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In the search for functional organic biomaterials, leather constituted by collagen fibers was coated with a conducting polymer, polypyrrole. The coating was carried out during the oxidation of pyrrole in an aqueous solution of poly(N-vinylpyrrolidone) in the presence of five organic dyes: crystal violet, neutral red, methyl orange, acriflavine, and methylene blue. This technique ensures the uniform coating of collagen fibers with polypyrrole and incorporation of organic dyes. The surface morphology was observed with scanning electron microscopy and the transverse profile, reflecting the penetration of the conducting phase into the leather body with optical microscopy. While the polypyrrole coating endows leather with electrical conductivity, organic dyes are expected to affect the polymer morphology and to provide an antibacterial effect. The lowest sheet resistance and antibacterial activity were obtained with crystal violet. This type of coating was characterized in more detail. Infrared spectroscopy confirmed the coating of collagen fibers with polypyrrole and dye incorporation. Mechanical properties were extended to the cyclic bending of the leather at various angles over 5000 cycles. The relative resistance changes were a few percent, indicating good electrical stability during repeated mechanical stress., Ministry of Education, Youth and Sports of the Czech Republic [FRC RO70200003025/2102], Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMT: FRC RO70200003025/2102

Melamine sponges were coated with polypyrrole during the in situ polymerization of pyrrole. The precipitation polymerization was compared with the dispersion mode, that is, with the preparation in the presence of poly(N-vinylpyrrolidone) and nanosilica as colloidal stabilizers. The coating of sponges during the dispersion polymerization leads to the elimination of the undesired polypyrrole precipitate, improved conductivity, and increased specific surface area. The sponges were tested with respect to their conductivity and as pressure-sensitive conducting materials with antibacterial performance. © 2021 The Authors. Published by American Chemical Society., Czech Science FoundationGrant Agency of the Czech Republic [19-04859S, 21-09830S]; internal Prague University research project [A2_FCHI_2021_003]; Ministry of Education, Youth and Sports of the Czech RepublicMinistry of Education, Youth & Sports - Czech Republic [DKRVO RP/CPS/2020/001], RP/CPS/2020/001; A2_FCHI_2021_003; Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMT; Grantová Agentura České Republiky, GA ČR: 19-04859S, 21-09830S

The present feature article offers a concise overview of recent research progress of the authors working in the design of macroporous conducting materials represented by polypyrrole-coated melamine sponges. The article highlights innovative results from the authors and suggests a perspective for future directions in the field of macroporous conducting polymer composites. The article also overviews this particular subject area and defines key challenges for this emerging field. The feasibility of diverse applications of polypyrrole/melamine sponges is demonstrated and includes deformation-sensitive materials, electromagnetic radiation shielding and electrically heated insulation materials. Cytotoxicity is addressed with respect to applications in biomedicine, and the adsorption of an organic dye serves as an example of the uses in environmental water-pollution treatment. A single-step deposition of polypyrrole during the oxidative polymerization of pyrrole provides the uniform coating of the sponge with an organic conducting phase. The conductivity of sponges was of the order of 10−3 S cm−1, increased with polypyrrole loading, and also by two orders of magnitude after the compression. Derived materials have also been prepared and tested. They are represented by polypyrrole-coated sponge converted by pyrolysis to a macroporous nitrogen-containing carbon, magnetic ferrosponge obtained by incorporation of magnetite, or the conventional globular polypyrrole coating replaced with polypyrrole nanotubes. Polypyrrole can also be simply decorated with silver nanoparticles. The macroporous conducting polypyrrole/melamine sponges and derived materials are considered to be of future scientific interest with broad application potential.

