The most commonly used organic semiconducting polymers are linear polymers. The discovery that hyperbranched and dendritic structures show some advantages over their linear counterparts lead to intensive research into branched polymer architectures. Hyperbranched polymers belonging to the class of branched polymers are especially appealing since they can be generated by an one-step polymerization of monomers with more than two functionalities (e. g. AB₂, AB₃, A₂ + B₃).
The first part of the thesis focuses on the the synthesis of two novel AB₂-type monomers, based on a truxene core and their use in the synthesis of hyperbranched polytruxenes. The polymers were characterised and their degree of branching (DB) was estimated by NMR spectroscopy. In a research project in cooperation with Prof. T. Yokozawa from Kanagawa University in Yokohama, Japan, the influence of different, synthetic methods on the resulting DB was tested.
The second part describes the synthesis of elongated, hyperbranched copolymers made by statistical copolymerisation of AB₂-type truxene monomer and linear AB-type fluorene monomers. Different molar ratios of both monomers were used and the copolymers were characterized in relation to the monomer ratio.
The synthesis of endfunctionalised, hyperbranched polymers is discussed in the third part of the thesis. Different monofunctional dyes as endcappers were synthesised and added during the polycondensation of the AB₂-type truxene monomer. In spectroscopic experiments, excitation energy transfer from the polytruxene core to the terminal functions for the copolymers with a lower HOMO/ LUMO energy gap of the endcapping functions in relation to the polytruxene core. Here, after excitation into the polytruxene core, the emission mainly occurs from the endcapping functions thus illustrating the energy transfer process. For some copolymers, the energy transfer process was further analysed by TCSPC (time-correlated single photon counting) in cooperation with the work group of Prof. Johan Hofkens (K. U. Leuven, Belgium).
Last, the synthesis of hyperbranched multiblock copolymers is described. These polymers contain a hyperbranched polytruxene core and terminal polythiophene blocks. Two different synthetic routes were tested. For these multiblock copolymers, an efficient excitation energy transfer from the hyperbranched polytruxene core to the terminal polythiophene blocks was detected. The energy transfer process was further analysed in a research project with Prof. João Sérgio Seixas de Melo at Unversidade the Coimbra, Portugal.