Carbonized polyaniline cryogel: A spectroscopic study

Cryogels are chemically or physically crosslinked systems of polymer chains swollen with water. They are produced by the preparation of conducting polymers in frozen media, in ice. They contain a conducting component, typically a conducting polymer, such as polyaniline [1] and suitable supporting polymer. Raman spectroscopy allows for the analysis of wet samples or of aqueous solutions. Freeze-dried polyaniline cryogel has been prepared from polyaniline and was also analyzed with Raman spectroscopy. The carbonization has been followed by thermogravimetric analysis in inert atmosphere [2]. The macroporous morphology of polymer aerogel was retained after carbonization (Fig. 1). Raman spectra of polyaniline salt at 20 and 100 oC present the bands of the phenazine-like segments in polyaniline at 1646, 1401 and 578 cm–1, indicating extensive cross-linking of units (Fig. 2) [3]. The conversion to nitrogen-containing carbon is complete at 500 °C. Please click Additional Files below to see the full abstract

Polyaniline cryogels: Soft and conducting

Polyaniline is important conducting polymer [1]. It is prepared by the oxidation of aniline with ammonium peroxydisulfate in acidic aqueous media [2] (Fig. 1). When the oxidative polymerization of aniline is carried out in the presence of a water-soluble supporting polymer in frozen reaction media, in ice, a composite hydrogels are obtained after thawing. Such hydrogels are called cryogels and the prefix cryo refers to the way of their preparation. Please click Additional Files below to see the full abstract

The Phenomenon of Female Songwriting

Práce se snaží přiblížit tvorbu žen-písničkářek a její specifika. Vychází ze tří hloubkových sond do písňové produkce Dagmar Andrtové, Zuzany Navarové a Sester Steinových. Cílem je odhalit či popřít společné rysy jejich tvorby, ale především proniknout k nej vlastnější podstatě jejich písní. Jednotlivé studie mapují témata, motivy a jazykovou vrstvu jejich písňových textů, ale neopomíjí ani hudební a interpretační stránku, která je nedílnou součástí písňového umění. Úvodní kapitola je členěna do šesti podkapitol. První podkapitla se pokouší definovat útvar písně a začlenit písňový text do kontextu literatury. Druhá podkapitola jej vymezuje vůči příbuzným útvarům, jakými jsou báseň a zhudebněná báseň, následující čtyři podkapitoly se pak věnují fenoménu písničkáře, kořenům českého písničkářství a mapování tvorby žen-písničkářek. Další tři kapitoly jsou věnovány analýzám tvorby vybraných písničkářek. Závěr diplomové práce se snaží nalézt odpověď na základní otázku: Je možné nějak vymezit oblast ženského písničkářství? Odpověď vychází z jednotlivých provedených analýz, ale i obecnější genderové problematiky.Práce se snaží přiblížit tvorbu žen-písničkářek a její specifika. Vychází ze tří hloubkových sond do písňové produkce Dagmar Andrtové, Zuzany Navarové a Sester Steinových. Cílem je odhalit či popřít společné rysy jejich tvorby, ale především proniknout k nej vlastnější podstatě jejich písní. Jednotlivé studie mapují témata, motivy a jazykovou vrstvu jejich písňových textů, ale neopomíjí ani hudební a interpretační stránku, která je nedílnou součástí písňového umění. Úvodní kapitola je členěna do šesti podkapitol. První podkapitla se pokouší definovat útvar písně a začlenit písňový text do kontextu literatury. Druhá podkapitola jej vymezuje vůči příbuzným útvarům, jakými jsou báseň a zhudebněná báseň, následující čtyři podkapitoly se pak věnují fenoménu písničkáře, kořenům českého písničkářství a mapování tvorby žen-písničkářek. Další tři kapitoly jsou věnovány analýzám tvorby vybraných písničkářek. Závěr diplomové práce se snaží nalézt odpověď na základní otázku: Je možné nějak vymezit oblast ženského písničkářství? Odpověď vychází z jednotlivých provedených analýz, ale i obecnější genderové problematiky.Katedra českého jazyka a katedra české literaturyPedagogická fakultaFaculty of Educatio

Cotton fabric coated with conducting polymers and its application in monitoring of carnivorous plant response

The paper describes the electrical plant response to mechanical stimulation monitored with the help of conducting polymers deposited on cotton fabric. Cotton fabric was coated with conducting polymers, polyaniline or polypyrrole, in situ during the oxidation of respective monomers in aqueous medium. Thus, modified fabrics were again coated with polypyrrole or polyaniline, respectively, in order to investigate any synergetic effect between both polymers with respect to conductivity and its stability during repeated dry cleaning. The coating was confirmed by infrared spectroscopy. The resulting fabrics have been used as electrodes to collect the electrical response to the stimulation of a Venus flytrap plant. This is a paradigm of the use of conducting polymers in monitoring of plant neurobiology.Web of Science164art. no. 49

The chemical and electrochemical oxidative polymerization of 2-amino-4-tert-butylphenol

