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The blue thin polyaniline base film changes its color to green after immersion of the film into dibutyl phosphonate. The green color of the film converts to a greenish-blue after heating to 200 °C in air, which is characteristic for the protonated conducting form of polyaniline. This is in contrast to the "standard" polyaniline hydrochloride, which is transformed into a cross-linked polyaniline base under such conditions. To explain this unexpected observation, the interaction of polyaniline base with dibutyl phosphonate at ambient conditions and after heating to 200 °C was studied using UV-visible, FTIR and Raman spectroscopies. On the basis of these studies, we propose that the dibutyl phosphite tautomeric form of dibutyl phosphonate, which interacts with polyaniline base at 20 °C, converts to the oxidized form, dibutyl phosphate, at 200 °C and subsequently protonates the film. Quantum-chemical modeling of the interaction of polyaniline base with dibutyl phosphite and dibutyl phosphate supports this explanation.

Polypyrrole nanotubes rank among the most conducting forms of organic semiconductors. They are prepared by the oxidation of pyrrole in the presence of methyl orange. Other organic dyes, viz. ethyl orange, Acid Blue 25, and Acid Blue 129, have been used in the present study to prepare globules or nanofibers. The resulting polypyrroles were studied in detail by Raman spectroscopy. The apparent paradox when a dye contribution to spectra is absent with 785 nm excitation line and present with shorter wavelengths is explained by the resonance character of the Raman scattering, which allows the separation of the contributions from the polypyrrole surface and from the bulk. These differ depending on the laser excitation wavelength and the position of absorption maximum of the individual dyes in ultraviolet-visible spectra and affect both the laser-penetration depth and observation of the resonance effect. The spectra are discussed in terms of different ordering of polymer chains in individual morphologies. The correlation between conductivity, surface areas, and the proportions of ordered and disordered polypyrrole phases at the surface and in the interior of nanostructures is proposed and established using resonance Raman spectroscopy.

The development of new catalytic transformations with easy separation and recyclability is essential in chemical synthesis. An efficient heterogeneous catalytic system composed of a conducting polymer, polypyrrole (PPy), deposited on cotton fabric support, and decorated with silver nanoparticles is described. Such ternary composites can be used in environmental issues, such as water-pollution treatment. The model reduction of p-nitrophenol to p-aminophenol with sodium borohydride was investigated by means of UV–visible spectroscopy. The reaction was catalyzed even by PPy alone and the catalytic effect was strongly enhanced by silver nanoparticles. It obeys the first-order kinetics. The catalytic effect increases with the catalyst dose due to increased number of catalytic sites. This also applies to the increased content of silver. The elevated temperature as well as the reduced polarity of the reaction medium have negative effect on the catalyst performance. The catalysts can be reused several times while maintaining good efficiency. The ternary composites are thus good candidates for the catalytic reductive removal of toxic compounds from water.

Nitrogen-containing carbon derivatives were prepared by the carbonization of poly(aniline-co-p-phenylenediamine) cryogels in inert atmosphere. Lower aniline fraction in the comonomer mixture used for preparation of the cryogels led to the decrease of their thermal stability, a consequent increase of carbonization degree, and less defective structure of carbonized materials. The resulting carbonaceous products had up to 4 orders of magnitude higher specific surface area than their respective cryogel precursors, the highest value 931 m2 g&minus, 1 being achieved for carbonized poly(p-phenylenediamine) cryogel. Electrochemical characterization of the carbon derivatives demonstrated that the decrease in aniline concentration during the synthesis of the precursor cryogels led to higher gravimetric capacitance for corresponding carbonized materials. These materials can potentially be used for energy storage applications.

Polypyrrole/molybdenum disulfide (PPy/MoS2) composites were synthesized by in-situ chemical polymerization of pyrrole in the presence of MoS2 flakes. The conductivity of the composite with a moderate content of PPy (15–30 wt%) reached 13 S cm−1, which is markedly higher than the conductivity of both the pristine PPy and MoS2, 1 and 10−6 S cm−1, respectively. The improved conductivity was explained by the formation of ordered thin PPy films with high conductivity at the MoS2 surface. At higher pyrrole content, globular PPy was formed in the bulk of the composite resulting in an increase of a disordered polymer fraction, and the conductivity decreased. The composite conductivity is thus controlled not only by content of PPy but also by the proportions between ordered and disordered PPy phases. The structural and morphological characterization of composite materials is based on Fourier-transform infrared and Raman spectroscopies, wide-angle X-ray diffraction, and scanning and transmission electron microscopies. The charge-carrier transport in the composites fits the Mott variable-range hopping mechanism.

Lignin/polypyrrole composites were prepared by single-step coating of water-insoluble kraft lignin with polypyrrole. The polymerization of pyrrole was performed with and without the presence of methyl orange, leading to the formation of polypyrrole films of two different morphologies, globular and nanotubular, respectively, on the lignin surface. Such composites were converted to double-carbon composites enriched in inert atoms by pyrolysis in nitrogen atmosphere at 650 °C. The carbonization process was followed by thermogravimetric analysis and confirmed by Raman spectroscopy. The properties of all composites were investigated by FTIR spectroscopy, XPS, EPR, SEM, specific surface area and electrical conductivity measurements. Electrochemical properties were analyzed in terms of their capacitive behavior mainly in acidic solutions, but also in neutral and alkaline media.

