photoelectron spectroscopy (XPS), high-resolution electron energy loss spectroscopy (HREELS) and low energy electron diffraction (LEED) were employed to investigate interfacial interactions in multiple catalytic systems, including ZnO-Pd, ZnO-Pt, and MoOx-Pt. To utilize the capabilities of the surface science techniques and to mimic a catalytic metal nanoparticle in SMSI state, ultrathin oxide films were prepared on metal single crystals as inverse model catalysts.</p> <p>The structural and chemical transformations of ultrathin zinc (hydroxy)oxide films on Pd(111) were studied under varying gas phase conditions (UHV, 5×10−7 mbar of O2 and D2/O2 mixture). Under oxidative conditions, zinc oxide forms partially hydroxylated bilayer islands on Pd(111). Sequential treatments of the submonolayer ZnOxHy films in D2/O2 mixture (1:4) at 550 K evoked structural transformations from bilayer to monolayer and to a PdZn near-surface alloy, in accompany with the reduction of Zn, demonstrating that zinc oxide as a non-reducible oxide, can spread on metal surface and show an SMSI-like behavior in the presence of hydrogen. A mixed canonical – grand canonical phase diagram revealed that the monolayer intermediate structure is a metastable structure formed during the kinetic transformation, and the near-surface alloys are stable under the D2/O2 conditions. Grand canonical phase diagram predicted that under real SMSI conditions zinc oxide films on Pd nanoparticles would be stabilized by hydroxylation with stoichiometries such as ZnOH and Zn2O3H3. Based on the experimental and theoretical observations, we propose that the mechanism of metal nanoparticle encapsulation involves both surface (hydroxy)oxide formation as well as alloy formation, depending on the environmental conditions.</p> <p>Hydroxylation plays a more important role in the ZnO/Pt(111) system. Different from Pd(111), zinc oxide tends to form monolayer graphite-like ZnO films on Pt(111) under oxidative conditions at submonolayer coverages. This structure is extremely susceptible to hydroxylation at room temperature, leading to spontaneous formation of honeycomb-like Zn6O5H5 films in hydrogen. The interaction of the two distinct structures with Pt were investigated by XPS, STM, and HREELS with CO, C2H4, and NO as probe molecules. Zn exhibits a partially reduced oxidation state in Zn6O5H5 and donates negative charge to surface Pt in the confined rings, leading to a switch from linear CO adsorption to bridged CO adsorption in accompany with a 50 cm-1 shift of ν(CO) towards lower frequencies. C2H4 readily forms ethylidyne (*CCH3) species at room temperature once adsorbed on Pt(111), while the formation of ethylidyne is weakened on the Zn6O5H5/Pt(111) surface. In summary, this study demonstrated a unique metal-hydroxide interaction, which serves as a novel approach for the modification of metal catalysts.</p> <p>The partial coverage of metal surfaces by oxides could be utilized to passivate specific sites of catalysts, improving the activity and stability. Herein, we studied the structure of surface Mo oxides on Pt(111) and Pt(544) using STM, XPS, and HREELS. At 0.08 ML coverage, Mo oxide tends to form 1~2 nm clusters and the majority of Mo is in +5 oxidation state. The Mo oxide clusters tend to aggregate near the monoatomic Pt steps, showing a higher local density compared to the wide terraces. Therefore, our results provide experimental evidence for the site-selective growth of Mo oxides at step sites, which could prevent the leaching of active component in catalysts under real reaction conditions.</p> <p>Overall, through atomic-level characterization of inverse model catalysts, we provided insights into the nature of metal-oxide interactions in multiple systems. The surface oxide films influence the property of metal surfaces in various ways, including migration, alloy formation, electronic perturbation, geometric confinement, and site-selective blocking. These findings emphasize the necessity of understanding the real structure of catalytic surfaces under different reaction conditions and shed light on rational design of oxide supported metal nanoparticle catalysts.</p>

In der vorliegenden Dissertation werden verschiedene plasmonisch aktive Kern/Schale- Nanopartikel synthetisiert, experimentell und theoretisch charakterisiert und in analytischen Anwendungen der oberflächenverstärkten Raman-Spektroskopie (engl. surface-enhanced Raman scattering, SERS) eingesetzt. Es werden die optischen Eigenschaften von Gold/Silber-Nanoschalen mit durchstimmbaren Plasmonbanden behandelt. Motivation dafür ist die Frage nach optimalen SERS-Markern für die rote Laseranregung (λ = 632.8 nm). In SERS-Anwendungen gibt es die Möglichkeit mehrere Marker-Moleküle auf die Oberfläche der Nanopartikel aufzubringen, um so eine erhöhte Multiplexing-Kapazität zu generieren. Diese Option der gemischten Monolagen wird in der vorliegenden Arbeit untersucht. Es werden SERS-Marker-Konzepte für die rote Laseranregung basierend auf einzelnen Nanopartikeln gezeigt. Außerdem wird dargestellt, inwieweit sich durch die Anordnung von Nanopartikeln in allen drei Raumdimensionen neue SERS-Marker- Konzepte mit sehr guten plasmonischen Eigenschaften realisieren lassen. In den oben beschriebenen Kapiteln übernehmen Nanopartikel die Rolle des SERS-Substrats für den selektiven Nachweis eines bestimmten Zielmoleküls (z.B. Antigens). Neben diesen Anwendungen können Nanopartikel jedoch auch noch als SERS-Substrat für die markierungsfreie Detektion von Analytmolekülen eingesetzt werden. In dieser Dissertation wird die Herstellung, Charakterisierung und der Einsatz eines integrierten SERS-Substrats für die kombinierte Festphasensynthese und Analytik mittels plamonisch aktiver Gold/Glas-Kern/Schale-Nanopartikel auf Harz-Mikrokugeln behandelt.

