Polyaniline Emeraldine Research Articles

Conductive Fibre Prepared From Ultra-High Molecular Weight Polyaniline for Smart Fabric and Interactive Textile Applications

Panion™ fibre is prepared from a high molecular weight version of chlorine and defect free polyaniline (PANI). It is processed into textile fibre by continuous wet spinning techniques. The room temperature DC conductivity for unstretched and stretched (5x at 373 K) high molecular weight samples was 72 and 725 Ω −1 cm −1, respectively. Resistivity measurements of Panion™, from 4 to 350 K, indicate that the fibre manufacturing process and the polymer synthetic route both serve to minimize structural disorder in the solid-state. The transport resides on the metallic side of the metal-insulator (M-I) phase boundary for unstretched and stretched fibre samples prepared from high M w PANI emeraldine base. The monofilament fibre can be formed into yarns for weaving fabric, braided into 2- and 3- dimensional structures, or used to form knitted fabrics, all with tunable electronic functionality.

Preparation of inclusion complex between polyaniline and β‐cyclodextrin in aqueous solution

AbstractTwo routes have been developed inorder to prepare an inclusion complex of polyaniline (PANI) and β‐cyclodextrin (βCyD). The first route was to in situ polymerize N‐phenyl‐1,4‐phenylenediamine (PPD) which was encapsulated in βCyD in advance. The formation of an inclusion complex was confirmed by UV‐vis, circular dichroism (CD), and NMR spectra. It was found that the synthesized complex was readily dissolved in a range of solvents due to the solubility of βCyD. In these solvents, PANI was well encapsulated by βCyD with some conformation change in the chain of PANI, which was proved by the CD spectra of PANI. The second route involved preparing the inclusion complex by post‐encapsulation of PANI emeraldine base (EB) into βCyD in aqueous solution at room temperature. The encapsulation of EB into βCyD was confirmed by FT‐IR and UV‐vis spectra. The band shift in UV‐vis spectra indicated that the inclusion complexation was a gradual process, and the change in the chain conformation of PANI was also observed after it was encapsulated into βCyD. Copyright © 2003 John Wiley & Sons, Ltd.

Nonlinear electrical properties of polyaniline: role of conjugation length

Undoped polyaniline (emeraldine base) exhibits nonlinear effects at high electric field. Conductivity measurements, as a function of a) temperature and b) aging induced disorder, are presented. Current-voltage curves are modeled in a space charge limited current scheme with a field dependent mobility and a non vanishing free carrier density. All the variations of the modeling parameters (cases a and b) are accounted for by models in which transport occurs by hopping between conjugated segments of finite length. For the first time, the relationship between the conjugation length distribution and the mobility behavior is evidenced in conjugated systems.

Structure–electrical property study of anisotropic polyaniline films

AbstractThe relationships of the structure and electrical properties of anisotropic HCl‐doped polyaniline (PANI) films cast from N,N′‐dimethylpropylene urea (DMPU) solutions and stretched to different draw ratios were studied. The anisotropic structure of the stretched PANI films was examined by X‐ray diffraction, near‐infrared wave‐guide coupling, and polarized infrared measurements. The PANI emeraldine base (EB) films cast from DMPU solutions had a single‐phase noncrystalline structure, and stretching of the films did not cause crystallization to occur. The transition moment angles of two weakly absorbing infrared bands were determined, and the Hermans' orientation functions for the PANI EB films were calculated. The PANI films were then doped with HCl, and the electrical properties were determined by impedance spectroscopy. With a specially designed test fixture, the in‐plane and through‐plane impedance was obtained. The conductivity along the stretch direction increased with orientation. The in‐plane conductivity was significantly higher than the through‐plane conductivity. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 823–841, 2003

Composite doped emeraldine–polyethylene oxide-bonded lithium-ion nano-tin anodes with electronic–ionic mixed conduction

Mixed-conducting lithium-ion doped emeraldine polyaniline (PAni)–polyethylene oxide (PEO) blends have been developed to achieve an optimal electronic–ionic conductivity balance in nano-tin composite anodes. Electrochemical evaluation was performed on the anodes with differing electrode preparation procedures, doping methods and PEO contents. Results indicate that both good electronic and ionic conductivity in the binder are required for rapid lithium insertion/extraction and low polarization. This doped PAni–PEO polymer blend is an attractive binder for high capacity composite anodes with low polarization.