[EN] Poly(2-amino-4-tert-butylphenol), poly(2A-4TBP), was synthesized from monomer aqueous solution using either electrochemical or chemical oxidation procedures. Several spectroscopic characterization techniques were employed to gain information on the chemical structure and redox behavior of the obtained materials. It was found that the chemical polymerization product could be described as an oligomer mixture containing up to 16 monomer units. In parallel to other polymers derived from o-aminophenol, phenoxazine rings constitute also the basic structure of poly(2A-4TBP). In addition, the occurrence of N-N couplings, which are favored by the presence of the voluminous tert-butyl substituent, seems also relevant. No significant structural differences were found between the chemically or electrochemically synthesized materials. © 2016 Published by Elsevier Ltd.Financial support from the Spanish Ministerio de Economía y Competitividad and FEDER funds (MAT2013-42007-P) and from the Generalitat Valenciana (PROMETEO2013/038) is gratefully acknowledged. M. Abidi thanks the Ministry of Higher Education and Scientific Research of Tunisia for funding her stay at the University of Alicante.Abidi, M.; López-Bernabeu, S.; Huerta, F.; Montilla-Jiménez, F.; Besbes-Hentati, S.; Morallón, E. (2016). The chemical and electrochemical oxidative polymerization of 2-amino-4-tert-butylphenol. Electrochimica Acta. 212:958-965. https://doi.org/10.1016/j.electacta.2016.07.060S95896521

One-dimensional nanostructures of polypyrrole for shielding of electromagnetic interference in the microwave region

Polypyrrole one-dimensional nanostructures (nanotubes, nanobelts and nanofibers) were prepared using three various dyes (Methyl Orange, Methylene Blue and Eriochrome Black T). Their high electrical conductivity (from 17.1 to 60.9 S cm−1), good thermal stability (in the range from 25 to 150◦ C) and resistivity against ageing (half-time of electrical conductivity around 80 days and better) were used in preparation of lightweight and flexible composites with silicone for electromagnetic interference shielding in the C-band region (5.85–8.2 GHz). The nanostructures’ morphology and chemical structure were characterized by scanning electron microscopy, Brunauer–Emmett–Teller specific surface measurement and attenuated total reflection Fourier-transform infrared spectroscopy. DC electrical conductivity was measured using the Van der Pauw method. Complex permittivity and AC electrical conductivity of respective silicone composites were calculated from the measured scattering parameters. The relationships between structure, electrical properties and shielding efficiency were studied. It was found that 2 mm-thick silicone composites of polypyrrole nanotubes and nanobelts shield almost 80% of incident radiation in the C-band at very low loading of conductive filler in the silicone (5% w/w). Resulting lightweight and flexible polypyrrole composites exhibit promising properties for shielding of electromagnetic interference in sensitive biological and electronic systems. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.Ministry of Education, Youth and Sports of the Czech Republicproject DKRVO [RP/CPS/2020/006]; [A2_FCHI_2020_030

Coating of leather with dye-containing antibacterial and conducting polypyrrole

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 RO70200003025/210

Bidisperse magnetorheological fluids utilizing composite polypyrrole nanotubes/magnetite nanoparticles and carbonyl iron microspheres

Conductive polypyrrole nanotubes were synthesized with a two-step one-pot synthesis. During synthesis, the nanotubes were decorated with magnetite nanoparticles at different concentrations granting them magnetic properties. The characterization of the tubes revealed differences from the theoretical reactions. A bidisperse magnetorheological fluid (MRF) was prepared by mixing the composite polypyrrole nanotubes/magnetite nanoparticles with commercial carbonyl iron spherical microparticles in silicone oil. The rheological properties of the bidisperse system were studied under the presence of magnetic field at room and elevated temperature. An enhancement of the MR effect with the presence of the nanotubes was observed when compared with a standard MRF consisted only of magnetic microparticles. Due to the faster magnetic saturation of the nanotubes, this enhancement is exceptionally high at low magnetic fields. The stability of the system is studied under dynamic conditions where it is revealed that the nanotubes keep the standard particles well dispersed with the sedimentation improving by more than 50%.Internal Grant Agency of Tomas Bata University in Zlín, (IGA/CPS/2022/004, RP/CPS/2022/003); National Technical Library in Prague; Tomas Bata University in Zlin, TBU; Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMT, MŠMT; en:MEYS, (RP/CPS/2022/007); Univerzita Tomáše Bati ve ZlíněNational Technical Library in Prague; Internal Grant Agency of Tomas Bata University in Zlin [IGA/CPS/2022/004]; project DKRVO [RP/CPS/2022/007, RP/CPS/2022/003]; Ministry of Education, Youth and Sports of the Czech Republi

Pressure-sensitive conducting and antibacterial materials obtained by in situ dispersion coating of macroporous melamine sponges with polypyrrole

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, 21-09830

Polypyrrole nanotubes and their carbonized analogs: Synthesis, characterization, gas sensing properties

Polypyrrole (PPy) in globular form and as nanotubes were prepared by the oxidation of pyrrole with iron(III) chloride in the absence and presence of methyl orange, respectively. They were subsequently converted to nitrogen-containing carbons at 650 °C in an inert atmosphere. The course of carbonization was followed by thermogravimetric analysis and the accompanying changes in molecular structure by Fourier Transform Infrared and Raman spectroscopies. Both the original and carbonized materials have been tested in sensing of polar and non-polar organic vapors. The resistivity of sensing element using globular PPy was too high and only nanotubular PPy could be used. The sensitivity of the PPy nanotubes to ethanol vapors was nearly on the same level as that of their carbonized analogs (i.e., ~18% and 24%, respectively). Surprisingly, there was a high sensitivity of PPy nanotubes to the n-heptane vapors (~110%), while that of their carbonized analog remained at ~20%. The recovery process was significantly faster for carbonized PPy nanotubes (in order of seconds) compared with 10 s of seconds for original nanotubes, respectively, due to higher specific surface area after carbonization. © 2016 by the authors; licensee MDPI, Basel, Switzerland