Czech Science FoundationGrant Agency of the Czech Republic [19-04859S, 21-09830S]; specific research project of the University of Chemistry and Technology, Prague [A2-FCHI-2021-003]

Polyaniline (PANI) salts with tungstosilicic (TSA) and phosphotungstic acids (PTA) were prepared by reprotonation of PANI base. Partial protonation of the precursor base was confirmed by Raman spectroscopy and by conductivity measurements. Conductivity of polyaniline tungstosilicate (PANI-TSA) and polyaniline phosphotungstate (PANI-PTA) after reprotonation measured on compressed pellets was found to be 1 × 10–5 S cm−1 and 4 × 10–6 S cm−1, that is significantly higher compared to conductivity of PANI base (⁓ 10–11 S cm–1). According to thermogravimetric and elemental analyses, the amount of heteropolyacids in the resulting salts was ≈ 20 wt%, which corresponded to ≈ 15 wt% of tungsten. Tungsten- and nitrogen-containing carbon derivatives were obtained by carbonization of the prepared PANI salts without losing their conductivity (⁓10–7 S cm–1). Successful carbonization was confirmed by vibrational spectroscopy. Electron microscopy showed that globular morphology typical for PANI base was not affected by reprotonation and carbonization procedures. Elemental analysis confirmed 25.6 and 17.9 wt% of tungsten, 9.7 and 9.6 wt% of nitrogen in the carbonized PANI-PTA and PANI-TSA, respectively. The prepared carbon derivatives can be potentially useful for electrocatalysis.

The study aims at the design of nanostructured hybrid materials that are both conducting and magnetic. Conducting polypyrrole nanotubes were prepared by the oxidation of pyrrole with iron(III) chlo...

Thiocyanate anions represent serious environmental hazards and the ways for their extraction from ecosystem are sought. In the testing of new adsorbents, polyaniline nanotubes have been utilized as a host polymer in which silver nanoparticles were distributed to produce polyaniline nanotubes/silver nanocomposite. The interaction of thiocyanate anions in aqueous medium with the nanocomposite deposited on the quartz-crystal microbalance was studied. The results indicated that polyaniline nanotubes adsorb thiocyanate anions, and silver nanoparticles are suspected in addition to catalyze the transformation of thiocyanate. The extraction of thiocyanate anions using nanocomposites from the aqueous solution was then monitored with the UV–visible spectroscopy. The effect of different parameters including concentration, adsorbent dose, and pH has been mentioned. The pH effect demonstrated that ion exchange and electrostatic interaction as well as chemisorption mechanisms are involved in the adsorption. The results were fitted into various kinetic models. It was concluded that pseudo-second-order kinetic model best matched the adsorption and the extraction capacity of thiocyanate anions, 112 mg g−1, exceeds the results reported so far in the literature. In addition, the results showed that the separation of SCN− depends on a synergetic effect of interaction and reduction of SCN− with polyaniline nanotubes/silver nanocomposite.

Extensive research has been focused on the removal of various pollutants from wastewaters. Hexavalent chromium Cr(VI) is of special concern as it is a known carcinogen. In the present study, macroporous polyaniline/poly(vinyl alcohol) aerogel was applied as a promising material form which can act as both adsorbent and reductant for Cr(VI) in aqueous solutions. The removal of Cr(VI) was assessed by monitoring the decrease in optical absorption with UV–visible absorption spectroscopy. The effect of different parameters, such as the initial Cr(VI) concentration, contact time, and the adsorbent dose, on the removal process has been studied. The intraparticle diffusion model was found to characterize the adsorption process well, but Freundlich isotherm best fits the adsorption isotherm data. Investigation of the substrate regeneration revealed that polyaniline-based aerogel can be reused for the removal of Cr(VI) with good efficiency. The maximum adsorption capacity of composite aerogel reached 41.2 mg g−1, which is one of the best results reported in the literature. The conductivity and electroactivity of the material may subsequently be used in the design of intelligent adsorbents when the adsorption/desorption could be controlled by the applied electrical potential.

Polypyrrole nanotubes were prepared by the oxidation of pyrrole in aqueous solutions of methyl orange and in the presence of 1–5 wt% of surface-active additives, surfactants, or amino acids. Three types of additives – anionic, non-ionic, and cationic – have been tested in the control of polypyrrole morphology and conductivity. The morphology of nanotubes was little dependent on surfactant type but the changes in size and aspect ratios were more pronounced with amino acids. Except for anionic surfactant, bis(2-ethylhexyl) sulfosuccinate, which behaved indifferently, all additives reduced the conductivity of polypyrrole, some even by four orders of magnitude. Based on FTIR spectroscopy, it is proposed that the hydrophobic interactions and/or hydrogen bonding between the additives and growing polypyrrole chains play the important role in reducing chain ordering, while the ionic interactions have limited effect.

