An oligothiophene/chiral oligo(ethyleneoxy) block copolymer (PolyT6) has been synthesized in which a sexithiophene block alternates with a well-defined chiral undeca(ethyleneoxy) block. The polymer shows good solubility in chloroform, and ultraviolet-visible studies in this solvent reveal a spectrum similar to that of the chirally substituted monomeric sexithiophene (T6) analogue. The aggregation of PolyT6 occurs in dioxane; however, no helicity is present in this aggregate, in contrast to aggregated T6. This behavior illustrates that although the processability and mechanical robustness of block copolymers may be superior to those of analogous oligomers, the degree of self-assembled order found in oligomer-based systems may be lost in the polymers. (C) 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1737-1743, 2003.