Pollution caused by organic dyes is of serious environmental and health concern to the population. Dyes are widely used in textile coloring applications. In the present work, cotton textile was coated with a conducting polymer, polypyrrole (PPy), in situ during the oxidative polymerization of pyrrole. The resulting materials were utilized as easily separated and recyclable adsorbent for the removal of methylene blue (MB) as a model of cationic dyes in alkaline solutions. It showed also some affinity to remove Acid Green 25 as an anionic dye in acidic medium. The adsorption was assessed by monitoring the decrease in dye concentration by UV–Visible absorption spectroscopy. The influence of various parameters such as initial dye concentration, contact time, pH, temperature, and adsorbent dose on the adsorption process was studied. The pseudo-second-order kinetic model and Freundlich isotherm model were found to describe the adsorption process. The thermodynamic study revealed that the adsorption of MB by PPy was feasible, spontaneous, and exothermic process. Investigation of the substrate regeneration revealed that PPy deposited on cotton textile can be reused for dye adsorption several times with good efficiency and it allows for the recovery of MB for recycling purposes.

When a conducting polymer, polyaniline, is prepared in the aqueous solutions of poly(vinyl alcohol), it is obtained as a colloidal dispersion of submicrometer particles. When the reaction mixture is frozen before the oxidation of aniline takes place, polyaniline is produced in ice, and a cryogel results after thawing. This technique of conducting hydrogel preparation has been reported only recently. It is newly demonstrated, that colloidal hydrogels are obtained after freezing of colloidal dispersions. Finally, the cryogenic preparation of polyaniline in polyaniline colloids combines latter two techniques of hydrogel preparation to generate a dispersion cryogel. It is thus illustrated that, by using a simple initial system, various macroporous-conducting hydrogels differing in morphology, conductivity, and mechanical properties can be achieved.

Polypyrrole has been prepared by facile single-step chemical oxidative polymerization of the monomer in aqueous medium containing an anthraquinone dye, Acid Blue 25 or Acid Blue 129. The addition of the former structure-guiding agent results in the formation of polypyrrole nanowires with conductivity improved up from the units S cm–1 to 60 S cm−1. The second closely related dye, Acid Blue 129, had no impact on polymer morphology but in its presence the conductivity of polypyrrole also increased. It has been shown that the pyrrole concentration and oxidant-to-pyrrole mole ratio significantly affect the conductivity of synthesized polypyrrole. Polypyrroles have been characterized by FTIR and Raman spectroscopies to assess their molecular structure and intermolecular interactions. Considering the applications in biomedicine, the cytotoxicity of the samples has also been tested. Polypyrrole prepared with Acid Blue 129 has significantly lower cytotoxicity compared to that prepared with Acid Blue 25. The cytotoxicity of both polypyrroles can be eliminated by purification step. Low cytotoxicity combined with high conductivity enables application of these conducting polymers in biomedicine.

Aim of this study is to bring systematic comparison of structure and properties of the redox-active oxidation products of various phenylenediamines prepared under various acidic conditions. According to literature, structure and properties of the phenylenediamine oxidation products depend on the reaction conditions. Various ladder-like structures have widely been accepted in the literature since they can be potentially created from any phenylenediamine isomer. The presence of polyaniline-like structural units, however, has also been reported and often discussed. The conductivity of the reaction products was compared for the oxidation of o-, m- and p-phenylenediamine with ammonium peroxydisulfate in 1 M methanesulfonic acid, water, or in 1 M ammonium hydroxide. The combination of size exclusion chromatography with UV–visible, FTIR and Raman spectroscopies allow us to analyze the molecular structure of the oxidation products and to bring significant information on (1) the formation of oligomer and polymer fractions, (2) the content of benzenoid and quinonoid units suggesting the presence of polyaniline-like segments, and (3) the participation of phenazine-like constitutional units indicating the formation of polycyclic structures. The oxidation products have also been tested for their cytotoxicity in order to estimate their application potential in biomedicine. The dilution of extracts below 5% concentration was generally needed to suppress the cytotoxicity.

A low-molecular-weight organic semiconducting material was prepared by the redox interaction between pyrrole and p-benzoquinone. The reaction between pyrrole and p-benzoquinone in aqueous solutions of methanesulfonic acid proceeded smoothly at room temperature. The product with a globular morphology obtained in high yield in 0.1 M methanesulfonic acid had the highest conductivity, 4.6 × 10−6 S cm−1. On the other hand, the samples prepared in the absence of acid or at high acid concentration were non-conducting. EPR spectroscopy confirmed the presence of electronic species as charge carriers responsible for conductivity. The dominating component was proved to be a low-molecular-weight adduct composed of the quinhydrone complex and the pyrrole molecule. FTIR and Raman spectra were used to discuss the molecular structure in detail. A strong electrorheological effect with a very fast response time was demonstrated by the reproducible increase in the viscosity of suspensions in silicone oil after application of the electric field. The effect is discussed with the help of dielectric spectroscopy.

The impact of various sterilization methods on the conductivity of polyaniline and polypyrrole has been tested. The sterilization methods included β- and γ-irradiation, UV-light irradiation, immersion in aqueous ethanol, and moist and dry heat treatment. Except for the dry heat, all methods can be used for the sterilization of conducting polymers without any significant reduction in their conductivity. Any changes in the conductivity associated with the modified molecular structure due to polymer deprotonation are discussed with the help of FTIR spectroscopy. The morphology of conducting polymers has not been affected by the sterilization.

Polypyrrole was prepared by the oxidation of pyrrole with solid manganese dioxide. The present study concerns the chemistry of this process rather than materials properties of the products. The oxidant alone is insoluble in aqueous medium but the reductive dissolution takes place in the presence of pyrrole. Polypyrrole is the exclusive product below the stoichiometric mole ratio [MnO2]/[pyrrole] = 1.25, and polypyrrole/manganese dioxide composites result at higher ratios. Unlike with iron(III) chloride where protons are generated during the oxidation of pyrrole, with manganese dioxide they are consumed and water is a by-product. The sufficient acidity of the reaction medium is thus needed in order to obtain conducting materials. The presence of organic dyes in the preparation of polypyrrole improved the conductivity. One-dimensional morphology of polypyrrole was observed when methyl orange was introduced to the reaction mixture.

