Electrochemical Polymerization Of Polypyrrole Research Articles

Textile Actuators Comprising Reduced Graphene Oxide as the Current Collector

AbstractElectronic textiles (E‐textiles) are made using various materials including carbon nanotubes, graphene, and graphene oxide. Among the materials here, e‐textiles are fabricated with reduced graphene oxide (rGO) coating on commercial textiles. rGO‐based yarns are prepared for e‐textiles by a simple dip coating method with subsequent non‐toxic reduction. To enhance the conductivity, the rGO yarns are coated with poly(3,4‐ethylene dioxythiophene): poly(styrenesulfonic acid) (PEDOT) followed by electrochemical polymerization of polypyrrole (PPy) as the electromechanically active layer, resulting in textile actuators. The rGO‐based yarn actuators are characterized in terms of both isotonic displacement and isometric developed forces, as well as electron microscopy and resistance measurements. Furthermore, it is demonstrated that both viscose rotor spun (VR) and viscose multifilament (VM) yarns can be used for yarn actuators. The resulting VM‐based yarn actuators exhibit high strain (0.58%) in NaDBS electrolytes. These conducting yarns can also be integrated into textiles and fabrics of various forms to create smart e‐textiles and wearable devices.

The effect of electroactive length and intrinsic conductivity on the actuation behaviour of conducting polymer-based yarn actuators for textile muscles

Recently, electrically driven conducting polymer (CP) coated yarns have shown great promise to develop soft wearable applications because of their electrical and mechanical behaviour. However, designing a suitable yarn actuator for textile-based wearables with high strain is challenging. One reason for the low strain is the voltage drop along the yarn, which results in only a part of the yarn being active. To understand the voltage drop mechanism and overcome this issue intrinsically conductive yarns were used to create a highly conductive path along the full length of the yarn actuator. Ag plated knit-de-knit (Ag-KDK) structured polyamide yarns were used as the intrinsically conductive core material of the CP yarn actuators and compared with CP yarn actuators made of a non-conductive core knit-de-knit (KDK) yarn. The CP yarn actuators were fabricated by coating the core yarns with poly(3,4-ethylene dioxythiophene): poly(styrene sulfonic acid) followed by electrochemical polymerization of polypyrrole. Furthermore, to elucidate the effect of the capillarity of the electrolyte through the yarn actuator, two different approaches to electrochemical actuation were applied. All actuating performance of the materials were investigated and quantified in terms of both isotonic displacement and isometric developed forces. The resultant electroactive yarn exhibits high strain (0.64 %) in NaDBS electrolytes as compared to previous CP yarn actuator. The actuation and the electroactivity of the yarn were retained up to 100 cycles. The new highly conductive yarns will shed light on the development of next-generation textile-based exoskeleton suits, assistive devices, wearables, and haptics garments.

Electrochemical polymerization of polypyrrole on carbon cloth@ZIF67 using alizarin red S as redox dopant for flexible supercapacitors

Metal-organic frameworks (MOFs) are promising candidates for supercapacitors due to their intrinsic porous structure. However, their low conductivity limits their supercapacitive performances. Herein, carbon cloth/ZIF67/polypyrrole composites (CZPAs) are prepared by first in-situ growing ZIF67 on carbon cloth and then electrochemical polymerizing pyrrole on carbon cloth/ZIF67 utilizing alizarin red S (ARS) as redox dopant. The synergistic effects of ZIF67 and ARS including porous structure, doping effect and inducing limited/ordered growth of polyprrole are contributed to the improved electrochemical performances. The resulted composite doped by 35 mM ARS (CZPA-35) achieves the highest areal capacitance of 1198 mF cm−2 among the CZPAs. The asymmetric supercapacitor assembled by CZPA-35 and carbon cloth/active carbon as flexible electrodes demonstrates high areal capacitance (288 mF cm−2), high energy density (57.6 μWh cm−2) and power density (300.96 μW cm−2). Moreover, the flexible supercapacitor provides excellent cycle stability after 5000 cycles (87.1% capacitance retention) and flexibility (85% capacitance retention after bending angle of 180 °). This strategy can be extended to fabricate other kinds of flexible MOF/PPy composites for the potential application of flexible wearable and portable electronic products.

