“Conformons”: Self-Localized Electrons in Soluble Conjugated Polymers

We examine, with the aid of a much simplified model, the competition between π-electron delocalization energy and chain conformation entropy that occurs when a conjugated polymer is placed in solution. For a lightly doped π-band we predict the existence of "conformons", i.e. locally rigid regions, each containing one or more π-electrons, on an otherwise flexible chain. We also consider the case of a half-filled band, and in this case find that the freezing out of chain degrees of freedom can contribute significantly to the sharpness of a rod-to-coil transition.