Molybdenum and tungsten sulfides are semiconducting materials with flake-like morphology. Their applicability in electrorheological suspensions was enabled by the coating with a conducting polymer, polyaniline, after its conversion to non-conducting polyaniline base. For instance, the conductivity of tungsten sulfide, 0.056 S cm−1, increased to 0.98 S cm−1 after coating with polyaniline, and was conveniently reduced to 6.3 × 10−6 S cm−1 after conversion to polyaniline base. Such approach reduces the potential current drifts in electrorheological suspensions and allows for the application of sulfides in electrorheology. The optical microscopy demonstrated the formation of particle chains in silicone-oil suspensions after application of electric field. The electrorheological performance was assessed by the measurement of viscosity on the shear rate in the absence and in the presence of electric field and it is discussed on the bases of dielectric spectra.

Polyaniline (PANI) is conducting when doped, typically with an acid. However, acids are not the only species able to dope PANI. In this study, we show that non-conducting PANI base powder interacts with dimethyl H-phosphonate (DMPH), diethyl H-phosphonate (DEPH), dibutyl H-phosphonate (DBPH) and diphenyl H-phosphonate (DPPH) and yields conducting adducts; the highest conductivity 0.23 S cm −1 is observed for DPPH. The samples were analyzed by FTIR, Raman, NMR, and EPR spectroscopies. We have shown that the doping of PANI with H-phosphonates is only partial and at least part of DEPH and DPPH molecules preserves the H-phosphonate structure, in contrast with DMPH and DBPH. We have also correlated the information on polaron delocalization and mobility obtained from Raman and EPR spectra – polarons in the PANI adduct with DEPH and DPPH have higher mobility. This paper represents a comparative study of a class of PANI-based materials and shows a connection between chain conformation of PANI and materials properties.

The oxidation of aniline with ammonium peroxydisulfate in the presence of gelatin yields spindle-like colloidal polyaniline particles having the particle size smaller than 200 nm. The similar oxidation of aniline with silver nitrate leads to hybrid composite polyaniline–silver nanoparticles with more complex morphology. The composites were characterized by transmission electron microscopy, dynamic light scattering and UV–vis spectroscopy. The cytoxicity of colloids has also been investigated. To test biointerface properties, the synthetized colloids were deposited to poly(ethylene terephthalate) foil using spiral bar coating and flexography printing technique. Prepared layers were tested for eukaryotic cell adhesion and proliferation, and antibacterial activity. The prepared surfaces do not only allow for eukaryotic cell adhesion and proliferation but also they possess significant antibacterial properties against Escherichia coli and Staphylococcus aureus, even without silver nanoparticles. This newly prepared surface has therefore high practical potential in variety of application in regenerative medicine or biosensing.

Non-conducting polyaniline base interacts with organic phosphites to a conducting product resembling classical polyaniline salts. Polyaniline–phosphite complexes were carbonized in inert atmosphere at 650 °C to phosphorus- and nitrogen-containing carbons. The resulting materials were tested with respect to their electrochemical performance by considering their capacitive properties and electrocatalytic activity towards oxygen reduction reaction (ORR). Carbonized polyaniline–diphenyl phosphite displayed the highest capacitance among all investigated carbons, reaching the values above 100 F g −1 at 5 mV s −1 in concentrated potassium hydroxide solution, while the same material also displayed the highest ORR activity in alkaline media. Considering small specific surface area of obtained carbon materials, the synthetic procedures lead to the surface structures which are exceptionally active for charge storage and in electrocatalysis of ORR. It is proposed that further improvement of electrochemical properties can be obtained by preserving the type of the present surface functional groups with simultaneous increase of their number by the increase of the specific surface.

The aim of this work was to describe polyaniline salts synthesized and to assess the mechanical and anticorrosion properties of alkyd resin-based coating materials pigmented with them, in dependence on the pigment volume concentration and type. Polyaniline salts were prepared by oxidative polymerization in the solutions of inorganic (hydrochloric, phosphoric, and sulfuric) and organic (p-toluenesulfonic and 5-sulfosalicylic) acids. Polyaniline salts were characterized by thermal analysis and spectroscopic methods. Electrical conductivity was also measured by the van der Pauw method, and the molecular weight of the polyaniline was determined by gel permeation chromatography. Furthermore, the particle size of the solid salts was measured, and the morphology was studied by scanning electron microscopy. Subsequently, the parameters required to formulate pigmented organic coatings, i.e., density and critical pigment volume concentration were determined. A soybean oil-based fast drying alkyd resin of medium oil length was used as the binder for the organic coating material. Organic coatings containing the polyaniline salts at pigment volume concentrations 0%, 1%, 5%, 10%, and 15% were formulated and subjected to a standard accelerated cyclic corrosion tests. The organic coatings (paint films) were also subjected to mechanical tests and to the electrochemical test by potentiodynamic polarization studies.

Polypyrrole nanotubes rank among important functional materials with high application potential. They are prepared by the oxidative polymerization of pyrrole usually in the presence of methyl orange and represent conducting polymers with the highest bulk conductivity, 40–50 S cm −1 . The role of methyl orange in promoting the nanotubular morphology of polypyrrole is discussed on the basis of FTIR and Raman spectra. The model based on the organization of acid form of methyl orange molecules to an in-situ -generated solid template is proposed. Various factors controlling the morphology and conductivity of polypyrrole have been identified. Higher acidity of reaction medium or the addition of ethylene glycol increased the diameter of nanotubes or even converted nanotubes to globules, and the conductivity was reduced. Nanotubes have not been obtained at temperature elevated to 60 °C but one-dimensional polypyrrole morphology was surprisingly produced even when the oxidation of pyrrole took place in frozen reaction medium, in ice, at −24 °C. The counter-ions in iron(III) salt used for the oxidation and the presence of water-soluble polymers had virtually no influence on morphology and conductivity. On the other hand, a series of organic dyes used as replacement of methyl orange had substantial effect on both the nanotubular morphology and conductivity. The role of template formation is discussed by comparing methyl orange and ethyl orange dyes. While the former dye precipitates under acidic conditions and supports the growth of nanotubes, the latter does not and globules are obtained instead.

