Simulation studies of correlation functions and relaxation in polymeric systems

We investigate the statics and dynamics of a glassy,non-entangled, short bead-spring polymer melt with moleculardynamics simulations. Temperature ranges from slightlyabove the mode-coupling critical temperature to the liquidregime where features of a glassy liquid are absent. Ouraim is to work out the polymer specific effects on therelaxation and particle correlation. We find the intra-chain static structure unaffected bytemperature, it depends only on the distance of monomersalong the backbone. In contrast, the distinct inter-chainstructure shows pronounced site-dependence effects at thelength-scales of the chain and the nearest neighbordistance. There, we also find the strongest temperaturedependence which drives the glass transition. Both the siteaveraged coupling of the monomer and center of mass (CM) andthe CM-CM coupling are weak and presumably not responsiblefor a peak in the coherent relaxation time at the chain'slength scale. Chains rather emerge as soft, easilyinterpenetrating objects. Three particle correlations arewell reproduced by the convolution approximation with theexception of model dependent deviations. In the spatially heterogeneous dynamics of our system weidentify highly mobile monomers which tend to follow eachother in one-dimensional paths forming ``strings''. Thesestrings have an exponential length distribution and aregenerally short compared to the chain length. Thus, arelaxation mechanism in which neighboring mobile monomersmove along the backbone of the chain seems unlikely.However, the correlation of bonded neighbors is enhanced. When liquids are confined between two surfaces in relativesliding motion kinetic friction is observed. We study ageneric model setup by molecular dynamics simulations for awide range of sliding speeds, temperatures, loads, andlubricant coverings for simple and molecular fluids. Instabilities in the particle trajectories are identified asthe origin of kinetic friction. They lead to high particlevelocities of fluid atoms which are gradually dissipatedresulting in a friction force. In commensurate systemsfluid atoms follow continuous trajectories for sub-monolayercoverings and consequently, friction vanishes at low slidingspeeds. For incommensurate systems the velocity probabilitydistribution exhibits approximately exponential tails. Weconnect this velocity distribution to the kinetic frictionforce which reaches a constant value at low sliding speeds. This approach agrees well with the friction obtaineddirectly from simulations and explains Amontons' law on themicroscopic level. Molecular bonds in commensurate systemslead to incommensurate behavior, but do not change thequalitative behavior of incommensurate systems. However,crossed chains form stable load bearing asperities whichstrongly increase friction.

Genesis of metasomatic sapphirine-corundum-spinel-bearing granulites in Sri Lanka

The goal of the present study is to understand the mechanism of mass transfer, the composition and the role of fluids during crustal metasomatism in high-temperature metamorphic terranes. A well constrained case study, a locality at Rupaha, Sri Lanka was selected. It is located in the Highland Complex of Sri Lanka, which represents a small, but important fragment of the super-continent Gondwana. Excellent exposures of ultramafic rocks, which are embedded in granulites, were found at 10 localities. These provide a unique background for understanding the metasomatic processes. The boundary between the ultramafic and the granulite rocks are lined with metasomatic reaction zones up to 50cm in width. Progressing from the ultramafics to the granulite host rock, three distinct zones with the following mineral assemblages can be distinguished: (1). phlogopite + spinel + sapphirine, (2). spinel + sapphirine and (3). corundum + biotite + plagioclase. In order to assess the P-T-t path, the peak metamorphism and the exhumation history were constrained using different thermobarometers, as well as a diffusion model of garnet zoning. A maximum temperature of 875 ± 20oC (Opx-Cpx thermometer) and at the peak pressure of 9.0 ± 0.1 kbar (Grt-Cpx-Pl-Qtz) was calculated for the silicic granulite. The ultramafic rocks recorded a peak temperature of 840 ± 70oC (Opx-Cpx thermometer) at 9 kbar. Coexisting spinel and sapphirine from the reaction zone yield a temperature of 820 ± 40oC. This is in agreement with the peak-temperatures recorded in the adjacent granulites and ultramafics rocks. The structural concordance of the ultramafic rocks with the siliceous granulite host rock further support the suggestion, that all units have experienced the same peak metamorphism. Diffusion modeling of retrograde zoning in garnets from mafic granulites suggests a three-step cooling history. A maximum cooling rate of 1oC/Ma is estimated during the initial stage of cooling, followed by a cooling rate of ~30oC/Ma. The outermost rims of garnet indicate a slightly slower cooling rate at about 10-15oC/Ma. The sequences of mineral zones, containing a variety of Al-rich, silica undersaturated minerals in the reaction zones separating the ultramafic rocks from the silica-rich rocks can be explained by a diffusion model. This involves the diffusion of Mg from ultramafic rocks across the layers, and K and Si diffuse in opposite direction. Chemical potential of Mg and Si generated continuous monotonic gradient, allowing steady state diffusional transport across the profile. The strong enrichment in Al, and the considerable loss of Si, during the formation of reaction bands can be inferred from isocon diagrams. Some Al was probably added to the reaction zones, while Si was lost. This is most likely due to fluids percolating parallel to the zones at the boundary of the rock units. This study has shown that not only pressure and temperature conditions but most importantly PH2O and the concentration of the chlorine and fluorine in aqueous fluids also control the mass transport in different geological environments.

