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Im Laufe dieser Arbeit wurden neuartige Synthesen zur Darstellung von nanostrukturierten, hochtemperaturbeständigen Materialien entwickelt. Die bei den Synthesen der Polyimiden erläuterten Ergebnisse zeigen, dass die Synthese von hochtemperaturbeständigen Polymer-Nanopartikeln in Heterophase möglich ist. Als Heterophase dient dabei eine ionische Flüssigkeit; die Polykondensationen laufen ohne die Zugabe von Aktivatoren oder Hilfsreagenzien ab. Wegen der charakteristischen Eigenschaften der ionischen Flüssigkeit konnten selbst Hochtemperaturpolykondensationen bei ca. 220 °C ohne besondere Reaktionsgefäße durchgeführt werden. Die erhaltenen Polymer-Nanopartikel wurden durch IR-Spektroskopie charakterisiert und mittels TEM/REM-Aufnahmen auf Struktur und Morphologie der Partikel analysiert. Die thermische Belastbarkeit der erhaltenen Polyimid-Nanopartikel wurde durch TGA ermittelt. Die durchschnittliche Teilchengröße der erhaltenen Partikel liegt in Abhängigkeit der verwendeten Edukte zwischen 100 und 350 nm. Die mittels DLS-Messungen erhaltenen Teilchengrößen wurden durch die TEM-Abbildungen bestätigt. Da die Partikel nach der Isolierung als feines Pulver vorliegen, können sie in einem weiteren Schritt als leicht zu verarbeitende Polymerdispersion verarbeitet werden. Die erfolgreiche Synthese der nanostrukturierten, mesoporösen Silica-Matrices erfolgte nach der Sedimentations-Aggregations-Methode unter der Verwendung von unterschiedlichen PNIPAM-co-PS-Nanopartikeln als Templat. Die Analysenergebnisse der REM-Aufnahmen zeigen, dass die Synthese von mesoporösen Silica-Matrices auch unter der Verwendung von „weichen“ Templatpartikeln möglich ist.

A personal survey of some of the polymer-related work which I had the chance to carry out in Ciba-Geigy's Central Research and in the polymer departments of Ciba SC, Vantico and Huntsman is given, including a few short comments on the eventful history of the former Ciba-Geigy Central Research and Polymer Division. In the early 1970s, high-temperature-stable aromatic [polyamide – polyimide] block copolymers and the relatively easy processable bismaleimides as high-temperature thermoset materials were the dominant theme. Work on photocrosslinkable DMI polymers which ultimately led to the development of a non-silver graphic film and a presensitized negative offset printing plate was pursued at the Centre de Recherche Marly. In the field of epoxy resin chemistry, 'latent' hardeners, featuring a relatively long pot-life at room temperature and a short cure cycle at the processing temperature, were devised in the form of benzyl-sulfonium salts and imidazole-functionalized microgels. Ciba-Geigy's polymer division has pioneered the development of liquid, photoimageable soldermasks with it's Probimer® range of products. Here binderpolymers constitute the main components of the complex formulation recipes. High molecular weight polymers carrying acryloyl and carboxyl functional groups were synthesized for this purpose and have found commercial application in new soldermask generations.

In der vorliegenden Arbeit wird die nichtinvasive Kopplung von synaptisch verbundenen Neuronen mit einem Halbleiterchip charakterisiert. Dazu wurden Neurone der Schnecke Lymnaea stagnalis in Polymerkäfigen auf der Chipoberfläche immobilisiert. Unter Kulturbedingungen vernetzten die Neurone über elektrische Synapsen. Mit einem kapazitiven Stimulator konnte in einer adhärierten Zelle neuronale Aktivität, Aktionspotenziale, ausgelöst werden. Die Aktionspotenziale depolarisierten über die Synapse ein zweites Neuron, dessen Aktivität im darunterliegenden Transistor detektiert wurde. Der vollständige Signalweg vom Halbleiter über ein minimales neuronales Netzwerk zurück zum Halbleiter stellt die Grundlage neuroelektronischer Systeme dar. The present work describes the noninvasive coupling of synaptically connected neurons and a semiconductor chip. Nerve cells from the snail Lymnaea stagnalis were immobilized on the chip surface by microscopic picket fences of polyimide. The cells formed a network with electrical synapses after outgrowth in conditioned medium. Pairs of neurons were electronically interfaced for noninvasive stimulation and recording. Voltage pulses were applied to a capacitive stimulator on the chip to excite the attached neuron. Signals were transmitted in the neuronal net and elicited an action potential in a second neuron.The postsynaptic excitation modulated the current of a transistor on the chip. The implementation of the silicon-neuron-neuron-silicon circuit constitutes a proof-of-principle experiment for the development of neuroelectronic systems.

The present work concerns the characterisation of the chemical and physical properties of the surface, which arise when switching the wetting characteristics of the polyimide surface. A reversible loop consists of four processes: the hydrolysis of the polyimide surface to generate a hydrophilic surface, the UV-exposure, rubbing of the exposed areas and the erasure of the structures with a commercial cleaning agent. The structured surface can be used in an offset printing press as a printing-plate. After the erasure the loop is closed. All processes are limited to a thin layer on the surface of the polyimide. Therefore, surface sensitive-characterisation methods are required for their investigation. To acquire information about the chemical modification after the individual process steps measurements with infrared spectroscopy in attenuated total reflexion (FTIR-ATR spectroscopy) and X-ray photoelectron spectroscopy (XPS) were carried out. The structures produced by light exposure could be mapped with white light interference microscopy, scanning electron microscopy and atomic force microscopy. The important wetting characteristics for the offset printing could be determined macroscopically with contact angle measurements and microscopically by means of special atomic force microscopy procedures. The generation of hydrophilic zones on the polyimide was accomplished by the hydrolysis of its surface. The samples were brought into contact with an alkaline solution. The cyclic imide groups were opened. Upon opening amide and carboxylate groups are formed, which were detected by means of FTIR-ATR and XP-spectroscopy. The patterning of the surfaces was realized by two different UV light sources: a mercury vapor lamp and a laser system (Ti:Sa laser). Although the physical and chemical process induced by the UV irradiation is very diverse, due to the energy density, the result of the UV irradiation namely the destruction of the polymer chain at the surface is comparable. Residues of the gradest polyimide chain stays as debris. After exposure to irradiation the surfaces did not show uniform wettability. Therefore, subsequently a development step was carried out for removing the polyimide which was destroyed by the UV irradiation. This was done via rubbing the surface with a cellulose pad. By removing the ablated material, indentations on the surface of the polyimide arose. These could be mapped by atomic force microscopy and white light interference microscopy. The depth of these structures depends on the kind and the fluence of the UV source. It varied between 100 and 200 nm. The exposed and rubbed zones were hydrophobic. For obtaining a rewritable printing plate it is necessary to erase the surface at the end of the cycle, so that a new print format on the same surface can be produced. This takes place via abrasion the surface with a commercial cleaning agent. The XPS analysis showed that both element composition and chemical shift of the treated surface corresponds to that of the untreated polyimide surface. This surface behaved in each regard like the original surface, so that the entire cycle could be repeated several times with reproducible results.