Doped non‐conjugated polymers with enhanced electrical conductivity

Abstract

AbstractIn order to elucidate the dependence of electrical conductivity on conjugation length, polyketones built up of short conjugated aromatic blocks and methylene chains of different length were studied. As obtained, the polymer exhibit very low electrical conductivities of about 10−15 S/cm. Upon doping with iodine the conductivity increases up to 10 orders of magnitude and samples become paramagnetic. The colour turns from yellow to black, and a new absorption maximum appears in UV spectrum at 365 nm characteristic of I3−. The monomers and a model compound do not absorb iodine. In the polymers we assume some ordering of the aromatic moieties, which enables enhanced π‐π interaction. The result could be considered as an extension of the conjugation, thus allowing partial oxidation (doping) and therefrom enhanced conductivity. We explain the doping and the conductivity of polydienes in a simillar way. The conclusion is that extended conjugation along the chain is not a prerequisite for higher conductivity.