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 ...

Cotton fabric was coated with conducting polymers, polyaniline or polypyrrole, in situ during the oxidation of respective monomers. Raman and FTIR spectra proved the complete coating of substrates. Polypyrrole content was 19.3 wt.% and that of polyaniline 6.0 wt.%. Silver nanoparticles were deposited from silver nitrate solutions of various concentrations by exploiting the reduction ability of conducting polymers. The content of silver was up to 11 wt.% on polypyrrole and 4 wt.% on polyaniline. The sheet resistivity of fabrics was determined. The conductivity was reduced after deposition of silver. The chemical cleaning reduced the conductivity by less than one order of magnitude for polypyrrole coating, while for polyaniline the decrease was more pronounced. The good antibacterial activity against S. aureus and E. coli and low cytotoxicity of polypyrrole-coated cotton, both with and without deposited silver nanoparticles, were recorded, and they promise a broad applicability of this material. Polyaniline-coated samples showed lower antibacterial activity and higher cytotoxicity compared to polypyrrole-based materials.

The materials composed of pairs of conducting polymers, polyaniline, polypyrrole and non-conducting poly( p -phenylenediamine), were prepared by the coating of one polymer with the other. The course of polymerizations and morphology of the resulting composites have been recorded and the products were characterized by FTIR and Raman spectroscopies, DC and broad-band AC conductivity and permittivity measurements. The interfacial interaction between conducting polymers does not introduce any new effects concerning the conductivity. On the other hand, using composites where the conducting polymer is embedded in non-conducting polymer matrix allows for the control of structure at nanoscale and for the design of materials with new conductivity properties. This is illustrated by coating the conducting polymers with the poly( p -phenylenediamine) which has the conductivity by eight orders of magnitude lower, which yields composites with an intermediate conductivity, by three orders of magnitude lower than that of the conducting polymers.

Polyaniline colloids stabilized with poly(N-vinylpyrrolidone) were prepared by the oxidation of aniline with peroxydisulfate. The replacement of a part of aniline with p-phenylenediamine converted the original globular colloidal particles into nanofibers, which is a favorable morphology for the deposition of conducting patterns, but the colloidal stability was retained. The corresponding poly(aniline-co-p-phenylenediamine) powders have been characterized using FTIR spectroscopy. The copolymers have a more pronounced temperature dependence compared with the parent polyaniline; the ratio of the conductivity at 300 and 100 K is 24 for polyaniline, 235 for a copolymer containing 20 mol% p-phenylenediamine, and 3690 for 30 mol% p-phenylenediamine. Due to their fibrillar morphology, copolymer colloids prepared with 10 and 20 mol% p-PDA produced films with conductivity nearly three orders of magnitude higher than that from globular PANI colloids. The conductivity of the film cast from the copolymer colloid prepared with 20 mol% p-PDA exhibits a temperature dependence much steeper than its powder counterpart. The processable copolymer colloids are thus well suited for the preparation of conducting temperature-sensitive films.

The preparation of highly conducting polymer nanostructures with defined and uniform nanoscale morphologies presents a research challenge. Polypyrrole nanotubes were prepared by the oxidation of pyrrole with iron(III) chloride in the presence of methyl orange. The reactant concentrations and the oxidant-to-pyrrole mole ratio were varied in order to obtain the product with the highest conductivity in good yield. The conductivity increased from 1.55 S cm−1 for the standard globular morphology to 119 S cm−1 for nanotubes prepared under optimized conditions. The replacement of methyl orange with the closely related ethyl orange has led exclusively to the globular morphology of polypyrrole but the conductivity still improved to 27.3 S cm−1. The marked difference in morphology is explained by the ability of methyl orange salt to produce a solid template for the nanotubular growth of polypyrrole under acidic conditions, in contrast to ethyl orange. The latter dye, however, acts similarly to surfactants and it also enhances the conductivity of polypyrrole. The results are discussed in detail on the basis of FTIR and Raman spectra.

Conducting polymer hydrogels are gels, which are swollen with water, and contain a conducting polymer along with a supporting polymer as constituents. Polyaniline, polypyrrole or poly(3,4-ethylenedioxythiophene) represent the conducting moiety, while water-soluble polymers the other part. Various ways of hydrogel preparation are reviewed. The properties, such as mixed electronic and ionic conductivity, redox activity, and responsivity, are conveniently combined with materials properties afforded by supporting polymers, such as elasticity, mechanical integrity, and biocompatibility. The derived materials, aerogels obtained after freeze-drying of hydrogels, or carbogels produced after carbonization of aerogels, are also considered. The applications are expected especially in biomedicine and energy-storage devices but many other uses proposed in the literature are listed and discussed.

Polyaniline is an important conducting polymer with numerous applications and its surface properties, and consequently functionality, can be significantly influenced by bacterial biofilm. This paper represents the first ever study of biofilm formation on surface of polyaniline salt, polyaniline base and polyaniline doped with biologically active poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (PAMPSA) and phosphotungstic acid. The surface energy and conductivity of the films were measured and correlated to capability of selected strains of biofilm-positive bacteria and filamentous fungi to form a biofilm thereon. It was observed that polyaniline salt did not inhibit the growth of microorganisms, whereas polyaniline doped with PAMPSA exhibited a notable effect against growth of biofilm for all the bacterial strains used. The results advance present knowledge of biofilm formation on polyaniline.

