Synthese und Strukturierung von funktionalisierten Oligothiophenen

AbstractIn this thesis t-BOC and methacrylate functionalisedoligothiophenes with 3 – 5 thiophene units where synthesizedby Stille coupling. The material was structured by methodslike stamping and photolithography.The polymerizability of the methacrylates was proved by thepolymerization in solution with AIBN and subsequent analysisby gel permeation chromatography and differential scanningcalorimetry. The conductivities of the doped polymer filmswere in the range published for oligothiophenes.The optical and electrochemical properties of the compoundswere measured and compared to known compounds.The cleavage of the t-BOC groups was followed bythermogravimetry and infrared spectroscopy. The cleavagetemperature can be lowered by up to 100 °C by the use ofphoto acid generators. The cleavage is complete after 2hours annealing.The methacrylates were structured by microinjection mouldingin capillaries (MIMIC), stamping with soft silicone moulds,filling of patterned substrates and preperation of an opalreplica. By MIMIC line patterns with 5- 50 µm line widthswere obtained. The stamping succeeded in structures with 500nm line width only, on which liquid crystals wereorientated. This shows the possible application asorientation layers in LED’s with polarized emission. Withsilica opal templates the three-dimensional structuring ofthe oligomers succeeded.ZusammenfassungIn dieser Arbeit wurden neue funktionalisierteOligothiophene hergestellt und unter Anwendung verschiedenerVerfahren wie Stempeltechniken oder Photolithographiestrukturiert. Dazu wurden Oligothiophene mit drei bis fünfThiopheneinheiten durch Stille-Kupplung synthetisiert. Alsfunktionelle Gruppen wurden t-BOC-Ester undMethacrylsäureester eingeführt.Die Polymerisierbarkeit der Methacrylate wurde durch diePolymerisation mit AIBN in Lösung und anschließendeGelpermeationschromatographie und Differentialkalorimetrienachgewiesen. Die Leitfähigkeiten der dotierten Polymerfilmelagen im Bereich der für Oligothiophene bekannten Werte.Die optischen und elektrochemischen Eigenschaften derVerbindungen wurden untersucht und mit den Eigenschaftenbekannter Verbindungen verglichen. Die Abspaltung der t-BOC-Gruppen wurde thermogravimetrischund infrarotspektroskopisch verfolgt. Es wurde gezeigt, daßdie Abspaltungstemperatur durch den Zusatz einesPhotosäuregenerators um bis zu 100°C gesenkt wird und dieAbspaltung nach zweistündigem Tempern vollständig ist.Die methacrylatfunktionalisierten Verbindungen wurdenstrukturiert durch Micro Injection Moulding in Capillaries(MIMIC), Prägen mit weichen Silikonstempeln, Füllen vonstrukturierten Substraten und die Herstellung einerOpalreplika. Durch die Strukturierung mit MIMIC wurdenLinienstrukturen mit Linienbreiten von 5-50 µm erhalten.Durch Prägen wurden Strukturen mit Linienbreiten von nur 500nm erreicht, auf diesen gelang die Orientierung vonFlüssigkristallen. Dies zeigt die mögliche Anwendung alsOrientierungsschichten in Leuchtdioden mit polarisierterEmission. Durch die Verwendung von Siliziumoxidopalen alsTemplate gelang die dreidimensionale Strukturierung derOligomere.

High quality colloidal crystals with different architectures and their optical properties

In this present work high quality PMMA opals with different sphere sizes, silica opals from large size spheres, multilayer opals, and inverse opals were fabricated. Highly monodisperse PMMA spheres were synthesized by surfactant-free emulsion polymerization (polydispersity ~2%). Large-area and well-ordered PMMA crystalline films with a homogenous thickness were produced by the vertical deposition method using a drawing device. Optical experiments have confirmed the high quality of these PMMA photonic crystals, e.g., well resolved high-energy bands of the transmission and reflectance spectra of the opaline films were observed. For fabrication of high quality opaline photonic crystals from large silica spheres (diameter of 890 nm), self-assembled in patterned Si-substrates a novel technique has been developed, in which the crystallization was performed by using a drawing apparatus in combination with stirring. The achievements comprise a spatial selectivity of opal crystallization without special treatment of the wafer surface, the opal lattice was found to match the pattern precisely in width as well as depth, particularly an absence of cracks within the size of the trenches, and finally a good three-dimensional order of the opal lattice even in trenches with a complex confined geometry. Multilayer opals from opaline films with different sphere sizes or different materials were produced by sequential crystallization procedure. Studies of the transmission in triple-layer hetero-opal revealed that its optical properties cannot only be considered as the linear superposition of two independent photonic bandgaps. The remarkable interface effect is the narrowing of the transmission minima. Large-area, high-quality, and robust photonic opal replicas from silicate-based inorganic-organic hybrid polymers (ORMOCER® s) were prepared by using the template-directed method, in which a high quality PMMA opal template was infiltrated with a neat inorganic-organic ORMOCER® oligomer, which can be photopolymerized within the opaline voids leading to a fully-developed replica structure with a filling factor of nearly 100%. This opal replica is structurally homogeneous, thermally and mechanically stable and the large scale (cm2 size) replica films can be handled easily as free films with a pair of tweezers.

