The influence of pyrrole concentration on the dielectric properties of polypyrrole composite material

A flexible polypyrrole composite material with good dielectric properties was produced, using pyrrole as the monomer, by in situ polymerization on cotton fabric. Firstly, the influence of pyrrole concentration on the dielectric constant of the real part and imaginary part, loss tangent, and surface resistance of composite material are discussed. Secondly, exterior morphology of the polymerized cotton surface was analyzed. The results show that the concentration of pyrrole has great influence on the dielectric constant of the real part and imaginary part, loss tangent, and surface resistance of the composite material. The produced polypyrrole composite displays good dielectric properties and conductivity performance.     

Electro-conductive Palmyra Fibers By In Situ Polymerization of Pyrrole

Palmyra (Borassus flabellifer L.) is one of the natural fruit fibers that are available in plenty. This fiber has many advantages, such as biodegradability, renewability, low density, and low cost, which offer greater opportunities to develop new applications. Imparting electrical conductivity to this fiber may open up avenues for various novel applications. In the present study, Palmyra fibers are made electro-conductive by in situ chemical polymerization of pyrrole with FeCl₃ oxidant and PTSA dopant. Prepared electro-conductive fibers show average electrical resistivity 2.96 kΩ cm^?1. A positive correlation is found between fiber-length and electrical resistance, whereas a negative correlation is found in between fiber-diameter and electrical resistance. FTIR study is conducted to understand the chemical interaction between lingo-cellulose and polypyrrole. Tensile properties and thermal degradation behavior of the prepared electro-conductive fibers are evaluated, and significant deterioration of both tensile properties and thermal stability is observed. Due to this reason, these electro-conductive fibers are unsuitable for mechanical processing and high-tech applications. But the response of these fibers in different pH solution is investigated, and their possible application as a pH sensor has been explored.     

Electrochemical properties of free‐standing polypyrrole/graphene oxide/zinc oxide flexible supercapacitor

We report the preparation of a polypyrrole/graphene oxide/zinc oxide nanocomposite on a nickel foam using a simple and rapid single‐step electrochemical deposition process under ambient conditions. A free‐standing flexible supercapacitor was fabricated by sandwiching a polyvinyl alcohol hydrogel polymer electrolyte between two layers of the as‐prepared ternary nanocomposite electrodes. The electrochemical properties of the free‐standing supercapacitor were analyzed using a two‐electrode system. The supercapacitor achieved a specific capacitance of 123.8 F/g at 1 A/g, which was greater than its single (39.1 F/g) and binary (81.3 F/g) counterparts. This suggests that ZnO acts as a spacer and support that hinders the ternary structure from collapsing and subsequently enhances the diffusion of ions within the matrix. The flexible supercapacitor exhibited remarkable electrochemical stability when subjected to bending at various angles. The cycling stability of the ternary nanocomposite showed a favorable specific capacitance retention of more than 90% after 1000 cycles for mild alkaline electrolytes compared with strong alkali electrolytes. The presence of glycerin in the polymer electrolyte enabled the supercapacitor to perform better under the vigorous cycling condition. The potential of the as‐fabricated supercapacitor for real applications was manifested by its ability to light up a light‐emitting diode after being charged. Copyright © 2014 John Wiley & Sons, Ltd.     

Manufacturing of polypyrrole-FeOOH supercapacitors

The low capacitance of charge storage materials for negative electrodes of supercapacitors (SCap) is a bottleneck in the manufacturing of asymmetric SCap with high operation voltage and high power. Polypyrrole (PPR)-FeOOH-carbon nanotube (NT) electrodes with high electrochemically active material mass (AM) of 32 mg cm^?2 are manufactured for operation in a negative potential range. The manufacturing method involves the use of copolymer of styrenesulfonic and maleic acids (PSAMA) as a new poly-charged dopant for PPR and pyrocatechol violet (PCV) as a co-dispersant for NT and FeOOH. PPR-FeOOH-NT electrodes show enhanced properties in the negative potential range, compared to PPR-NT electrodes. A capacitance (C_S) of 3.8 F cm^?2 is obtained for PPR-FeOOH-NT electrodes with PPR:FeOOH mass ratio of 7:2. The electrodes offer advantages of low resistance and high ratio of AM to conductive support mass. The C_S of negative PPR-FeOOH-NT electrodes matches the C_S of positive MnO₂-NT electrodes of the same AM. Asymmetric SCap is fabricated, which shows high capacitance in a voltage range of 0–1.6 V and low resistance, high power, and energy, which make it important for industrial SCap applications.     

