Since the rediscovery of carbon nanotubes (CNTs) due to the publication of Sumio Iijima's article Helical microtubules of graphitic carbon in the magazine Nature in 1991 the interest in carbon nanotubes has rapidly increased. This bachelor thesis also deals with this popular material with the aim to functionalize CNTs for further uses in the microelectronic industry. A promising approach is the functionalization of the CNTs with metal nanoparticles or metal films. To achieve this, one can perform an atomic layer deposition (ALD) on CNTs. In the present work the Trimethylaluminum (TMA) ALD is the chosen process for the functionalization of the CNTs, which will be studied here. Since the available knowledge on the CNT-functionalization by gas phase reactions is very limited, a theoretical study of possible reaction pathways is necessary. Those studies are carried out with two modern quantumchemical programs, Turbomole and DMol³, which are described together with an introduction into Density Functional Theory, as well as an introduction of CNTs and the ALD process. A basic model of a CNT with a Single Vacancy defect, which had been selected according to the demands of the studies, is introduced. Because the TMA ALD process requires hydroxyl groups as its starting point, not only is the performance of a TMA ALD cycle on a CNT studied, but also reactions which result in the CNTs owning of hydroxyl groups. Consequently, this bachelor thesis will focus on two di erent aspects: The performance of one TMA ALD cycle and the study of possible educts for the TMA ALD process. This study of the educts includes possible structures which can be formed when a CNT comes into contact with air.

The adsorption and organization of reactive microgels has been investigated on technical aluminium. By means of a two-step emulsion polymerisation with phosphate substituted monomer we obtain polymeric nano-particles with phosphate groups on the surface. In a first step cross-linked butyl acrylate/styrene particles were formed. In a second step a mixture of functionalised acrylate and butyl acrylate/styrene was added to the system. In this way, the composite particles were obtained. Particle size and size distribution were measured by F-FFF and light scattering methods. For phosphate functionalised dispersions, it was possible to show the distribution of P-species around particles by energy dispersive TEM easurements. These nano-particles adsorb spontaneously onto aluminium surfaces from aqeous dispersion. They form well packed layers, which have been proved by SEM measurements. The properties of the adsorbed microgel layers were confirmed by industrial linked adhesion and corrosion tests. Panels with adsorbed phosphate funczionalised particles have an excellent corrosion inhibition effect.

Im Rahmen der vorliegenden Arbeit wurde der Einfluss der nichtenzymatischen Glykosylierung auf das Denaturierungsverhalten und die funktionellen Eigenschaften von Molkenproteinen, hier im speziellen die emulgierenden Eigenschaften, untersucht. Nach einer Bestimmung technologisch relevante Glykosylierungsgrade sollten in unterschiedlich glykosylierten Molkenproteinpräparaten das Denaturierungsverhalten sowie die Emulgiereigenschaften in Abhängigkeit vom Glykosylierungsgrad mit unterschiedlichen Methoden bestimmt werden. Der aus praktischer Sicht relevante Einfluss der Glykosylierung auf die sensorischen Eigenschaften wurde einerseits in Molkenproteinlösungen und andererseits in einem komplexen System (Modell-Schmelzkäsezubereitung) erfasst. Schließlich galt es, den Einfluss der Glykosylierung auf die Mikrostruktur und die Festigkeit am Beispiel der Modell- Schmelzkäsezubereitung zu untersuchen und daraus unmittelbare Konsequenzen für die technologische Praxis abzuleiten.

The main objective of the present thesis is to deepen the understanding of the mechanisms involved in catalytic growth of carbon nanotubes (CNT) and related processes, such as the catalytic hydrogenation, and to use this knowledge to optimize the experimental approaches in order to gain better control in the synthesis and modification of carbon nanomaterials. Controlled growth of the CNT is achieved using gas-phase prepared catalyst particles (Fe, Co) which serve as individual catalytic nucleation sites in a chemical vapor deposition (CVD) process. These studies highlight that the controlled preparation of catalyst particles is a crucial step in order to control the CNT morphology. The resultant CNT diameter and the CNT density are found to increase with increasing nanoparticle diameter and density, respectively. The number of walls of the CNT also increases with increasing primary catalyst size. The experimentally derived correlations between the particle diameter on one hand and the CNT diameter and the CNT number of walls on the other hand are attributed to an increase of the catalyst's volume-to-surface area ratio with increasing particle size. While the availability of carbon dissolved within the catalyst at the point of nucleation is determined by the catalyst volume, the amount of carbon required to form a cap depends on the surface area of the catalyst particle. Electron microscopy studies of the catalyst/substrate/carbon interfaces of CNT grown from Fe nanoparticles reveal that the CNT walls are anchored to the oxide substrate which contests the general argument that the CNT walls stem from atomic steps at the catalyst. It is argued that after nucleation, the substrate itself provides a catalytic functionality towards the stimulation of ongoing CNT growth, whereas the catalytic activity of the metal particle is more restricted to the nucleation process. Selective hard-magnetic functionalization of CNT tips has been achieved in a plasma-enhanced CVD process. Hard-magnetically terminated CNT, i.e. CNT with a FePt nanoparticle at each tip, are directly grown using FePt catalysts. Fe/Pt thin films with a strongly over-stoichiometric Fe content in the starting catalyst composition yield CNT with a significant number of particles in the hard-magnetic phase. Anisotropic etching of graphite through Co catalyst particles in hydrogen atmosphere at elevated temperatures (i.e. catalytic hydrogenation) is reported. Catalytic hydrogenation is a potential key engineering route for the fabrication of graphene nanoribbons with atomic precision. While in previous studies the etching of zigzag channels was preferred, the present investigations reveal preferential etching of armchair channels, which provides a means to tailor graphene nanostructures with specific edge termination. Further, detailed morphological and structural characterization of the Co particles provide insight into the hydrogenation mechanism which is still a matter of controversy.