Poly(aniline-co-m-phenylenediamine) cryogels supported by poly(vinyl alcohol) were obtained by oxidative cryocopolymerization of aniline and m-phenylenediamine in the presence of poly(vinyl alcohol) in the frozen aqueous medium. Morphology, specific surface area, and mechanical properties of aerogels obtained after freeze-drying with pore size up to 35 μm were dependent on initial freezing temperature and total concentration of comonomers in polymerization mixture. The materials initially frozen at higher temperatures and synthesized at higher comonomers concentrations were found to have in general smaller pore sizes and consequently better mechanical stability. Initial freezing temperature − 24 °C and total comonomer concentration 0.77 M were found to be the optimum parameters for the preparation of conducting cryogels with conductivity of solid phase 1 × 10−3 S cm−1, a relatively high specific surface area 23.1 m2 g−1, and excellent mechanical properties with tensile modulus 255 kPa. The molecular structure of cryogels is discussed with the help of FTIR and Raman spectra.

A facile preparation of a conducting one-dimensional polypyrrole nanostructure (1-D PPy) was achieved in the presence of safranin dye. The polymerization temperature has a significant effect on the conductivity, specific surface area and morphology of PPy. A decrease in the polymerization temperature leads to a significant increase in the conductivity. The highest conductivity was obtained by frozen polymerization (−24 °C) with a value of 175 ± 4 and 23.7 ± 2.9 S cm−1 for 1-D PPy and globular PPy, respectively. The temperature dependence of the conductivity of 1-D PPy prepared at −24 °C revealed a semiconducting behaviour with a 3-D variable range hopping charge transfer mechanism. Raman spectroscopy results suggested that the high conductivity can be attributed to the high protonation level of 1-D PPy. Nuclear magnetic resonance spectroscopy has been used to study the chemical structure of 1-D PPy and the incorporation of safranin into the polymer matrix.

Electrospun membranes with an active response are playing an increasing role in tissue regeneration by improving the ability of the materials to mimic the cellular microenvironment during cell culture. In this context, this work reports on the development of poly(vinylidene fluoride) (PVDF) electrospun fibers coated with polyaniline (PANI) and with polypyrrole (PPy). Both PANI and PPy successfully coated the fibers, with the surface electrical conductivity of the coatings reaching values of =1.19S.m1 for PVDF-PPy and =3.84×103S.m1 for PVDF-PANI. Furthermore, the PVDF samples became hydrophilic upon their coating with either PANI or PPy, the fiber mats adsorbing the water drop after a few seconds. The coated samples remain biocompatible, resulting in a slight improvement in the metabolic activity of L929 fibroblasts., ERDF -European Regional Development Fund(PTDC/BTM-MAT/28237/2017), info:eu-repo/semantics/publishedVersion

Conducting polymers, such as polyaniline and polypyrrole, have frequently been discussed in the literature due to ease of preparation and high application potential. These polymers have been observed to interact with organic dyes because of the similarity in the conjugated molecular structure of both moieties. The interaction manifests itself in three fundamental directions that have been so far treated separately. The first is represented by the conductivity enhancement and morphology control when using organic dyes as templates in polypyrrole preparation. The adsorption of dyes on conducting polymers is the second field oriented at the water pollution treatment. Finally, the photocatalytic decomposition of organic dyes aims at the similar environmental target. The last two applications do not require the presence of conductivity which, on the other hand, is a key parameter of conducting polymers. The future design of advanced adsorbents, however, has to exploit both the conductivity and electroactivity in the control of pollutant adsorption or degradation. For this reason, all these interactions and their practical impact are considered in the present review.

A conducting polymer, polypyrrole, was deposited on tungsten disulfide flakes in situ during the oxidation of pyrrole. The conductivity of composites exceeded the conductivities of the parent components. This synergistic effect is explained by the deposition of more conducting ordered polypyrrole at first, and less conducting globular polypyrrole later after the whole available tungsten disulfide surface was coated. Such scenario was confirmed by electron microscopies. Raman and X-ray photoelectron spectroscopies proved the completeness of the coating. Despite the increase in the conductivity, the electrocatalysis of hydrogen evolution reaction on tungsten disulfide was reduced after polypyrrole deposition, confirming also effective coating of the substrate. A simple mixture of both components, however, improved the electrocatalytic effect compared with the composite or any of its components.

