The electroconductivity and electron spin resonance in doped natural /spl pi/-conjugated polymers

Summary form only given. In searching of new conductive polmers for practical application, the natural /spl pi/-conjugated polmers based on the petroleum pitches have been examined. Sceletons of these polymers mostly consists of condensed aromatic rings connected with short polyene chains. The pristine petroleum pitches are dielectrics with d.c. electroconductivity less than 10/sup -13/ (/spl Omega/ cm)/sup -1/. Although these materials possess amorphous structure they may be effectivel doped with iodine resulting in the increase of electrical conductivity for eight orders of magnitude at maximum dopant concentration 50 wt.% similar to polyacetylene. Also the strong temperature dependence of similar to described for conductive polymers is observed. In contrast to conductivity, the intensity of signal of electron spin resonance in petroleum pitches are increased slightly at iodine doping. The temperature behavior of ESR line intensity becomes Curie-like. The absence of relation between strong increase of d.c. electrical conductivity with doping and weak changes in dynamical spin susceptibility in natural /spl pi/-conjugated polymers are discussed.