Electrostrictive and Structural Properties of Poly(Vinylidene Fluoride-Hexafluoropropylene) Composite Nanofibers Filled with Polyaniline (Emeraldine Base)

Previous studies have reported that poly(vinylidene fluoride-hexafluoropropylene) (P(VDF-HFP)) copolymers can exhibit large electrostrictive strains depending on the filler. This work examines the electrostrictive and structural properties of P(VDF-HFP) nanofibers modified with conductive polymer polyaniline (PANI). The P(VDF-HFP)/PANI composite nanofibers were prepared by an electrospinning method with different PANI concentrations (0, 0.5, 1, 1.5, 3 and 5 wt.%). The average diameter, water contact angle and element were analyzed by SEM, WCA and EDX, respectively. The crystalline, phase structure and mechanical properties were investigated by XRD, FTIR and DMA, respectively. The dielectric properties and electrostrictive behavior were also studied. The results demonstrated that the composite nanofibers exhibited uniform fibers without any bead formation, and the WCA decreased with increasing amount of PANI. However, a high dielectric constant and electromechanical response were obtained. The electrostrictive coefficient, crystalline, phase structure, dielectric properties and interfacial charge distributions increased in relation to the PANI content. Moreover, this study indicates that P(VDF-HFP)/PANI composite nanofibers may represent a promising route for obtaining electrostrictive composite nanofibers for actuation applications, microelectromechanical systems and sensors based on electrostrictive phenomena.

Synthesis and Characterization of Bacterial Cellulose-Polyaniline Composite with Variation of Dopant Concentration

Polyaniline is a type of conductive polymer. Bacterial cellulose has high mechanical properties, so it can be made into polyaniline base composite materials. A stable form of polyaniline oxidation at room temperature is emeraldine base. The emeraldine base has a conductivity value of 10-6 S/cm. Dopants can change the shape of emeraldine base to emeraldine salt by protonation process. Emeraldine salt is a conductive form of polyaniline. The conductivity value of emeraldine salt is 0,03-0,07 S/cm. The addition of dopan in synthesis of polymer was carried out to determine its effect on the conductivity value. The disadvantage of polyaniline is that its mechanical properties are weak and easily brittle. Modifications are needed to improve the mechanical properties of polyaniline, one of which is the manufacture of composite. Bacterial celluloce has high mechanical properties so it can be made into polyaniline base composite materials. Synthesis of bacterial cellulose-polyaniline composites by in situ chemical polymerization methods. Syntehsis is started with BC membrane was dipped into aniline solution for about 2h with stirring at room temperature. The BC was immersed into ammonium peroxydisulfate solution for about 30m with stirring. The bacterial cellulose-polyaniline compositions obtained are black color which is characteristic of the emeraldine salt. The highest conductivity value of composite was obtained from the addition of 3,5M HCl dopant which was 4,70x10-4 S/cm. FTIR analysis of composite obtained peak of the characteristic polyanilin was conductive at 1565,92 cm-1 as C=C quinoid ring and 1442,95 cm-1 as C=C benzoid ring.

Polymer-metal complexes as emerging catalysts for electrochemical reduction of carbon dioxide

A class of metal-doped polyanilines (PANIs) was synthesized and investigated as electrocatalysts for the carbon dioxide reduction reaction (CO2RR). These materials show good affinity for the electrode substrate and allow to obtain stable binder-free electrodes, avoiding the utilization of expensive ionomer and additives. The emeraldine-base polyaniline (EB-PANI), in absence of metal dopant, shows negligible electrocatalytic activity and selectivity toward the CO2RR. Such behavior significantly improves once EB-PANI is doped with an appropriate cationic metal (Mn, Cu or Sn). In particular, the Sn-PANI outperforms other metal-doped samples, showing a good turnover frequency of 72.2 h−1 for the CO2RR at − 0.99 V vs the reversible hydrogen electrode and thus satisfactory activity of metal single atoms. Moreover, the Sn-PANI also displays impressive stability with a 100% retention of the CO2RR selectivity and an enhanced current density of 4.0 mA cm−2 in a 10-h test. PANI, a relatively low-cost substrate, demonstrates to be easily complexed with different metal cations and thus shows high tailorability. Complexing metal with conductive polymer represents an emerging strategy to realize active and stable metal single-atom catalysts, allowing efficient utilization of metals, especially the raw and precious ones. Graphic abstract