Conjugated Polymer Actuators and Devices: Progress and Opportunities

Conjugated polymers (CPs), as exemplified by polypyrrole, are intrinsically conducting polymers with potential for development as soft actuators or “artificial muscles” for numerous applications. Significant progress has been made in the understanding of these materials and the actuation mechanisms, aided by the development of physical and electrochemical models. Current research is focused on developing applications utilizing the advantages that CP actuators have (e.g., low driving potential and easy to miniaturize) over other actuating materials and on developing ways of overcoming their inherent limitations. CP actuators are available as films, filaments/yarns, and textiles, operating in liquids as well as in air, ready for use by engineers. Here, the milestones made in understanding these unique materials and their development as actuators are highlighted. The primary focus is on the recent progress, developments, applications, and future opportunities for improvement and exploitation of these materials, which possess a wealth of multifunctional properties.     

A water‐soluble self‐doped conducting polypyrrole‐based copolymer

A water‐soluble self‐doped conducting polypyrrole‐based copolymer was synthesized via the grafting of pyrrole onto the p‐aminodiphenylamine moieties of a water‐soluble copolymer. The conductive copolymer exhibited a conductivity as large as 3.4 S/cm. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 86–89, 2001     

Two reduction processes of conducting polypyrrole tosylate film in aqueous solutions

The electrochemical properties of polypyrrole tosylate [PPy(TsO⁻)] in aqueous solutions were investigated by cyclic voltammetry and ac impedance measurements. The cyclic voltammograms (CVs) of PPy(TsO⁻) show two reduction processes. Two doping sites of the counteranions in PPy(TsO⁻), site A with the counteranions located between the PPy layers and site B with the counteranions located in the PPy layers, were proposed based on the results of the electrochemical studies, and the partial counteranion exchange occurred when PPy(TsO⁻) was dipped in a 1 mol/L HNO₃ aqueous solution. The reduction of site A is accompanied by the dedoping of counteranions and the reduction of site B is carried out with the insertion of solution cations. The electrochemical kinetics of the redox processes of site A was analyzed based on the ac impedance results. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 350–355, 2001     

Formation of transparent conducting films based on core‐shell latices: Influence of the polypyrrole shell thickness

Transparent conducting latex films have been prepared from core‐shell latices. The latex particles have a poly(butyl methacrylate) (PBMA) core of about 700 nm and a very thin polypyrrole (PPy) shell. We have studied the film formation of latices with 1, 2, and 4 wt % PPy and compared this with the film formation of the pure PBMA latex. The film formation process was studied by transparency measurements, atomic force microscopy surface flattening, and transmission electron microscopy on ultrathin sections of films after various annealing times at 120°C. It is demonstrated that highly transparent (>90%) and antistatic films can be produced using these latices. The presence of a polypyrrole shell around the PBMA latex particle seriously hinders the deformation of the particles. The amount of polypyrrole, and thus the shell thickness, is the determining factor for the speed of film formation. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 900–909, 2001     

Dynamic mechanical properties of the chemical oxidation on UHMWPE fibers for improved adhesion to epoxy resin matrix

The improved adhesion of an ultrahigh molecular weight polyethylene (UHMWPE) fiber to an epoxy from applying polypyrrole (PPy) was investigated using chemical oxidation polymerization. The interfacial shear strength of the PPy-treated fiber/epoxy was enhanced by 280%. Such an improvement was verified in the previous research using a pull-out test. Dynamic mechanical analysis (DMA) and a morphological examination were performed to evaluate the characteristics of the molecular motions of the UHMWPE fiber/PPy/epoxy composites. Two composite materials, a UHMWPE fiber/PPy and a UHMWPE fiber/PPy/epoxy, were tested by DMA. The results show that both the α_c transitions of the PPy-treated fibers and its composites shift toward higher temperature. In the SEM photos of the UHMWPE fiber/PPy, a very clear roughening effect on the surface of PPy-treated UHMWPE fiber was also observed, which contributes much to the modification of the interface to the epoxy. The results show that an adhesion improvement mechanism for the PPy-treaded UHMWPE fiber is due to the surface roughening effect and the intermolecular interaction. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 1387–1395, 1998     

Effects of applied potentials on permselectivity of ions through polypyrrole/porous-polypropylene composite membrane

A composite membrane was prepared by the combination of polypyrrole with a porous-polypropylene film, and its permselectivity was investigated. The permeability and selectivity of various sodium salts through the membrane were changed with an applied potential. The permeation of anions at the positive potentials was due to the migration through the positive sites of the polypyrrole layer, as well as the diffusion from the difference of concentration and potential. The contribution of the migration effect to the anion permeation was very large. The main factors dominating the permeation character of different anion species were the size and valence of the anions. The composite membrane worked effectively as a functional separation membrane to control the ionic permeability by potential application. © 1998 John Wiley & Sons, Inc. J. Appl. Polym. Sci. 70: 647–653, 1998