Comparison of polypyrrole, poly(3,4-dimethylpyrrole) and poly(3-methoxy-4-methylpyrrole)

As-grown polypyrrole (PPy), poly(3,4-dimethylpyrrole) (DMPPy) and poly(3-methoxy-4-methylpyrrole) (MMPPy) films doped with p-toluenesulfonate were characterized. The FT-IR spectra of thick films originate by selective scattering and should be interpreted as due to a molecular solid and not to functional group frequencies. Electronic absorption spectra agree with the polaron-bipolaron absorption model, although for MMPPy strong differences between the energy gap of neutral and doped polymers should be taken into account to fulfil the model. DMPPy shows an electrical conductivity dependence of the type σ = A exp(B/T14), in a higher range of temperatures than PPy and MMPPy.