Surface-confined polymerization in vacuum and water: insights into Ullmann and Schiff-base couplings

The drive for miniaturization in technology has spurred interest in nanostructures based on organic materials due to their cost-effectiveness, scalability, flexibility, and transparency compared to inorganic alternatives. This research focuses on achieving covalently interlinked molecular building blocks, such as π-conjugated polymers, for applications in organic electronic devices. These polymers exhibit enhanced mechanical stability and charge transport efficiency. The on-surface synthesis of polymers provides precise control over the formation of ordered graphene-like architectures with tunable properties. While polymerization in ultrahigh vacuum allows in-depth analysis of surface reactions, efforts are ongoing to replicate such processes under less demanding, application-relevant conditions. This study investigates the on-surface synthesis of one-dimensional π-conjugated polymers via two methodologies: Ullmann coupling in ultrahigh vacuum on Cu(110) and Schiff-base coupling at the solid-water interface on Au(111). Using synchrotron radiation-based spectroscopy and scanning tunneling microscopy, the research provides insights into the role of halogens in Ullmann coupling and the pH-dependent evolution of molecular species in Schiff-base coupling. Collaborative efforts with international research groups enriched this work, which has been presented at conferences and published in high-impact journals. The Thesis is structured into six chapters, covering an introduction to surface-confined polymerization, experimental techniques, materials, and procedures, followed by detailed results from the two polymerization methods. Concluding remarks highlight the significance of the findings and propose future research directions.