In-situ Preparation of Metallic Nanoparticles Using Photo-Initiated Processes

With the currently high interest into research on nanoparticle catalysis comes an ever-growing need for novel composites based on embedded metallic nanoparticles. While numerous methods for their physical and wet-chemical fabrication already exist, purely photochemical approaches are still of only minor relevance despite of their high practicability and simplicity. To demonstrate the applicability of photo-initiated processes in nanoparticle (-composite) fabrication, this thesis presents a simple and systematic approach to the fabrication, characterization and application assessment of such materials.

The demonstrated methods are based on the observation, that the light induced α-cleavage of phenylbis(2,4,6-trimethy-lbenzoyl)phosphine oxide yields radical species of different reactivity. One of these radicals is able to reduce metal cations to metallic nanoparticles, while others can simultaneously initiate polymerization reactions. This allows for a facile one-step fabrication of
polymeric composites with embedded metal-nanoparticles.

The thesis is subdivided into thematically independent chapters concerned with the individual steps involved in the development of such materials. In the first chapter, suitable precursor species are selected and porous polymer matrices with embedded gold, silver, copper and palladium nanoparticles are fabricated. The second chapter comprises a characterization of the obtained nanoparticle composites by utilizing crystallographic, micrographic and spectroscopic techniques to investigate their chemical nature, porosity and elemental composition. Lastly, the suitability of the materials as catalysts in different benchmark reactions is assessed. The focus here is on the synthesis of tetrazoles; a class of substances serving as a vital building block for antihypertensive pharmaceutical agents.