A novel fiber-shaped asymmetric supercapacitor prepared by twisting carbon fiber/carbon nanotube/MnO2 and carbon fiber/carbon nanotube/polypyrrole electrodes+

In the study, a novel fiber-shaped asymmetric supercapacitor with high specific capacitance has been successfully constructed by twisting two self-made composite electrodes. Prior to manufacturing these electrodes, carbon nanotube is first deposited on carbon fiber by electrophoretic deposition to obtain carbon fiber/carbon nanotube composites. Subsequently, the positive and negative composite electrodes are prepared by the electrochemical deposition of manganese dioxide and electrochemical polymerization of polypyrrole, respectively. As a result, the novel fiber-shaped asymmetric supercapacitor performs a wide potential window of 1.7 V and a high energy density of 22.8 μWh cm−1 at the current density of 0.5 A g−1. Meanwhile, it still maintains great capacitance retention of 91.6% and 86.1% from 500 bending repetitions and 5000 cycles, respectively, which is due to the excellent flexibility and long cycle life. It is significant that the promising performance of the novel fiber-shaped asymmetric supercapacitor is of greatly potential for portable and wearable electronics in the future.

Polypyrrole electrode with a greater electroactive surface electrochemically polymerized in plasmon-activated water

ABSTRACT Conventionally, electrochemical polymerization of polypyrrole (PPy) was generally performed in deionized (DI) water-based electrolyte. In this work, an innovative and facile strategy to substantially enhance the electroactive surface areas of electrochemically polymerized PPy is proposed by using plasmon-activated water (PAW)-based electrolyte. Compared to the DI water-based system, the prepared PPy with higher electron transfer rate and more-reversible redox performance was observed by using PAW-based system. In addition, a greater electroactive surface area of three-dimensional PPy was obtained with PAW-based electrolyte. These distinct properties of PPy electrodes prepared with PAW were responsible for their better performances in supercapacitors (with ca. 25.2% increased capacitance) and sensors (with ca. 50.0% increased sensitivity), compared to those prepared with DI water. These encouraging findings show the potential of PPy prepared with newly developed PAW for application to PPy-related devices to further enhance various performances.

Electrochemical behavior of polypyrrole-coated AZ31 alloy modified by fluoride anions

The electrochemical polymerization of polypyrrole (Ppy) films on AZ31Mg alloys was carried out using cyclic voltammetery in 0.5 M sodium salicylate solution containing 0.25 M pyrrole and different concentration of sodium fluoride (NaF). Corrosion performance of the Ppy film was assessed by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization tests in 3.5 % NaCl solution. It was observed that Ppy coatings doped in the presence of 100 ppm NaF provide the best corrosion protection for magnesium and the corrosion potential shifted about 290 mV toward nobler potentials and decrease the corrosion current density about one order of magnitude. The surface analysis of the coatings showed that the addition of F− dopant anions led to an improvement in the smoothness, thickness, and adhesion quality of the synthesized Ppy coating on the Mg surface. The scanning electron microscopy (SEM) studies of the fluoride-doped Ppy films revealed that the synthesized coating has a closely packed globular structure which was composed of nanoparticles of Ppy.

Fast-moving bimorph actuator based on electrochemically treated millimeter-long carbon nanotube electrodes and ionic liquid gel

The development is described of an electromechanical bimorph actuator composed of ionic liquid gel sandwiched by electrochemically treated millimeter-long single-walled carbon nanotubes (SG-SWNT). Electrochemical doping of the SG-SWNT and electrochemical polymerization of polypyrrole on the surface of the SG-SWNT improved the performance of a previously reported actuator using non-treated SG-SWNTs. The conductivity of the SG-SWNT sheets treated at the anodic potential (doped) was found to be three times larger than that of the original film. The generated strain of the actuator prepared from the doped SG-SWNT sheets was increased compared to that prepared from non-doped sample. Moreover, the generated strain of the actuator from the doped SG-SWNT sheets swelled with ionic liquid (IL) was increased to twice that without ILs. The electropolymerization of pyrrole on the surface of the SG-SWNT sheet was carried out. The conductivity of the SG-SWNT was seven times larger after the electropolymerization. The generated strain of the SG-SWNT actuator prepared from the SG-SWNT sheets with electropolymerization was twice as large as that without the electropolymerization at low frequency. At higher frequency, both actuators provide almost the same performance. Both actuators exhibit mechanical resonance at about 100 Hz.