Chemie an funktionalen Polymer-Opalen

In dieser Arbeit wird die Herstellung und Anwendung von funktionalen Polymer-Opalen beschrieben. Für die Synthese von funktionalen monodipsersen Kolloiden, den Bausteinen der Opale, wird die emulgatorfreie Emulsionspolymerisation (SFEP) verwendet. Je nach einzubauendem funktionalem Molekül werden verschiedene Varianten der SFEP verwendet, wie z. B. Homopolymerisation, Copolymerisation, Polymerisation mit Fremdstoffen und die Herstellung von Kern-Schale-Kolloiden. Die so hergestellten monodispersen Kolloide formen durch Selbstorganisation über horizontale (Aufpipettieren, Rakeln, Sprühen) oder vertikale Kristallisation (Ziehmaschine)hochqualitative künstliche Opale. Die eingebauten Funktionalitäten öffnen den Weg zu einer Vielzahl von Anwendungen. Über die Spaltung von funktionalen Estergruppen kann eine lichtinduzierte Strukturierung durchgeführt werden. Der Einbau von Epoxidgruppen ermöglicht eine makroskopische Vernetzung wodurch die mechanische Stabilität der Struktur erhöht wird. Der Einsatz von Reaktivestern kann zur Oberflächen- funktionalisierung verwendet werden. Durch Replizierung der Struktur zum inversen Opal können weitere funktionale Materialien eingeführt werden, was die Einsatzmöglichkeiten noch erweitert.

Complex materials via colloidal crystallization

The work presented in this thesis deals with complex materials, which were obtained by self-assembly of monodisperse colloidal particles, also called colloidal crystallization. Two main fields of interest were investigated, the first dealing with the fabrication of colloidal monolayers and nanostructures, which derive there from. The second turned the focus on the phononic properties of colloidal particles, crystals, and glasses. For the fabrication of colloidal monolayers a method is introduced, which is based on the sparse distribution of dry colloidal particles on a parent substrate. In the ensuing floating step the colloidal monolayer assembles readily at the three-phase-contact line, giving a 2D hexagonally ordered film under the right conditions. The unique feature of this fabrication process is an anisotropic shrinkage, which occurs alongside with the floating step. This phenomenon is exploited for the tailored structuring of colloidal monolayers, leading to designed hetero-monolayers by inkjet printing. Furthermore, the mechanical stability of the floating monolayers allows the deposition on hydrophobic substrates, which enables the fabrication of ultraflat nanostructured surfaces. Densely packed arrays of crescent shaped nanoparticles have also been synthesized. It is possible to stack those arrays in a 3D manner allowing to mutually orientate the individual layers. In a step towards 3D mesoporous materials a methodology to synthesize hierarchically structured inverse opals is introduced. The deposition of colloidal particles in the free voids of a host inverse opal allows for the fabrication of composite inverse opals on two length scales. The phononic properties of colloidal crystals and films are characterized by Brillouin light scattering (BLS). At first the resonant modes of colloidal particles consisting of polystyrene, a copolymer of methylmethacrylate and butylacrylate, or of a silica core-PMMA shell topography are investigated, giving insight into their individual mechanical properties. The infiltration of colloidal films with an index matching liquid allows measuring the phonon dispersion relation. This leads to the assignment of band gaps to the material under investigation. Here, two band gaps could be found, one originating from the fcc order in the colloidal crystal (Bragg gap), the other stemming from the vibrational eigenmodes of the colloidal particles (hybridization gap).

Structured antibody surfaces for bio-recognition and a label-free detection of bacteria

Antibody microarrays are of great research interest because of their potential application as biosensors for high-throughput protein and pathogen screening technologies. In this active area, there is still a need for novel structures and assemblies providing insight in binding interactions such as spherical and annulus-shaped protein structures, e.g. for the utilization of curved surfaces for the enhanced protein-protein interactions and detection of antigens. Therefore, the goal of the presented work was to establish a new technique for the label-free detection of bio-molecules and bacteria on topographically structured surfaces, suitable for antibody binding.rnIn the first part of the presented thesis, the fabrication of monolayers of inverse opals with 10 μm diameter and the immobilization of antibodies on their interior surface is described. For this purpose, several established methods for the linking of antibodies to glass, including Schiff bases, EDC/S-NHS chemistry and the biotin-streptavidin affinity system, were tested. The employed methods included immunofluorescence and image analysis by phase contrast microscopy. It could be shown that these methods were not successful in terms of antibody immobilization and adjacent bacteria binding. Hence, a method based on the application of an active-ester-silane was introduced. It showed promising results but also the need for further analysis. Especially the search for alternative antibodies addressing other antigens on the exterior of bacteria will be sought-after in the future.rnAs a consequence of the ability to control antibody-functionalized surfaces, a new technique employing colloidal templating to yield large scale (~cm2) 2D arrays of antibodies against E. coli K12, eGFP and human integrin αvβ3 on a versatile useful glass surface is presented. The antibodies were swept to reside around the templating microspheres during solution drying, and physisorbed on the glass. After removing the microspheres, the formation of annuli-shaped antibody structures was observed. The preserved antibody structure and functionality is shown by binding the specific antigens and secondary antibodies. The improved detection of specific bacteria from a crude solution compared to conventional “flat” antibody surfaces and the setting up of an integrin-binding platform for targeted recognition and surface interactions of eukaryotic cells is demonstrated. The structures were investigated by atomic force, confocal and fluorescence microscopy. Operational parameters like drying time, temperature, humidity and surfactants were optimized to obtain a stable antibody structure.