Polypyrrole nanotubes exhibit conductivity of tens S cm−1 which is one of the highest among the current conducting polymers.

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.

Polyaniline is an organic semiconductor. It is prepared by the oxidative chemical or electrochemical oxidations of aniline in acidic aqueous media. The course of the oxidation can be followed by monitoring changes in temperature or pH. Depending on acidity conditions, polyaniline has globular, nanofibrilar, or nanotubular morphology. Polyaniline may also be obtained as thin films, coatings, or as colloidal dispersions. The conducting polyaniline salt convers to nonconducting polyaniline base under alkaline conditions. Its reprotonation by various acids offers a route for preparation of polyanilines with various properties. These processes are reflected in UV–vis, FTIR, and Raman spectra. The mechanism of conduction is based on the presence of delocalized polarons and protons. Polyaniline exhibits both the electronic and ionic conductivity. The stability of polyaniline at elevated temperature and in aggressive media is good. Polyaniline is converted to nitrogen‐containing carbon in inert atmosphere at 600°C. Biological properties and antimicrobial activity of polyaniline are outlined. The applications of polyaniline in batteries, corrosion protection, fuel cells, sensors, and supercapacitors are briefly reviewed.

The preparation of highly conducting polymer nanostructures with defined and uniform nanoscale morphologies represents a research challenge.

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Conducting polymers (CP), namely polyaniline (PANI) and polypyrrole (PPy), are promising materials applicable for the use as biointerfaces as they intrinsically combine electronic and ionic conductivity. Although a number of works have employed PANI or PPy in the preparation of copolymers, composites, and blends with other polymers, there is no systematic study dealing with the comparison of their fundamental biological properties. The present study, therefore, compares the biocompatibility of PANI and PPy in terms of cytotoxicity (using NIH/3T3 fibroblasts and embryonic stem cells) and embryotoxicity (their impact on erythropoiesis and cardiomyogenesis within embryonic bodies). The novelty of the study lies not only in the fact that embryotoxicity is presented for the first time for both studied polymers, but also in the elimination of inter-laboratory variations within the testing, such variation making the comparison of previously published works difficult. The results clearly show that there is a bigger difference between the biocompatibility of the respective polymers in their salt and base forms than between PANI and PPy as such. PANI and PPy can, therefore, be similarly applied in biomedicine when solely their biological properties are considered. Impurity content detected by mass spectroscopy is presented. These results can change the generally accepted opinion of the scientific community on better biocompatibility of PPy in comparison with PANI.

The reaction between two non‐conducting chemicals, aniline and silver nitrate, yields a composite of two conducting components, polyaniline and metallic silver. Such conducting polymer composites combine the electrical properties of metals and the materials properties of polymers. In the present study, aniline was oxidized with silver nitrate in solutions of acetic acid; in this context, aniline oligomers are often a major component of the oxidation products. An insoluble precipitate of silver acetate is also present in the samples. The optimization of reaction conditions with respect to aniline and acetic acid concentrations leads to a conductivity of the composite as high as 8000 S cm−1 at ca 70 wt% (ca 21 vol%) of silver. A sufficient concentration of acetic acid, as well as a time extending to several weeks, has to be provided for the successful polymerization of aniline. Polyaniline is present as nanotubes or nanobrushes composed of thin nanowires. The average size of the silver nanoparticles is 30–50 nm; silver nanowires are also observed. Copyright © 2009 Society of Chemical Industry

The present contribution reports the single-step preparation of new type of soft macroporous conducting cryogels, a special type of hydrogels. Polyaniline/poly­(vinyl alcohol) cryogel was prepared by the oxidation of aniline hydrochloride in frozen reaction mixtures, in ice, containing a supporting polymer, poly­(vinyl alcohol). The cryogel used for illustration contained of polyaniline, poly­(vinyl alcohol) and 93 wt % of aqueous phase. It was macroscopically homogeneous and it had macroporous structure with average pore size of ≈100 μm. The conducting polyaniline phase was fibrillary. The molecular structure of polyaniline was confirmed by Raman spectroscopy. The conductivity of cryogel was 0.004 S cm–1 in water and 0.105 S cm–1 in 0.1 M sulfuric acid. It still increased to 0.29 S cm–1 when the content of monomer increased five times. Because of the contribution of electronic transport, the conductivity of cryogel was always higher than the ionic conductivity of aqueous phase used for its penetration. The conductivity of freeze-dried cryogel was 0.003 S cm–1. Viscoelastic and mechanical properties, controlled mainly by the conducting polymer phase, have been assessed and demonstrated good mechanical integrity and feasibility of potential applications.