The microcomposites of a conducting polymer, polyaniline, with four layered zirconium phosphonates, viz. 4-sulfophenylphosphonate, 2-sulfoethylphosphonate, 4-carboxyphenylphosphonate, carboxymethylphosphonate, were prepared and characterized by wide-angle X-ray diffraction and FTIR and Raman spectroscopies. Aniline hydrochloride was proved to intercalate the hosts containing sulfonic group. The intercalation was not observed with the carboxyl-containing phosphonates. Two methods of aniline oxidation, using peroxydisulfate anion, cerium(IV) or iron(III) cations as aniline oxidants, were tested. FTIR and Raman spectra suggest that the intercalated aniline does not polymerize. Polyaniline grows on phosphonates during surface polymerization rather than to be generated as a free polymer in the bulk of reaction mixture. Conductivity varied from 10−9 S cm−1 to 10−3 S cm−1 depending on the way of preparation and the type of the phosphonate filler. The conductivity response to the ambient humidity strongly depends on the filler and suggests the possibility to apply these materials in humidity sensors.

Polypyrrole was prepared in the presence of cationic dyes, safranin and phenosafranin. The safranin supported the one-dimensional growth of polypyrrole, converting globules to nanorods and later also to nanotubes, particularly at higher dye concentrations. In the case of phenosafranin, the produced nanotubes were considerably thicker and were always accompanied by globules. Upon oxidation both dyes are expected to generate insoluble oligomeric templates that serve as loci for the deposition of polypyrrole. The formation of globular morphology takes place when the dye becomes depleted, due to its low concentration for safranin, or because of robust templates produced by phenosafranin. In addition to scanning and transmission electron microscopies, the resultant polypyrroles were characterized by FTIR and Raman spectroscopies, and DC conductivity measurements. The conversion of globular morphology to nanotubes/nanofibers was accompanied by the increase in conductivity from 5 to 35 S cm−1, which was explained by the improved ordering of polypyrrole chains more preferable for charge transport. The series of syntheses at varying oxidant-to-pyrrole mole ratios confirmed the stoichiometric ratio 2.5 to be the best for pyrrole oxidation but a good stability of polypyrrole was demonstrated even at extremely high stoichiometric ratio 15.

Conducting macroporous soft cryogels were prepared by the oxidation of pyrrole within the frozen aqueous solutions of 5–8 wt.% poly(vinyl alcohol) at −24 °C. Mechanical properties of cryogels were independent of poly(vinyl alcohol) concentration, Young moduli were ≈20 kPa. The conductivity of compressed freeze-dried composites reached 18 S cm−1 thus exceeding the conductivity of polypyrrole alone. This level of conductivity was also preserved after long-term treatment with water, i.e. close to physiological conditions. In-vitro determined cytotoxicity demonstrated high potential applications due to low cytotoxicity. Moreover, compared to the steel based materials, the cryogels mimic the properties of soft tissues. All these properties are a prerequisite for the utilization in biomedical applications.

An alteration of electrical conductivity of the conducting polymers from a conducting to a non-conducting form and vice versa is a feature of the high importance. Here, the changes in conductivity of the polypyrrole nanotubes (PPy-NT) associated with a deprotonation/reprotonation in alkaline (various concentrations of ammonium or sodium hydroxide) or acidic (1 M hydrochloric or hydrobromic acid) solutions are presented. All experiments were followed by energy dispersive X-ray spectroscopy (EDX) elemental analyses and van der Pauw conductivity measurements. Extensive measurements of conductivity of samples during 2-years' timespan have also been made in order to determine the kinetics of natural ageing of the deprotonated/reprotonated PPy-NT. EDX measurements have allowed for a deeper insight into the process of the deprotonation/reprotonation of PPy-NT, which is generally characterized by the exchange of counter-ions and by the increase in the oxygen content. Correlations among conductivities of original, deprotonated and reprotonated samples revealed the universal behaviour, which can be used for the precise prediction of the ability of PPy-NT to be reprotonated by acids. Kinetics of the degradation of PPy-NT by natural ageing is faster for deprotonated sample and, on the contrary, the reprotonation by acids had a stabilizing effect.

