THE EFFECTS OF THE PROPORTION OF BIPHENYL-ALCL3-CUCL2 POLYMERIZATION SYSTEM ON STRUCTURE AND ELECTRICAL-CONDUCTIVITY OF INSOLUBLE POLYPHENYLENES

Polyphenylenes insoluble in chlorobenzene were prepared by cationic ox idative polymerization of biphenyl with aluminum trichloride as cataly st and cupric chloride as oxidizer. The fraction insoluble in chlorobe nzene was doped in a solution of FeCl3 in acetonitrile. The alternatin g electrical conductivity, the X-ray diffractograms and the FTIR-spect ra of undoped and doped polyphenylenes were measured. The undoped mate rial was observed to be an insulator. Only one sample exhibited differ ent behavior which was similar to the doped material, that was found t o be semiconducting. Both undoped and doped polyphenylenes were found to have a monoclinic crystallographic unit cell. For the preparation o f polyphenylenes with maximum electrical conductivity after doping, th e stoichiometric proportion of biphenyl/CuCl2 = 1/2 has to be chosen. Similarly, the catalyst proportion biphenyl/AlCl3 has to be either 1/0 .75 or 1/1.5. Under these conditions the undoped polyphenylenes had a ratio of para/meta substitution of about 1, the degree of crystallinit y was below 60% and the unit cell volume was quite low. The results we re discussed according to the reactions taken place during polymerizat ion.