The Effect of pH and Monomer Concentration on Polyaniline Thin Films Grown Using Electrodeposition

Polyaniline (PANI) thin films were successfully prepared from an aqueous electrolyte bath containing aniline and sulphuric acid (H2SO4) using electrodeposition method. The present study demonstrates that the properties of PANI thin film depends on the variation of pH and aniline concentration in prepared precursor. The optical and structural of PANI thin films were characterized using UV-Visible spectrometer (UV-Vis), X-ray diffraction spectrometer (XRD), Fourier Transform Infra-Red spectrometer (FTIR) and Raman spectrometer. PANI layer grown at pH 2.00 displayed green colour layer which denoted as emeraldine base (half oxidized state of PANI) while at pH 3.80 the colour of PANI layer was yellow representing the leucoemeraldine base (fully reduced state of PANI). Result obtained from FTIR confirmed the footprint of PANI and Raman spectrometer confirmed the half oxidized emeraldine base of PANI. Optical analysis using UV-Vis demonstrated the smallest energy band gap, Eg of PANI is 3.54 eV for sample with 0.50 M aniline concentration and pH 2.00. The trend shows that the bandgap of PANI is increased as the pH increased from 2.00 to 3.80. XRD result showed that all the deposited PANI layers were amorphous. Full characterization of this material is providing some information on PANI behavior due to pH and concentration in the prepared precursor.

Preparation of PANI Modified ZnO Composites via Different Methods: Structural, Morphological and Photocatalytic Properties

Polyaniline modified zinc oxide (PANI-ZnO) photocatalyst composites were synthesized by focusing on dissolution disadvantage of ZnO. In-situ chemical oxidation polymerization method was performed under neutral conditions (PANI-ES) whereas in hybridization method physical blending was applied using emeraldine base of polyaniline (PANI-EB). PANI-ZnO composites were prepared in various ratios of aniline (ANI) to ZnO as 1%, 3%, 6% and 9%. The alterations on the structural and morphological properties of PANI-ZnO composites were compared by Fourier Transform Infrared (FT-IR), Raman Spectroscopy, X-Ray Diffraction (XRD) and Scanning Electron Microscopy-Energy Dispersive X-ray Analysis Unit (SEM-EDAX) techniques. FT-IR and Raman spectroscopy confirmed the presence of PANI in all composites. SEM images revealed the morphological differences of PANI-ZnO composites based on PANI presence and preparation methods. Photocatalytic performances of PANI-ZnO specimens were investigated by following the degradation of methylene blue (MB) in aqueous medium under UVA irradiation. The effects of catalyst dose and initial dye concentration were also studied. MB degradation was followed by both decolorization extents and removal of aromatic fractions. PANI-ZnO composites expressed enhanced photocatalytic performance (~95% for both methods) as compared to sole ZnO (~87%). The hybridization method was found to be more efficient than the in-situ chemical oxidation polymerization method emphasizing the significance of the neutral medium.

Comparison of Optical Characteristics of GO-PANI Composite in Solution and Thin Film

Reduced Graphene Oxide (rGO) is a promising material as an active electrodes material for supercapacitors. However, in its application, rGO can only store electrostatic charges so there is no electron transfer between surface of the electrode and electrolyte. In order to improve electrode performance, rGO can be composite with conductive polymers such Polyaniline (PANi). It was reported that rGO-PANi composite can increase conductivity of rGO and support pseudocapacitance of the material so the electron transfer can be carried out actively through reduction-oxidation (redox) reactions. In this work we study preparation of rGO-PANI composite using UV oven spraying method. Thin layers of rGO-PANi composite were prepared from mixture of 0.5 mg/ml GO dispersion (Graphenia) and PANi-HCl solution with a ratio of 1:1. PANi-HCl solution were prepared from PANi Emeraldine Base and 1 M HCl with mole ratio of 1:2. The samples were spray coated onto quartz substrates under photo-irradiation using UV Oven Spraying apparatus. In order to obtain a proper thickness for electrode application we varied deposition repetition. The optical characteristics of the rGO-PANi composites were measured using UV-Vis Spectroscopy. The results were compared with the optical spectra of rGO and PANi, respectively. Acknowledgement This work was funded by Hibah Kemenristek Dikti Indonesia, contract no: 1827/UN6.3.1/LT/2020 date 12 May 2020.