Nos travaux ont porté sur le développement d'une méthode contrôlée de complexation de polyélectrolytes. La complexation est un processus spontané, sous contrôle cinétique et irréversible dans le cas de polysaccharides tels que le chitosane et les polysulfates, essentiellement le sulfate de dextrane ou l'héparine. Une conséquence de ce contrôle cinétique est que l'obtention d'objets de taille colloïdale requiert de travailler à fortes dilutions. De plus, les nanovecteurs obtenus ne sont pas toujours compatibles avec des conditions d'utilisation dans des milieux physiologiques. Le contrôle de l'association de polysaccharides se fait par écrantage des interactions électrostatiques attractives en présence de chlorure de sodium à la concentration au moins égale à 2 mol.L-1. L'élimination du sel par dialyse induit la formation d'hydrogels dont les caractéristiques et les propriétés dépendent principalement du rapport de charges n+/n- et de la cinétique d'élimination du sel. Ainsi, l'on peut former des hydrogels massifs ou des systèmes dispersés à des concentrations en polymères jusqu'à 30 fois plus élevées que par les méthodes sous contrôle cinétique. De plus, cette technologie permet l'encapsulation des principes actifs dans les particules qui peuvent aussi être fonctionnalisées par des biomolécules d'adressage. Le résultat majeur de ce travail réside en la maîtrise des associations entre polysaccharides de charges opposées, permettant d'obtenir des systèmes colloïdaux et massifs à fort potentiels d'applications biomédicales / Our work dealt with the development of a controlled method of polyelectrolyte complexation. The complexation is a spontaneous process, under kinetic control and irreversible in the case of polysaccharides such as the chitosan and polysulfates, essentially dextran sulfate or heparin. A consequence of this kinetic control is the requirement to work at high dilution to obtain objects of colloidal size. Moreover, the obtained nanovectors were not always adapted for use in physiological media. The control of the association of polysaccharides was achieved by screening the attractive electrostatic interactions in the presence of sodium chloride at concentration at least equal to 2 mol. L-1. Removal of salt by dialysis resulted in the formation of hydrogels, whose characteristics and properties depended mainly on the charge ratio n +/ n- and the kinetics of the salt elimination. Thus, massive or dispersed hydrogels were formed at polymer concentrations up to 30 times higher than by the methods under kinetic control. Furthermore, this technology allowed the encapsulation of active ingredients in the particles that could also be functionalized with biomolecules for targeting. The major result of this work was the control over the associations between oppositely charged polysaccharides which provided colloidal and massive systems of high potentialities in biomedical applications

<p>   </p> <p>Colloidal cesium lead bromide (CsPbBr₃) quantum dots (QDs) have emerged as an exciting class of quantum emitters due to their near-unity quantum yields, large oscillator strengths, and long coherence time. Ordered superlattices (SLs) grown from these QDs exhibit emergent properties resulting from their assembly. In this work, we explore the self-assembly, disorder, and superradiant properties of 3D superlattices of CsPbBr₃ to understand how structural heterogeneity influences optical properties.</p> <p>A thorough understanding of the competition between coherence and dephasing from phonon scattering and energetic disorder is currently lacking in the literature. Here, we present an investigation of exciton coherence in perovskite QD solids using temperature-dependent photoluminescence linewidth and lifetime measurements. The properties of perovskite QDS described above should also enable them to overcome hurdles experienced by other materials that limit solid-state superradiance, such as fast dephasing processes from inherent disorder and thermal fluctuations. Our results demonstrate that excitons can coherently delocalize in highly ordered CsPbBr₃ superlattices leading to superradiant emission. We observe loss of coherence and exciton localization to a single QD at higher temperatures, resulting from scattering by optical phonons. At low temperatures, static disorder and defects limit exciton coherence, and a wide range of coherence numbers are observed across a self-assembled sample of SLs. These results highlight the promise and challenge in achieving long-range coherence in perovskite QD solids.</p> <p>A thorough understanding of structural heterogeneity in CsPbBr₃ quantum dot superlattices is necessary for the realization of robust exciton coherence in these systems. 