Polyaniline, polypyrrole and conjugated polymers modified with silver nanoparticles have been studied as sorbents of influenza viruses from aqueous media. The sorption of various strains of influenza viruses, including A and B viruses circulating in recent years in Russia Federation, The United States of America, and in Western Europe, have been examined. It is shown that the sorbents based on conducting polymers removed from water large variety of virus strains and the efficiency of adsorption was higher compared with a carbon sorbent. The sorption of both purified and unpurified viruses associated with non-viral proteins were studied. The sorption takes place rapidly enough in the temperature range 4–37 °C and, as a result, the infection viral activity of solution was reduced by 4–6 orders of magnitude. The effectiveness of virus adsorption virtually unchanged in the whole temperature range. Polyaniline and polypyrrole composites with silver provide almost complete removal of viruses and complete water treatment, and this also applies to unpurified influenza viruses. Preliminary assessment of toxicity in vitro has not identified the cytopathic action of polyaniline that is the most problematic in terms of toxicity.

Although poly(p-phenylenediamine) is an electric non-conductor, it exhibits, analogously to conducting polymers, redox activity and could, therefore, find applications in biomedicine. In the current work, the cytotoxicity of poly(p-phenylenediamine) polymer powder produced by the chemical oxidation of p-phenylenediamine with ammonium peroxydisulfate in acidic aqueous media has been studied. Primary mouse embryonic fibroblasts were used for this purpose. Interestingly, the standard methods for the determination of polymer cytotoxicity based on international standard EN ISO 10993-5 could not be applied. The reason was the interaction of polymer extracts with MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay. On the basis of the evaluation of flow cytometry and micrographs taken by fluorescence microscopy on cells treated with extracts of poly(p-phenylenediamine), it can be concluded that the powder polymer possesses severe cytotoxicity. The results suggest that practical application of the polymer within biomedicine is, at the current state of knowledge, difficult, and modification of the preparation techniques and/or subsequent purification of poly(p-phenylenediamine) is needed.

Poly(aniline- co -1,3-phenylenediamine) cryogels were prepared by a simple one-step approach involving oxidative cryopolymerization of respective comonomers in the presence of poly(vinyl alcohol) stabilizer. Resulting cryogels were characterized by SEM, Raman spectroscopy, conductivity and tensile measurements. The addition of small amounts (1 mol%) of 1,3-phenylenediamine into copolymerization with aniline allows for the significant increase of cryogel pore sizes without substantial change in conductivity and mechanical stability. This is the important parameter for future use of such composites cryogels in biomedicine and electrochemistry.

Hemocompatibility is an essential prerequisite for the application of materials in the field of biomedicine and biosensing. In addition, mixed ionic and electronic conductivity of conducting polymers is an advantageous property for these applications. Heparin-like materials containing sulfate, sulfamic, and carboxylic groups may have an anticoagulation effect. Therefore, sodium dodecylbenzenesulfonate, 2-aminoethane-1-sulfonic acid andN-(2-acetamido)-2-aminoethanesulfonic acid were used for modification of the representative of conducting polymers, polyaniline, and the resulting products were studied in the context of interactions with human blood. The anticoagulation activity was then correlated to surface energy and conductivity of the materials. Results show that anticoagulation activity is highly affected by the presence of suitable functional groups originating from the used heparin-like substances, and by the properties of polyaniline polymer itself. © 2019 by the authors., Czech Science FoundationGrant Agency of the Czech Republic [19-16861S]; Ministry of Education, Youth and Sports of the Czech Republic (NPU I) [LO1504]; TBU in Zlin [IGA/CPS/2019/004]; Slovenian Research AgencySlovenian Research Agency - Slovenia [P2-0082]

Polyaniline (PANI) and 2,5-dianilino-p-benzoquinone both are formed by oxidation of aniline in an acidic aqueous environment. The aim of this study is to understand the impact of addition of p-benzoquinone on the structure of PANI prepared by the oxidation of aniline hydrochloride with ammonium peroxydisulfate and to elucidate the formation of low-molecular-weight byproducts. An increasing yield and size-exclusion chromatography, Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy, and nuclear magnetic resonance analyses of the products show that p-benzoquinone does not act as a terminating agent in the synthesis of PANI and the content of 2,5-dianilino-p-benzoquinone increases with the increasing molar concentration of p-benzoquinone in the reaction mixture, [BzQ]. Regarding the structure of PANI, Raman and UV–visible spectra show that the doping level and the charge delocalization both decrease with the increase of [BzQ], and the FTIR spectra of the PANI bases indicate an increased concentration of benzenoid units at higher [BzQ]. We explain these observations by an increasing concentration of structural defects in PANI chains and propose a 2,5-dianilino-p-benzoquinone-like structure of these defects present as pendant groups. The bands typical of 2,5-dianilino-p-benzoquinone-like moiety are observed even in the vibrational spectra of the sample prepared without addition of p-benzoquinone. This confirms in situ oxidation of aniline to p-benzoquinone within the course of the oxidation of aniline hydrochloride to PANI.

By using methyl orange template, polypyrrole nanotubes were obtained by the oxidative polymerization of pyrrole. The nanotubes were carbonized in inert atmosphere to nitrogen-enriched carbon nanotubes. These were subsequently coated with 20 wt% of polypyrrole prepared in the absence or the presence of anionic dyes (methyl orange or Acid Blue 25). The morphology of all the samples was examined by the electron microscopies, FTIR and Raman spectroscopies. Moreover, X-ray photoelectron spectroscopy and elemental analysis were used to prove the chemical structure and the successful coating process. Electron paramagnetic resonance analysis was used to calculate the spin concentrations. Significant impact of coating method is evidenced with neat polypyrrole coating providing a two-fold capacitance increase compared to uncoated nanotubes, while coating in the presence of Acid Blue 25 decreasing it slightly. With respect to oxygen reduction reaction, coatings irreversibly transformed in the first few cycles in the presence of the products of O2 reduction, presumably hydrogen peroxide, altering the oxygen reduction mechanism. This transformation allows the tailoring of the polymeric shell, over ORR active carbonaceous core, and tuning of the catalyst selectivity and optimization of materials performance for a given application – from alkaline fuel cells to hydrogen peroxide generation.

