Highly conductive graphite film prepared from pyrolysis of poly(p-phenylene vinylene)

Pyrolysis of poly(p-phenylene vinylene), PPV, up to 3000 °C was studied in relation to the molecular orientation in the PPV film prepared via decomposition of a soluble precursor sulphonium salt polymer and simultaneous biaxial stretching. The conductivity of PPV pyrolysed at 3000 °C was strongly influenced by biaxial stretching and reached 104 S/cm as it was and 105 S/cm by SO3 doping at three-fold stretching, while conductivities of non-stretched PPV were 103 S/cm and 104 S/cm, respectively. The conductivity obtained for the stretched PPV is comparable to that of a highly oriented pyrolytic graphite (HOPG) or natural graphite. X-ray diffraction analyses for the stretched PPV and the pyrolysed products suggest that the biaxial stretching induces planer orientation in PPV and facilitates its graphitization. It is noteworthy that PPV film is pyrolysed to give a highly oriented graphite maintaining the film form. The Raman spectrum analysis indicated that the film is converted into a pure graphite above 2750 °C.