Conducting polymer- hydrogel blends for electrochemically controlled drug release devices

Blends formed by electrochemical polymerization of polypyrrole (PPy) into polyacrylamide (PAAm) hydrogels were used as devices for controlled drug release. The influence of several parameters in the synthesis, such as type of hydrogel matrix and polymerization conditions was studied by using a fractional factorial design. The final goal was to obtain an adequate device for use in controlled release tests, based on electrochemical potential control. For controlled release tests, Safranin was used as model drug and release curves (amount of drug vs. time) have shown that these blends are promising materials for this use. The optimized blends obtained were characterized by cyclic voltammetry and Raman spectroscopy.

Catalytic electroxidation pathway for electropolymerization of polypyrrole in solutions containing gold nanoparticles

We report here the first electrochemical polymerization of polypyrrole (PPy) on Au substrates in aqueous solutions containing additives of prepared Au nanoparticles with a diameter of ca. 2 nm. Encouragingly, the synthesized PPy films demonstrate novel characteristics due to the effects of Au nanoparticles, which provide a catalytic electroxidation pathway. The prepared PPy shows a stereomorphology, which is distinguishable from the typically granular raspberry morphology of pure PPy, and a rougher surface. The conductivity of PPy is significantly increased (∼10 times), which also reflects on the extremely high oxidation level of 0.36 revealed from the analysis of X-ray photoelectron spectroscopy (XPS). The mechanism of the nucleation and growth, and the X-ray diffraction (XRD) pattern were investigated to explain the specific characteristics of PPy films.

Catalytic electroxidation pathway for the polymerization of polypyrrole in the presence of ultrafine silver nanoparticles

In this work, we report the first electrochemical polymerization of polypyrrole (PPy) on Au substrates in aqueous solutions containing additives of prepared Ag nanoparticles with a diameter less than 2 nm. Due to the effect of Ag nanoparticles, which can provide a catalytic electroxidation pathway for the polymerization of PPy, the synthesized PPy film demonstrates some novel characteristics. It shows a finer and granular raspberry morphology with nano-scaled particles, and a rougher surface. The conductivity of PPy is significantly increased (∼8 times), which also reflects on the extremely high oxidation level of 0.35 revealed from the analysis of X-ray photoelectron spectroscopy (XPS). The mechanism of the nucleation and growth was investigated to explain the specific characteristics of PPy films.

Effect of TiO 2 nanoparticles on the electropolymerization of polypyrrole

We report here the first electrochemical polymerization of polypyrrole (PPy) on gold substrates in aqueous solutions containing additives of 1 mM rutile TiO 2 nanoparticles under the irradiation of UV light. As a result, PPy/TiO 2 composites were prepared with an increased conductivity of 135 S cm −1, raising one order as compared with that of pure PPy. Furthermore, the thermal stability of the PPy-based composites was improved, as shown from thermogravimetric analysis (TGA). The effects of TiO 2 on the PPy electropolymerization under UV irradiation were examined by its nucleation and growth mechanism and the onset potential of polymerization. The results indicate that the nucleation and growth are instantaneous two-dimensional and three-dimensional processes before and after nuclei overlapping, respectively, for the composite electropolymerization, which are distinguishable from those of pure PPy electropolymerization before nuclei overlapping.

Electrochemical and Transport Properties of Templated Gold/Polypyrrole-Composite Microtube Membranes

We have been investigating the transport properties of nanotube membranes prepared via the template method. Membranes containing gold (Au) nanotubes prepared by electroless deposition of Au within the pores of commercially available filters have been studied most extensively. The advantage of these membranes is that the inside diameter of the Au nanotubes can be precisely controlled down to molecular dimensions. Currently, we have no other materials synthesis strategy that allows for such precise control over the diameter of the nanotubes obtained. We are interested in developing such chemistries so that nanotubes having any desired inside diameter that are composed of materials other than metals can be prepared. We describe here the electrochemical polymerization of polypyrrole (PPy) microtubes within templated prepared Au microtubes. We demonstrate that the effective inside diameter of the PPy microtubes can be controlled by varying the number of voltammetric scans used during the PPy electropolymerization. The electrochemical characteristics and transport properties of these composite Au/PPy microtube membranes are described here. © 2003 The Electrochemical Society. All rights reserved.