Distribution Of Polyaniline Research Articles

Enhancing electrochemical performance of graphene oxide/polyaniline composite through plasma-assisted chemical cross-linking and surface modification

The composite of graphene oxide (GO) and polyaniline (PANI) is a promising electrode material for supercapacitors. A high loading of PANI can provide large specific capacitance, but it is a pervasive challenge to reconcile long-term cycling stability and high-rate discharge. Herein, we focus on a GO/PANI composite with low PANI content (∼25 wt%), developing a stable network of GO with an even distribution of PANI. Moreover, significantly enhanced electrochemical performance is achieved by utilizing plasma technology. The specific capacitance increases by 99 % to 433 F g−1 at 1.5 A g−1 after Argon (Ar) plasma treatment. Even at 15 A g−1, a capacitance retention rate of 91 % is obtained. After 15,000 cycles, the capacitance retention rate is 93 %, surpassing most previously reported GO/PANI composite electrodes. The further assembled all-solid-state supercapacitors can deliver a high energy density of 13.6 Wh kg−1 and exceptional cycling stability. According to results of characterization, it is demonstrated that Ar plasma imparts GO/PANI better surface morphology and achieves etching, reduction of GO, and cross-linking of GO and PANI, thereby activating the electrochemical activities of GO and PANI while ensuring stability. In this regard, the synergistic effects of cross-linking, reduction, and etching, and the mechanism are theoretically illustrated by dynamic differential equations. This work presents plasma processing unique charm for designing graphene-based materials via a customized strategy, exploiting an effectual approach to drive the applications of graphene-based materials in energy storage.

Evolution of electrical conductivity in semi‐interpenetrating polymer network of shape memory polyvinyl chloride and polyaniline

AbstractElectrically conductive semi‐interpenetrating polymer network (IPN) from shape memory polyvinyl chloride (PVC) and polyaniline (PANI) is realized. The mechanical properties and shape memory performance of semi‐IPN are slightly different from the original PVC. The distribution of PANI within PVC is found to be non‐uniform in the thickness direction. The electrical conductivity of the as‐fabricated sample at room temperature is around 4.5 × 10−2 S/cm. However, after heating, thermal strain results in significant drop in electrical conductivity. Programming remarkably reduces the electrical conductivity as well. A higher programming temperature and higher programming strain result in more reduction. Subsequent heating for shape recovery causes further reduction in electrical conductivity, despite nearly full shape recovery is achieved. Doping (dedoping and redoping) is confirmed not the major player, but microgaps/fracture in PANI chains during stretching in programming and heating for shape recovery.

Electrochemical Properties of the Graphite Electrode after Electrochemical Exfoliation and its Application as a Substrate for Hydrogen Evolution Reaction

AbstractElectrochemical exfoliation is an environmentally friendly method to obtained high quality graphene, while the graphite after exfoliation could also behave as a graphene modified graphite electrode. In this study, a graphene layer/graphite plate (GL/GP) electrode obtained by electrochemical exfoliation provided a special surface with enhanced hydrophilicity, improved electron transfer rate, and more electrochemical active sites. The surface characteristics of GL/GP electrodes were visually investigated with the formation and distribution of polyaniline (PANI). When the GL/GP electrode was used as a supporter to fabricate a Pt modified GL/GP electrode (Pt‐GL/GP electrode), it favored the HER activity of modified Pt. The surface density of Pt loading on the Pt‐GL/GP electrode was lower than commercial Pt/C (wt. 20%) by one order of magnitude. In addition, the enhanced hydrophilicity of the GL/GP electrode was beneficial for hydrogen bubbles escaping from its surface. GL/GP electrodes could potentially be an environmentally friendly and commercially attractive substrate to fabricating new electrocatalysts.

Preferential distribution of polyaniline in different phases of acrylate triblock copolymer

Preferential distribution of polyaniline in different phases of acrylate triblock copolymer

Catalytic-assisted synthesis, characterization and low frequency AC conduction of nanostructured conducting polyaniline

Polymerizations of aniline at the reaction temperatures of 25 and 50 °C have been performed in the presence of iron catalyst. The prepared conducting polyaniline at different reaction periods was investigated for physicochemical and electrical properties, through X-ray diffraction (XRD), scanning electron microscopy (SEM), UV–Visible spectroscopy (UV–Vis), Fourier transform infrared spectroscopy (FTIR) and frequency-dependent electrical conductivity measurements, respectively. XRD studies established the improved nanostructured crystalline nature for the polymer prepared at 50 °C. Size of the particles ranging from 10 to 20 nm was calculated for the prepared polyaniline. SEM analysis shows the cauliflower-like morphology for optimized reaction temperature. The study further establishes the attainment of uniform distribution of polyaniline at the reaction temperature of 50 °C. The charge transitions between benzenoid (B-band) and quinonoid (Q-band) bands were witnessed by UV–Vis spectrum analysis. The band gap analysis revealed the narrow band gap direct transition semiconducting nature of the conducting polymer. Quinonoid and phenylene rings were identified through vibrational bands between 1570 and 827 cm−1 via FTIR spectroscopy analysis. The AC conductivity of the sample synthesized at 50 °C showed 1.50 × 10−1 S cm−1. Enhancement in conductivity with increasing temperature represented the improved crystalline nature of the polyaniline prepared at 50 °C.