Effects of Doping on Zeta Potential and pH of Polyaniline Colloidal Suspension

Polyaniline (PANI) has successfully been prepared by chemical oxidation polymerization of aniline monomer. The prepared polymer was confirmed by XRD. The conducting form of PANI known as emeraldine salt (ES) through different concentrations of formic acid; 0.4 mmol/ L, 2mmol/ L, 6 mmol/ L, 8 mmol/ L, 10 mmol/ L, and 12 mmol/L is prepared from its insulating emeraldine base (EB) by levels of doping. The objective is to establish a correlation between the levels of doping, the zeta potential of the suspension. Positive zeta potential values (24.75, 27, 33.25, 36.75, 40.50, and 42) mV were obtained for the various PANI suspension. This showed the acquisition of positive charges by the PANI after doping. The observation was made that zeta potential values increases as formic acid concentration increased. This was correlated using UV/VIS spectra and electrophoretic coating with the polyaniline suspensions.

Passivation of Carbon Steel Using Intelligent Epoxy Paint

This paper presents the production of an epoxy paint associated with a determined concentration of PAni emeraldine base binder, in order to increase dispersion of PAni polymer chains in the paint allow physical contact between PAni chains, the electrolytic medium, and the metal of interest. The coating called Intelligent Epoxy Paint (IEP) seeks to potentialize the electrolytic capacity of PAni to produce passivation, differentiated research which uses PAni in oxidized and conductive form as paint pigment that needs high PAni concentrations. The physicochemical characterization and morphological presented results that indicate the preservation of the desirable properties of PAni in order to make the passivation process possible. The electrochemical tests showed the passivation and/or maintenance of the passivation of the metal of interest, without the need to apply an external current.

Polyaniline Based Pt-Electrocatalyst for a Proton Exchanged Membrane Fuel Cell

Calcination reduction reaction is used to prepare Pt/EB (emeraldine base)-XC72 (Vulcan carbon black) composites as the cathode material of a proton exchange membrane fuel cell (PEMFC). The EB-XC72 core-shell composite obtained from directly polymerizing aniline on XC72 particles is able to chelate and capture the Pt-ions before calcination. X-ray diffraction spectra demonstrate Pt particles are successfully obtained on the EB-XC72 when the calcined temperature is higher than 600 °C. Micrographs of TEM and SEM illustrate the affluent, Pt nanoparticles are uniformly distributed on EB-XC72 at 800 °C (Pt/EB-XC72/800). More Pt is deposited on Pt/EB-XC72 composite as temperatures are higher than 600 °C. The Pt/EB-XC72/800 catalyst demonstrates typical type of a cyclic voltammograms (C-V) curve of a Pt-catalyst with clear Pt–H oxidation and Pt–O reduction peaks. The highest number of transferred electrons during ORR approaches 3.88 for Pt/EB-XC72/800. The maximum power density of the single cell based on Pt/EB-XC72/800 reaches 550 mW cm−2.

Tunable electrochemical activity of polyaniline salt by doping anion exchange

The exchange of mobile anion of chemically synthesized polyaniline with counter anions of electrolyte solutions is studied by using cyclic voltammetry (CV). The synthesized polyaniline (PANI) doped with sulfuric acid (H2SO4) and dodecyl benzenesulfonic acid (DBSA) is soluble in a wide range of organic solvents which makes it appealing for further processability. The exchange of dopant anions (of H2SO4 and DBSA) with a variety of counter anion has been inspected by electrochemical cycling in aqueous sodium sulfate (Na2SO4), sodium perchlorate (NaClO4), and sodium hydroxide (NaOH) solution. The CV measurements have revealed that PANI remains redox active at higher scan rate and there is exchange of dopant anion with SO42- and ClO41- of electrolytes. In NaOH solution, the emeraldine salt form of PANI is transformed into emeraldine base due to deintercalation of the anion form polymer matrix. The results indicate a significant change in electrochemical conductance and behavior of PANI in each electrolyte. Furthermore, the polymer film displayed a high specific capacitance value of 588 F/g in 1.0 M NaClO4 solution in the optimized potential window of -0.2 V to 0.9 V at 20 mV/s.