Conventional Conductive Polymers Research Articles

Electrical Stimulation-Mediated Differentiation of Neural Cells on Conductive Carbon Nanofiller-Based Scaffold

An important strategy in neural tissue engineering involves imparting electrical properties to the regenerative template to encourage cell proliferation and differentiation. Several clinical studies have confirmed that direct or indirect electrical stimulation therapy greatly impacts the treatment of peripheral and central nerve injury. Nerve regeneration can be accelerated by the application of electrical stimulations of different methods and with varying parameters. For a long period, electrical stimulation along with conventional conductive polymers have played an important role in nerve tissue regeneration, due to their conductivity. However, the low biocompatibility of these materials has brought attention toward the need for the alternative of the conductive polymers. Carbon nanofillers (graphene, nanotubes, and their derivatives) have been showing promising results in bioimaging, biosensing, and composites, simultaneously, proving themselves as a prospective biomaterial in neural tissue repair and regeneration due to their excellent electrical and mechanical properties, alongside, biocompatibility. Therefore, carbon nanofiller-based scaffolds synchronized with electrical stimulation may lead to a breakthrough in the treatment of nerve injury. This review article focuses on the influence of the electrical properties of carbon-based material on nerve tissue engineering. In this article, we explicitly focus on the different methods to deliver electrical stimulation and the pathways involved in the differentiation of neuronal cells. Emphasis is given to the analysis of the suitable fabrication strategies of carbon-based neural scaffold and the way its interfaces interact with neurons for promoting neuronal differentiation. Furthermore, this review summarizes the ongoing advancements to augment the conductivity and biological activities (cell adhesion, proliferation, neural differentiation, neurite outgrowth), as well as to reduce the potential toxicity in conductive carbon nanofiller-based scaffolds.

Poly(1,5-diaminonaphthalene)-Grafted Monolithic 3D Hierarchical Carbon as Highly Capacitive and Stable Supercapacitor Electrodes.

A holistic approach to fabricate a hierarchical electrode that consists of redox-active poly(1,5-diaminonaphthalene), 1,5 PDAN, uniformly and conformally grafted onto a 3D carbon nanotube (CNT-a-CC) electrode is set forth. The CNT-a-CC electrode was formed by direct growth of high-density CNTs on the surface of every individual microfiber, the constituent of activated carbon cloth (a-CC). Owing to the naphthalene backbone, conformal deposition of 1,5 PDAN on carbon surfaces has been readily attained via electropolymerization. This hierarchical platform with open and continuous nanochannels formed by CNTs coupled with excellent electrical connectivity between CNTs and the polymer provides a reproducible platform for electrochemical investigation. According to multiple sample analyses on CNT-a-CC, the gravimetric capacitance of 1,5 PDAN is up to 1250 F/g, and this value can be maintained up to 100 mV/s. Hierarchical organization provides a specific capacitance of 650 F/g at 2 mV/s at a 1,5 PDAN loading of 2.5 mg/cm2. The conjugated ladder structure of the polymer led to strong π-π interactions between the polymer and CNT-a-CC together with mechanically robust CNT-a-CC. A capacitance retention of 94% for 1,5 PDAN has been obtained after 25,000 cycles at 100 mV/s, a significant cycle stability improvement over conventional conductive polymers such as polyaniline. This new lightweight electrode that seamlessly integrates functional species with nanochannel-like CNT-a-CC opens up a new opportunity to harness electrochemical reactions in the 3D carbon electrode for energy storage and electrocatalysis as well as electrochemical sensing.

Ultraflexible and Mechanically Strong Polymer/Polyaniline Conductive Interpenetrating Nanocomposite via In Situ Polymerization of Vinyl Monomer

Simultaneous enhancement of conductivity and mechanical properties for polyaniline/polymer nanocomposite still remains a big challenge. Here, a reverse approach via in situ polymerization (RIP) of vinyl monomers in waterborne polyaniline dispersion was raised to prepare conductive polyaniline (GPANI)/polyacrylate (PMB) interpenetrating polymer (GPANI-PMB) nanocomposite. GPANI/PMB physical blend was simultaneously prepared as reference. The conductive GPANI-PMB nanocomposite film with compact pomegranate-shape morphology is homogeneous, ultraflexible and mechanically strong. With incorporating a considerable amount of PMB into GPANI via the RIP method, only a slight decrease from 3.21 to 2.80 S/cm was detected for the conductivity of GPANI-PMB, while the tensile strength significantly increased from 25 to 43.5 MPa, and the elongation at break increased from 40% to 234%. The water absorption of GPANI-PMB3 after 72 h immersion decreased from 24.68% to 10.35% in comparison with GPANI, which is also higher than that of GPANI/PMB. The conductivity and tensile strength of GPANI-PMB were also much higher than that of GPANI/PMB (0.006 S/cm vs. 5.59 MPa). Moreover, the conductivity of GPANI-PMB remained almost invariable after folding 200 times, while that of GPANI/PMB decreased by almost half. This RIP approach should be applicable for preparing conventional conductive polymer nanocomposite with high conductivity, high strength and high flexibility.