Composite materials of BEA zeolite and polyaniline (PANI) were prepared by the chemical oxidative polymerization of aniline in the presence of zeolite in water (without added acid) and in an aqueous solution of sulfuric acid, using ammonium peroxydisulfate as an oxidant. Protonated (as-synthesized) and deprotonated forms of the composites and pristine PANIs were characterized by scanning electron microscopy, conductivity and zeta potential measurements, FTIR, Raman and XPS spectroscopies, and thermogravimetric analysis. Adsorption properties of synthesized materials for removal of nicosulfuron pesticide from aqueous solutions were studied, using HPLC technique. The obtained adsorption isotherms were analyzed using Freundlich and Langmuir-Freundlich equations. Protonated PANI/BEA composites showed excellent adsorption capacity (18.4–25.4 mg g−1), that was higher than the adsorption capacity of pristine BEA zeolite (18.2 mg g−1) but slightly less than neat PANI. Among PANIs, the highest adsorption capacity of 29.8 mg g−1 of adsorbent was found for protonated PANI prepared in sulfuric acid solution. Analysis of adsorption isotherms revealed high degree of surface homogeneity for all prepared composite materials and PANIs. Proposed mechanism for enhanced adsorption of nicosulfuron on protonated composites is based on hydrogen bonding of nicosulfuron O- and N-containing groups with bridging hydroxyls of BEA zeolite and –NH/ = NH+/−NH•+ groups in protonated emeraldine salt form of PANI chains (PANI-ES), accompanied with electrostatic attractive interaction between anionic nicosulfuron species and positive = NH+/−NH•+ groups in bipolaron/polaron containing structures of PANI-ES. Presence of protons in bridging hydroxyls in BEA zeolite and in protonated PANI-ES chains is essential for excellent adsorption of nicosulfuron via hydrogen bonding on all protonated composite samples. In support of this interpretation, deprotonated PANI/BEA composites and deprotonated PANIs showed significantly lower adsorption capacities (in the range 5.5–13.0 mg g−1) compared to those of their protonated counterparts.

Polyaniline cryogels supported with poly(vinyl alcohol) represent soft conducting macroporous materials suitable for conversion to aerogels by freeze-drying and, subsequently, to nitrogen- containing carbogels by carbonization in an inert atmosphere at 500-600 degrees C. The process was followed by thermogravimetric analysis and Raman spectroscopy at the molecular level. The spectral features indicate a significant degree of structural disorder in the material due to the extensive nitrogen and oxygen incorporation into the carbon sp(2) network, which is important for the improvement of capacitive performance. The macroporous morphology is preserved after carbonization but the specific surface area increased from 12 to 680 m(2) g(-1) after exposure to 500 degrees C in an inert atmosphere. The original conductivity of the cryogel swollen with an acid solution, 0.07 S cm(-1), was reduced to 2 x 10(-4) S cm(-1) for the aerogel and again to 10(-9) S cm(-1) as the carbonization progressed. The impedance spectra display Maxwell-Wagner-Sillars relaxation typical of heterogeneous composite systems with the contribution of ionic conductivity. The decrease in conductivity is in agreement with the significant drop in the static dielectric constant observed by broad-band dielectric spectroscopy and decrease in the spin number determined by electron paramagnetic resonance spectroscopy. Switching in the capacitive response from that dominated by faradaic surface processes at lower treatment temperatures to that of double-layer charging at elevated temperatures is evidenced, while the correlation between surface spin density and specific capacitance is emphasized. The results can be used as guidance for the rational design of novel active materials for electrochemical capacitors.

Polyindole particles were prepared by the oxidative polymerization, where ammonium peroxydisulfate was used as an oxidant at several mole ratios to indole. Prepared spherical micrometre-sized polyindole particles were further used as a dispersed phase in silicone-oil electrorheological (ER) fluids and their rheological behaviour was investigated in the presence and in the absence of an electric field. While different oxidant-to-indole mole ratios did not affect the size and morphology of the particles, their electric and dielectric properties were significantly changed. The highest ER effect was observed for the ER fluid based on the particles with low oxidant-to-indole mole ratio (1:1). Such system exhibited yield stress around 100 Pa at 10 wt% concentration of solid phase. Chain-like structures created upon an application of an electric field were further investigated using an optical microscopy, where significant disparities were found according to electric and dielectric properties of the particles. These findings clearly show that varying mole ratio between the indole and oxidant provides systems with tuneable ER effect.

Novel composite films combining biocompatible polysaccharides with conducting polyaniline (PANI) were prepared via the in-situ polymerization of aniline hydrochloride in the presence of sodium hyaluronate (SH) or chitosan (CH). The composite films possess very good cytocompatibility in terms of adhesion and proliferation of two lines of human induced pluripotent stem cells (hiPSC). Moreover, the cardiomyogenesis and even formation of beating clusters were successfully induced on the films. The proportion of formed cardiomyocytes demonstrated excellent properties of composites for tissue engineering of stimuli-responsive tissues. The testing also demonstrated antibacterial activity of the films against E. coli and PANI-SH was able to reduce bacterial growth from 2 × 105 to < 1 cfu cm-2. Physicochemical characterization revealed that the presence of polysaccharides did not notably influence conductivities of the composites being ∼1 and ∼2 S cm-1 for PANI-SH and PANI-CH respectively; however, in comparison with neat PANI, it modified their topography making the films smoother with mean surface roughness of 4 (PANI-SH) and 14 nm (PANI-CH). The combination of conductivity, antibacterial activity and mainly cytocompatibility with hiPSC opens wide application potential of these polysaccharide-based composites.