Chemische und enzymatische Synthese von orthogonal stabil geschützten Kohlenhydrat-Scaffolds für kombinatorische Anwendungen

Auf der Suche nach potenten pharmakologischen Wirkstoffen hat die Kombinatorische Chemie in der letzten Dekade eine große Bedeutung erlangt, um innerhalb kurzer Zeit ein breites Spektrum von Verbindungen für biologische Tests zu erzeugen. Kohlenhydrate stellen als Scaffolds interessante Kandidaten für die kombinatorische Synthese dar, da sie mehrere Derivatisierungspositionen in stereochemisch definierter Art und Weise zur Verfügung stellen. So ist die räumlich eindeutige Präsentation angebundener pharmakophorer Gruppen möglich, wie es für den Einsatz als Peptidmimetika wünschenswert ist. Zur gezielten Derivatisierung einzelner Hydroxylfunktionen ist der Einsatz eines orthogonalen Schutz-gruppenmusters erforderlich, das gegenüber den im Lauf der kombinatorischen Synthese herrschenden Reaktionsbedingungen hinreichend stabil ist. Weiterhin ist ein geeignetes Ankersystem zu finden, um eine Festphasensynthese und damit eine Automatisierung zu ermöglichen.Zur Minimierung der im Fall von Hexosen wie Galactose benötigten fünf zueinander orthogonal stabilen Schutzgruppen wurde bei der vorliegenden Arbeit von Galactal ausgegangen, bei dem nur noch drei Hydroxylfunktionen zu differenzieren sind. Das Galactose-Gerüst kann anschließend wiederhergestellt werden. Die Differenzierung wurde über den Einsatz von Hydrolasen durch regioselektive Acylierungs- und Deacylierungs-reaktionen erreicht, wobei auch immobilisierte Enzyme Verwendung fanden. Dabei konnte ein orthogonales Schutzgruppenmuster sequentiell aufgebaut werden, das auch die nötigen Stabilitäten gegenüber sonstigen, teilweise geeignet modifizierten Reaktionsbedingungen aufweist. Für die Anbindung an eine Festphase wurde ein metathetisch spaltbarer Anker entwickelt, der über die anomere Position unter Wiederherstellung des Galactose-Gerüsts angebunden wurde. Auch ein oxidativ spaltbares und ein photolabiles Ankersystem wurden erprobt.

Selektiv deblockierbare 2,6-Diamino-2,6-didesoxy-D-glucose-Scaffolds für die kombinatorische Synthese potentieller RNA-Liganden