Preparation of MF-4SC composite membranes with the anisotropic distribution of polyaniline and ion-transport asymmetry

A method of preparing MF-4SK membranes with the anisotropic distribution of aniline over the thickness is developed. The processes of aniline polymerization in the matrix of the MF-4SC sulfocationite membrane are investigated via electronic-absorption and IR spectroscopy. The processes of ion transport in the obtained composite membranes are studied via impedance spectroscopy, voltammetry, and potentiometry.

Preparation of conducting nylon‐6 electrospun fiber webs by the in situ polymerization of polyaniline

AbstractFor the preparation of conducting polyaniline (PANI)/nylon composites with high electrical conductivity as well as superior mechanical properties such as flexibility and lightness, PANI/nylon‐6 composite nanofiber webs were prepared via the electrospinning process with a nylon‐6/formic acid polymer solution, and then PANI on the surface of the nylon‐6 electrospun nanofiber webs was chemically polymerized. The electrical conductivity measurements showed that the conductivity of the PANI/nylon‐6 composite electrospun fiber webs was superior to that of PANI/nylon‐6 plain‐weave fabrics because of the high surface‐area/volume ratios. On the other hand, the volume conductivities of the PANI/nylon‐6 composite electrospun fiber webs increased from 0.5 to 1.5 S/cm as the diffusion time increased from 10 min to 4 h because of the even distribution of PANI in the electrospun fiber webs. However, the surface conductivities of the PANI/nylon‐6 composite electrospun fiber webs somewhat decreased from 0.22 to 0.14 S/cm as the diffusion time increased because of PANI contaminated with aniline monomers, aniline oligomers, and some alkyl chains, which served as electrical resistants. These results were confirmed with Fourier transform infrared, electron spectroscopy for chemical analysis, and morphology analysis. It was concluded that the diffusion time for the in situ polymerization of PANI in electrospun fiber webs was optimized at approximately 3 h. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 983–991, 2005

AC electrical conductivity of Cr-doped polyaniline/poly(vinyl alcohol) blends

Polyaniline (PANI) and their charge transfer complexes are engineering materials that continue to attract considerable attention from engineers due to their unique electrochemical behavior, environmental stability and high degree of processability. Extensive works on the preparation of electrically conductive PANI blends containing a polymeric matrix having desirable physical and good mechanical characteristics have pointed as a promising route to overcome the PANI intractabilities. This paper reports the electrical properties of the dichromated PANI/poly(vinyl alcohol) (PANI:Cr3+/PVA) blends. Doped polyaniline powder in the emeraldine base form was synthesized by the classical chemical oxidation of aniline with ammonium persulfate as the oxidant in the presence of chromium (Cr3+). The SEM (Phillips XL 30) was used to understand the changes occurring in the conductivity to a microstructure level. The distribution of PANI:Cr3+ (50% w/w) in the host polymer (PVA) show some tendency to occur in flocculated structures. The samples were cut into circular shapes to form films about 500 microns thick. Electrical contacts were made by sputtering gold over sample surfaces. We have carried out impedance spectroscopy measurements in the range of 20Hz to 1MHz. Measurements carried at 100K and 250K indicates that thermally activated carrier process between PANI:Cr3+ grains in the PANI:Cr3+/PVA blend sample are responsible for its high temperature conductivity.

Study of polyaniline and water-based polyurethane nanocomposite by TEM, AFM and SNOM

Polymer blends of polyaniline complexes and water-based polyurethane were studied in nanometer scale by TEM, AFM and SNOM. TEM photographs show the distribution of polyaniline complexes. The image of AFM and SNOM show the topography of the blends. The image of SNOM can also show the distribution of conductive emeraldine salt, emeraldine base and pernigraaniline forms. SNOM results show that the conductive polyaniline is distributed around the particles, and the polyaniline base from is distributed in the center of the particle. The results agree with AFM results using phase detector, which show the phase rich in polyurethane is in the center of the particle, and the phase rich in polyaniline salt is around the particle. Combination of TEM, AFM and SNOM provides a good way to study the distribution of conductive polyaniline in the blend.

Polyaniline/polypropylene film composites with high electric conductivity and good mechanical properties

AbstractPolyaniline/polypropylene composites were prepared by oxidative polymerization of aniline in biaxially stretched polypropylene microporous films with ammonium persulfate as the oxidant. A continuous permeation/diffusion polymerization process was used in order to incorporate more polyaniline in the composite. The influence of reaction time and temperature and the concentration of monomer and oxidant aqueous solutions on the electric conductivity of the composites was investigated. The composites may exhibit a loose particulate surface morphology and a compact surface with a ring‐shaped structure. The content and distribution of polyaniline in the composite and, hence, its electric conductivity and surface properties can be controlled over a wide range. Composites with the combination of high electric conductivity and good mechanical properties can be obtained under proper conditions. The composite films were flexible and strong enough and have electric conductivity as high as 5–6 S/cm. © 1995 John Wiley & Sons, Inc.