CORRELATION BETWEEN STRUCTURE AND ELECTRICAL-CONDUCTIVITY OF SOLUBLE POLYPHENYLENES

Polyphenylenes were prepared by using biphenyl-AlCl3-CuCl2 according t o cationic oxidative polymerization. The chlorobenzene soluble fractio n was doped with 10% (w/v) solution of FeCl3, in acetonitrile. The alt ernating electrical conductivity, X-ray diffractograms and the FTIR-sp ectra of both undoped and doped polyphenylenes were measured. The prop ortion of the components used for the preparation of polyphenylenes st rongly influences their structure as well as their conductive properti es. The undoped polyphenylenes were found to be insulators, but most o f them became semiconductors after doping. The increase of the alterna ting electrical conductivity sigma'(resulting from the real part of th e admittance-vector) of the doped polyphenylenes has been explained co nsidering the factors that influence the polyphenylenes structure: the high ratio of para/meta, the presence of both amorphous and crystalli ne regions, and the presence of polynuclear structures. On the other h and, the presence of aliphatic structures interrupts the conjugation s ystem, leading to lower sigma' values.