Aminoglydosid-Antibiotika wie Neomycin B oder Cyclopeptid-Antibiotike wie Viaomycin sind dafür bekannt, daß sie selektiv an RNA binden können. Diese Interaktionen beruhen sowohl auf elektrostatischen Wechselwirkungen als auch auf H-Brücken-Bindungen. Des weiteren ist die definierte räumliche Anordnung von Donor- und Akzeptor-Resten in den Strukturen der RNA-Liganden wichtig für die Affinität. Eine Möglichkeit natürliche RNA-Liganden zu imitieren ist der Einsatz polyfunktioneller Template wie zum Beispiel das 2,6-Diamino-2,6-didesoxy-D-glucose-Scaffold. Mit Hilfe dieser Scaffolds können dann verschiedene positv geladene Reste und Donatoren sowie Akzeptoren für H-Brücken-Bindungen oder auch Interkalatoren räumlich definiert präsentiert werden. Für die unabhängige Funktionalisierung einer jeden Position ist ein Satz orthogonal stabiler Schutzgruppen nötig, wobei eine Hydroxylguppe durch einen Anker ersetzt wird, der eine Anbindung des Scaffolds an einen polymeren Träger ermöglicht. Das neu entwickelte 2,6-Diamino-2,6-didesoxy-D-glucose-Scaffold ist das erste Monosaccharid-Templat, das in allen fünf Positionen mit orthogonal stabilen Schutzgruppen blockiert ist. Alle Positionen könne in beliebiger Reihenfolge selektiv deblockiert und anschließend derivatisiert werden. Das Scaffold kann mit Aminosäuren, Guanidinen oder Interkalatoren umgesetzt werden, um so natürlich vorkommende RNA-bindende Aminoglycoside oder Peptide zu imitieren. Aufbauend auf diesem Monosaccharid-Templat wurde eine Bibliothek von über 100 potentiellen RNA-Liganden synthetisiert, die im Rahmen des Sonderforschungsbereichs 579 (RNA-Liganden-Wechselwirkungen) in Zellassays auf ihre Fähigkeit zur Hemmung der Tat/TAR-Wechselwirkung untersucht wurden, wobei bis jetzt 9 Verbindungen mit einer hemmenden Wirkung im micromolaren Bereich gefunden wurden.

Weathering of Fe-bearing minerals under extraterrestrial conditions, investigated by Mössbauer spectroscopy

The weathering of Fe-bearing minerals under extraterrestrial conditions was investigated by Mössbauer (MB) spectroscopy to gain insights into the role of water on the planet Mars. The NASA Mars Exploration Rovers Spirit and Opportunity each carry a miniaturized Mössbauer spectrometer MIMOS II for the in situ investigation of Martian soils and rocks as part of their payload. The MER flight instruments had to be modified in order to work over the Martian diurnal temperature range (180 K – 290 K) and within the unique electronic environment of the rovers. The modification required special calibration procedures. The integration time necessary to obtain a good quality Mössbauer spectrum with the MIMOS II flight instruments was reduced by 30 % through the design of a new collimator. The in situ investigation of rocks along the rover Spirit's traverse in Gusev crater revealed weakly altered olivine basalt on the plains and pervasively altered basalt in the Columbia Hills. Correlation plots of primary Fe-bearing minerals identified by MB spectroscopy such as olivine versus secondary Fe-bearing phases such as nanophase Fe oxides showed that olivine is the mineral which is primarily involved in weathering reactions. This argues for a reduced availability of water. Identification of the Fe-oxyhydroxide goethite in the Columbia Hills is unequivocal evidence for aqueous weathering processes in the Columbia Hills. Experiments in which mineral powders were exposed to components of the Martian atmosphere showed that interaction with the atmosphere alone, in the absence of liquid water, is sufficient to oxidize Martian surface materials. The fine-grained dust suspended in the Martian atmosphere may have been altered solely by gas-solid reactions. Fresh and altered specimens of Martian meteorites were investigated with MIMOS II. The study of Martian meteorites in the lab helped to identify in Bounce Rock the first rock on Mars which is similar in composition to basaltic shergottites, a subgroup of the Martian meteorites. The field of astrobiology includes the study of the origin, evolution and distribution of life in the universe. Water is a prerequisite for life. The MER Mössbauer spectrometers identified aqueous minerals such as jarosite and goethite. The identification of jarosite was crucial to evaluate the habitability of Opportunity's landing site at Meridiani Planum during the formation of the sedimentary outcrop rocks, because jarosite puts strong constrains on pH levels. The identification of olivine in rocks and soils on the Gusev crater plains provide evidence for the sparsity of water under current conditions on Mars. Ratios of Fe2+/Fe3+ were obtained with Mössbauer spectroscopy from basaltic glass samples which were exposed at a deep sea hydrothermal vent. The ratios were used as a measure of potential energy for use by a microbial community. Samples from Mars analogue field sites on Earth exhibiting morphological biosignatures were also investigated.