Zugl.: Bayreuth, Universiẗat, Diss., 2009.

A new approach for the fine tuning of flexibility in MOFs, involving functionalization of the secondary building unit, is presented. The 'gate pressure' MOF [Zn3(bpydc)2(HCOO)2] was used as a model material and SBU functionalization was performed by using monocarboxylic acids such as acetic, benzoic or cinnamic acids instead of formic acid in the synthesis. The resulting materials are isomorphous to [Zn3(bpydc)2(HCOO)2] in the 'as made' form, but show different structural dynamics during the guest removal. The activated materials have entirely different properties in the nitrogen physisorption experiments clearly showing the tunability of the gate pressure, at which the structural transformation occurs, by using monocarboxylic acids with varying backbone structure in the synthesis. Thus, increasing the number of carbon atoms in the backbone leads to the decreasing gate pressure required to initiate the structural transition. Moreover, in situ adsorption/PXRD data suggest differences in the mechanism of the structural transformations: from 'gate opening' in the case of formic acid to 'breathing' if benzoic acid is used.

In der vorliegenden Arbeit wird die Synthese von Carbosiloxandendrimeren der dritten Generation durch repetitive Alkoholyse-Hydrosilylierungs-cyclen auf dem divergenten Syntheseweg beschrieben. Im Mittelpunkt der Arbeit stand jedoch die Funktionalisierung dieser Dendrimere mit einer Vielzahl metallorganischer (Ferrocenyl-, Übergangsmetallcarbonyl-verbindungen) bzw. organischer (stickstoffhaltige Ligandsysteme) Einheiten. Zudem wird die Darstellung amphiphiler und bifunktionaler Carbosiloxandendrimere vorgestellt. Die neu synthetisierten Verbindungen wurden analytisch umfassend charakterisiert, wobei die 29Si-{1H}-NMR-Spektroskopie sowie die Massenspektrometrie einen besonderen Stellenwert einnehmen.

The aim of this work was to functionalize silicon dioxide surfaces with biochemical molecules in such a way that biorecognition of target molecules in solution will be possible. By introducing a tool set of different molecules and characterization methods, a more universal approach towards various biosensor setups is presented. This includes on the one hand preparation of the biosensor surfaces to allow further molecule attachment via their reactive functional groups. Secondly, the selection of chemical molecules providing suitable counterparts for abundant functional groups of potential receptors is discussed. Two detection schemes are introduced – based on an antibody to detect the antibiotic amoxicillin and aptamers to detect thrombin. The antibody was implemented in an inverse competition assay to probe such small target molecules. Antibiotic residues are often present in wastewater. Aptamers, so-called artificial antibodies, were selected as they provide many advantages over antibodies. As a model system, two different thrombin binding aptamers were chosen which allowed to perform sandwich assays as well. The protein thrombin plays an important role in the blood coagulation cascade. To probe the individual modification steps, different techniques for analysis were applied. Surface micropatterning was introduced to improve recognition of modified areas and fluorescence-to-background ratios resulting in a thrombin detection limit down to 20 pM. One important goal was the integration in ion-sensitive field-effect transistor devices. Aptamers are small in size which might enable a higher sensitivity of these devices compared to the use of antibodies because of the Debye layer thickness. As a final step, first measurements towards silicon nanowire based field-effect transistor biosensors were carried out on devices with bottom-up and top-down fabricated nanowires using both proposed receptor-analyte combinations. The potential of these devices as portable sensors for real-time and label-free biosensing is demonstrated. / Ziel dieser Arbeit war es Siliziumdioxidoberflächen so mit biochemischen Molekülen zu funktional- isieren, dass die biologisch spezifische Erkennung von Zielmolekülen in Lösung möglich wird. Hier wird eine Auswahl an geeigneten Molekülen und Charakterisierungsmethoden für einen vielseitigen Ansatz gezeigt, der auf verschiedene Biosensorsysteme anwendbar ist. Das beinhaltet zum Einen die Präparation der Biosensoroberflächen, so dass die Moleküle über reaktive funktionelle Gruppen angebunden werden können. Als zweites ist die Auswahl der chemischen Moleküle wichtig, da diese die passenden Gegenstücke zu potentiellen funktionellen Gruppen der Rezeptoren darstellen. Zwei verschiedene Detektionsvarianten werden eingeführt – Antikörper gegen das Antibiotikum Amoxicillin und Aptamere gegen Thrombin. Der Antikörper wurde in einen inversen Wettbewerbsassay integriert um einen solch kleinen Ana- lyten detektieren zu können. Rückstände von Antibiotika sind häufig in Abwässern zu finden. Ap- tamere, sogenannte künstliche Antikörper, weisen gegenüber Antikörpern viele Vorteile auf. Als ein Modellsystem wurden zwei unterschiedliche Thrombin bindende Aptamere verwendet, was auch die Durchführung von Sandwich Assays ermöglichte. Das Protein Thrombin spielt eine wichtige Rolle bei der Blutgerinnung. Um die einzelnen Modifikationsschritte zu untersuchen, wurden verschiedene Charakterisierungsmethoden angewendet. Die Mikrostrukturierung der Funktionalisierung erleichterte die Erkennung der modifizierten Flächen und verbesserte das Fluoreszenz-zu-Hintergrund Verhältnis. Das führte zu einer Detektionsgrenze von 20 pM für Thrombin. Ein wichtiges Ziel dieser Arbeit war die Integration der Funktionalisierung in einen ionen-sensitiven Feldeffekttransistor. Die kleinen Aptamere könnten dabei aufgrund der geringen Debye-Schichtdicke bei diesen Sensoren eine höhere Sensitivität als mit Antikörpern ermöglichen. Zuletzt wurden erste Messungen hin zu Silizium Nanodraht basierten Feldeffekttransistor Biosen- soren mit beiden untersuchten Rezeptor-Analyt-Kombinationen durchgeführt. Sowohl die Chips mit bottom-up als auch mit top-down gewachsenen Nanodrähten zeigen dabei ihr Potential als handliche Sensoren zur markerfreien Detektion in Echtzeit.

