Polydimethylsiloxan (PDMS)-basierte Materialien finden Verwendung als Schirmmaterial für Verbundisolatoren in der Hochspannungstechnik. Diese Schirmmaterialen benötigen im Außeneinsatz eine herausragende Hydrophobie, um Spannungsüberschläge durch leitfähige Elektrolytfilme zu vermeiden. Im Außeneinsatz widerfährt ein Schirmmaterial unterschiedliche Witterungsbedingungen wie z.B.: Regen oder Betauungsvorgänge. Unter Wirkung hoher elektrischer Felder können dann auf der Oberfläche Tropfenteilentladungen auftreten, die zu einer Hydrophilisierung der Oberfläche führen. Ziel der Arbeit ist es die Materialparameter zu beleuchten, die einen Einfluss auf die Hydrophobiebeständigkeit von Schirmmaterialien besitzen. Kommerziell erhältliche Silikon-Komposite besitzen neben dem eigentlichen Silikonnetzwerk auch Füllstoffe in unbekannter Art und Konzentration, wodurch eine Ursachenfindung für den Hydrophobieverlust erschwert ist. Aus diesem Grund wurde auf eigens synthetisierte Silikonelastomere zurückgegriffen. Diese wurden durch platinkatalysierte Hydrosilylierungsreaktion aus vinylterminierten PDMS (vPDMS) und dem tetrafunktionalem Vernetzer Tetrakis(dimethylsiloxysilan) (TDSS) hergestellt. Durch Variation der Kettenlängen des vPDMS und durch Variation des stöchiometrischen Verhältnisses konnte ein vPDMS-TDSS-Modell-Silikonsystem entwickelt werden, worin Netzwerkparameter (Netzwerkdichte und Sol-Anteil) gezielt justiert werden konnten. Die hergestellten Silikonelastomere wurden anschließend hinsichtlich ihrer Hydrophobie untersucht und im Anschluss gegenüber ihrer Beständigkeit gegenüber Tropfenteilentladungen getestet. Zur Simulation der kombinierten elektrischen und elektrolytischen Beanspruchung wurden dynamische Tropfentests durchgeführt, um die Hydrophobiebeständigkeit zu untersuchen. Im Rahmen der Arbeit wurde festgestellt, dass insbesondere die Steifigkeit der Materialien einen wesentlichen Einfluss auf die Hydrophobiebeständigkeit von Silikonen hat. Zusätzlich beeinflusst die Rauheit eines Materials die Ausfallzeiten im dynamischen Tropfentest maßgeblich. Darüber hinaus führt ein überlagerter Ölfilm auf der strukturierten Oberfläche dazu, dass sich das Abgleitverhalten von Wassertropfen im Laufe der Zeit verändert.

Material discovery and development has been playing a significant role in shaping human civilizations, by studying and improving materials for appealing observations to aid in our survival as well as to satisfy our curiosity. From the common earthly materials that give us strong building structures and hunting weapons to the Silicon Age that contributes to the creation of modern electronics and computers, the development of novel and enhanced materials continues to grow. Recently, a new field has emerged that is rapidly expanding the engineering circle; these are called nanomaterials. By shrinking bulk materials into structures with nanoscale dimensions, there is a deviation from classical physics, and quantum effects begin to dominate the properties of these materials. The nanometer range brings a high surface area-volume ratio which enhances the reactivity of the material, and thus size-dependent properties are materialized. Such behaviors can be applicable in several areas such as biomedical, catalysis, optics, processing, sensing and more. Nanomaterials can be further functionalized to grant new and enhanced functions, features and capabilities needed for a specific application. This dissertation aids to explore the functionalization of 1D and 2D nanomaterials for various applications. The proposed 1D and 2D nanostructures for testing will be polymer hydrogel nanofibers and silica nanoparticulate thin films, respectively. Nanofibers are unique by acting like swollen nanoreactors to enable functionalization via aqueous absorption and reaction. Silica nanoparticulate films have high nano-porosity, which can wet the thin coating intrinsically with aqueous and organic solvents or with non-organic solvents upon additional surface chemistry modification. In this dissertation, the functionalization of 1D and 2D nanostructures with chemical compounds and metal colloids will be tested, and the performance of the nanomaterials and nanocomposites for various applications will be evaluated.

Surface science is a multidisciplinary subject which affects us on a daily basis. Surfaces are of particular interest because the chemical bonding and atomic structure is different at the surface compared to the bulk properties of a material. This interface is of great significance because it is where charge exchange, or new chemical bonds occur. One essential aspect of surface science is surface wettability, which can be harnessed to produce self-cleaning surfaces. This very lucrative notion, where surfaces with low adhesion to liquids, can result in quick and autonomous shedding, has inspired a multitude of device fabrication and implementation. Over the past decade, several self-cleaning surfaces have been fabricated from superhydrophobic surfaces, which depends on a stable interface between solid, liquid and gas. These surfaces, however, are restricted in their applications and fail to operate upon mechanical damage or nonhomogeneous fabrication processes. Recent advances in wettability science have produced omniphobic lubricant-infused surfaces (OLIS). These surfaces are created by tethering a liquid to a surface, providing a stable liquid interface, which results in excellent aqueous and organic liquid repellency, and high robustness toward physical damage. This thesis will encompass an overview of the classical models for surface wettability, new models for liquid mobility, the criteria required to obtain OLIS, as well as some of the biomedical engineering applications fabricated from this technology. Herein, a novel manufacturing process was developed to produce smooth channeled polymeric microfluidic devices from rough 3D printed molds. Additionally, we integrated OLIS technology with electroconductive sensors to create high surface area electroactive material with self-cleaning properties, ideal to combat non-specific adhesion of biomolecules. Furthermore, our fabrication methods are inexpensive and have the potential to be easily integrated into manufacturing processes to create highly functional microfluidic devices, optimal for lab-on-chip diagnostic platforms. / Thesis / Master of Applied Science (MASc) / Recent advances in wettability science have produced omniphobic lubricant-infused surfaces (OLIS) inspired by the Nepenthes pitcher plant. These surfaces are created by tethering a liquid to a surface, providing a stable liquid interface, which results in excellent aqueous and organic liquid repellency, as well high robustness toward physical damage and high pressure dispensing scenarios. The motivation for this thesis is to expand on the applications for OLIS devices. Herein, a novel manufacturing process was developed to produce smooth channeled polymeric microfluidic devices from rough 3D printed molds. Additionally, we integrated OLIS technology with electroconductive sensors to create high surface area electroactive material with self-cleaning properties, ideal to combat non-specific adhesion of biomolecules.