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.

Poly(aniline-co-p-phenylenediamine) cryogels stabilized by poly(vinyl alcohol) were prepared by one-step oxidative cryocopolymerization. Composite cryogels have macroporous structure with pore sizes up to tens of micrometers; however, copolymer cryogels have smaller pores compared to homopolymer cryogels. The cryogels containing 70 mol% and 80 mol% of aniline have the smallest pores and have the highest mechanical stability. The decrease in aniline fraction led to decrease of conductivity from 5×10–2 S cm–1 for polyaniline-based cryogel to

The active role of biomaterials in the regeneration of tissues and their ability to modulate the behavior of stem cells in terms of their differentiation is highly advantageous. Here, polypyrrole, as a representantive of electro-conducting materials, is found to modulate the behavior of embryonic stem cells. Concretely, the aqueous extracts of polypyrrole induce neurogenesis within embryonic bodies formed from embryonic stem cells. This finding ledto an effort to determine the physiological cascade which is responsible for this effect. The polypyrrole modulates signaling pathways of Akt and ERK kinase through their phosphorylation. These effects are related to the presence of low-molecularweight compounds present in aqueous polypyrrole extracts, determined by mass spectroscopy. The results show that consequences related to the modulation of stem cell differentiation must also be taken into account when polypyrrole is considered as a biomaterial. © 2021 by the authors. Licensee MDPI, Basel, Switzerland., Czech Science FoundationGrant Agency of the Czech Republic [19-16861S, 17-05466S]; internal grant agency of Tomas Bata University in Zlin [IGA/CPS/2021/001]; Slovenian Research AgencySlovenian Research Agency - Slovenia [P2-0082]; Ministry of Education, Youth and Sports of the Czech Republic-DKRVO [RP/CPS/2020/001], RP/CPS/2020/001; Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMT; Grantová Agentura České Republiky, GA ČR: 17-05466S, 19-16861S; Javna Agencija za Raziskovalno Dejavnost RS, ARRS: P2-0082; Univerzita Tomáše Bati ve Zlíně: IGA/CPS/2021/001

New types of materials were produced by gradual heating of a conducting polymer, polypyrrole, to elevated temperatures. Three polymers differing in morphology - globules, nanofibers, and nanotubes - were exposed to temperatures from 100 to 700 degrees C in an argon atmosphere. The yields always exceeded 50 wt%, and the morphological features of the polymer were preserved. The transformation of polypyrrole salts to the corresponding bases followed by the carbonization was monitored by FTIR spectroscopy. The elemental analysis confirmed the subsequent conversion of polypyrrole to nitrogen-containing carbon. The specific surface areas were of the order of tens of m(2) g(-1); they increased from globules to nanotubes and nanofibers but were virtually independent of the exposition temperature. The conductivity of the powders was compared with that of the pellets when their preparation was possible. As the temperature was increased up to 400 degrees C, the conductivity decreased for all samples by ca. 5 orders of magnitude, e.g., for nanofibers from 10 to 10(-4) S cm(-1) but recovered to 10(-1) S cm(-1) after the subsequent carbonization up to 700 degrees C. Polypyrroles exposed to various temperatures were then tested for the adsorption of organic dye, Reactive Black 5, from water. The dye adsorption on original polypyrroles strongly depended on the polymer morphology. Polypyrrole nanofibers were able to remove the dye completely with a capacity of 100 mg g(-1), while the adsorption on polypyrrole globules was poor. The adsorption efficiency thus increased from globules to nanotubes and nanofibers. The adsorption performance was reduced after the carbonization, but the general trends were preserved. Postupným zahříváním vodivého polymeru polypyrrolu na zvýšené teploty byly vyráběny nové typy materiálů. Tři polymery lišící se morfologií - globule, nanovlákna a nanotrubice - byly vystaveny teplotám od 100 do 700 °C v argonové atmosféře. Výtěžky vždy přesáhly 50 % hm. a morfologické vlastnosti polymeru byly zachovány. Transformace polypyrrolových solí na odpovídající báze s následnou karbonizací byla sledována pomocí FTIR spektroskopie. Elementární analýza potvrdila následnou konverzi polypyrrolu na uhlík obsahující dusík. Specifické povrchy byly řádově desítky m(2) g(-1); zvýšily se z globulí na nanotrubice a nanovlákna, ale byly prakticky nezávislé na teplotě expozice. Vodivost prášků byla srovnávána s vodivostí pelet, pokud byla možná jejich příprava. Když se teplota zvýšila až na 400 °C, vodivost se u všech vzorků snížila o cca. 5 řádů, např. pro nanovlákna od 10 do 10(-4) S cm(-1), ale obnovena na 10(-1) S cm(-1) po následné karbonizaci až do 700 °C. Polypyrroly vystavené různým teplotám následně byly testovány na adsorpci organického barviva, Reactive Black 5, z vody. Adsorpce barviva na původních polypyrrolech silně závisela na morfologii polymeru. Polypyrrolová nanovlákna dokázala barvivo úplně odstranit s kapacitou 100 mg g(-1), zatímco adsorpce na polypyrrolové globule byla špatná. Adsorpční účinnost se tak zvýšila z globulí na nanotrubice a nanovlákna. Adsorpční výkon byl po karbonizaci snížen, ale obecné trendy byly zachovány.

