To extend the time of service of asphalt roads modified montmorillonite nanoparticles were incorporated into bitumen with the aim of creating a gas barrier inside the bitumen which slows down the diffusion of oxygen through the bitumen. For this purpose [montmorillonite/alkyl-quat-primer] adducts ([MMT/PEI(nkD)xQyR]) were fabricated in which single-montmorillonite platelets were coated by a ultrathin polymer film by reacting montmorillonite particles with poly(ethylenimine) based polycations. The alkyl-quat-primer polymers were synthesised by adding ammonium groups and alkyl chains to hyperbranched poly(ethylenimine)s in a solvent-free reaction. Adducts with fully intercalated polymers were obtained when the polymers were reacted with an aqueous solution of [MMT/CTAB] or by mixing the polymers with montmorillonite and CTAB in an aqueous solution. The polymers replaced the CTAB in an intermediate formed [MMT/CTAB] adduct and adhered strongly to the montmorillonite due to a cooperative electrostatic interaction between the positively charged ammonium moieties of the macromolecules and the negatively charged montmorillonite surface. [MMT/alkyl-quat-primer] and [MMT/CTAB] adducts were incorporated via a single screw extruder into polymer- and non-polymer-modified bitumina to create bitumen-nanocomposites. Composites prepared under optimised conditions exhibited an adduct network inside the bitumen at adduct concentrations larger 5 wt.% and when non-polymer modified bitumina were modified. The aspect ratio of the incorporated montmorillonite platelets depended strongly on the adduct composition and the used bitumen, and was with [MMT/PEI(10kD)10Q80R10] adducts were very high (~ 300 - 1000) but with [MMT/PEI(10kD)10Q60R14] and [MMT/CTAB] adducts considerably lower (~ 30 - 90).

Synthese starrer Donor-Akzeptor-Verbindungen und Untersuchung des Magnetfeldeffektes auf Lebenszeit resultierender Biradikale mittels optischer Spektroskopie. / Synthesis of rigid donor-acceptor compounds and investigation of the magnetic field effect on the lifetimes of resulting biradicals using optical spectroscopy.

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This doctoral thesis focuses on synthesis of rigid star-shaped and rod-like viologen oligomers. The work is divided in two parts: synthesis, characterization and electropolymerization of star-shaped (i) and rod-like viologens oligomers (ii). In the first part the synthesis of viologen stars consisting of a phenyl core with triple 1,3,5-branching, each branch consisting of a linear alternating series of diphenyl (PhV++) and dibenzyl (BnV++) viologens and a variety of peripheral groups –X (Br, OH), is presented. A new electrochemical method of electrode modification (Gold, GC, ITO and CNTs) with viologen derivatives based on a benzyl radical coupling mechanism is described. The radicals are excessively generated at the star periphery resulting in a highly cross-linked polyviologen film with persisting star subunits. It is characterized by CV, STM and UV-Vis methods. Redox-titration experiments monitored by UV-Vis reveals that the reduction of the viologen stars begins at the periphery with the formation of PhV+•, continues with generation of BnV+• and ends with the reduction of the radical cations in the same sequence. Thus, viologen stars combine the unique redox and electrochromic property of isolated phenyl and benzyl viologen in one molecule. The second part of the thesis focuses on the step-wise synthesis of a library of rigid rod-like conjugated difunctional viologen/diphenyl oligomers with varying chain lengths including different side chain substitution. All oligomers are soluble in DMSO or MeOH depending on the counter anion (PF6- or Cl-). In order to tune the solubility of the oligomers, the side chains are tailored as methoxy, butoxy and oligo(ethylene oxide). The most solubilizing side-chains are of the oligo(ethylene oxide) type. All viologen oligomers are characterized by means of 1H-NMR, 13C-NMR, elemental analysis, optical spectroscopy and cyclic voltammetry. A simple surface functionalization and grafting technique has been developed for covalent binding of the viologen oligomers onto various conductive substrates e.g.: Au, GC and ITO. These modified electrodes are suitable for potential applications in designing field-effect transistors, sensors and supercapacitors. The polymer layers are characterized by means of FT-IR, STM, XPS and CV. The combined results presented in thesis represent a major advance in electrode functionalization by n-dopable viologen polymers and herald a variety of potential applications that make use of n-type semiconductors.

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