3D SLs self-assemble from a colloidal solution of cubic QDs as the solvent evaporates, leading to SLs ranging widely in macroscopic size, shape, and aspect ratio. Scanning transmission electron microscopy (STEM) coupled to fast-Fourier transform (FFT) analysis is utilized to characterize the structural properties of individual SLs, such as the average constituent quantum dot size, size dispersity, and number of crystalline domains. Analysis reveals that SLs are structurally heterogeneous but tend to have a narrower size distribution than the precursor solution due to size selection that occurs during evaporative self-assembly. We directly correlate STEM-FFT structural properties to low-temperature photoluminescence spectra for individual SLs, demonstrating that substructure in the photoluminescence peak arises from multiple, locally-ordered domains within the SL. In addition, we show that long-range structural disorder in a SL does not necessarily impact short-range phenomena such as exciton delocalization.</p> <p>  </p>

<p dir="ltr">The recent COVID-19 pandemic has emphasized the risk of respiratory infections leading to acute respiratory distress syndrome (ARDS). A significant factor contributing to poor ARDS outcomes is the impairment of lung surfactant due to infiltrating surface-active proteins and phospholipases during lung inflammation. Lung surfactant's vital role in stabilizing alveoli by reducing air-water interfacial tension becomes evident as its dysfunction severely compromises respiratory function. Although lung surfactant (LS) replacement therapy effectively addresses neonatal LS deficiencies, its efficacy in ARDS treatment for adults remains limited. The challenge lies in the chemical similarity between current animal-extracted surfactants and human lung surfactant which are both phospholipid-based. To address this issue, this dissertation outlines a transformative "polymer lung surfactant (PLS)" designed to overcome the limitations of conventional exogenous surfactants in treating ARDS.</p><p dir="ltr">Firstly, a formulation method, referred to as equilibration-nanoprecipitation (ENP), is established which achieves reproducibility, controls sizing, and limits dispersity of the PLS formulation consisting of block copolymer (BCP) kinetically "frozen" micelles/nanoparticles suspended in water. The method uses a two-step approach of 1) equilibrating the BCP nanoparticles in a water/co-solvent mixture and 2) removing co-solvent using dialysis against a large water reservoir. Comparison of ENP with a conventional solvent-exchange technique through experimental and computational analysis yields further insights into ENP's advantages.</p><p dir="ltr">Next, various studies are highlighted which provide fundamental characterizations of the air-water surface behavior and physical properties of BCP nanoparticles in water. The air-water surface properties of block copolymers have been studied extensively when spread as free chains in organic solvent; however, little was previously known about air-water interfacial behavior of water-spread polymer nanoparticles. The studies address such topics as the effect of nanoparticle size, effect of nanoparticle core chemistry, and the effect of temperature on surface-mechanical behavior. Insights into nanoparticle molecular structure at the interface are provided through X-ray reflectivity and grazing incidence X-ray diffraction. The effect of temperature is further characterized by developing novel NMR and Langmuir trough methods to determine the physical state (glassy vs rubbery) of the core domain in the nanoconfined state at temperatures above and below physiologic temperature.</p><p dir="ltr">Lastly, <i>in vivo </i>studies are presented which demonstrate the detailed and promising proof-of-concept results on the efficacy of the PLS technology in mouse models of lung injury. The PLS therapy not only improves biomechanical function of the lung, but it also significantly lowers the extent of lung injury as shown by histological analysis and inflammatory marker measurements. An additional <i>in vivo </i>study is presented which highlights challenges in the delivery of the liquid PLS suspension to the lungs. The <i>in vivo </i>studies ultimately provide solid motivation for continued research into the development of the PLS therapy.</p><p dir="ltr">Given the promising potential of the PLS technology shown in the <i>in vivo</i> studies, the materials characterizations shared in this presentation offer valuable insights into the design of a novel PLS therapy. From these insights, key design parameters such as nanoparticle size characteristics, core chemistry, and core molecular weight can be chosen to produce the most desirable material properties. Overall, this dissertation furthers the progress of PLS therapeutic development and will hopefully ultimately contribute to improved health outcomes in patients suffering from ARDS.</p>