This article presents a contribution to better understanding of the processes which take place during the synthesis of polypyrrole nanotubes using a structure-guiding agent, methyl orange. Polypyrrole was prepared by oxidation of pyrrole monomer with iron(III) chloride. In the presence of methyl orange, the formation of nanotubes was observed instead of the globular morphology. Two reaction schemes with reversed additions of oxidant and monomer have been tested and they show remarkable influence on the produced morphology. Nanotubes with circular or rectangular profiles and diameters from tens to hundreds of nanometres have been obtained. FTIR and Raman spectra were used to assess the molecular structure of polypyrrole and detect residual methyl orange in the samples. The conductivity of nanotubes compressed into pellets was as high as 68 S cm À1 . The mechanism of nanotubular formation starting at the nucleus produced with the participation of organic dye is proposed. The growth of a nanotube, however, proceeds in the absence of a template. An alternative mechanism for the formation of nanotubes, the coating of solid templates with a polypyrrole overlayer, is also discussed.

Polypyrrole nanotubes (PPy-NTs) were prepared by the oxidation of pyrrole with iron(III) chloride in the presence of a structure-guiding agent, methyl orange. Upon carbonization of the salt form of PPy-NTs, the conducting nitrogencontaining nanotubular carbonaceous material (C-PPy-NT) was obtained. The morphology, structure, and physicochemical properties of PPy-NTs in salt and base form as well as C-PPy-NTs were investigated by transmission electron microscopy, Fourier transform infrared and Raman spectroscopies, conductivity measurements, elemental microanalysis, inductively coupled plasma optical emission spectroscopy, Xray photoelectron spectroscopy, and nitrogen physisorption. Results of the material characterization were linked to their electrochemical behavior. Specific capacitance of around 120 F g −1 at low potential sweep rate of 5 mV s −1 was observed for original PPy-NTs. However, when the potential sweep rate was increased to 100 mV s −1 , PPy-NT salt retained the value of specific capacitance, while the capacitance of PPy-NT base decreased by 70%. Upon carbonization of PPy-NT salt, the specific capacitance was doubled and capacitance fade measured in the interval 5−100 mV s −1 was determined to be around 45%. It is proposed that the absolute value of specific capacitance is determined by specific surface area and surface functional groups, while the capacitance fade is determined by the conductivity of the electrode material. In this manner, a linear relationship between the percent of capacitance fade and the logarithm of the conductivity was revealed. C-PPy-NTs were also tested as an electrocatalyst for the oxygen reduction reaction (ORR) in alkaline media. High ORR activity was observed, characterized by the onset potential of −0.1 V versus saturated calomel electrode and the apparent number of electrons consumed per oxygen molecule higher than 3. Appreciable ORR activity can be linked with a high fraction of mesopores and the presence of surface functional groups, especially pyridinic and pyrrolic nitrogens, and also with a high degree of structural disorder.

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Three azo dyes bearing hydrophilic functional groups at different positions on a hydrophobic naphthylphenyldiazene skeleton were used as structure-guiding agents in the synthesis of highly organised supramolecular structures of PPy in aqueous media.

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Polypyrrole nanotubes with diameter 60–400 nm are synthesized with methyl orange as template and various oxidants, iron(III) chloride hexahydrate, iron(III) sulfate hydrate, and ammonium peroxydisulfate. The highest electrical conductivity of compressed pellets, 66 S cm−1, is found for iron(III) chloride. Regions with 3D variable range hopping in series with ordered regions near metal–insulator transition govern the charge transport. Other oxidants and globular morphology provide less conducting samples, <10 S cm−1. The transport mechanism is identified with the heterogeneous model of tunneling between (bi)polaronic clusters with parallel contribution of Arrhenius‐like activated conductivity. The results of conductivity are correlated with the protonation level reflected in the infrared spectra and with the ratio of bipolaron/polaron bands revealed by Raman spectroscopy. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015, 53, 1147–1159