DNA block copolymers - synthesis, morphologies and applications

The last decades have witnessed significant and rapid progress in polymer chemistry and molecular biology. The invention of PCR and advances in automated solid phase synthesis of DNA have made this biological entity broadly available to all researchers across biological and chemical sciences. Thanks to the development of a variety of polymerization techniques, macromolecules can be synthesized with predetermined molecular weights and excellent structural control. In recent years these two exciting areas of research converged to generate a new type of nucleic acid hybrid material, consisting of oligodeoxynucleotides and organic polymers. By conjugating these two classes of materials, DNA block copolymers are generated exhibiting engineered material properties that cannot be realized with polymers or nucleic acids alone. Different synthetic strategies based on grafting onto routes in solution or on solid support were developed which afforded DNA block copolymers with hydrophilic, hydrophobic and thermoresponsive organic polymers in good yields. Beside the preparation of DNA block copolymers with a relative short DNA-segment, it was also demonstrated how these bioorganic polymers can be synthesized exhibiting large DNA blocks (>1000 bases) applying the polymerase chain reaction. Amphiphilic DNA block copolymers, which were synthesized fully automated in a DNA synthesizer, self-assemble into well-defined nanoparticles. Hybridization of spherical micelles with long DNA templates that encode several times the sequence of the micelle corona induced a transformation into rod-like micelles. The Watson-Crick motif aligned the hydrophobic polymer segments along the DNA double helix, which resulted in selective dimer formation. Even the length of the resulting nanostructures could be precisely adjusted by the number of nucleotides of the templates. In addition to changing the structural properties of DNA-b-PPO micelles, these materials were applied as 3D nanoscopic scaffolds for organic reactions. The DNA strands of the corona were organized by hydrophobic interactions of the organic polymer segments in such a fashion that several DNA-templated organic reactions proceeded in a sequence specific manner; either at the surface of the micelles or at the interface between the biological and the organic polymer blocks. The yields of reactions employing the micellar template were equivalent or better than existing template architectures. Aside from its physical properties and the morphologies achieved, an important requirement for a new biomaterial is its biocompatibility and interaction with living systems, i.e. human cells. The toxicity of the nanoparticles was analyzed by a cell proliferation assay. Motivated by the non-toxic nature of the amphiphilic DNA block copolymers, these nanoobjects were employed as drug delivery vehicles to target the anticancer drug to a tumor tissue. The micelles obtained from DNA block copolymers were easily functionalized with targeting units by hybridization. This facile route allowed studying the effect of the amount of targeting units on the targeting efficacy. By varying the site of functionalization, i.e. 5’ or 3’, the outcome of having the targeting unit at the periphery of the micelle or in the core of the micelle was studied. Additionally, these micelles were loaded with an anticancer drug, doxorubicin, and then applied to tumor cells. The viability of the cells was calculated in the presence and absence of targeting unit. It was demonstrated that the tumor cells bearing folate receptors showed a high mortality when the targeting unit was attached to the nanocarrier.

Selektiv deblockierbare Diamino-D-Galactose-Scaffolds für die kombinatorische Synthese potentieller RNA-Liganden