Electrochemical stability of polyaniline

The kinetics of the electrochemical degradation of polyaniline (PANI) films has been investigated in 0.5 M sulfuric acid solution at different electrode potentials ranging from 0.3 to 1.0 V vs. Ag/AgCl. Two kinds of PANI films were used, one doped with poly(styrene sulfonate) (PSS), and the other—with indigotetrasulfonate (ITS). Within a range of relatively low electrode potential (0.3–0.6 V), the degradation was found to proceed at a first-order rate constant of 4×10 −5 to 5×10 −5 s −1, corresponding to degradation half-period of 4–5 h. A sharp increase in the degradation rate proceed by extending the electrode potential to higher values, with a maximum rate constant of ≈2.5×10 −3 s −1 for PANI-PSS, and ≈1.2×10 −3 s −1 for PANI-ITS films, obtained at a higher potential of 0.9–1.0 V. The data obtained are interpreted by different degradation rate for two distinct redox forms of PANI—emeraldine (slow degradation), and pernigraniline (fast degradation).

Novel Secondary Dopants for Camphorsulfonic Acid Doped Polyaniline Emeraldine Salts

The doping of emeraldine base with (±)-10-camphorsulfonic acid (HCSA) or (+)-HCSA in molten thymol (60°C) or liquid carvacrol (5-isopropyl-2-methylphenol) as solvents provides emeraldine polyaniline (PAn)�HCSA salts (1) with 'expanded coil'-type conformations for their polyaniline chains. Conversion of both racemic PAn�(±)-HCSA (1a) and optically active PAn�(+)-HCSA (1b) films from a 'compact coil' into a partial 'expanded coil' conformation is also facilitated by exposure of the films to either thymol or carvacrol vapours. These conformational changes are supported by modifications to their ultraviolet-visible-near-infrared and circular dichroism spectra and by the marked increase in the electrical conductivity of the films. In the case of carvacrol vapour, treated films of (1a) and (1b) exhibited conductivities of ≥ 130 S/cm, similar to conductivities previously generated by m-cresol. In view of the much lower toxicity of carvacrol compared with m-cresol, it would appear to have considerable promise as an effective 'secondary dopant' for emeraldine salts leading to materials with enhanced electrical conductivity.

Preparation and degradation of highly conducting polyaniline doped with picric acid

Preparation and characterization of highly conducting polyaniline (PANI) doped with picric acid (PA) was proved with the help of various techniques. Elemental analysis, FTIR and XPS spectroscopic measurements confirm that the PA operates as a protonating agent to induce the internal conversion of PANI emeraldine base (PANI-EB) to the PANI emeraldine salt (PANI-ES) with the doping level 50%. Molecular modeling calculations (MM+) showed that the optimum geometric structure of 2PA:1PANI (energy 38.231388 kcal/mol, and gradient 0.065246). The observed higher conductivity ( σ ∼150 S/cm) of PA-doped PANI film prepared at molar ratio 2PA:1PANI (EB) is attributed to the change in the molecular conformation from coil to expanded coil-like. PA-doped PANI is thermally unstable above ∼135 °C and the thermal processing with other insulating matrix is not profitable but the solution casting is highly promising. PA-doped PANI with acrylonitrile-butadiene-styrene copolymer has been fabricated and showed the threshold value ∼4 wt.% of a conducting material. The reduced PA-doped PANI reveals an ability to store electrical energy of about 110.43 Wh/kg in a condensed lightweight form. The immediate decoloration of the dark green ( λ max ∼815 nm ) PANI after addition of 5.5 μg/ml KMnO 4 in strong acid medium (pH 1.0, H 2SO 4, 40% DMF) is due to the highest oxidized form of PANI. Increasing the absorbance with increases in the KMnO 4 concentration (μg/ml) at ∼385 nm has been successfully applied to the determination of trace amount (0.55 μg/ml) of Mn(VII) in a synthetic solution.

Conducting blends of polyaniline and aromatic main-chain liquid crystalline polymer, XYDAR SRT-900

Conductive polyaniline/fully aromatic main-chain liquid crystalline polymer, XYDAR SRT-900 films have been prepared by solution blend of polyaniline (PANI) emeraldine salt and the liquid crystalline polymer. The polymer blends exhibit excellent mechanical properties and good conductivity at moderate PANI concentration. Moreover, polymer films have optical transparent property at concentration lower than 10 wt.%. The morphology of the blends has been investigated using scanning electronic microscopy and X-ray scattering.