Thermally stimulated depolarization and polarization current study of C60-PU based conducting interpenetrated polymer networks (IPNs)

Rubber-like conductive polyaniline-polyurethane interpenetration networks (IPNs) were synthesized by a sequence of poly condensation and doping reactions. The thermally stimulated depolarization and polarization current (TSDC/TSPC) and the differential scanning calorimetry (DSC) techniques were used for the characterization of fullerenol-derived urethane copolymer and polyaniline/fullerenol-PU IPNs. Dual glass transitions of fullerenol-derived polyurethane copolymers at −71 °C and 72 °C have been assigned as the motion of PTMO soft segment in the glassy state and the motion of network around fullerenol crosslinking sites respectively. A major crystal melting transition at −3 °C for all polyurethanes and an additional electric field induced crystal-crystal transformation at 17°C of the fullerenol derived polyurethane network are seen. Within polyaniline/fullerenol-PU IPN, the network of polyaniline phase hinders the relaxation of higher Tg and the electric field induced crystal-crystal transformation. Physical aging treatment provides an indirect method for the characterization of glass transitions of current network structure. TSDC technique provides a higher sensitivity in detecting structural relaxation and serves as a direct measurement of phase transitions.