The synthesis and properties of helical polyisocyanopeptides

Abstract

In this thesis the synthesis of new functional isocyanide polymers and their properties, both fundamentally and in applications, are described. Polyisocyanides prepared from amino acids form very stiff, beta-sheet helical polymers with a well-defined architecture due to the presence of a hydrogen-bonding chain parallel to the covalent polymer backbone. This unique hydrogen bonding array was used to gain a more profound understanding of the polymer architecture; by using femtosecond vibrational pump-probe spectroscopy, it was implied that vibrational energy can, in principle, be transported though these molecules. The well-defined architectures also make the polymers attractive scaffolds for the arrangement of chromophores over large distances. In this way, perylenes and porphyrins, two widely studied chromophores employed in organic electronics, were incorporated into the polymer and their architecture and function were studied.In addition, the surface-initiated polymerisation of two isocyanide monomers in a controlled manner is described. So-called polymer brushes up to 200 nm in length could be easily obtained within a time span of three hours of polymerisation. The growth of the polymer brushes was studied using various spectroscopic techniquesand is was confirmed that the well-defined helical conformation with hydrogen bonds along the polymer chains was retained in the polyisocyanide brushes.