The adsorption and organization of reactive microgels has been investigated on technical aluminium. By means of a two-step emulsion polymerisation with phosphate substituted monomer we obtain polymeric nano-particles with phosphate groups on the surface. In a first step cross-linked butyl acrylate/styrene particles were formed. In a second step a mixture of functionalised acrylate and butyl acrylate/styrene was added to the system. In this way, the composite particles were obtained. Particle size and size distribution were measured by F-FFF and light scattering methods. For phosphate functionalised dispersions, it was possible to show the distribution of P-species around particles by energy dispersive TEM easurements. These nano-particles adsorb spontaneously onto aluminium surfaces from aqeous dispersion. They form well packed layers, which have been proved by SEM measurements. The properties of the adsorbed microgel layers were confirmed by industrial linked adhesion and corrosion tests. Panels with adsorbed phosphate funczionalised particles have an excellent corrosion inhibition effect.

The main objective of the present thesis is to deepen the understanding of the mechanisms involved in catalytic growth of carbon nanotubes (CNT) and related processes, such as the catalytic hydrogenation, and to use this knowledge to optimize the experimental approaches in order to gain better control in the synthesis and modification of carbon nanomaterials. Controlled growth of the CNT is achieved using gas-phase prepared catalyst particles (Fe, Co) which serve as individual catalytic nucleation sites in a chemical vapor deposition (CVD) process. These studies highlight that the controlled preparation of catalyst particles is a crucial step in order to control the CNT morphology. The resultant CNT diameter and the CNT density are found to increase with increasing nanoparticle diameter and density, respectively. The number of walls of the CNT also increases with increasing primary catalyst size. The experimentally derived correlations between the particle diameter on one hand and the CNT diameter and the CNT number of walls on the other hand are attributed to an increase of the catalyst's volume-to-surface area ratio with increasing particle size. While the availability of carbon dissolved within the catalyst at the point of nucleation is determined by the catalyst volume, the amount of carbon required to form a cap depends on the surface area of the catalyst particle. Electron microscopy studies of the catalyst/substrate/carbon interfaces of CNT grown from Fe nanoparticles reveal that the CNT walls are anchored to the oxide substrate which contests the general argument that the CNT walls stem from atomic steps at the catalyst. It is argued that after nucleation, the substrate itself provides a catalytic functionality towards the stimulation of ongoing CNT growth, whereas the catalytic activity of the metal particle is more restricted to the nucleation process. Selective hard-magnetic functionalization of CNT tips has been achieved in a plasma-enhanced CVD process. Hard-magnetically terminated CNT, i.e. CNT with a FePt nanoparticle at each tip, are directly grown using FePt catalysts. Fe/Pt thin films with a strongly over-stoichiometric Fe content in the starting catalyst composition yield CNT with a significant number of particles in the hard-magnetic phase. Anisotropic etching of graphite through Co catalyst particles in hydrogen atmosphere at elevated temperatures (i.e. catalytic hydrogenation) is reported. Catalytic hydrogenation is a potential key engineering route for the fabrication of graphene nanoribbons with atomic precision. While in previous studies the etching of zigzag channels was preferred, the present investigations reveal preferential etching of armchair channels, which provides a means to tailor graphene nanostructures with specific edge termination. Further, detailed morphological and structural characterization of the Co particles provide insight into the hydrogenation mechanism which is still a matter of controversy.