Fabrication of adsorbents with excellent adsorption capacity, outstanding stability, easy separation ability, excellent recyclability and widely generality for organic dyes removal from wastewater remains challenging. Herein, three-dimensional polyaniline/poly(vinyl alcohol)/montmorillonite (PANI/PVAL/MMT) hybrid aerogels with easy separation performance and highly effective reusable adsorption on both anionic and cationic dyes were fabricated by a simple in-situ polymerization method. As-prepared hybrid aerogels were characterized via infrared and Raman spectra, scanning electron microscopy, energy dispersive spectra mapping, small and wide-angle X-ray scattering, thermogravimetric analysis, mercury intrusion porosimetry and elemental analysis. The results showed that MMT particles were successfully incorporated into aerogel matrix. Well-defined hierarchical structure, where PANI nanofibers are coated on the skeleton wall, can be observed for PANI/PVAL/MMT when the incorporation amount of MMT was around 11.1 wt%. The adsorption performance of as-prepared hybrid aerogels on both anionic and cationic dyes was systemically carried out at different solution pH, adsorbent dosage and initial dye concentration. The data analysis showed that the adsorption process for PVAL/PANI/MMT aerogel for Reactive Black 5, methyl orange and safranin followed Freundlich isotherm and the maximum experimental adsorption capacities were found to be 199, 251 and 57.0 mg g

Polypyrrole globules, nanofibers and nanotubes were activated by their carbonization at 650 °C in the 3:1 mass excess of molten potassium hydroxide in argon. They have been compared with parent polypyrroles and analogous samples obtained by the carbonization in the absence of hydroxide. The yields after activation, 12–18 wt%, were lower compared to the carbonization, which exceeded 50 wt%. The changes in molecular structure are discussed on the basis of FTIR and Raman spectra. One-dimensional morphologies, especially nanotubes, were superior to globules in most respects. They have higher conductivity close to 10 S cm−1, which was reduced by two orders of magnitude after arbonization but partly recovered after activation. The specific surface areas of nanotubes of the order of tens m2g−1 was several times higher compared with globules. They have not changed after carbonization but increased several times upon activation. The activated polypyrroles were tested as adsorbents of anionic azo dye, Reactive Black 5. Activated nanotubes performed the best in adsorption followed by parent nanotubes and nanofibers. The mechanism of dye adsorption is proposed by considering the presence of dye tautomers identified on the basis of FTIR spectra Polypyrrolové globule, nanovlákna a nanotrubičky byly aktivovány karbonizací při 650 °C v hmotnostním přebytku 3:1 roztaveného hydroxidu draselného v atmosféře argonu. Byly porovnány s původními polypyrroly a analogickými vzorky získanými karbonizací v nepřítomnosti hydroxidu. Výtěžky po aktivaci, 12–18 hm. %, byly nižší ve srovnání s karbonizací, která přesáhla 50 hm. %. Změny v molekulární struktuře jsou diskutovány na základě FTIR a Ramanových spekter. Jednorozměrné morfologie, zejména nanotrubice, byly ve většině ohledů lepší než globule. Mají vyšší vodivost blízkou 10 S cm−1, která se po karbonizaci snížila o dva řády, ale po aktivaci se částečně obnovila. Specifický povrch nanotrubic v řádu desítek m2g−1 byl několikanásobně vyšší než u globulí. Po karbonizaci se nezměnily, ale po aktivaci se několikrát zvýšily. Aktivované polypyrroly byly testovány jako adsorbenty aniontového azobarviva Reactive Black 5. Aktivované nanotrubice si vedly nejlépe v adsorpci následované mateřskými nanotrubičkami a nanovlákny. Mechanismus adsorpce barviva je navržen s ohledem na přítomnost tautomerů barviva identifikovaných na základě FTIR spekter