Soft macroporous conducting polypyrrole/gelatin cryogels were prepared by a single-step oxidation of pyrrole in the frozen aqueous solution of gelatin. Corresponding aerogels were obtained after freeze-drying of cryogels. Polypyrrole component was collected after removing gelatin by acid hydrolysis. Such polypyrrole has unique macroporous morphology with pore walls composed of two-dimensional sheets. Its mechanical integrity proved the connectivity of the conducting phase in cryogels. Macroporous free-standing polypyrrole obtained after hydrolytic removal of gelatin had conductivity and specific surface area one order of magnitude higher than both the precursor aerogel and the reference polypyrrole prepared by cryotechnique in the absence of gelatin.

Microcomposites of zirconium 4-sulfophenylphosphonate and polyaniline (PANI) and zirconium 4-carboxyphenylphosphonate and PANI were prepared and their thermal decomposition in air and in nitrogen was studied by thermogravimetry. The products of the decomposition of the parent zirconium phosphonates as well as the composites formed with PANI were characterized by energy-dispersive X-ray analysis, elemental analysis, powder X-ray diffraction, IR spectroscopy, and Raman spectroscopy. Heating of the parent hosts and the composites in air to 850 °C leads to their total or almost total conversion to amorphous zirconium diphosphate. In nitrogen, on the other hand, a significant amount of carbon is retained after heating of both the hosts and the composites to 850 °C. The Raman spectra reveal that PANI, which is present as a thin film on the host particles in the starting composites, is converted to a carbon-like material when it is heated in a nitrogen atmosphere. The originally crystalline phosphonates become amorphous after being heated in nitrogen, which means that the heating leads to the destruction of the layered structure of these compounds. IR spectra indicate that the phosphonate particles either in the parent host or in the nanocomposites heated in nitrogen are protected against condensation to zirconium diphosphate.

The strategies of the preparation of twin carbon materials, a carbon produced by the carbonization of cellulose combined with a nitrogen-containing carbon resulting in similar process from conducting polymer, have been investigated. Cellulose or carbonized cellulose was used as templates for the coating with a conducting polymer, polyaniline, followed by their carbonization. Such approach allows for the preparation of novel nanostructured carbonaceous systems. The process was followed by FTIR and Raman spectroscopies and by thermogravimetric analysis. The conductivity, specific surface areas, and elemental compositions of templates, intermediates, and twin carbons have been determined, and are discussed along with their morphology.

Stable colloidal dispersions of polypyrrole (PPy) nanotubes/nanorods were obtained by the chemical polymerization of pyrrole in the presence of methyl orange and poly(N‐vinypyrrolidone). Due to extended morphology of colloidal particles, the films deposited from colloids with PPy nanotubes/nanorods had conductivity two orders of magnitudes higher than those from colloids of ordinary PPy nanoglobules. Dynamic light scattering measurement demonstrated that PPy nanotubes/nanorods have average particles sizes around 500 nm with a dispersity index around 0.3. The PPy colloids were stored over 3 months without visible agglomeration or precipitation. UV–vis spectra of PPy nanotubes/nanorods were recorded both in acidic or alkaline media. Raman spectra excited with 785 nm excitation laser confirmed the same mechanism of protonation of nanoglobular and nanotubular PPy. The colloid of PPy nanotubes/nanorods also exhibited good electrochemical redox activity, which makes them promising for the deposition of thin conducting layers used in sensors or energy-storage devices. The dispersions were used for the coating of films on poly(ethylene terephthalate) foils.

Polyaniline–maghemite (PANI–γ-Fe 2 O 3 ) based dispersion has been prepared in several steps. First, iron oxide nanoparticles with mixed-phase composition were synthesized by coprecipitation method. Second, obtained particles were transformed to γ-Fe 2 O 3 with sodium hypochlorite. Finally, aniline hydrochloride was in-situ polymerized with ammonium peroxydisulfate in the presence of γ-Fe 2 O 3 particles in aqueous solution of poly( N -vinylpyrrolidone). Colloidal PANI–γ-Fe 2 O 3 hybrid particles have average size of about 350 nm and the dispersity between 0.12 and 0.38. Hybrid dispersions with different concentration of conducting phase were characterized by electron microscopy, dynamic light scattering, UV–vis spectroscopy, thermogravimetric analysis, magnetization curve and conductivity measurements, as well as dielectric spectroscopy. Cytotoxicity on mouse embryonic fibroblast cell of PANI–γ-Fe 2 O 3 colloid has been investigated.

Polypyrrole nanotubes were prepared by the oxidation of pyrrole with iron(III) chloride in the presence of methyl orange. They were subsequently used as a substrate for the reductive deposition of noble metal particles. Polypyrrole nanotubes decorated with palladium, platinum, rhodium, or ruthenium nanoparticles were characterized by electron microscopy, conductivity, energy dispersive X-ray analysis, and FTIR and Raman spectroscopies. A typical metal content varied between 15 and 20 wt.%. The catalytic activity of composites was illustrated on the reduction of 4-nitrophenol to 4-aminophenol. The carbonization of composites has been followed by thermogravimetric analysis in nitrogen atmosphere. The nanotubular morphology of polypyrrole was retained after carbonization up to 830 °C. The noble-metal nanoparticles, nanometres in size, fused to clusters during this process, except for ruthenium. Polypyrrole nanotubes were converted to a nitrogen-containing carbon and platinum nanoparticles still preserved during carbonization at 400–500 °C.