Boosting the Adhesivity of π-Conjugated Polymers by Embedding Platinum Acetylides towards High-Performance Thermoelectric Composites.

Single-walled carbon nanotubes (SWCNTs) incorporated with π-conjugated polymers, have proven to be an effective approach in the production of advanced thermoelectric composites. However, the studied polymers are mainly limited to scanty conventional conductive polymers, and their performances still remain to be improved. Herein, a new planar moiety of platinum acetylide in the π-conjugated system is introduced to enhance the intermolecular interaction with the SWCNTs via π–π and d–π interactions, which is crucial in regulating the thermoelectric performances of SWCNT-based composites. As expected, SWCNT composites based on the platinum acetylides embedded polymers displayed a higher power factor (130.7 ± 3.8 μW·m−1·K−2) at ambient temperature than those without platinum acetylides (59.5 ± 0.7 μW·m−1·K−2) under the same conditions. Moreover, the strong interactions between the platinum acetylide-based polymers and the SWCNTs are confirmed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) measurements.

Recent Progress in the Development of Conducting Polymer-Based Nanocomposites for Electrochemical Biosensors Applications: A Mini-Review.

Among various immobilizing materials, conductive polymer-based nanocomposites have been widely applied to fabricate the biosensors, because of their outstanding properties such as excellent electrocatalytic activity, high conductivity, and strong adsorptive ability compared to conventional conductive polymers. Electrochemical biosensors have played a significant role in delivering the diagnostic information and therapy monitoring in a rapid, simple, and low cost portable device. This paper reviews the recent developments in conductive polymer-based nanocomposites and their applications in electrochemical biosensors. The article starts with a general and concise comparison between the properties of conducting polymers and conducting polymer nanocomposites. Next, the current applications of conductive polymer-based nanocomposites of some important conducting polymers such as PANI, PPy, and PEDOT in enzymatic and nonenzymatic electrochemical biosensors are overviewed. This review article covers an 8-year period beginning in 2010.

Pulse electrosynthesis of novel wormlike gadolinium oxide nanostructure and its nanocomposite with conjugated electroactive polymer as a hybrid and high efficient electrode material for energy storage device

An effective approach for increasing the life cycle of pure p-type conductive polymers is combining conventional conductive polymers and nanomaterials to fabricate hybrid electrodes. In this paper, Gadolinium oxide (Gd2O3) has first been synthesized using pulse electrochemical approach. Hybrid POAP/Gd2O3 films have then been fabricated by POAP electropolymerization in the presence of Gd2O3 nanoparticles as active electrodes for electrochemical supercapacitors. Surface and electrochemical analyses have been used for characterization of Gd2O3 and POAP/Gd2O3 composite films. Different electrochemical methods including galvanostatic charge discharge experiments, cyclic voltammetry and electrochemical impedance spectroscopy have been applied to study the system performance. Specific capacitance, specific energy and specific power of the composite film are calculated 300F·g−1, 41.66Wh·kg−1 and 833.22W·kg−1 respectively. This work introduces new nanocomposite materials for electrochemical redox capacitors with such advantages as the ease of synthesis, high active surface area and stability in an aqueous electrolyte.

Nanocomposite of p-type conductive polymer/functionalized graphene oxide nanosheets as novel and hybrid electrodes for highly capacitive pseudocapacitors

An effective approach for increasing the life cycle of poly ortho aminophenol (POAP) as a p-type conductive polymers is combining conventional conductive polymers and nanomaterials to fabricate hybrid electrodes. In this paper, functionalized graphene oxide (FGO) has first been synthesized using a chemical approach. Hybrid POAP/FGO films have then been fabricated by POAP electropolymerization in the presence of FGO nanoparticles as active electrodes for electrochemical supercapacitors. Based on the atomic scale study results, it seems that H3PO4− oxygen atoms and terminal pyridine ring nitrogen atoms play a crucial role in the intramolecular charge and energy transfer in the FGO molecular systems. Theoretical studies, surface and electrochemical analyses have been used for characterization of POAP/FGO composite films. Different electrochemical methods including galvanostatic charge discharge experiments, cyclic voltammetry and electrochemical impedance spectroscopy have been applied to study the system performance. This work introduces new nanocomposite materials for electrochemical redox capacitors with such advantages as the ease of synthesis, high active surface area and stability in an aqueous electrolyte.

A simple and innovative route to electrosynthesis of Eu2O3 nanoparticles and its nanocomposite with p-type conductive polymer: Characterisation and electrochemical properties

Conductive polymers are usually used as an electrode in redox supercapacitor. However, due to accumulation of stress on polymer during repeating charge-discharge process, the cycle life of pure conductive polymer is poor, which needs to be further improved. For this purpose, combining conventional conductive polymers active material and nanomaterials to fabricate hybrid electrode has been considered to be one of the efficient avenues. In this paper, a simple and rapid electrochemical method has been carried out to prepare Eu2O3 nanoparticles and hybrid POAP/Eu2O3 to serve as the active electrode for electrochemical supercapacitor. Structural and morphological characterisations of Eu2O3 and composite film were carried out using powder X-ray diffraction, field emission scanning electron microscopy and energy dispersion of X-rays. Their electrochemical properties were also investigated using cyclic voltammetry, galvanostatic charge–discharge and electrochemical impedance spectroscopy. The as-prepared composites had excellent properties in the specific capacitance and a coulombic efficiency of 95%. The as-prepared composites had excellent properties in the capacitance, and its specific capacitance was up to 375Fg−1 and a coulombic efficiency of 95%. This work introduces new nanocomposite materials for electrochemical redox capacitors with advantages including ease synthesis, high active surface area and stability in an aqueous electrolyte.