Macroporous open-cell melamine sponges were coated with a conducting polymer, polypyrrole, during in-situ oxidative polymerization of pyrrole. Two samples, differing in polypyrrole content, 8.2 and 27.4 wt%, were prepared. They were exposed to various temperatures up to 700 °C in an inert atmosphere. The macroporous structure and mechanical integrity were preserved after this process. This converted both the polypyrrole coating and the melamine sponge to macroporous nitrogen-containing carbons. The changes in molecular structure in the course of carbonization were followed by elemental analysis and FTIR and Raman spectra. The specific surface area of polypyrrole-coated sponge increased from ca. 90 to ca. 300 m2 g−1 along with accompanying increase in the porosity. The conductivity of the sponges was recorded as a function of compression in a newly developed apparatus. The sponge containing 27.4 wt% pyrrole had conductivity of the order of 10−2 S·cm−1 at 0.1 MPa pressure, which was reduced by four orders of magnitude when exposed to 400–500 °C and nearly recovered after the temperature reached 700 °C. The sponges were tested in electromagnetic radiation shielding and displayed both radiation absorption and, to a lower extent, radiation reflection proportional mainly to the samples’ conductivity.

Conducting polymers (CP) can be used as pH- and/or electro-responsive components in various bioapplications, for example, in 4D smart scaffolds. The ability of CP to maintain conductivity under physiological conditions is, therefore, their crucial property. Unfortunately, the conductivity of the CP rapidly decreases in physiological environment, as their conducting salts convert to non-conducting bases. One of the promising solutions how to cope with this shortcoming is the use of alternative "doping" process that is not based on the protonation of CP with acids but on interactions relying in acidic hydrogen bonding. Therefore, the phosphonates (dimethyl phosphonate, diethyl phosphonate, dibutyl phosphonate, or diphenyl phosphonate) were used to re-dope two most common representatives of CP, polyaniline (PANI) and polypyrrole (PPy) bases. As a result, PANI doped with organic phosphonates proved to have significantly better stability of conductivity under different pH. It has also been shown that cytotoxicity of studied materials determined on embryonic stem cells and their embryotoxicity, determined as the impact on cardiomyogenesis and erythropoiesis, depend both on the polymer and phosphonate types used. With the exception of PANI doped with dibutyl phosphonate, all PPy-based phosphonates showed better biocompatibility than the phosphonates based on PANI.

Polyaniline is a conducting polymer with an application potential in the field of biomedical engineering. By employing FTIR spectroscopy and conductivity measurements, it has been shown that the oxidation at stoichiometric peroxydisulfate-to-aniline mole ratio 1.25 in the solutions of formic acid in the range 0–10 M provides samples of a moderate conductivity of the orders 0.01–0.1 S cm−1. They consist of polyaniline and aniline oligomers as typical of the aniline oxidation in weak acids. The detailed investigation of the infrared spectra indicates a partial ring-carboxylation of polyaniline at high acid concentrations. The extent of structural defects is higher for a series prepared at over-stoichiometric peroxydisulfate-to-aniline mole ratio 2.5, which provided only non-conducting samples. The reference sample series represented by poly(aniline-co-o-aminobenzoic acid) was also prepared and is used in the discussion of the infrared spectra.