A chemoresistive ammonia sensor with sensitive polyaniline layer has been fabricated by gravure printing on flexible poly(ethylene terephthalate) substrate. Novel colloids of polyaniline hydrochloride, which were synthetized in xylene or chloroform in the presence of surfactant, were used as a printing formulation. The sensor characteristics of the colloid-based sensitive layers were compared with in-situ polymerized layers of polyaniline. The colloid-based sensors showed a good response to ammonia concentrations in the range from hundreds of ppb to tens of ppm. This provides an opportunity to use these sensors for both monitoring of maximum exposure limits for humans in workplaces as well as environmental air-pollution. Therefore, these fully printed, metal-free, low cost and flexible ammonia sensors based on organic materials can be used in detection systems for monitoring of hazardous gases.

Polypyrrole nanotubes exhibit conductivity of tens S cm−1 which is one of the highest among the current conducting polymers. They are thus superior to the common globular form with the conductivity of units of S cm−1 or lower. The conductivity of both forms is reduced after treatment with alkalis but still remains high, units of S cm−1 and 10−2 S cm−1, respectively. The deprotonation, which is responsible for conductivity reduction, is discussed on the basis of salt–base transition in polypyrrole. It is not fully reversible, and the reprotonation with acids recovers the conductivity only in part. The role of methyl orange, which was used to support the formation of nanotubes, is proposed to be similar to that of surfactants. FTIR and Raman spectroscopies prove that methyl orange is strongly bound to polypyrrole in its acid form, and an “insertion” mechanism is proposed to explain the resistance towards the deprotonation of nanotubes. The spectra also illustrate that the molecular structure of nanotubular polypyrrole is preserved even under highly alkaline conditions at a pH close to 14, where the globular form becomes damaged. Polypyrrole, especially in its nanotubular form, is of promise in applications requiring electrical conduction even under neutral or alkaline conditions, where other conducting polymers, such as polyaniline, lose their exploitable conductivity.

The oxidation of aniline with ammonium peroxydisulfate in the aqueous solution of acetic acid has two subsequent phases: the oxidation of the neutral aniline molecules at low acidity, which was followed by the oxidation of the anilinium cations after the acidity became higher. The final polyaniline film deposited on immersed surfaces is usually contaminated with semi-crystalline oligomers which precipitated during induction period from the reaction medium. To obtain a homogeneous film, which is important in the fabrication of many molecular electronic devices, we have studied the course of aniline oxidation in a view of new experimental evidence. In the unique series of experiments, the silicon or gold supports have been immersed in the reaction mixture at crucial stages of oxidation reaction, and the deposits at the end of the reaction were analyzed. The growth of a highly homogenous film on the gold-coated glass substrate immersed in the reaction mixture at the end of the polymerization period has been observed. The molecular structure of the products was monitored with UV–visible, infrared, and Raman spectroscopies. The possible mechanism of the film formation and the molecular mechanism of the surface interaction of chemisorbed aniline oligomers with gold support are proposed.

Polypyrrole was prepared by the oxidation of pyrrole with iron(III) chloride in aqueous medium in the presence of methyl red dye. While the acid form of dye had no effect on the polypyrrole synthesis, the presence of its sodium salt increased the conductivity from 1–5 S cm−1 up to 84 S cm−1 for the polymerizations carried out with variable dye concentration at 20 °C. When the reaction temperature was reduced to −50 °C, the conductivity increased up to 104 S cm−1. At temperatures below −20 °C, the polymerization took place in frozen reaction medium, in ice. The morphology of polypyrrole was mainly globular and often converted to particles of irregular size and shape. It was concluded that one-dimensional morphology, nanotubes or nanofibers characteristic of polypyrrole, is not an automatic prerequisite for the high conductivity of this polymer.

Polyaniline was prepared by the oxidation of aniline hydrochloride or aniline with ammonium peroxydisulfate in the presence of 37 anionic or cationic organic dyes. Similar preparation of polypyrrole used iron(III) chloride as an oxidant. The goal of the study is to evaluate the effect of dyes on the conductivity of both polymers and their morphology at nanoscale. The preparation of polyaniline using aniline hydrochloride as a monomer was unaffected by the dyes presence, its conductivity was of the order of units S cm−1 and morphology was globular. The similar oxidation of aniline has led to the products with reduced conductivity and unresolved morphology. On the other hand, the presence of dyes had significant impact on the conductivity of polypyrrole, and all tested dyes improved the conductivity, for example methyl red from 1 S cm−1 to 42 S cm−1. Most of the samples were globular, but several dyes, such as Acid Blue 25, acriflavine, methyl orange, methylene blue, neutral red, phenosafranin or safranin stimulated the growth of one-dimensional morphologies, polypyrrole nanofibers or nanotubes.

Polypyrrole (PPy) synthesized by the oxidation of pyrrole with iron(III) chloride in the presence of sulfonic azo dyes exhibits fascinating nanometer-scale morphology and high conductivity, which are distinctly different from their counterparts prepared without dyes. The present work systematically studied the roles of sulfonic azo dye aggregates formed in acidic medium during the growth of PPy based on structural and elemental analysis. The formation of PPy nanostructures have been investigated by following the pH profile, by adjusting the precipitation rate of dye aggregates and by comparing the molecular structure of three azo dyes, viz. methyl orange, ethyl orange and Orange I. The results showed that the ethyl orange derived aggregates formed in iron(III) chloride solution and in hydrochloric acid solution had exactly the same structure as well as elemental composition. Aggregates derived from methyl orange formed in iron(III) chloride solution involved a trace amount of iron element. Orange I, another azo dye that can induce aggregates rapidly in iron(III) chloride solution, contributed negligibly to both the morphology and conductivity of PPy. The structure-directing effects of methyl orange/iron(III) complexes in directing PPy nanostructures seems to be unique and cannot be simply extended to other azo dyes, probably due to the dye interaction with iron ions.