Die Aufklärung der Schlüsselrolle der RNA in zahlreichen biologischen Prozessen, die sich aus ihren selektiven Wechselwirkungen mit anderen RNA-Molekülen, Proteinen, Peptiden bzw. Antibiotika ergibt, ist für die Wirkstoffforschung von großer Bedeutung. Die Aminoglycoside und Antibiotika, die durch eine Hemmung der Proteinbiosynthese schon seit längerem bekannt sind, dienen als Leitstrukuren für die Synthese von weiteren Wirkstoffen. Die meisten Aminoglycosid-Antibiotika beinhalten Aminozucker, die mit dem rn2-Desoxystreptamin-Gerüst verbunden sind. Die stereochemische Vielfalt der Substitutionsstellen für Amino- und Hydroxylgruppen in diesem Gerüst und deren beschränkte konformative Flexibilität bieten vielseitige Möglichkeiten, um potenzielle RNA-Liganden so zu gestalten, dass es zu einer spezifischen Erkennung von RNA-Strukturen kommen kann. Ein wichtiger Vertreter dieser Antibiotika, Neomycin B, von dessen Struktur die Entwicklung des Diaminogalactose-Templates abgeleitet wurde, wurde in dieser Arbeit als Leitstruktur gewählt. Die Synthese von Diaminogalactose-Scaffolds wurde zunächst in Lösung durchgeführt. Anschließend wurden die Bausteine 2 und 4 an einen polymeren Träger gebunden.rnNach Prüfung der orthogonalen Stabilität der Schutzgruppen wurde mit den Scaffolds 2 und 4 eine Bibliothek von 65 Verbindungen hergestellt. Mit 42 dieser Verbindungen wurden anschließend Zellassays im Rahmen des Sonderforschungsbereichs 579 (RNA-Liganden-Wechselwirkungen) durchgeführt, um ihre Cytotoxizität zu prüfen. Für einzelne Verbindungen konnten die optimalen Konzentrationen bestimmt werden, bei denen zukünftige Tests für die Tat/TAR Wechselwirkung ohne störende cytotoxische Effekte durchgeführt werden können.rn

Die Rolle von Ephrin-B2 in der Invasion maligner Gliome

Das Glioblastoma multiforme zählt zu den häufigsten glialen Neoplasien des Menschen und weist zudem unter den Gliomen die höchste Malignität auf. Glioblastompatienten haben trotz aggressiver therapeutischer Ansätze eine mittlere Überlebenszeit von weniger als einem Jahr. Die diffuse Invasion in das umliegende Hirngewebe ist einer der Hauptgründe für die Rezidivbildung und die infauste Prognose von Glioblastompatienten. Neuere Untersuchungen lassen vermuten, dass die starke Invasion auch einer der Gründe für die beobachtete anti-angiogene Resistenz bei der Behandlung von Glioblastomen ist. Das bidirektionale EphB/Ephrin-B-System wurde bei der axonalen Wegfindung als Vermittler repulsiver Signale identifiziert und auch im Zusammenhang der Migration und Invasion von Zellen überprüft. In der vorliegenden Arbeit sollte daher die Funktion der bidirektionalen Eph- und Ephrin-Signaltransduktion in Bezug auf die Glioblastominvasion und Progression untersucht werden. rn Genetische und epigenetische Untersuchungen der EphB/Ephrin-B-Familie in einer Kohorte von Gliompatienten unterschiedlicher Malignitätsgrade identifizierten Ephrin-B2 als mögliches Tumorsuppressorgen. In Übereinstimmung damit führte die Inaktivierung von Ephrin-B2 in einem murinen Gliommodell zu einer verstärkten Invasion und einem erhöhtem Tumorwachstum in vivo. Dies konnte in verschiedenen Invasion-Assays in vitro bestätigt werden. Weiterhin zeigten unsere Untersuchungen, dass Ephrin-B2 transkriptionell durch das hypoxische Mikromilieu HIF-1α-vermittelt reprimiert wird. Da HIF-1α als transkriptioneller Aktivator Ephrin-B2 nicht direkt reprimieren kann, wurden potentielle HIF-1α-regulierte Repressoren untersucht, die für die Ephrin-B2 Herunterregulation verantwortlich sein könnten. Dabei wurde anhand von Ephrin-B2-Promotoranalysen und ChIP-Assays ZEB2 als HIF-1α-induzierbarer Repressor von Ephrin-B2 identifiziert. Zur Bestätigung der Hypothese, dass ZEB2 ein wichtiger Regulator der Tumorinvasion ist, wurden humane ZEB2-Knockdown-Glioblastomzellen generiert und in vitro sowie in vivo untersucht. Im Hinblick auf mögliche therapeutische Anwendungen wurden die ZEB2-Knockdown-Glioblastomzellen zusätzlich im Zusammenhang anti-Angiogenese-induzierter Invasion analysiert. Der Verlust von ZEB2 führte dabei zu einer verringerten Glioblastominvasion und Progression in einem Maus-Xenograft Modell. Die Behandlung der Tumoren mit dem anti-VEGF-Antikörper Avastin resultierte in einer stark erhöhten Invasion, die durch die Inaktivierung von ZEB2 und der dadurch reaktivierten repulsiven Signale von Ephrin-B2 wieder aufgehoben werden konnte. Zusammenfassend konnte in der vorliegenden Arbeit erstmals gezeigt werden, dass Ephrin-B2 als Tumorsuppressor in Gliomen agiert und durch verschiedene Mechanismen wie der genetischen und epigenetischen Kontrolle, aber auch der HIF-1α-vermittelten, ZEB2-abhängigen Repression inaktiviert wird. Dies resultiert in einer Blockade repulsiver Signale, so dass Tumorzellen diffus in das Parenchym und zu den Blutgefäßen migrieren können. Der in dieser Arbeit neu identifizierte Signalweg stellt ein attraktives therapeutisches Ziel zur Inhibition der Tumorzellinvasion dar und ermöglicht darüber hinaus der Ausbildung von Resistenzen gegenüber anti-angiogener Behandlung entgegenzuwirken. rn

