Water-soluble self-doped 3-substituted polypyrroles

The prepn. of Na 3-pyrrole(Cn-alkanesulfonates) (I; n = 3, 4, 6) and their electrochem. polymn. was described. The low oxidn. potential of the monomers permitted a direct oxidative electrochem. polymn., without addnl. conduction salts. The exptl. conditions provided, for the first time, solid evidence of the existence of self-doped conducting polypyrroles. The polymers were characterized by spectroscopy (FTIR, UV-visible-near IR, ESR, proton NMR in D2O soln.), x-ray diffraction, cyclic voltammetry, and elemental analyses. The covalently attached sulfonate groups acted as counterions for the charged backbone. The charge carriers were mainly spinless bipolarons. The conductivities were in the range of 0.5 to 10-3 S/cm, with the lower value assocd. with the I (n = 6) homopolymer. Indications were given for deviations from planarity of the main chain. The substituted polypyrroles were water sol. in the self-doped state. Proton NMR spectra of the aq. solns. of the self-doped polymers were discussed. [on SciFinder (R)]