Ligand Doping on the Hybrid Thermoelectric Materials Based on Terthiophene-Capped Silicon Nanoparticles

Over the past 2 years, silicon nanoparticles (SiNPs) functionalised with conjugated molecules have been shown to have potential as low-temperature thermoelectric materials. One key challenge with such materials relates to the introduction of charge carriers. There are two components of organic/silicon nanocomposite materials in which charge carriers can be introduced: the silicon nanoparticle or the organic ligand. Investigation into the effect of introducing charge carriers on the ligands via oxidation is another step towards understanding and optimising this kind of system. Terthiophene-capped SiNPs have been synthesised and characterised before and after doping. Using different ratios and the oxidant NOBF4 to dope the surface ligands, the electrical conductivity has been measured at ambient temperature. The ratio of oxidant to nanoparticles shows similar trends in electrical resistivity to that of conventional conductive polymers and shows significant improvements over the undoped material.

Carrier Localization Suppression by Multipath Transport in Helical Polyacetylene

The conduction sites in the main chain of helical polyacetylene (HPA) are arranged in a unique helical configuration, whereas conventional conductive polymers such as cis-polyacetylene and trans-polyacetylene have almost collinearly aligned conduction sites. Here we report the distinctive hole transport properties in HPA caused by the helical structure. Analyses of the hole diffusion with different models of the range of transfer integrals (TIs) reveal that the helical configuration produces multiple conduction paths in HPA. The holes propagate through multiple pathways, avoiding local paths with small TIs. This mechanism suppresses the localization of electronic states in HPA, which is inevitable in conventional one-dimensional conductive polymers.

3D nanostructured conductive polymer hydrogels for high-performance electrochemical devices

Conducting polymer hydrogels (CPHs) represent a unique class of materials that synergize the advantageous features of hydrogels and organic conductors and have been used in many applications such as bioelectronics and energy storage devices. This perspective provides a brief overview of current research activities in the field of three-dimensional (3D) nanostructured CPHs for high-performance electrochemical devices. The synthesis methods of conventional conductive polymers (CPs) and hydrogels are outlined with emphasis on newly developed methods for the preparation of 3D nanostructured CPs and CPHs. Following this discussion is an outline of the applications of 3D CPH nanostructures with particular focus on those applications in which nanostructured CPHs are clearly advantageous over their conventional counterparts. Other potential applications of nanostructured CPHs are also discussed in this perspective along with the main challenges and future research directions for this new class of conductive hydrogels.

A new method for extending the range of conductive polymer sensors for contact force

This paper describes a technique for extending the force range of thin conductive polymer force sensors used for measuring contact force. These sensors are conventionally used for measuring force by changing electrical resistance when they are compressed. The new method involves measuring change in electrical resistance when the flexible sensor, which is sensitive to both compression and bending, is sandwiched between two layers of spring steel, and the structure is supported on a thin metal ring. When external force is applied, the stiffened sensor inside the spring steel is deformed within the annular center of the ring, causing the sensor to bend in proportion to the applied force. This method effectively increases the usable force range, while adding little in the way of thickness and weight. Average error for loads between 10 N and 100 N was 2.2 N (SD = 1.7) for a conventional conductive polymer sensor, and 0.9 N (SD = 0.4) using the new approach. Although this method permits measurement of greater loads with an error less than 1 N, it is limited since the modified sensor is insensitive to loads less than 5 N. These modified sensors are nevertheless useful for directly measuring normal force applied against handles and tools and other situations involving forceful manual work activities, such as grasp, push, pull, or press that could not otherwise be measured in actual work situations.

A novel method to prepare high‐resistivity polymer composites

AbstractA novel method was developed for the preparation of high‐resistivity conductive polymer composites reproducibly. The conventional method which involves the simple mixing of a conductive filler and a polymer usually produces a conductive polymer composite having a loading curve with a region in which the resistivity changes rapidly as the filler concentration changes. Hence, it is very difficult to obtain reproducible materials in that region. This newly developed method involves the preparation of a conventional conductive polymer composite, which is prepared by the simple mixing of carbon black and a polymer as the first step. The resulting compound, which is crosslinked by either electron‐beam radiation or a chemical‐crosslinking agent, is ground into a fine powder (composite filler) with the particle size less than 250 microns. The composite filler is mixed with another polymer to form a conductive particulate composite which has a loading curve showing a more gradual change of resistivity as a function of filler concentration. The modification of the loading curve is controlled by the resistivity, the shape, and the size of the composite filler.