Wet and dry model granulates under mechanical load : a confocal microscopy study

Granular matter, also known as bulk solids, consists of discrete particles with sizes between micrometers and meters. They are present in many industrial applications as well as daily life, like in food processing, pharmaceutics or in the oil and mining industry. When handling granular matter the bulk solids are stored, mixed, conveyed or filtered. These techniques are based on observations in macroscopic experiments, i.e. rheological examinations of the bulk properties. Despite the amply investigations of bulk mechanics, the relation between single particle motion and macroscopic behavior is still not well understood. For exploring the microscopic properties on a single particle level, 3D imaging techniques are required.rnThe objective of this work was the investigation of single particle motions in a bulk system in 3D under an external mechanical load, i.e. compression and shear. During the mechanical load the structural and dynamical properties of these systems were examined with confocal microscopy. Therefor new granular model systems in the wet and dry state were designed and prepared. As the particles are solid bodies, their motion is described by six degrees of freedom. To explore their entire motion with all degrees of freedom, a technique to visualize the rotation of spherical micrometer sized particles in 3D was developed. rnOne of the foci during this dissertation was a model system for dry cohesive granular matter. In such systems the particle motion during a compression of the granular matter was investigated. In general the rotation of single particles was the more sensitive parameter compared to the translation. In regions with large structural changes the rotation had an earlier onset than the translation. In granular systems under shear, shear dilatation and shear zone formation were observed. Globally the granular sediments showed a shear behavior, which was known already from classical shear experiments, for example with Jenike cells. Locally the shear zone formation was enhanced, when near the applied load a pre-diluted region existed. In regions with constant volume fraction a mixing between the different particle layers occurred. In particular an exchange of particles between the current flowing region and the non-flowing region was observed. rnThe second focus was on model systems for wet granular matter, where an additional binding liquid is added to the particle suspension. To examine the 3D structure of the binding liquid on the micrometer scale independently from the particles, a second illumination and detection beam path was implemented. In shear and compression experiments of wet clusters and bulk systems completely different dynamics compared to dry cohesive models systems occured. In a Pickering emulsion-like system large structural changes predominantly occurred in the local environment of binding liquid droplets. These large local structural changes were due to an energy interplay between the energy stored in the binding droplet during its deformation and the binding energy of particles at the droplet interface. rnConfocal microscopy in combination with nanoindentation gave new insights into the single particle motions and dynamics of granular systems under a mechanical load. These novel experimental results can help to improve the understanding of the relationship between bulk properties of granular matter, such as volume fraction or yield stress and the dynamics on a single particle level.rnrn

Multifunctional polyether architectures : versatile materials for surface attachment and functionalization

