Electrical properties and structure characterizations of pyrolyzed polypyrrolone

Insulating polypyrrolone (DEDA-TADPE) was converted into conducting material after having been pyrolyzed at 700–1200 °C in nitrogen atmosphere. The conductivity of the pyrolysate strongly depends on the pyrolytic temperature and time. The pyrolysis of DEDA-TADPE film consists of two processes: below 800 °C it is mainly carbonization; above 800 °C it is dominated by graphitization. A maximum value of room-temperature conductivity of about 193 S/cm was obtained for DEDA-TADPE film pyrolyzed at 1200 °C for 1 h, which is 18 orders of magnitude greater than that of the original polymer. The conducting mechanism of pyrolyzed DEDA-TADPE film is similar to that of semiconductors and the temperature dependence of conductivity can be expressed by Mottʹs 3D variable-range hopping (3D VRH) model. Structure characterizations indicate large-area aromatic fused rings, i.e., 2D graphite-like structure was formed in pyrolyzed DEDA-TADPE film, but no 3D graphite-like structure was formed even when pyrolyzed at 1200 °C.