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In a first part of this article, the synthesis of AB type block copoly(3-alkylthiophene)s initiated by Ni(dppp)Cl 2 , the most commonly used initiator for these polymers, is investigated. For this study the respective 1 H NMR resonances of all possible end-groups are identified. This result confirms the hypothesis that the Ni(dppp) species can walk back to the beginning of the polymer chain and that propagation can occur at both chain ends. The next part of the article studies the chiroptical behavior of AB-type block copoly(3-alkylthiophene)s with one chiral block and compares the results with those of the corresponding random copolymers. In order to obtain exclusively AB-type block copolymers, the polymers were prepared from a modified Ni initiator. They all have the same degree of polymerization but vary in the length of the respective blocks. The chiroptical behavior was studied by changing the ratio solvent/nonsolvent, meanwhile monitoring the UVÀvis and circular dichroism (CD) spectra. Three series were investigated: one in which both blocks aggregate simultaneously, one in which the achiral block stacks before the chiral block, and one in which the chiral block stacks first followed by the achiral block. It was found that when the blocks stack independently, the (chiral/achiral) stacking of the latter is significantly influenced by the former. If both blocks of the polymer chains aggregate simultaneously, Cotton effects which are significantly larger than those of the chiral homopolymer are found.

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Chiral poly(3-(3,7-dimethyloctyloxy)thiophene)s were prepared using three different methodologies, rendering polymers with different degrees of regioregularity. In a first attempt, 3alkoxythiophene was polymerized using FeCl 3 , resulting in a highly regioirregular poly(3alkoxythiophene).Secondly, the GRIM methodology was applied, which yielded poly(3alkoxythiophene)s with relatively high, but not perfect, degrees of regioregularity. Finally, an alternative methodology was used, which consisted of the exclusive formation and subsequent 2 polymerization of 2-bromomagnesio-3-(3,7-dimethyloctyloxy)-5-bromothiophene) and which resulted in poly(3-alkoxythiophene)s with (almost) perfect regioregularity. The degrees of regioregularity were evaluated with 1 H NMR, UV-Vis and CD spectroscopy and cyclic voltammetry. These (regioregular) poly(3-alkoxythiophene)s show a very high λ max , indicating very high conjugation lengths. Moreover, the polymers could easily be oxidized and they were stable in both neutral as well as oxidized state.This stability can be correlated with the decrease in oxidation potential. The reproducibility and reversibility of the oxidation was demonstrated by UV-Vis spectroscopy. Finally, the chiral properties of the polymers were investigated with circular dichroism spectroscopy. These experiments demonstrated again the difference in regioregularity of the polymers.