Chapter 1 of this thesis comprises a review of polyether polyamines, i.e., combinations of polyether scaffolds with polymers bearing multiple amino moieties. Focus is laid on controlled or living polymerization methods. Furthermore, fields in which the combination of cationic, complexing, and pH-sensitive properties of the polyamines and biocompatibility and water-solubility of polyethers promise enormous potential are presented. Applications include stimuli-responsive polymers with a lower critical solution temperature (LCST) and/or the ability to gel, preparation of shell cross-linked (SCL) micelles, gene transfection, and surface functionalization.rnIn Chapter 2, multiaminofunctional polyethers relying on the class of glycidyl amine comonomers for anionic ring-opening polymerization (AROP) are presented. In Chapter 2.1, N,N-diethyl glycidyl amine (DEGA) is introduced for copolymerization with ethylene oxide (EO). Copolymer microstructure is assessed using online 1H NMR kinetics, 13C NMR triad sequence analysis, and differential scanning calorimetry (DSC). The concurrent copolymerization of EO and DEGA is found to result in macromolecules with a gradient structure. The LCSTs of the resulting copolymers can be tailored by adjusting DEGA fraction or pH value of the environment. Quaternization of the amino moieties by methylation results in polyelectrolytes. Block copolymers are used for PEGylated gold nanoparticle formation. Chapter 2.2 deals with a glycidyl amine monomer with a removable protecting group at the amino moiety, for liberation of primary amines at the polyether backbone, which is N,N-diallyl glycidyl amine (DAGA). Its allyl groups are able to withstand the harsh basic conditions of AROP, but can be cleaved homogeneously after polymerization. Gradient as well as block copolymers poly(ethylene glycol)-PDAGA (PEG-PDAGA) are obtained. They are analyzed regarding their microstructure, LCST behavior, and cleavage of the protecting groups. rnChapter 3 describes applications of multi(amino)functional polyethers for functionalization of inorganic surfaces. In Chapter 3.1, they are combined with an acetal-protected catechol initiator, leading to well-defined PEG and heteromultifunctional PEG analogues. After deprotection, multifunctional PEG ligands capable of attaching to a variety of metal oxide surfaces are obtained. In a cooperative project with the Department of Inorganic and Analytical Chemistry, JGU Mainz, their potential is demonstrated on MnO nanoparticles, which are promising candidates as T1 contrast agents in magnetic resonance imaging. The MnO nanoparticles are solubilized in aqueous solution upon ligand exchange. In Chapter 3.2, a concept for passivation and functionalization of glass surfaces towards gold nanorods is developed. Quaternized mPEG-b-PqDEGA diblock copolymers are attached to negatively charged glass surfaces via the cationic PqDEGA blocks. The PEG blocks are able to suppress gold nanorod adsorption on the glass in the flow cell, analyzed by dark field microscopy.rnChapter 4 highlights a straightforward approach to poly(ethylene glycol) macrocycles. Starting from commercially available bishydroxy-PEG, cyclic polymers are available by perallylation and ring-closing metathesis in presence of Grubbs’ catalyst. Purification of cyclic PEG is carried out using α-cyclodextrin. This cyclic sugar derivative forms inclusion complexes with remaining unreacted linear PEG in aqueous solution. Simple filtration leads to pure macrocycles, as evidenced by SEC and MALDI-ToF mass spectrometry. Cyclic polymers from biocompatible precursors are interesting materials regarding their increased blood circulation time compared to their linear counterparts.rnIn the Appendix, A.1, a study of the temperature-dependent water-solubility of polyether copolymers is presented. Macroscopic cloud points, determined by turbidimetry, are compared with microscopic aggregation phenomena, monitored by continuous wave electron paramagnetic resonance (CW EPR) spectroscopy in presence of the amphiphilic spin probe and model drug (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO). These thermoresponsive polymers are promising candidates for molecular transport applications. The same techniques are applied in Chapter A.2 to explore the pH-dependence of the cloud points of PEG-PDEGA copolymers in further detail. It is shown that the introduction of amino moieties at the PEG backbone allows for precise manipulation of complex phase transition modes. In Chapter A.3, multi-hydroxyfunctional polysilanes are presented. They are obtained via copolymerization of the acetal-protected dichloro(isopropylidene glyceryl propyl ether)methylsilane monomer. The hydroxyl groups are liberated through acidic work-up, yielding versatile access to new multifunctional polysilanes.