Journal of Applied Polymer Science, Vol.84, No.14, 2583-2590, 2002
Synthesis and characterization of soluble polypyrrole with improved electrical conductivity
Polypyrroles doped with two dopants were prepared by chemical polymerization in aqueous solutions of pyrrole monomer. The solutions contained dodecylbenzenesulfonic acid (DBSA) as a dopant, tetraethylammonium tetrafluoroborate (TEABF(4)) as a codopant, and ammonium persulfate (APS) as an oxidant. The PPy composites [polypyrrole-dodecylbenzenesulfonates (PPy-DBS) codoped with tetrafluoroborate (BF4-)-PPy-DBS-BF] were soluble in m-cresol, NMP, and conditionally soluble in chloroform. Cyclic voltammetry was measured to know the electrochemical property of PPy-DBS-BF. The maximum electrical conductivity of room temperature for PPy-DBS-BF is 1.18 s/cm, which is greatly higher than that of polypyrrole doped with DBS- (0.04 s/cm). The composition and structural characterization of PPy-DBS-BF were inferred from elemental analysis, nuclear magnetic resonance, and Fourier transform infrared spectroscopy. Scanning electron microscopy was performed to know the morphology of PPy-DBS-BF. The results of UV-Vis spectra and electron spin resonance measurements showed that polaron and bipolaron existed as charge carrier of soluble PPy-DBS-BF. From the temperature dependence of the electrical conductivity, it was suggested that possible conduction mechanism for soluble PPy-DBS-BF should be hopping conduction.
Keywords:soluble polypyrrole;chemical polymerization;dodecylbenzenesulfonic acid;tetraethylammonium tetrafluoroborate;codoping;hopping mechanism